summaryrefslogtreecommitdiff
path: root/tools/buildman/kconfiglib.py
blob: c67895ced6b352190c62c2984ce61b65d39dda77 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
6304
6305
6306
6307
6308
6309
6310
6311
6312
6313
6314
6315
6316
6317
6318
6319
6320
6321
6322
6323
6324
6325
6326
6327
6328
6329
6330
6331
6332
6333
6334
6335
6336
6337
6338
6339
6340
6341
6342
6343
6344
6345
6346
6347
6348
6349
6350
6351
6352
6353
6354
6355
6356
6357
6358
6359
6360
6361
6362
6363
6364
6365
6366
6367
6368
6369
6370
6371
6372
6373
6374
6375
6376
6377
6378
6379
6380
6381
6382
6383
6384
6385
6386
6387
6388
6389
6390
6391
6392
6393
6394
6395
6396
6397
6398
6399
6400
6401
6402
6403
6404
6405
6406
6407
6408
6409
6410
6411
6412
6413
6414
6415
6416
6417
6418
6419
6420
6421
6422
6423
6424
6425
6426
6427
6428
6429
6430
6431
6432
6433
6434
6435
6436
6437
6438
6439
6440
6441
6442
6443
6444
6445
6446
6447
6448
6449
6450
6451
6452
6453
6454
6455
6456
6457
6458
6459
6460
6461
6462
6463
6464
6465
6466
6467
6468
6469
6470
6471
6472
6473
6474
6475
6476
6477
6478
6479
6480
6481
6482
6483
6484
6485
6486
6487
6488
6489
6490
6491
6492
6493
6494
6495
6496
6497
6498
6499
6500
6501
6502
6503
6504
6505
6506
6507
6508
6509
6510
6511
6512
6513
6514
6515
6516
6517
6518
6519
6520
6521
6522
6523
6524
6525
6526
6527
6528
6529
6530
6531
6532
6533
6534
6535
6536
6537
6538
6539
6540
6541
6542
6543
6544
6545
6546
6547
6548
6549
6550
6551
6552
6553
6554
6555
6556
6557
6558
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
6600
6601
6602
6603
6604
6605
6606
6607
6608
6609
6610
6611
6612
6613
6614
6615
6616
6617
6618
6619
6620
6621
6622
6623
6624
6625
6626
6627
6628
6629
6630
6631
6632
6633
6634
6635
6636
6637
6638
6639
6640
6641
6642
6643
6644
6645
6646
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
6706
6707
6708
6709
6710
6711
6712
6713
6714
6715
6716
6717
6718
6719
6720
6721
6722
6723
6724
6725
6726
6727
6728
6729
6730
6731
6732
6733
6734
6735
6736
6737
6738
6739
6740
6741
6742
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
6793
6794
6795
6796
6797
6798
6799
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
6828
6829
6830
6831
6832
6833
6834
6835
6836
6837
6838
6839
6840
6841
6842
6843
6844
6845
6846
6847
6848
6849
6850
6851
6852
6853
6854
6855
6856
6857
6858
6859
6860
6861
6862
6863
6864
6865
6866
6867
6868
6869
6870
6871
6872
6873
6874
6875
6876
6877
6878
6879
6880
6881
6882
6883
6884
6885
6886
6887
6888
6889
6890
6891
6892
6893
6894
6895
6896
6897
6898
6899
6900
6901
6902
6903
6904
6905
6906
6907
6908
6909
6910
6911
6912
6913
6914
6915
6916
6917
6918
6919
6920
6921
6922
6923
6924
6925
6926
6927
6928
6929
6930
6931
6932
6933
6934
6935
6936
6937
6938
6939
6940
6941
6942
6943
6944
6945
6946
6947
6948
6949
6950
6951
6952
6953
6954
6955
6956
6957
6958
6959
6960
6961
6962
6963
6964
6965
6966
6967
6968
6969
6970
6971
6972
6973
6974
6975
6976
6977
6978
6979
6980
6981
6982
6983
6984
6985
6986
6987
6988
6989
6990
6991
6992
6993
6994
6995
6996
6997
6998
6999
7000
7001
7002
7003
7004
7005
7006
7007
7008
7009
7010
7011
7012
7013
7014
7015
7016
7017
7018
7019
7020
7021
7022
7023
7024
7025
7026
7027
7028
7029
7030
7031
7032
7033
7034
7035
7036
7037
7038
7039
7040
7041
7042
7043
7044
7045
7046
7047
7048
7049
7050
7051
7052
7053
7054
7055
7056
7057
7058
7059
7060
7061
7062
7063
7064
7065
7066
7067
7068
7069
7070
7071
7072
7073
7074
7075
7076
7077
7078
7079
7080
7081
7082
7083
7084
7085
7086
7087
7088
7089
7090
7091
7092
7093
7094
7095
7096
7097
7098
7099
7100
7101
7102
7103
7104
7105
7106
7107
7108
7109
7110
7111
7112
7113
7114
7115
7116
7117
7118
7119
7120
7121
7122
7123
7124
7125
7126
7127
7128
7129
7130
7131
7132
7133
7134
7135
7136
7137
7138
7139
7140
7141
7142
7143
7144
7145
7146
7147
7148
7149
7150
7151
7152
7153
7154
7155
7156
7157
7158
7159
7160
# Copyright (c) 2011-2019, Ulf Magnusson
# SPDX-License-Identifier: ISC

"""
Overview
========

Kconfiglib is a Python 2/3 library for scripting and extracting information
from Kconfig (https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt)
configuration systems.

See the homepage at https://github.com/ulfalizer/Kconfiglib for a longer
overview.

Since Kconfiglib 12.0.0, the library version is available in
kconfiglib.VERSION, which is a (<major>, <minor>, <patch>) tuple, e.g.
(12, 0, 0).


Using Kconfiglib on the Linux kernel with the Makefile targets
==============================================================

For the Linux kernel, a handy interface is provided by the
scripts/kconfig/Makefile patch, which can be applied with either 'git am' or
the 'patch' utility:

  $ wget -qO- https://raw.githubusercontent.com/ulfalizer/Kconfiglib/master/makefile.patch | git am
  $ wget -qO- https://raw.githubusercontent.com/ulfalizer/Kconfiglib/master/makefile.patch | patch -p1

Warning: Not passing -p1 to patch will cause the wrong file to be patched.

Please tell me if the patch does not apply. It should be trivial to apply
manually, as it's just a block of text that needs to be inserted near the other
*conf: targets in scripts/kconfig/Makefile.

Look further down for a motivation for the Makefile patch and for instructions
on how you can use Kconfiglib without it.

If you do not wish to install Kconfiglib via pip, the Makefile patch is set up
so that you can also just clone Kconfiglib into the kernel root:

  $ git clone git://github.com/ulfalizer/Kconfiglib.git
  $ git am Kconfiglib/makefile.patch  (or 'patch -p1 < Kconfiglib/makefile.patch')

Warning: The directory name Kconfiglib/ is significant in this case, because
it's added to PYTHONPATH by the new targets in makefile.patch.

The targets added by the Makefile patch are described in the following
sections.


make kmenuconfig
----------------

This target runs the curses menuconfig interface with Python 3. As of
Kconfiglib 12.2.0, both Python 2 and Python 3 are supported (previously, only
Python 3 was supported, so this was a backport).


make guiconfig
--------------

This target runs the Tkinter menuconfig interface. Both Python 2 and Python 3
are supported. To change the Python interpreter used, pass
PYTHONCMD=<executable> to 'make'. The default is 'python'.


make [ARCH=<arch>] iscriptconfig
--------------------------------

This target gives an interactive Python prompt where a Kconfig instance has
been preloaded and is available in 'kconf'. To change the Python interpreter
used, pass PYTHONCMD=<executable> to 'make'. The default is 'python'.

To get a feel for the API, try evaluating and printing the symbols in
kconf.defined_syms, and explore the MenuNode menu tree starting at
kconf.top_node by following 'next' and 'list' pointers.

The item contained in a menu node is found in MenuNode.item (note that this can
be one of the constants kconfiglib.MENU and kconfiglib.COMMENT), and all
symbols and choices have a 'nodes' attribute containing their menu nodes
(usually only one). Printing a menu node will print its item, in Kconfig
format.

If you want to look up a symbol by name, use the kconf.syms dictionary.


make scriptconfig SCRIPT=<script> [SCRIPT_ARG=<arg>]
----------------------------------------------------

This target runs the Python script given by the SCRIPT parameter on the
configuration. sys.argv[1] holds the name of the top-level Kconfig file
(currently always "Kconfig" in practice), and sys.argv[2] holds the SCRIPT_ARG
argument, if given.

See the examples/ subdirectory for example scripts.


make dumpvarsconfig
-------------------

This target prints a list of all environment variables referenced from the
Kconfig files, together with their values. See the
Kconfiglib/examples/dumpvars.py script.

Only environment variables that are referenced via the Kconfig preprocessor
$(FOO) syntax are included. The preprocessor was added in Linux 4.18.


Using Kconfiglib without the Makefile targets
=============================================

The make targets are only needed to pick up environment variables exported from
the Kbuild makefiles and referenced inside Kconfig files, via e.g.
'source "arch/$(SRCARCH)/Kconfig" and commands run via '$(shell,...)'.

These variables are referenced as of writing (Linux 4.18), together with sample
values:

  srctree          (.)
  ARCH             (x86)
  SRCARCH          (x86)
  KERNELVERSION    (4.18.0)
  CC               (gcc)
  HOSTCC           (gcc)
  HOSTCXX          (g++)
  CC_VERSION_TEXT  (gcc (Ubuntu 7.3.0-16ubuntu3) 7.3.0)

Older kernels only reference ARCH, SRCARCH, and KERNELVERSION.

If your kernel is recent enough (4.18+), you can get a list of referenced
environment variables via 'make dumpvarsconfig' (see above). Note that this
command is added by the Makefile patch.

To run Kconfiglib without the Makefile patch, set the environment variables
manually:

  $ srctree=. ARCH=x86 SRCARCH=x86 KERNELVERSION=`make kernelversion` ... python(3)
  >>> import kconfiglib
  >>> kconf = kconfiglib.Kconfig()  # filename defaults to "Kconfig"

Search the top-level Makefile for "Additional ARCH settings" to see other
possibilities for ARCH and SRCARCH.


Intro to symbol values
======================

Kconfiglib has the same assignment semantics as the C implementation.

Any symbol can be assigned a value by the user (via Kconfig.load_config() or
Symbol.set_value()), but this user value is only respected if the symbol is
visible, which corresponds to it (currently) being visible in the menuconfig
interface.

For symbols with prompts, the visibility of the symbol is determined by the
condition on the prompt. Symbols without prompts are never visible, so setting
a user value on them is pointless. A warning will be printed by default if
Symbol.set_value() is called on a promptless symbol. Assignments to promptless
symbols are normal within a .config file, so no similar warning will be printed
by load_config().

Dependencies from parents and 'if'/'depends on' are propagated to properties,
including prompts, so these two configurations are logically equivalent:

(1)

  menu "menu"
      depends on A

  if B

  config FOO
      tristate "foo" if D
      default y
      depends on C

  endif

  endmenu

(2)

  menu "menu"
      depends on A

  config FOO
      tristate "foo" if A && B && C && D
      default y if A && B && C

  endmenu

In this example, A && B && C && D (the prompt condition) needs to be non-n for
FOO to be visible (assignable). If its value is m, the symbol can only be
assigned the value m: The visibility sets an upper bound on the value that can
be assigned by the user, and any higher user value will be truncated down.

'default' properties are independent of the visibility, though a 'default' will
often get the same condition as the prompt due to dependency propagation.
'default' properties are used if the symbol is not visible or has no user
value.

Symbols with no user value (or that have a user value but are not visible) and
no (active) 'default' default to n for bool/tristate symbols, and to the empty
string for other symbol types.

'select' works similarly to symbol visibility, but sets a lower bound on the
value of the symbol. The lower bound is determined by the value of the
select*ing* symbol. 'select' does not respect visibility, so non-visible
symbols can be forced to a particular (minimum) value by a select as well.

For non-bool/tristate symbols, it only matters whether the visibility is n or
non-n: m visibility acts the same as y visibility.

Conditions on 'default' and 'select' work in mostly intuitive ways. If the
condition is n, the 'default' or 'select' is disabled. If it is m, the
'default' or 'select' value (the value of the selecting symbol) is truncated
down to m.

When writing a configuration with Kconfig.write_config(), only symbols that are
visible, have an (active) default, or are selected will get written out (note
that this includes all symbols that would accept user values). Kconfiglib
matches the .config format produced by the C implementations down to the
character. This eases testing.

For a visible bool/tristate symbol FOO with value n, this line is written to
.config:

    # CONFIG_FOO is not set

The point is to remember the user n selection (which might differ from the
default value the symbol would get), while at the same sticking to the rule
that undefined corresponds to n (.config uses Makefile format, making the line
above a comment). When the .config file is read back in, this line will be
treated the same as the following assignment:

    CONFIG_FOO=n

In Kconfiglib, the set of (currently) assignable values for a bool/tristate
symbol appear in Symbol.assignable. For other symbol types, just check if
sym.visibility is non-0 (non-n) to see whether the user value will have an
effect.


Intro to the menu tree
======================

The menu structure, as seen in e.g. menuconfig, is represented by a tree of
MenuNode objects. The top node of the configuration corresponds to an implicit
top-level menu, the title of which is shown at the top in the standard
menuconfig interface. (The title is also available in Kconfig.mainmenu_text in
Kconfiglib.)

The top node is found in Kconfig.top_node. From there, you can visit child menu
nodes by following the 'list' pointer, and any following menu nodes by
following the 'next' pointer. Usually, a non-None 'list' pointer indicates a
menu or Choice, but menu nodes for symbols can sometimes have a non-None 'list'
pointer too due to submenus created implicitly from dependencies.

MenuNode.item is either a Symbol or a Choice object, or one of the constants
MENU and COMMENT. The prompt of the menu node can be found in MenuNode.prompt,
which also holds the title for menus and comments. For Symbol and Choice,
MenuNode.help holds the help text (if any, otherwise None).

Most symbols will only have a single menu node. A symbol defined in multiple
locations will have one menu node for each location. The list of menu nodes for
a Symbol or Choice can be found in the Symbol/Choice.nodes attribute.

Note that prompts and help texts for symbols and choices are stored in their
menu node(s) rather than in the Symbol or Choice objects themselves. This makes
it possible to define a symbol in multiple locations with a different prompt or
help text in each location. To get the help text or prompt for a symbol with a
single menu node, do sym.nodes[0].help and sym.nodes[0].prompt, respectively.
The prompt is a (text, condition) tuple, where condition determines the
visibility (see 'Intro to expressions' below).

This organization mirrors the C implementation. MenuNode is called
'struct menu' there, but I thought "menu" was a confusing name.

It is possible to give a Choice a name and define it in multiple locations,
hence why Choice.nodes is also a list.

As a convenience, the properties added at a particular definition location are
available on the MenuNode itself, in e.g. MenuNode.defaults. This is helpful
when generating documentation, so that symbols/choices defined in multiple
locations can be shown with the correct properties at each location.


Intro to expressions
====================

Expressions can be evaluated with the expr_value() function and printed with
the expr_str() function (these are used internally as well). Evaluating an
expression always yields a tristate value, where n, m, and y are represented as
0, 1, and 2, respectively.

The following table should help you figure out how expressions are represented.
A, B, C, ... are symbols (Symbol instances), NOT is the kconfiglib.NOT
constant, etc.

Expression            Representation
----------            --------------
A                     A
"A"                   A (constant symbol)
!A                    (NOT, A)
A && B                (AND, A, B)
A && B && C           (AND, A, (AND, B, C))
A || B                (OR, A, B)
A || (B && C && D)    (OR, A, (AND, B, (AND, C, D)))
A = B                 (EQUAL, A, B)
A != "foo"            (UNEQUAL, A, foo (constant symbol))
A && B = C && D       (AND, A, (AND, (EQUAL, B, C), D))
n                     Kconfig.n (constant symbol)
m                     Kconfig.m (constant symbol)
y                     Kconfig.y (constant symbol)
"y"                   Kconfig.y (constant symbol)

Strings like "foo" in 'default "foo"' or 'depends on SYM = "foo"' are
represented as constant symbols, so the only values that appear in expressions
are symbols***. This mirrors the C implementation.

***For choice symbols, the parent Choice will appear in expressions as well,
but it's usually invisible as the value interfaces of Symbol and Choice are
identical. This mirrors the C implementation and makes different choice modes
"just work".

Manual evaluation examples:

  - The value of A && B is min(A.tri_value, B.tri_value)

  - The value of A || B is max(A.tri_value, B.tri_value)

  - The value of !A is 2 - A.tri_value

  - The value of A = B is 2 (y) if A.str_value == B.str_value, and 0 (n)
    otherwise. Note that str_value is used here instead of tri_value.

    For constant (as well as undefined) symbols, str_value matches the name of
    the symbol. This mirrors the C implementation and explains why
    'depends on SYM = "foo"' above works as expected.

n/m/y are automatically converted to the corresponding constant symbols
"n"/"m"/"y" (Kconfig.n/m/y) during parsing.

Kconfig.const_syms is a dictionary like Kconfig.syms but for constant symbols.

If a condition is missing (e.g., <cond> when the 'if <cond>' is removed from
'default A if <cond>'), it is actually Kconfig.y. The standard __str__()
functions just avoid printing 'if y' conditions to give cleaner output.


Kconfig extensions
==================

Kconfiglib includes a couple of Kconfig extensions:

'source' with relative path
---------------------------

The 'rsource' statement sources Kconfig files with a path relative to directory
of the Kconfig file containing the 'rsource' statement, instead of relative to
the project root.

Consider following directory tree:

  Project
  +--Kconfig
  |
  +--src
     +--Kconfig
     |
     +--SubSystem1
        +--Kconfig
        |
        +--ModuleA
           +--Kconfig

In this example, assume that src/SubSystem1/Kconfig wants to source
src/SubSystem1/ModuleA/Kconfig.

With 'source', this statement would be used:

  source "src/SubSystem1/ModuleA/Kconfig"

With 'rsource', this turns into

  rsource "ModuleA/Kconfig"

If an absolute path is given to 'rsource', it acts the same as 'source'.

'rsource' can be used to create "position-independent" Kconfig trees that can
be moved around freely.


Globbing 'source'
-----------------

'source' and 'rsource' accept glob patterns, sourcing all matching Kconfig
files. They require at least one matching file, raising a KconfigError
otherwise.

For example, the following statement might source sub1/foofoofoo and
sub2/foobarfoo:

  source "sub[12]/foo*foo"

The glob patterns accepted are the same as for the standard glob.glob()
function.

Two additional statements are provided for cases where it's acceptable for a
pattern to match no files: 'osource' and 'orsource' (the o is for "optional").

For example, the following statements will be no-ops if neither "foo" nor any
files matching "bar*" exist:

  osource "foo"
  osource "bar*"

'orsource' does a relative optional source.

'source' and 'osource' are analogous to 'include' and '-include' in Make.


Generalized def_* keywords
--------------------------

def_int, def_hex, and def_string are available in addition to def_bool and
def_tristate, allowing int, hex, and string symbols to be given a type and a
default at the same time.


Extra optional warnings
-----------------------

Some optional warnings can be controlled via environment variables:

  - KCONFIG_WARN_UNDEF: If set to 'y', warnings will be generated for all
    references to undefined symbols within Kconfig files. The only gotcha is
    that all hex literals must be prefixed with "0x" or "0X", to make it
    possible to distinguish them from symbol references.

    Some projects (e.g. the Linux kernel) use multiple Kconfig trees with many
    shared Kconfig files, leading to some safe undefined symbol references.
    KCONFIG_WARN_UNDEF is useful in projects that only have a single Kconfig
    tree though.

    KCONFIG_STRICT is an older alias for this environment variable, supported
    for backwards compatibility.

  - KCONFIG_WARN_UNDEF_ASSIGN: If set to 'y', warnings will be generated for
    all assignments to undefined symbols within .config files. By default, no
    such warnings are generated.

    This warning can also be enabled/disabled via the Kconfig.warn_assign_undef
    variable.


Preprocessor user functions defined in Python
---------------------------------------------

Preprocessor functions can be defined in Python, which makes it simple to
integrate information from existing Python tools into Kconfig (e.g. to have
Kconfig symbols depend on hardware information stored in some other format).

Putting a Python module named kconfigfunctions(.py) anywhere in sys.path will
cause it to be imported by Kconfiglib (in Kconfig.__init__()). Note that
sys.path can be customized via PYTHONPATH, and includes the directory of the
module being run by default, as well as installation directories.

If the KCONFIG_FUNCTIONS environment variable is set, it gives a different
module name to use instead of 'kconfigfunctions'.

The imported module is expected to define a global dictionary named 'functions'
that maps function names to Python functions, as follows:

  def my_fn(kconf, name, arg_1, arg_2, ...):
      # kconf:
      #   Kconfig instance
      #
      # name:
      #   Name of the user-defined function ("my-fn"). Think argv[0].
      #
      # arg_1, arg_2, ...:
      #   Arguments passed to the function from Kconfig (strings)
      #
      # Returns a string to be substituted as the result of calling the
      # function
      ...

  def my_other_fn(kconf, name, arg_1, arg_2, ...):
      ...

  functions = {
      "my-fn":       (my_fn,       <min.args>, <max.args>/None),
      "my-other-fn": (my_other_fn, <min.args>, <max.args>/None),
      ...
  }

  ...

<min.args> and <max.args> are the minimum and maximum number of arguments
expected by the function (excluding the implicit 'name' argument). If
<max.args> is None, there is no upper limit to the number of arguments. Passing
an invalid number of arguments will generate a KconfigError exception.

Functions can access the current parsing location as kconf.filename/linenr.
Accessing other fields of the Kconfig object is not safe. See the warning
below.

Keep in mind that for a variable defined like 'foo = $(fn)', 'fn' will be
called only when 'foo' is expanded. If 'fn' uses the parsing location and the
intent is to use the location of the assignment, you want 'foo := $(fn)'
instead, which calls the function immediately.

Once defined, user functions can be called from Kconfig in the same way as
other preprocessor functions:

    config FOO
        ...
        depends on $(my-fn,arg1,arg2)

If my_fn() returns "n", this will result in

    config FOO
        ...
        depends on n

Warning
*******

User-defined preprocessor functions are called as they're encountered at parse
time, before all Kconfig files have been processed, and before the menu tree
has been finalized. There are no guarantees that accessing Kconfig symbols or
the menu tree via the 'kconf' parameter will work, and it could potentially
lead to a crash.

Preferably, user-defined functions should be stateless.


Feedback
========

Send bug reports, suggestions, and questions to ulfalizer a.t Google's email
service, or open a ticket on the GitHub page.
"""
import errno
import importlib
import os
import re
import sys

# Get rid of some attribute lookups. These are obvious in context.
from glob import iglob
from os.path import dirname, exists, expandvars, islink, join, realpath


VERSION = (14, 1, 0)


# File layout:
#
# Public classes
# Public functions
# Internal functions
# Global constants

# Line length: 79 columns


#
# Public classes
#


class Kconfig(object):
    """
    Represents a Kconfig configuration, e.g. for x86 or ARM. This is the set of
    symbols, choices, and menu nodes appearing in the configuration. Creating
    any number of Kconfig objects (including for different architectures) is
    safe. Kconfiglib doesn't keep any global state.

    The following attributes are available. They should be treated as
    read-only, and some are implemented through @property magic.

    syms:
      A dictionary with all symbols in the configuration, indexed by name. Also
      includes all symbols that are referenced in expressions but never
      defined, except for constant (quoted) symbols.

      Undefined symbols can be recognized by Symbol.nodes being empty -- see
      the 'Intro to the menu tree' section in the module docstring.

    const_syms:
      A dictionary like 'syms' for constant (quoted) symbols

    named_choices:
      A dictionary like 'syms' for named choices (choice FOO)

    defined_syms:
      A list with all defined symbols, in the same order as they appear in the
      Kconfig files. Symbols defined in multiple locations appear multiple
      times.

      Note: You probably want to use 'unique_defined_syms' instead. This
      attribute is mostly maintained for backwards compatibility.

    unique_defined_syms:
      A list like 'defined_syms', but with duplicates removed. Just the first
      instance is kept for symbols defined in multiple locations. Kconfig order
      is preserved otherwise.

      Using this attribute instead of 'defined_syms' can save work, and
      automatically gives reasonable behavior when writing configuration output
      (symbols defined in multiple locations only generate output once, while
      still preserving Kconfig order for readability).

    choices:
      A list with all choices, in the same order as they appear in the Kconfig
      files.

      Note: You probably want to use 'unique_choices' instead. This attribute
      is mostly maintained for backwards compatibility.

    unique_choices:
      Analogous to 'unique_defined_syms', for choices. Named choices can have
      multiple definition locations.

    menus:
      A list with all menus, in the same order as they appear in the Kconfig
      files

    comments:
      A list with all comments, in the same order as they appear in the Kconfig
      files

    kconfig_filenames:
      A list with the filenames of all Kconfig files included in the
      configuration, relative to $srctree (or relative to the current directory
      if $srctree isn't set), except absolute paths (e.g.
      'source "/foo/Kconfig"') are kept as-is.

      The files are listed in the order they are source'd, starting with the
      top-level Kconfig file. If a file is source'd multiple times, it will
      appear multiple times. Use set() to get unique filenames.

      Note that Kconfig.sync_deps() already indirectly catches any file
      modifications that change configuration output.

    env_vars:
      A set() with the names of all environment variables referenced in the
      Kconfig files.

      Only environment variables referenced with the preprocessor $(FOO) syntax
      will be registered. The older $FOO syntax is only supported for backwards
      compatibility.

      Also note that $(FOO) won't be registered unless the environment variable
      $FOO is actually set. If it isn't, $(FOO) is an expansion of an unset
      preprocessor variable (which gives the empty string).

      Another gotcha is that environment variables referenced in the values of
      recursively expanded preprocessor variables (those defined with =) will
      only be registered if the variable is actually used (expanded) somewhere.

      The note from the 'kconfig_filenames' documentation applies here too.

    n/m/y:
      The predefined constant symbols n/m/y. Also available in const_syms.

    modules:
      The Symbol instance for the modules symbol. Currently hardcoded to
      MODULES, which is backwards compatible. Kconfiglib will warn if
      'option modules' is set on some other symbol. Tell me if you need proper
      'option modules' support.

      'modules' is never None. If the MODULES symbol is not explicitly defined,
      its tri_value will be 0 (n), as expected.

      A simple way to enable modules is to do 'kconf.modules.set_value(2)'
      (provided the MODULES symbol is defined and visible). Modules are
      disabled by default in the kernel Kconfig files as of writing, though
      nearly all defconfig files enable them (with 'CONFIG_MODULES=y').

    defconfig_list:
      The Symbol instance for the 'option defconfig_list' symbol, or None if no
      defconfig_list symbol exists. The defconfig filename derived from this
      symbol can be found in Kconfig.defconfig_filename.

    defconfig_filename:
      The filename given by the defconfig_list symbol. This is taken from the
      first 'default' with a satisfied condition where the specified file
      exists (can be opened for reading). If a defconfig file foo/defconfig is
      not found and $srctree was set when the Kconfig was created,
      $srctree/foo/defconfig is looked up as well.

      'defconfig_filename' is None if either no defconfig_list symbol exists,
      or if the defconfig_list symbol has no 'default' with a satisfied
      condition that specifies a file that exists.

      Gotcha: scripts/kconfig/Makefile might pass --defconfig=<defconfig> to
      scripts/kconfig/conf when running e.g. 'make defconfig'. This option
      overrides the defconfig_list symbol, meaning defconfig_filename might not
      always match what 'make defconfig' would use.

    top_node:
      The menu node (see the MenuNode class) of the implicit top-level menu.
      Acts as the root of the menu tree.

    mainmenu_text:
      The prompt (title) of the top menu (top_node). Defaults to "Main menu".
      Can be changed with the 'mainmenu' statement (see kconfig-language.txt).

    variables:
      A dictionary with all preprocessor variables, indexed by name. See the
      Variable class.

    warn:
      Set this variable to True/False to enable/disable warnings. See
      Kconfig.__init__().

      When 'warn' is False, the values of the other warning-related variables
      are ignored.

      This variable as well as the other warn* variables can be read to check
      the current warning settings.

    warn_to_stderr:
      Set this variable to True/False to enable/disable warnings on stderr. See
      Kconfig.__init__().

    warn_assign_undef:
      Set this variable to True to generate warnings for assignments to
      undefined symbols in configuration files.

      This variable is False by default unless the KCONFIG_WARN_UNDEF_ASSIGN
      environment variable was set to 'y' when the Kconfig instance was
      created.

    warn_assign_override:
      Set this variable to True to generate warnings for multiple assignments
      to the same symbol in configuration files, where the assignments set
      different values (e.g. CONFIG_FOO=m followed by CONFIG_FOO=y, where the
      last value would get used).

      This variable is True by default. Disabling it might be useful when
      merging configurations.

    warn_assign_redun:
      Like warn_assign_override, but for multiple assignments setting a symbol
      to the same value.

      This variable is True by default. Disabling it might be useful when
      merging configurations.

    warnings:
      A list of strings containing all warnings that have been generated, for
      cases where more flexibility is needed.

      See the 'warn_to_stderr' parameter to Kconfig.__init__() and the
      Kconfig.warn_to_stderr variable as well. Note that warnings still get
      added to Kconfig.warnings when 'warn_to_stderr' is True.

      Just as for warnings printed to stderr, only warnings that are enabled
      will get added to Kconfig.warnings. See the various Kconfig.warn*
      variables.

    missing_syms:
      A list with (name, value) tuples for all assignments to undefined symbols
      within the most recently loaded .config file(s). 'name' is the symbol
      name without the 'CONFIG_' prefix. 'value' is a string that gives the
      right-hand side of the assignment verbatim.

      See Kconfig.load_config() as well.

    srctree:
      The value the $srctree environment variable had when the Kconfig instance
      was created, or the empty string if $srctree wasn't set. This gives nice
      behavior with os.path.join(), which treats "" as the current directory,
      without adding "./".

      Kconfig files are looked up relative to $srctree (unless absolute paths
      are used), and .config files are looked up relative to $srctree if they
      are not found in the current directory. This is used to support
      out-of-tree builds. The C tools use this environment variable in the same
      way.

      Changing $srctree after creating the Kconfig instance has no effect. Only
      the value when the configuration is loaded matters. This avoids surprises
      if multiple configurations are loaded with different values for $srctree.

    config_prefix:
      The value the CONFIG_ environment variable had when the Kconfig instance
      was created, or "CONFIG_" if CONFIG_ wasn't set. This is the prefix used
      (and expected) on symbol names in .config files and C headers. Used in
      the same way in the C tools.

    config_header:
      The value the KCONFIG_CONFIG_HEADER environment variable had when the
      Kconfig instance was created, or the empty string if
      KCONFIG_CONFIG_HEADER wasn't set. This string is inserted verbatim at the
      beginning of configuration files. See write_config().

    header_header:
      The value the KCONFIG_AUTOHEADER_HEADER environment variable had when the
      Kconfig instance was created, or the empty string if
      KCONFIG_AUTOHEADER_HEADER wasn't set. This string is inserted verbatim at
      the beginning of header files. See write_autoconf().

    filename/linenr:
      The current parsing location, for use in Python preprocessor functions.
      See the module docstring.
    """
    __slots__ = (
        "_encoding",
        "_functions",
        "_set_match",
        "_srctree_prefix",
        "_unset_match",
        "_warn_assign_no_prompt",
        "choices",
        "comments",
        "config_header",
        "config_prefix",
        "const_syms",
        "defconfig_list",
        "defined_syms",
        "env_vars",
        "header_header",
        "kconfig_filenames",
        "m",
        "menus",
        "missing_syms",
        "modules",
        "n",
        "named_choices",
        "srctree",
        "syms",
        "top_node",
        "unique_choices",
        "unique_defined_syms",
        "variables",
        "warn",
        "warn_assign_override",
        "warn_assign_redun",
        "warn_assign_undef",
        "warn_to_stderr",
        "warnings",
        "y",

        # Parsing-related
        "_parsing_kconfigs",
        "_readline",
        "filename",
        "linenr",
        "_include_path",
        "_filestack",
        "_line",
        "_tokens",
        "_tokens_i",
        "_reuse_tokens",
    )

    #
    # Public interface
    #

    def __init__(self, filename="Kconfig", warn=True, warn_to_stderr=True,
                 encoding="utf-8", suppress_traceback=False):
        """
        Creates a new Kconfig object by parsing Kconfig files.
        Note that Kconfig files are not the same as .config files (which store
        configuration symbol values).

        See the module docstring for some environment variables that influence
        default warning settings (KCONFIG_WARN_UNDEF and
        KCONFIG_WARN_UNDEF_ASSIGN).

        Raises KconfigError on syntax/semantic errors, and OSError or (possibly
        a subclass of) IOError on IO errors ('errno', 'strerror', and
        'filename' are available). Note that IOError is an alias for OSError on
        Python 3, so it's enough to catch OSError there. If you need Python 2/3
        compatibility, it's easiest to catch EnvironmentError, which is a
        common base class of OSError/IOError on Python 2 and an alias for
        OSError on Python 3.

        filename (default: "Kconfig"):
          The Kconfig file to load. For the Linux kernel, you'll want "Kconfig"
          from the top-level directory, as environment variables will make sure
          the right Kconfig is included from there (arch/$SRCARCH/Kconfig as of
          writing).

          If $srctree is set, 'filename' will be looked up relative to it.
          $srctree is also used to look up source'd files within Kconfig files.
          See the class documentation.

          If you are using Kconfiglib via 'make scriptconfig', the filename of
          the base base Kconfig file will be in sys.argv[1]. It's currently
          always "Kconfig" in practice.

        warn (default: True):
          True if warnings related to this configuration should be generated.
          This can be changed later by setting Kconfig.warn to True/False. It
          is provided as a constructor argument since warnings might be
          generated during parsing.

          See the other Kconfig.warn_* variables as well, which enable or
          suppress certain warnings when warnings are enabled.

          All generated warnings are added to the Kconfig.warnings list. See
          the class documentation.

        warn_to_stderr (default: True):
          True if warnings should be printed to stderr in addition to being
          added to Kconfig.warnings.

          This can be changed later by setting Kconfig.warn_to_stderr to
          True/False.

        encoding (default: "utf-8"):
          The encoding to use when reading and writing files, and when decoding
          output from commands run via $(shell). If None, the encoding
          specified in the current locale will be used.

          The "utf-8" default avoids exceptions on systems that are configured
          to use the C locale, which implies an ASCII encoding.

          This parameter has no effect on Python 2, due to implementation
          issues (regular strings turning into Unicode strings, which are
          distinct in Python 2). Python 2 doesn't decode regular strings
          anyway.

          Related PEP: https://www.python.org/dev/peps/pep-0538/

        suppress_traceback (default: False):
          Helper for tools. When True, any EnvironmentError or KconfigError
          generated during parsing is caught, the exception message is printed
          to stderr together with the command name, and sys.exit(1) is called
          (which generates SystemExit).

          This hides the Python traceback for "expected" errors like syntax
          errors in Kconfig files.

          Other exceptions besides EnvironmentError and KconfigError are still
          propagated when suppress_traceback is True.
        """
        try:
            self._init(filename, warn, warn_to_stderr, encoding)
        except (EnvironmentError, KconfigError) as e:
            if suppress_traceback:
                cmd = sys.argv[0]  # Empty string if missing
                if cmd:
                    cmd += ": "
                # Some long exception messages have extra newlines for better
                # formatting when reported as an unhandled exception. Strip
                # them here.
                sys.exit(cmd + str(e).strip())
            raise

    def _init(self, filename, warn, warn_to_stderr, encoding):
        # See __init__()

        self._encoding = encoding

        self.srctree = os.getenv("srctree", "")
        # A prefix we can reliably strip from glob() results to get a filename
        # relative to $srctree. relpath() can cause issues for symlinks,
        # because it assumes symlink/../foo is the same as foo/.
        self._srctree_prefix = realpath(self.srctree) + os.sep

        self.warn = warn
        self.warn_to_stderr = warn_to_stderr
        self.warn_assign_undef = os.getenv("KCONFIG_WARN_UNDEF_ASSIGN") == "y"
        self.warn_assign_override = True
        self.warn_assign_redun = True
        self._warn_assign_no_prompt = True

        self.warnings = []

        self.config_prefix = os.getenv("CONFIG_", "CONFIG_")
        # Regular expressions for parsing .config files
        self._set_match = _re_match(self.config_prefix + r"([^=]+)=(.*)")
        self._unset_match = _re_match(r"# {}([^ ]+) is not set".format(
            self.config_prefix))

        self.config_header = os.getenv("KCONFIG_CONFIG_HEADER", "")
        self.header_header = os.getenv("KCONFIG_AUTOHEADER_HEADER", "")

        self.syms = {}
        self.const_syms = {}
        self.defined_syms = []
        self.missing_syms = []
        self.named_choices = {}
        self.choices = []
        self.menus = []
        self.comments = []

        for nmy in "n", "m", "y":
            sym = Symbol()
            sym.kconfig = self
            sym.name = nmy
            sym.is_constant = True
            sym.orig_type = TRISTATE
            sym._cached_tri_val = STR_TO_TRI[nmy]

            self.const_syms[nmy] = sym

        self.n = self.const_syms["n"]
        self.m = self.const_syms["m"]
        self.y = self.const_syms["y"]

        # Make n/m/y well-formed symbols
        for nmy in "n", "m", "y":
            sym = self.const_syms[nmy]
            sym.rev_dep = sym.weak_rev_dep = sym.direct_dep = self.n

        # Maps preprocessor variables names to Variable instances
        self.variables = {}

        # Predefined preprocessor functions, with min/max number of arguments
        self._functions = {
            "info":       (_info_fn,       1, 1),
            "error-if":   (_error_if_fn,   2, 2),
            "filename":   (_filename_fn,   0, 0),
            "lineno":     (_lineno_fn,     0, 0),
            "shell":      (_shell_fn,      1, 1),
            "warning-if": (_warning_if_fn, 2, 2),
        }

        # Add any user-defined preprocessor functions
        try:
            self._functions.update(
                importlib.import_module(
                    os.getenv("KCONFIG_FUNCTIONS", "kconfigfunctions")
                ).functions)
        except ImportError:
            pass

        # This determines whether previously unseen symbols are registered.
        # They shouldn't be if we parse expressions after parsing, as part of
        # Kconfig.eval_string().
        self._parsing_kconfigs = True

        self.modules = self._lookup_sym("MODULES")
        self.defconfig_list = None

        self.top_node = MenuNode()
        self.top_node.kconfig = self
        self.top_node.item = MENU
        self.top_node.is_menuconfig = True
        self.top_node.visibility = self.y
        self.top_node.prompt = ("Main menu", self.y)
        self.top_node.parent = None
        self.top_node.dep = self.y
        self.top_node.filename = filename
        self.top_node.linenr = 1
        self.top_node.include_path = ()

        # Parse the Kconfig files

        # Not used internally. Provided as a convenience.
        self.kconfig_filenames = [filename]
        self.env_vars = set()

        # Keeps track of the location in the parent Kconfig files. Kconfig
        # files usually source other Kconfig files. See _enter_file().
        self._filestack = []
        self._include_path = ()

        # The current parsing location
        self.filename = filename
        self.linenr = 0

        # Used to avoid retokenizing lines when we discover that they're not
        # part of the construct currently being parsed. This is kinda like an
        # unget operation.
        self._reuse_tokens = False

        # Open the top-level Kconfig file. Store the readline() method directly
        # as a small optimization.
        self._readline = self._open(join(self.srctree, filename), "r").readline

        try:
            # Parse the Kconfig files. Returns the last node, which we
            # terminate with '.next = None'.
            self._parse_block(None, self.top_node, self.top_node).next = None
            self.top_node.list = self.top_node.next
            self.top_node.next = None
        except UnicodeDecodeError as e:
            _decoding_error(e, self.filename)

        # Close the top-level Kconfig file. __self__ fetches the 'file' object
        # for the method.
        self._readline.__self__.close()

        self._parsing_kconfigs = False

        # Do various menu tree post-processing
        self._finalize_node(self.top_node, self.y)

        self.unique_defined_syms = _ordered_unique(self.defined_syms)
        self.unique_choices = _ordered_unique(self.choices)

        # Do sanity checks. Some of these depend on everything being finalized.
        self._check_sym_sanity()
        self._check_choice_sanity()

        # KCONFIG_STRICT is an older alias for KCONFIG_WARN_UNDEF, supported
        # for backwards compatibility
        if os.getenv("KCONFIG_WARN_UNDEF") == "y" or \
           os.getenv("KCONFIG_STRICT") == "y":

            self._check_undef_syms()

        # Build Symbol._dependents for all symbols and choices
        self._build_dep()

        # Check for dependency loops
        check_dep_loop_sym = _check_dep_loop_sym  # Micro-optimization
        for sym in self.unique_defined_syms:
            check_dep_loop_sym(sym, False)

        # Add extra dependencies from choices to choice symbols that get
        # awkward during dependency loop detection
        self._add_choice_deps()

    @property
    def mainmenu_text(self):
        """
        See the class documentation.
        """
        return self.top_node.prompt[0]

    @property
    def defconfig_filename(self):
        """
        See the class documentation.
        """
        if self.defconfig_list:
            for filename, cond in self.defconfig_list.defaults:
                if expr_value(cond):
                    try:
                        with self._open_config(filename.str_value) as f:
                            return f.name
                    except EnvironmentError:
                        continue

        return None

    def load_config(self, filename=None, replace=True, verbose=None):
        """
        Loads symbol values from a file in the .config format. Equivalent to
        calling Symbol.set_value() to set each of the values.

        "# CONFIG_FOO is not set" within a .config file sets the user value of
        FOO to n. The C tools work the same way.

        For each symbol, the Symbol.user_value attribute holds the value the
        symbol was assigned in the .config file (if any). The user value might
        differ from Symbol.str/tri_value if there are unsatisfied dependencies.

        Calling this function also updates the Kconfig.missing_syms attribute
        with a list of all assignments to undefined symbols within the
        configuration file. Kconfig.missing_syms is cleared if 'replace' is
        True, and appended to otherwise. See the documentation for
        Kconfig.missing_syms as well.

        See the Kconfig.__init__() docstring for raised exceptions
        (OSError/IOError). KconfigError is never raised here.

        filename (default: None):
          Path to load configuration from (a string). Respects $srctree if set
          (see the class documentation).

          If 'filename' is None (the default), the configuration file to load
          (if any) is calculated automatically, giving the behavior you'd
          usually want:

            1. If the KCONFIG_CONFIG environment variable is set, it gives the
               path to the configuration file to load. Otherwise, ".config" is
               used. See standard_config_filename().

            2. If the path from (1.) doesn't exist, the configuration file
               given by kconf.defconfig_filename is loaded instead, which is
               derived from the 'option defconfig_list' symbol.

            3. If (1.) and (2.) fail to find a configuration file to load, no
               configuration file is loaded, and symbols retain their current
               values (e.g., their default values). This is not an error.

           See the return value as well.

        replace (default: True):
          If True, all existing user values will be cleared before loading the
          .config. Pass False to merge configurations.

        verbose (default: None):
          Limited backwards compatibility to prevent crashes. A warning is
          printed if anything but None is passed.

          Prior to Kconfiglib 12.0.0, this option enabled printing of messages
          to stdout when 'filename' was None. A message is (always) returned
          now instead, which is more flexible.

          Will probably be removed in some future version.

        Returns a string with a message saying which file got loaded (or
        possibly that no file got loaded, when 'filename' is None). This is
        meant to reduce boilerplate in tools, which can do e.g.
        print(kconf.load_config()). The returned message distinguishes between
        loading (replace == True) and merging (replace == False).
        """
        if verbose is not None:
            _warn_verbose_deprecated("load_config")

        msg = None
        if filename is None:
            filename = standard_config_filename()
            if not exists(filename) and \
               not exists(join(self.srctree, filename)):
                defconfig = self.defconfig_filename
                if defconfig is None:
                    return "Using default symbol values (no '{}')" \
                           .format(filename)

                msg = " default configuration '{}' (no '{}')" \
                      .format(defconfig, filename)
                filename = defconfig

        if not msg:
            msg = " configuration '{}'".format(filename)

        # Disable the warning about assigning to symbols without prompts. This
        # is normal and expected within a .config file.
        self._warn_assign_no_prompt = False

        # This stub only exists to make sure _warn_assign_no_prompt gets
        # reenabled
        try:
            self._load_config(filename, replace)
        except UnicodeDecodeError as e:
            _decoding_error(e, filename)
        finally:
            self._warn_assign_no_prompt = True

        return ("Loaded" if replace else "Merged") + msg

    def _load_config(self, filename, replace):
        with self._open_config(filename) as f:
            if replace:
                self.missing_syms = []

                # If we're replacing the configuration, keep track of which
                # symbols and choices got set so that we can unset the rest
                # later. This avoids invalidating everything and is faster.
                # Another benefit is that invalidation must be rock solid for
                # it to work, making it a good test.

                for sym in self.unique_defined_syms:
                    sym._was_set = False

                for choice in self.unique_choices:
                    choice._was_set = False

            # Small optimizations
            set_match = self._set_match
            unset_match = self._unset_match
            get_sym = self.syms.get

            for linenr, line in enumerate(f, 1):
                # The C tools ignore trailing whitespace
                line = line.rstrip()

                match = set_match(line)
                if match:
                    name, val = match.groups()
                    sym = get_sym(name)
                    if not sym or not sym.nodes:
                        self._undef_assign(name, val, filename, linenr)
                        continue

                    if sym.orig_type in _BOOL_TRISTATE:
                        # The C implementation only checks the first character
                        # to the right of '=', for whatever reason
                        if not (sym.orig_type is BOOL
                                and val.startswith(("y", "n")) or
                                sym.orig_type is TRISTATE
                                and val.startswith(("y", "m", "n"))):
                            self._warn("'{}' is not a valid value for the {} "
                                       "symbol {}. Assignment ignored."
                                       .format(val, TYPE_TO_STR[sym.orig_type],
                                               sym.name_and_loc),
                                       filename, linenr)
                            continue

                        val = val[0]

                        if sym.choice and val != "n":
                            # During .config loading, we infer the mode of the
                            # choice from the kind of values that are assigned
                            # to the choice symbols

                            prev_mode = sym.choice.user_value
                            if prev_mode is not None and \
                               TRI_TO_STR[prev_mode] != val:

                                self._warn("both m and y assigned to symbols "
                                           "within the same choice",
                                           filename, linenr)

                            # Set the choice's mode
                            sym.choice.set_value(val)

                    elif sym.orig_type is STRING:
                        match = _conf_string_match(val)
                        if not match:
                            self._warn("malformed string literal in "
                                       "assignment to {}. Assignment ignored."
                                       .format(sym.name_and_loc),
                                       filename, linenr)
                            continue

                        val = unescape(match.group(1))

                else:
                    match = unset_match(line)
                    if not match:
                        # Print a warning for lines that match neither
                        # set_match() nor unset_match() and that are not blank
                        # lines or comments. 'line' has already been
                        # rstrip()'d, so blank lines show up as "" here.
                        if line and not line.lstrip().startswith("#"):
                            self._warn("ignoring malformed line '{}'"
                                       .format(line),
                                       filename, linenr)

                        continue

                    name = match.group(1)
                    sym = get_sym(name)
                    if not sym or not sym.nodes:
                        self._undef_assign(name, "n", filename, linenr)
                        continue

                    if sym.orig_type not in _BOOL_TRISTATE:
                        continue

                    val = "n"

                # Done parsing the assignment. Set the value.

                if sym._was_set:
                    self._assigned_twice(sym, val, filename, linenr)

                sym.set_value(val)

        if replace:
            # If we're replacing the configuration, unset the symbols that
            # didn't get set

            for sym in self.unique_defined_syms:
                if not sym._was_set:
                    sym.unset_value()

            for choice in self.unique_choices:
                if not choice._was_set:
                    choice.unset_value()

    def _undef_assign(self, name, val, filename, linenr):
        # Called for assignments to undefined symbols during .config loading

        self.missing_syms.append((name, val))
        if self.warn_assign_undef:
            self._warn(
                "attempt to assign the value '{}' to the undefined symbol {}"
                .format(val, name), filename, linenr)

    def _assigned_twice(self, sym, new_val, filename, linenr):
        # Called when a symbol is assigned more than once in a .config file

        # Use strings for bool/tristate user values in the warning
        if sym.orig_type in _BOOL_TRISTATE:
            user_val = TRI_TO_STR[sym.user_value]
        else:
            user_val = sym.user_value

        msg = '{} set more than once. Old value "{}", new value "{}".'.format(
            sym.name_and_loc, user_val, new_val)

        if user_val == new_val:
            if self.warn_assign_redun:
                self._warn(msg, filename, linenr)
        elif self.warn_assign_override:
            self._warn(msg, filename, linenr)

    def load_allconfig(self, filename):
        """
        Helper for all*config. Loads (merges) the configuration file specified
        by KCONFIG_ALLCONFIG, if any. See Documentation/kbuild/kconfig.txt in
        the Linux kernel.

        Disables warnings for duplicated assignments within configuration files
        for the duration of the call
        (kconf.warn_assign_override/warn_assign_redun = False), and restores
        the previous warning settings at the end. The KCONFIG_ALLCONFIG
        configuration file is expected to override symbols.

        Exits with sys.exit() (which raises a SystemExit exception) and prints
        an error to stderr if KCONFIG_ALLCONFIG is set but the configuration
        file can't be opened.

        filename:
          Command-specific configuration filename - "allyes.config",
          "allno.config", etc.
        """
        load_allconfig(self, filename)

    def write_autoconf(self, filename=None, header=None):
        r"""
        Writes out symbol values as a C header file, matching the format used
        by include/generated/autoconf.h in the kernel.

        The ordering of the #defines matches the one generated by
        write_config(). The order in the C implementation depends on the hash
        table implementation as of writing, and so won't match.

        If 'filename' exists and its contents is identical to what would get
        written out, it is left untouched. This avoids updating file metadata
        like the modification time and possibly triggering redundant work in
        build tools.

        filename (default: None):
          Path to write header to.

          If None (the default), the path in the environment variable
          KCONFIG_AUTOHEADER is used if set, and "include/generated/autoconf.h"
          otherwise. This is compatible with the C tools.

        header (default: None):
          Text inserted verbatim at the beginning of the file. You would
          usually want it enclosed in '/* */' to make it a C comment, and
          include a trailing newline.

          If None (the default), the value of the environment variable
          KCONFIG_AUTOHEADER_HEADER had when the Kconfig instance was created
          will be used if it was set, and no header otherwise. See the
          Kconfig.header_header attribute.

        Returns a string with a message saying that the header got saved, or
        that there were no changes to it. This is meant to reduce boilerplate
        in tools, which can do e.g. print(kconf.write_autoconf()).
        """
        if filename is None:
            filename = os.getenv("KCONFIG_AUTOHEADER",
                                 "include/generated/autoconf.h")

        if self._write_if_changed(filename, self._autoconf_contents(header)):
            return "Kconfig header saved to '{}'".format(filename)
        return "No change to Kconfig header in '{}'".format(filename)

    def _autoconf_contents(self, header):
        # write_autoconf() helper. Returns the contents to write as a string,
        # with 'header' or KCONFIG_AUTOHEADER_HEADER at the beginning.

        if header is None:
            header = self.header_header

        chunks = [header]  # "".join()ed later
        add = chunks.append

        for sym in self.unique_defined_syms:
            # _write_to_conf is determined when the value is calculated. This
            # is a hidden function call due to property magic.
            #
            # Note: In client code, you can check if sym.config_string is empty
            # instead, to avoid accessing the internal _write_to_conf variable
            # (though it's likely to keep working).
            val = sym.str_value
            if not sym._write_to_conf:
                continue

            if sym.orig_type in _BOOL_TRISTATE:
                if val == "y":
                    add("#define {}{} 1\n"
                        .format(self.config_prefix, sym.name))
                elif val == "m":
                    add("#define {}{}_MODULE 1\n"
                        .format(self.config_prefix, sym.name))

            elif sym.orig_type is STRING:
                add('#define {}{} "{}"\n'
                    .format(self.config_prefix, sym.name, escape(val)))

            else:  # sym.orig_type in _INT_HEX:
                if sym.orig_type is HEX and \
                   not val.startswith(("0x", "0X")):
                    val = "0x" + val

                add("#define {}{} {}\n"
                    .format(self.config_prefix, sym.name, val))

        return "".join(chunks)

    def write_config(self, filename=None, header=None, save_old=True,
                     verbose=None):
        r"""
        Writes out symbol values in the .config format. The format matches the
        C implementation, including ordering.

        Symbols appear in the same order in generated .config files as they do
        in the Kconfig files. For symbols defined in multiple locations, a
        single assignment is written out corresponding to the first location
        where the symbol is defined.

        See the 'Intro to symbol values' section in the module docstring to
        understand which symbols get written out.

        If 'filename' exists and its contents is identical to what would get
        written out, it is left untouched. This avoids updating file metadata
        like the modification time and possibly triggering redundant work in
        build tools.

        See the Kconfig.__init__() docstring for raised exceptions
        (OSError/IOError). KconfigError is never raised here.

        filename (default: None):
          Path to write configuration to (a string).

          If None (the default), the path in the environment variable
          KCONFIG_CONFIG is used if set, and ".config" otherwise. See
          standard_config_filename().

        header (default: None):
          Text inserted verbatim at the beginning of the file. You would
          usually want each line to start with '#' to make it a comment, and
          include a trailing newline.

          if None (the default), the value of the environment variable
          KCONFIG_CONFIG_HEADER had when the Kconfig instance was created will
          be used if it was set, and no header otherwise. See the
          Kconfig.config_header attribute.

        save_old (default: True):
          If True and <filename> already exists, a copy of it will be saved to
          <filename>.old in the same directory before the new configuration is
          written.

          Errors are silently ignored if <filename>.old cannot be written (e.g.
          due to being a directory, or <filename> being something like
          /dev/null).

        verbose (default: None):
          Limited backwards compatibility to prevent crashes. A warning is
          printed if anything but None is passed.

          Prior to Kconfiglib 12.0.0, this option enabled printing of messages
          to stdout when 'filename' was None. A message is (always) returned
          now instead, which is more flexible.

          Will probably be removed in some future version.

        Returns a string with a message saying which file got saved. This is
        meant to reduce boilerplate in tools, which can do e.g.
        print(kconf.write_config()).
        """
        if verbose is not None:
            _warn_verbose_deprecated("write_config")

        if filename is None:
            filename = standard_config_filename()

        contents = self._config_contents(header)
        if self._contents_eq(filename, contents):
            return "No change to configuration in '{}'".format(filename)

        if save_old:
            _save_old(filename)

        with self._open(filename, "w") as f:
            f.write(contents)

        return "Configuration saved to '{}'".format(filename)

    def _config_contents(self, header):
        # write_config() helper. Returns the contents to write as a string,
        # with 'header' or KCONFIG_CONFIG_HEADER at the beginning.
        #
        # More memory friendly would be to 'yield' the strings and
        # "".join(_config_contents()), but it was a bit slower on my system.

        # node_iter() was used here before commit 3aea9f7 ("Add '# end of
        # <menu>' after menus in .config"). Those comments get tricky to
        # implement with it.

        for sym in self.unique_defined_syms:
            sym._visited = False

        if header is None:
            header = self.config_header

        chunks = [header]  # "".join()ed later
        add = chunks.append

        # Did we just print an '# end of ...' comment?
        after_end_comment = False

        node = self.top_node
        while 1:
            # Jump to the next node with an iterative tree walk
            if node.list:
                node = node.list
            elif node.next:
                node = node.next
            else:
                while node.parent:
                    node = node.parent

                    # Add a comment when leaving visible menus
                    if node.item is MENU and expr_value(node.dep) and \
                       expr_value(node.visibility) and \
                       node is not self.top_node:
                        add("# end of {}\n".format(node.prompt[0]))
                        after_end_comment = True

                    if node.next:
                        node = node.next
                        break
                else:
                    # No more nodes
                    return "".join(chunks)

            # Generate configuration output for the node

            item = node.item

            if item.__class__ is Symbol:
                if item._visited:
                    continue
                item._visited = True

                conf_string = item.config_string
                if not conf_string:
                    continue

                if after_end_comment:
                    # Add a blank line before the first symbol printed after an
                    # '# end of ...' comment
                    after_end_comment = False
                    add("\n")
                add(conf_string)

            elif expr_value(node.dep) and \
                 ((item is MENU and expr_value(node.visibility)) or
                  item is COMMENT):

                add("\n#\n# {}\n#\n".format(node.prompt[0]))
                after_end_comment = False

    def write_min_config(self, filename, header=None):
        """
        Writes out a "minimal" configuration file, omitting symbols whose value
        matches their default value. The format matches the one produced by
        'make savedefconfig'.

        The resulting configuration file is incomplete, but a complete
        configuration can be derived from it by loading it. Minimal
        configuration files can serve as a more manageable configuration format
        compared to a "full" .config file, especially when configurations files
        are merged or edited by hand.

        See the Kconfig.__init__() docstring for raised exceptions
        (OSError/IOError). KconfigError is never raised here.

        filename:
          Path to write minimal configuration to.

        header (default: None):
          Text inserted verbatim at the beginning of the file. You would
          usually want each line to start with '#' to make it a comment, and
          include a final terminating newline.

          if None (the default), the value of the environment variable
          KCONFIG_CONFIG_HEADER had when the Kconfig instance was created will
          be used if it was set, and no header otherwise. See the
          Kconfig.config_header attribute.

        Returns a string with a message saying the minimal configuration got
        saved, or that there were no changes to it. This is meant to reduce
        boilerplate in tools, which can do e.g.
        print(kconf.write_min_config()).
        """
        if self._write_if_changed(filename, self._min_config_contents(header)):
            return "Minimal configuration saved to '{}'".format(filename)
        return "No change to minimal configuration in '{}'".format(filename)

    def _min_config_contents(self, header):
        # write_min_config() helper. Returns the contents to write as a string,
        # with 'header' or KCONFIG_CONFIG_HEADER at the beginning.

        if header is None:
            header = self.config_header

        chunks = [header]  # "".join()ed later
        add = chunks.append

        for sym in self.unique_defined_syms:
            # Skip symbols that cannot be changed. Only check
            # non-choice symbols, as selects don't affect choice
            # symbols.
            if not sym.choice and \
               sym.visibility <= expr_value(sym.rev_dep):
                continue

            # Skip symbols whose value matches their default
            if sym.str_value == sym._str_default():
                continue

            # Skip symbols that would be selected by default in a
            # choice, unless the choice is optional or the symbol type
            # isn't bool (it might be possible to set the choice mode
            # to n or the symbol to m in those cases).
            if sym.choice and \
               not sym.choice.is_optional and \
               sym.choice._selection_from_defaults() is sym and \
               sym.orig_type is BOOL and \
               sym.tri_value == 2:
                continue

            add(sym.config_string)

        return "".join(chunks)

    def sync_deps(self, path):
        """
        Creates or updates a directory structure that can be used to avoid
        doing a full rebuild whenever the configuration is changed, mirroring
        include/config/ in the kernel.

        This function is intended to be called during each build, before
        compiling source files that depend on configuration symbols.

        See the Kconfig.__init__() docstring for raised exceptions
        (OSError/IOError). KconfigError is never raised here.

        path:
          Path to directory

        sync_deps(path) does the following:

          1. If the directory <path> does not exist, it is created.

          2. If <path>/auto.conf exists, old symbol values are loaded from it,
             which are then compared against the current symbol values. If a
             symbol has changed value (would generate different output in
             autoconf.h compared to before), the change is signaled by
             touch'ing a file corresponding to the symbol.

             The first time sync_deps() is run on a directory, <path>/auto.conf
             won't exist, and no old symbol values will be available. This
             logically has the same effect as updating the entire
             configuration.

             The path to a symbol's file is calculated from the symbol's name
             by replacing all '_' with '/' and appending '.h'. For example, the
             symbol FOO_BAR_BAZ gets the file <path>/foo/bar/baz.h, and FOO
             gets the file <path>/foo.h.

             This scheme matches the C tools. The point is to avoid having a
             single directory with a huge number of files, which the underlying
             filesystem might not handle well.

          3. A new auto.conf with the current symbol values is written, to keep
             track of them for the next build.

             If auto.conf exists and its contents is identical to what would
             get written out, it is left untouched. This avoids updating file
             metadata like the modification time and possibly triggering
             redundant work in build tools.


        The last piece of the puzzle is knowing what symbols each source file
        depends on. Knowing that, dependencies can be added from source files
        to the files corresponding to the symbols they depends on. The source
        file will then get recompiled (only) when the symbol value changes
        (provided sync_deps() is run first during each build).

        The tool in the kernel that extracts symbol dependencies from source
        files is scripts/basic/fixdep.c. Missing symbol files also correspond
        to "not changed", which fixdep deals with by using the $(wildcard) Make
        function when adding symbol prerequisites to source files.

        In case you need a different scheme for your project, the sync_deps()
        implementation can be used as a template.
        """
        if not exists(path):
            os.mkdir(path, 0o755)

        # Load old values from auto.conf, if any
        self._load_old_vals(path)

        for sym in self.unique_defined_syms:
            # _write_to_conf is determined when the value is calculated. This
            # is a hidden function call due to property magic.
            #
            # Note: In client code, you can check if sym.config_string is empty
            # instead, to avoid accessing the internal _write_to_conf variable
            # (though it's likely to keep working).
            val = sym.str_value

            # n tristate values do not get written to auto.conf and autoconf.h,
            # making a missing symbol logically equivalent to n

            if sym._write_to_conf:
                if sym._old_val is None and \
                   sym.orig_type in _BOOL_TRISTATE and \
                   val == "n":
                    # No old value (the symbol was missing or n), new value n.
                    # No change.
                    continue

                if val == sym._old_val:
                    # New value matches old. No change.
                    continue

            elif sym._old_val is None:
                # The symbol wouldn't appear in autoconf.h (because
                # _write_to_conf is false), and it wouldn't have appeared in
                # autoconf.h previously either (because it didn't appear in
                # auto.conf). No change.
                continue

            # 'sym' has a new value. Flag it.
            _touch_dep_file(path, sym.name)

        # Remember the current values as the "new old" values.
        #
        # This call could go anywhere after the call to _load_old_vals(), but
        # putting it last means _sync_deps() can be safely rerun if it fails
        # before this point.
        self._write_old_vals(path)

    def _load_old_vals(self, path):
        # Loads old symbol values from auto.conf into a dedicated
        # Symbol._old_val field. Mirrors load_config().
        #
        # The extra field could be avoided with some trickery involving dumping
        # symbol values and restoring them later, but this is simpler and
        # faster. The C tools also use a dedicated field for this purpose.

        for sym in self.unique_defined_syms:
            sym._old_val = None

        try:
            auto_conf = self._open(join(path, "auto.conf"), "r")
        except EnvironmentError as e:
            if e.errno == errno.ENOENT:
                # No old values
                return
            raise

        with auto_conf as f:
            for line in f:
                match = self._set_match(line)
                if not match:
                    # We only expect CONFIG_FOO=... (and possibly a header
                    # comment) in auto.conf
                    continue

                name, val = match.groups()
                if name in self.syms:
                    sym = self.syms[name]

                    if sym.orig_type is STRING:
                        match = _conf_string_match(val)
                        if not match:
                            continue
                        val = unescape(match.group(1))

                    self.syms[name]._old_val = val
                else:
                    # Flag that the symbol no longer exists, in
                    # case something still depends on it
                    _touch_dep_file(path, name)

    def _write_old_vals(self, path):
        # Helper for writing auto.conf. Basically just a simplified
        # write_config() that doesn't write any comments (including
        # '# CONFIG_FOO is not set' comments). The format matches the C
        # implementation, though the ordering is arbitrary there (depends on
        # the hash table implementation).
        #
        # A separate helper function is neater than complicating write_config()
        # by passing a flag to it, plus we only need to look at symbols here.

        self._write_if_changed(
            os.path.join(path, "auto.conf"),
            self._old_vals_contents())

    def _old_vals_contents(self):
        # _write_old_vals() helper. Returns the contents to write as a string.

        # Temporary list instead of generator makes this a bit faster
        return "".join([
            sym.config_string for sym in self.unique_defined_syms
                if not (sym.orig_type in _BOOL_TRISTATE and not sym.tri_value)
        ])

    def node_iter(self, unique_syms=False):
        """
        Returns a generator for iterating through all MenuNode's in the Kconfig
        tree. The iteration is done in Kconfig definition order (each node is
        visited before its children, and the children of a node are visited
        before the next node).

        The Kconfig.top_node menu node is skipped. It contains an implicit menu
        that holds the top-level items.

        As an example, the following code will produce a list equal to
        Kconfig.defined_syms:

          defined_syms = [node.item for node in kconf.node_iter()
                          if isinstance(node.item, Symbol)]

        unique_syms (default: False):
          If True, only the first MenuNode will be included for symbols defined
          in multiple locations.

          Using kconf.node_iter(True) in the example above would give a list
          equal to unique_defined_syms.
        """
        if unique_syms:
            for sym in self.unique_defined_syms:
                sym._visited = False

        node = self.top_node
        while 1:
            # Jump to the next node with an iterative tree walk
            if node.list:
                node = node.list
            elif node.next:
                node = node.next
            else:
                while node.parent:
                    node = node.parent
                    if node.next:
                        node = node.next
                        break
                else:
                    # No more nodes
                    return

            if unique_syms and node.item.__class__ is Symbol:
                if node.item._visited:
                    continue
                node.item._visited = True

            yield node

    def eval_string(self, s):
        """
        Returns the tristate value of the expression 's', represented as 0, 1,
        and 2 for n, m, and y, respectively. Raises KconfigError on syntax
        errors. Warns if undefined symbols are referenced.

        As an example, if FOO and BAR are tristate symbols at least one of
        which has the value y, then eval_string("y && (FOO || BAR)") returns
        2 (y).

        To get the string value of non-bool/tristate symbols, use
        Symbol.str_value. eval_string() always returns a tristate value, and
        all non-bool/tristate symbols have the tristate value 0 (n).

        The expression parsing is consistent with how parsing works for
        conditional ('if ...') expressions in the configuration, and matches
        the C implementation. m is rewritten to 'm && MODULES', so
        eval_string("m") will return 0 (n) unless modules are enabled.
        """
        # The parser is optimized to be fast when parsing Kconfig files (where
        # an expression can never appear at the beginning of a line). We have
        # to monkey-patch things a bit here to reuse it.

        self.filename = None

        self._tokens = self._tokenize("if " + s)
        # Strip "if " to avoid giving confusing error messages
        self._line = s
        self._tokens_i = 1  # Skip the 'if' token

        return expr_value(self._expect_expr_and_eol())

    def unset_values(self):
        """
        Removes any user values from all symbols, as if Kconfig.load_config()
        or Symbol.set_value() had never been called.
        """
        self._warn_assign_no_prompt = False
        try:
            # set_value() already rejects undefined symbols, and they don't
            # need to be invalidated (because their value never changes), so we
            # can just iterate over defined symbols
            for sym in self.unique_defined_syms:
                sym.unset_value()

            for choice in self.unique_choices:
                choice.unset_value()
        finally:
            self._warn_assign_no_prompt = True

    def enable_warnings(self):
        """
        Do 'Kconfig.warn = True' instead. Maintained for backwards
        compatibility.
        """
        self.warn = True

    def disable_warnings(self):
        """
        Do 'Kconfig.warn = False' instead. Maintained for backwards
        compatibility.
        """
        self.warn = False

    def enable_stderr_warnings(self):
        """
        Do 'Kconfig.warn_to_stderr = True' instead. Maintained for backwards
        compatibility.
        """
        self.warn_to_stderr = True

    def disable_stderr_warnings(self):
        """
        Do 'Kconfig.warn_to_stderr = False' instead. Maintained for backwards
        compatibility.
        """
        self.warn_to_stderr = False

    def enable_undef_warnings(self):
        """
        Do 'Kconfig.warn_assign_undef = True' instead. Maintained for backwards
        compatibility.
        """
        self.warn_assign_undef = True

    def disable_undef_warnings(self):
        """
        Do 'Kconfig.warn_assign_undef = False' instead. Maintained for
        backwards compatibility.
        """
        self.warn_assign_undef = False

    def enable_override_warnings(self):
        """
        Do 'Kconfig.warn_assign_override = True' instead. Maintained for
        backwards compatibility.
        """
        self.warn_assign_override = True

    def disable_override_warnings(self):
        """
        Do 'Kconfig.warn_assign_override = False' instead. Maintained for
        backwards compatibility.
        """
        self.warn_assign_override = False

    def enable_redun_warnings(self):
        """
        Do 'Kconfig.warn_assign_redun = True' instead. Maintained for backwards
        compatibility.
        """
        self.warn_assign_redun = True

    def disable_redun_warnings(self):
        """
        Do 'Kconfig.warn_assign_redun = False' instead. Maintained for
        backwards compatibility.
        """
        self.warn_assign_redun = False

    def __repr__(self):
        """
        Returns a string with information about the Kconfig object when it is
        evaluated on e.g. the interactive Python prompt.
        """
        def status(flag):
            return "enabled" if flag else "disabled"

        return "<{}>".format(", ".join((
            "configuration with {} symbols".format(len(self.syms)),
            'main menu prompt "{}"'.format(self.mainmenu_text),
            "srctree is current directory" if not self.srctree else
                'srctree "{}"'.format(self.srctree),
            'config symbol prefix "{}"'.format(self.config_prefix),
            "warnings " + status(self.warn),
            "printing of warnings to stderr " + status(self.warn_to_stderr),
            "undef. symbol assignment warnings " +
                status(self.warn_assign_undef),
            "overriding symbol assignment warnings " +
                status(self.warn_assign_override),
            "redundant symbol assignment warnings " +
                status(self.warn_assign_redun)
        )))

    #
    # Private methods
    #


    #
    # File reading
    #

    def _open_config(self, filename):
        # Opens a .config file. First tries to open 'filename', then
        # '$srctree/filename' if $srctree was set when the configuration was
        # loaded.

        try:
            return self._open(filename, "r")
        except EnvironmentError as e:
            # This will try opening the same file twice if $srctree is unset,
            # but it's not a big deal
            try:
                return self._open(join(self.srctree, filename), "r")
            except EnvironmentError as e2:
                # This is needed for Python 3, because e2 is deleted after
                # the try block:
                #
                # https://docs.python.org/3/reference/compound_stmts.html#the-try-statement
                e = e2

            raise _KconfigIOError(
                e, "Could not open '{}' ({}: {}). Check that the $srctree "
                   "environment variable ({}) is set correctly."
                   .format(filename, errno.errorcode[e.errno], e.strerror,
                           "set to '{}'".format(self.srctree) if self.srctree
                               else "unset or blank"))

    def _enter_file(self, filename):
        # Jumps to the beginning of a sourced Kconfig file, saving the previous
        # position and file object.
        #
        # filename:
        #   Absolute path to file

        # Path relative to $srctree, stored in e.g. self.filename (which makes
        # it indirectly show up in MenuNode.filename). Equals 'filename' for
        # absolute paths passed to 'source'.
        if filename.startswith(self._srctree_prefix):
            # Relative path (or a redundant absolute path to within $srctree,
            # but it's probably fine to reduce those too)
            rel_filename = filename[len(self._srctree_prefix):]
        else:
            # Absolute path
            rel_filename = filename

        self.kconfig_filenames.append(rel_filename)

        # The parent Kconfig files are represented as a list of
        # (<include path>, <Python 'file' object for Kconfig file>) tuples.
        #
        # <include path> is immutable and holds a *tuple* of
        # (<filename>, <linenr>) tuples, giving the locations of the 'source'
        # statements in the parent Kconfig files. The current include path is
        # also available in Kconfig._include_path.
        #
        # The point of this redundant setup is to allow Kconfig._include_path
        # to be assigned directly to MenuNode.include_path without having to
        # copy it, sharing it wherever possible.

        # Save include path and 'file' object (via its 'readline' function)
        # before entering the file
        self._filestack.append((self._include_path, self._readline))

        # _include_path is a tuple, so this rebinds the variable instead of
        # doing in-place modification
        self._include_path += ((self.filename, self.linenr),)

        # Check for recursive 'source'
        for name, _ in self._include_path:
            if name == rel_filename:
                raise KconfigError(
                    "\n{}:{}: recursive 'source' of '{}' detected. Check that "
                    "environment variables are set correctly.\n"
                    "Include path:\n{}"
                    .format(self.filename, self.linenr, rel_filename,
                            "\n".join("{}:{}".format(name, linenr)
                                      for name, linenr in self._include_path)))

        try:
            self._readline = self._open(filename, "r").readline
        except EnvironmentError as e:
            # We already know that the file exists
            raise _KconfigIOError(
                e, "{}:{}: Could not open '{}' (in '{}') ({}: {})"
                   .format(self.filename, self.linenr, filename,
                           self._line.strip(),
                           errno.errorcode[e.errno], e.strerror))

        self.filename = rel_filename
        self.linenr = 0

    def _leave_file(self):
        # Returns from a Kconfig file to the file that sourced it. See
        # _enter_file().

        # Restore location from parent Kconfig file
        self.filename, self.linenr = self._include_path[-1]
        # Restore include path and 'file' object
        self._readline.__self__.close()  # __self__ fetches the 'file' object
        self._include_path, self._readline = self._filestack.pop()

    def _next_line(self):
        # Fetches and tokenizes the next line from the current Kconfig file.
        # Returns False at EOF and True otherwise.

        # We might already have tokens from parsing a line and discovering that
        # it's part of a different construct
        if self._reuse_tokens:
            self._reuse_tokens = False
            # self._tokens_i is known to be 1 here, because _parse_props()
            # leaves it like that when it can't recognize a line (or parses a
            # help text)
            return True

        # readline() returns '' over and over at EOF, which we rely on for help
        # texts at the end of files (see _line_after_help())
        line = self._readline()
        if not line:
            return False
        self.linenr += 1

        # Handle line joining
        while line.endswith("\\\n"):
            line = line[:-2] + self._readline()
            self.linenr += 1

        self._tokens = self._tokenize(line)
        # Initialize to 1 instead of 0 to factor out code from _parse_block()
        # and _parse_props(). They immediately fetch self._tokens[0].
        self._tokens_i = 1

        return True

    def _line_after_help(self, line):
        # Tokenizes a line after a help text. This case is special in that the
        # line has already been fetched (to discover that it isn't part of the
        # help text).
        #
        # An earlier version used a _saved_line variable instead that was
        # checked in _next_line(). This special-casing gets rid of it and makes
        # _reuse_tokens alone sufficient to handle unget.

        # Handle line joining
        while line.endswith("\\\n"):
            line = line[:-2] + self._readline()
            self.linenr += 1

        self._tokens = self._tokenize(line)
        self._reuse_tokens = True

    def _write_if_changed(self, filename, contents):
        # Writes 'contents' into 'filename', but only if it differs from the
        # current contents of the file.
        #
        # Another variant would be write a temporary file on the same
        # filesystem, compare the files, and rename() the temporary file if it
        # differs, but it breaks stuff like write_config("/dev/null"), which is
        # used out there to force evaluation-related warnings to be generated.
        # This simple version is pretty failsafe and portable.
        #
        # Returns True if the file has changed and is updated, and False
        # otherwise.

        if self._contents_eq(filename, contents):
            return False
        with self._open(filename, "w") as f:
            f.write(contents)
        return True

    def _contents_eq(self, filename, contents):
        # Returns True if the contents of 'filename' is 'contents' (a string),
        # and False otherwise (including if 'filename' can't be opened/read)

        try:
            with self._open(filename, "r") as f:
                # Robust re. things like encoding and line endings (mmap()
                # trickery isn't)
                return f.read(len(contents) + 1) == contents
        except EnvironmentError:
            # If the error here would prevent writing the file as well, we'll
            # notice it later
            return False

    #
    # Tokenization
    #

    def _lookup_sym(self, name):
        # Fetches the symbol 'name' from the symbol table, creating and
        # registering it if it does not exist. If '_parsing_kconfigs' is False,
        # it means we're in eval_string(), and new symbols won't be registered.

        if name in self.syms:
            return self.syms[name]

        sym = Symbol()
        sym.kconfig = self
        sym.name = name
        sym.is_constant = False
        sym.rev_dep = sym.weak_rev_dep = sym.direct_dep = self.n

        if self._parsing_kconfigs:
            self.syms[name] = sym
        else:
            self._warn("no symbol {} in configuration".format(name))

        return sym

    def _lookup_const_sym(self, name):
        # Like _lookup_sym(), for constant (quoted) symbols

        if name in self.const_syms:
            return self.const_syms[name]

        sym = Symbol()
        sym.kconfig = self
        sym.name = name
        sym.is_constant = True
        sym.rev_dep = sym.weak_rev_dep = sym.direct_dep = self.n

        if self._parsing_kconfigs:
            self.const_syms[name] = sym

        return sym

    def _tokenize(self, s):
        # Parses 's', returning a None-terminated list of tokens. Registers any
        # new symbols encountered with _lookup(_const)_sym().
        #
        # Tries to be reasonably speedy by processing chunks of text via
        # regexes and string operations where possible. This is the biggest
        # hotspot during parsing.
        #
        # It might be possible to rewrite this to 'yield' tokens instead,
        # working across multiple lines. Lookback and compatibility with old
        # janky versions of the C tools complicate things though.

        self._line = s  # Used for error reporting

        # Initial token on the line
        match = _command_match(s)
        if not match:
            if s.isspace() or s.lstrip().startswith("#"):
                return (None,)
            self._parse_error("unknown token at start of line")

        # Tricky implementation detail: While parsing a token, 'token' refers
        # to the previous token. See _STRING_LEX for why this is needed.
        token = _get_keyword(match.group(1))
        if not token:
            # Backwards compatibility with old versions of the C tools, which
            # (accidentally) accepted stuff like "--help--" and "-help---".
            # This was fixed in the C tools by commit c2264564 ("kconfig: warn
            # of unhandled characters in Kconfig commands"), committed in July
            # 2015, but it seems people still run Kconfiglib on older kernels.
            if s.strip(" \t\n-") == "help":
                return (_T_HELP, None)

            # If the first token is not a keyword (and not a weird help token),
            # we have a preprocessor variable assignment (or a bare macro on a
            # line)
            self._parse_assignment(s)
            return (None,)

        tokens = [token]
        # The current index in the string being tokenized
        i = match.end()

        # Main tokenization loop (for tokens past the first one)
        while i < len(s):
            # Test for an identifier/keyword first. This is the most common
            # case.
            match = _id_keyword_match(s, i)
            if match:
                # We have an identifier or keyword

                # Check what it is. lookup_sym() will take care of allocating
                # new symbols for us the first time we see them. Note that
                # 'token' still refers to the previous token.

                name = match.group(1)
                keyword = _get_keyword(name)
                if keyword:
                    # It's a keyword
                    token = keyword
                    # Jump past it
                    i = match.end()

                elif token not in _STRING_LEX:
                    # It's a non-const symbol, except we translate n, m, and y
                    # into the corresponding constant symbols, like the C
                    # implementation

                    if "$" in name:
                        # Macro expansion within symbol name
                        name, s, i = self._expand_name(s, i)
                    else:
                        i = match.end()

                    token = self.const_syms[name] if name in STR_TO_TRI else \
                        self._lookup_sym(name)

                else:
                    # It's a case of missing quotes. For example, the
                    # following is accepted:
                    #
                    #   menu unquoted_title
                    #
                    #   config A
                    #       tristate unquoted_prompt
                    #
                    #   endmenu
                    #
                    # Named choices ('choice FOO') also end up here.

                    if token is not _T_CHOICE:
                        self._warn("style: quotes recommended around '{}' in '{}'"
                                   .format(name, self._line.strip()),
                                   self.filename, self.linenr)

                    token = name
                    i = match.end()

            else:
                # Neither a keyword nor a non-const symbol

                # We always strip whitespace after tokens, so it is safe to
                # assume that s[i] is the start of a token here.
                c = s[i]

                if c in "\"'":
                    if "$" not in s and "\\" not in s:
                        # Fast path for lines without $ and \. Find the
                        # matching quote.
                        end_i = s.find(c, i + 1) + 1
                        if not end_i:
                            self._parse_error("unterminated string")
                        val = s[i + 1:end_i - 1]
                        i = end_i
                    else:
                        # Slow path
                        s, end_i = self._expand_str(s, i)

                        # os.path.expandvars() and the $UNAME_RELEASE replace()
                        # is a backwards compatibility hack, which should be
                        # reasonably safe as expandvars() leaves references to
                        # undefined env. vars. as is.
                        #
                        # The preprocessor functionality changed how
                        # environment variables are referenced, to $(FOO).
                        val = expandvars(s[i + 1:end_i - 1]
                                         .replace("$UNAME_RELEASE",
                                                  _UNAME_RELEASE))

                        i = end_i

                    # This is the only place where we don't survive with a
                    # single token of lookback: 'option env="FOO"' does not
                    # refer to a constant symbol named "FOO".
                    token = \
                        val if token in _STRING_LEX or tokens[0] is _T_OPTION \
                        else self._lookup_const_sym(val)

                elif s.startswith("&&", i):
                    token = _T_AND
                    i += 2

                elif s.startswith("||", i):
                    token = _T_OR
                    i += 2

                elif c == "=":
                    token = _T_EQUAL
                    i += 1

                elif s.startswith("!=", i):
                    token = _T_UNEQUAL
                    i += 2

                elif c == "!":
                    token = _T_NOT
                    i += 1

                elif c == "(":
                    token = _T_OPEN_PAREN
                    i += 1

                elif c == ")":
                    token = _T_CLOSE_PAREN
                    i += 1

                elif c == "#":
                    break


                # Very rare

                elif s.startswith("<=", i):
                    token = _T_LESS_EQUAL
                    i += 2

                elif c == "<":
                    token = _T_LESS
                    i += 1

                elif s.startswith(">=", i):
                    token = _T_GREATER_EQUAL
                    i += 2

                elif c == ">":
                    token = _T_GREATER
                    i += 1


                else:
                    self._parse_error("unknown tokens in line")


                # Skip trailing whitespace
                while i < len(s) and s[i].isspace():
                    i += 1


            # Add the token
            tokens.append(token)

        # None-terminating the token list makes token fetching simpler/faster
        tokens.append(None)

        return tokens

    # Helpers for syntax checking and token fetching. See the
    # 'Intro to expressions' section for what a constant symbol is.
    #
    # More of these could be added, but the single-use cases are inlined as an
    # optimization.

    def _expect_sym(self):
        token = self._tokens[self._tokens_i]
        self._tokens_i += 1

        if token.__class__ is not Symbol:
            self._parse_error("expected symbol")

        return token

    def _expect_nonconst_sym(self):
        # Used for 'select' and 'imply' only. We know the token indices.

        token = self._tokens[1]
        self._tokens_i = 2

        if token.__class__ is not Symbol or token.is_constant:
            self._parse_error("expected nonconstant symbol")

        return token

    def _expect_str_and_eol(self):
        token = self._tokens[self._tokens_i]
        self._tokens_i += 1

        if token.__class__ is not str:
            self._parse_error("expected string")

        if self._tokens[self._tokens_i] is not None:
            self._trailing_tokens_error()

        return token

    def _expect_expr_and_eol(self):
        expr = self._parse_expr(True)

        if self._tokens[self._tokens_i] is not None:
            self._trailing_tokens_error()

        return expr

    def _check_token(self, token):
        # If the next token is 'token', removes it and returns True

        if self._tokens[self._tokens_i] is token:
            self._tokens_i += 1
            return True
        return False

    #
    # Preprocessor logic
    #

    def _parse_assignment(self, s):
        # Parses a preprocessor variable assignment, registering the variable
        # if it doesn't already exist. Also takes care of bare macros on lines
        # (which are allowed, and can be useful for their side effects).

        # Expand any macros in the left-hand side of the assignment (the
        # variable name)
        s = s.lstrip()
        i = 0
        while 1:
            i = _assignment_lhs_fragment_match(s, i).end()
            if s.startswith("$(", i):
                s, i = self._expand_macro(s, i, ())
            else:
                break

        if s.isspace():
            # We also accept a bare macro on a line (e.g.
            # $(warning-if,$(foo),ops)), provided it expands to a blank string
            return

        # Assigned variable
        name = s[:i]


        # Extract assignment operator (=, :=, or +=) and value
        rhs_match = _assignment_rhs_match(s, i)
        if not rhs_match:
            self._parse_error("syntax error")

        op, val = rhs_match.groups()


        if name in self.variables:
            # Already seen variable
            var = self.variables[name]
        else:
            # New variable
            var = Variable()
            var.kconfig = self
            var.name = name
            var._n_expansions = 0
            self.variables[name] = var

            # += acts like = on undefined variables (defines a recursive
            # variable)
            if op == "+=":
                op = "="

        if op == "=":
            var.is_recursive = True
            var.value = val
        elif op == ":=":
            var.is_recursive = False
            var.value = self._expand_whole(val, ())
        else:  # op == "+="
            # += does immediate expansion if the variable was last set
            # with :=
            var.value += " " + (val if var.is_recursive else
                                self._expand_whole(val, ()))

    def _expand_whole(self, s, args):
        # Expands preprocessor macros in all of 's'. Used whenever we don't
        # have to worry about delimiters. See _expand_macro() re. the 'args'
        # parameter.
        #
        # Returns the expanded string.

        i = 0
        while 1:
            i = s.find("$(", i)
            if i == -1:
                break
            s, i = self._expand_macro(s, i, args)
        return s

    def _expand_name(self, s, i):
        # Expands a symbol name starting at index 'i' in 's'.
        #
        # Returns the expanded name, the expanded 's' (including the part
        # before the name), and the index of the first character in the next
        # token after the name.

        s, end_i = self._expand_name_iter(s, i)
        name = s[i:end_i]
        # isspace() is False for empty strings
        if not name.strip():
            # Avoid creating a Kconfig symbol with a blank name. It's almost
            # guaranteed to be an error.
            self._parse_error("macro expanded to blank string")

        # Skip trailing whitespace
        while end_i < len(s) and s[end_i].isspace():
            end_i += 1

        return name, s, end_i

    def _expand_name_iter(self, s, i):
        # Expands a symbol name starting at index 'i' in 's'.
        #
        # Returns the expanded 's' (including the part before the name) and the
        # index of the first character after the expanded name in 's'.

        while 1:
            match = _name_special_search(s, i)

            if match.group() != "$(":
                return (s, match.start())
            s, i = self._expand_macro(s, match.start(), ())

    def _expand_str(self, s, i):
        # Expands a quoted string starting at index 'i' in 's'. Handles both
        # backslash escapes and macro expansion.
        #
        # Returns the expanded 's' (including the part before the string) and
        # the index of the first character after the expanded string in 's'.

        quote = s[i]
        i += 1  # Skip over initial "/'
        while 1:
            match = _string_special_search(s, i)
            if not match:
                self._parse_error("unterminated string")


            if match.group() == quote:
                # Found the end of the string
                return (s, match.end())

            elif match.group() == "\\":
                # Replace '\x' with 'x'. 'i' ends up pointing to the character
                # after 'x', which allows macros to be canceled with '\$(foo)'.
                i = match.end()
                s = s[:match.start()] + s[i:]

            elif match.group() == "$(":
                # A macro call within the string
                s, i = self._expand_macro(s, match.start(), ())

            else:
                # A ' quote within " quotes or vice versa
                i += 1

    def _expand_macro(self, s, i, args):
        # Expands a macro starting at index 'i' in 's'. If this macro resulted
        # from the expansion of another macro, 'args' holds the arguments
        # passed to that macro.
        #
        # Returns the expanded 's' (including the part before the macro) and
        # the index of the first character after the expanded macro in 's'.

        res = s[:i]
        i += 2  # Skip over "$("

        arg_start = i  # Start of current macro argument
        new_args = []  # Arguments of this macro call
        nesting = 0  # Current parentheses nesting level

        while 1:
            match = _macro_special_search(s, i)
            if not match:
                self._parse_error("missing end parenthesis in macro expansion")


            if match.group() == "(":
                nesting += 1
                i = match.end()

            elif match.group() == ")":
                if nesting:
                    nesting -= 1
                    i = match.end()
                    continue

                # Found the end of the macro

                new_args.append(s[arg_start:match.start()])

                # $(1) is replaced by the first argument to the function, etc.,
                # provided at least that many arguments were passed

                try:
                    # Does the macro look like an integer, with a corresponding
                    # argument? If so, expand it to the value of the argument.
                    res += args[int(new_args[0])]
                except (ValueError, IndexError):
                    # Regular variables are just functions without arguments,
                    # and also go through the function value path
                    res += self._fn_val(new_args)

                return (res + s[match.end():], len(res))

            elif match.group() == ",":
                i = match.end()
                if nesting:
                    continue

                # Found the end of a macro argument
                new_args.append(s[arg_start:match.start()])
                arg_start = i

            else:  # match.group() == "$("
                # A nested macro call within the macro
                s, i = self._expand_macro(s, match.start(), args)

    def _fn_val(self, args):
        # Returns the result of calling the function args[0] with the arguments
        # args[1..len(args)-1]. Plain variables are treated as functions
        # without arguments.

        fn = args[0]

        if fn in self.variables:
            var = self.variables[fn]

            if len(args) == 1:
                # Plain variable
                if var._n_expansions:
                    self._parse_error("Preprocessor variable {} recursively "
                                      "references itself".format(var.name))
            elif var._n_expansions > 100:
                # Allow functions to call themselves, but guess that functions
                # that are overly recursive are stuck
                self._parse_error("Preprocessor function {} seems stuck "
                                  "in infinite recursion".format(var.name))

            var._n_expansions += 1
            res = self._expand_whole(self.variables[fn].value, args)
            var._n_expansions -= 1
            return res

        if fn in self._functions:
            # Built-in or user-defined function

            py_fn, min_arg, max_arg = self._functions[fn]

            if len(args) - 1 < min_arg or \
               (max_arg is not None and len(args) - 1 > max_arg):

                if min_arg == max_arg:
                    expected_args = min_arg
                elif max_arg is None:
                    expected_args = "{} or more".format(min_arg)
                else:
                    expected_args = "{}-{}".format(min_arg, max_arg)

                raise KconfigError("{}:{}: bad number of arguments in call "
                                   "to {}, expected {}, got {}"
                                   .format(self.filename, self.linenr, fn,
                                           expected_args, len(args) - 1))

            return py_fn(self, *args)

        # Environment variables are tried last
        if fn in os.environ:
            self.env_vars.add(fn)
            return os.environ[fn]

        return ""

    #
    # Parsing
    #

    def _make_and(self, e1, e2):
        # Constructs an AND (&&) expression. Performs trivial simplification.

        if e1 is self.y:
            return e2

        if e2 is self.y:
            return e1

        if e1 is self.n or e2 is self.n:
            return self.n

        return (AND, e1, e2)

    def _make_or(self, e1, e2):
        # Constructs an OR (||) expression. Performs trivial simplification.

        if e1 is self.n:
            return e2

        if e2 is self.n:
            return e1

        if e1 is self.y or e2 is self.y:
            return self.y

        return (OR, e1, e2)

    def _parse_block(self, end_token, parent, prev):
        # Parses a block, which is the contents of either a file or an if,
        # menu, or choice statement.
        #
        # end_token:
        #   The token that ends the block, e.g. _T_ENDIF ("endif") for ifs.
        #   None for files.
        #
        # parent:
        #   The parent menu node, corresponding to a menu, Choice, or 'if'.
        #   'if's are flattened after parsing.
        #
        # prev:
        #   The previous menu node. New nodes will be added after this one (by
        #   modifying 'next' pointers).
        #
        #   'prev' is reused to parse a list of child menu nodes (for a menu or
        #   Choice): After parsing the children, the 'next' pointer is assigned
        #   to the 'list' pointer to "tilt up" the children above the node.
        #
        # Returns the final menu node in the block (or 'prev' if the block is
        # empty). This allows chaining.

        while self._next_line():
            t0 = self._tokens[0]

            if t0 is _T_CONFIG or t0 is _T_MENUCONFIG:
                # The tokenizer allocates Symbol objects for us
                sym = self._tokens[1]

                if sym.__class__ is not Symbol or sym.is_constant:
                    self._parse_error("missing or bad symbol name")

                if self._tokens[2] is not None:
                    self._trailing_tokens_error()

                self.defined_syms.append(sym)

                node = MenuNode()
                node.kconfig = self
                node.item = sym
                node.is_menuconfig = (t0 is _T_MENUCONFIG)
                node.prompt = node.help = node.list = None
                node.parent = parent
                node.filename = self.filename
                node.linenr = self.linenr
                node.include_path = self._include_path

                sym.nodes.append(node)

                self._parse_props(node)

                if node.is_menuconfig and not node.prompt:
                    self._warn("the menuconfig symbol {} has no prompt"
                               .format(sym.name_and_loc))

                # Equivalent to
                #
                #   prev.next = node
                #   prev = node
                #
                # due to tricky Python semantics. The order matters.
                prev.next = prev = node

            elif t0 is None:
                # Blank line
                continue

            elif t0 in _SOURCE_TOKENS:
                pattern = self._expect_str_and_eol()

                if t0 in _REL_SOURCE_TOKENS:
                    # Relative source
                    pattern = join(dirname(self.filename), pattern)

                # - glob() doesn't support globbing relative to a directory, so
                #   we need to prepend $srctree to 'pattern'. Use join()
                #   instead of '+' so that an absolute path in 'pattern' is
                #   preserved.
                #
                # - Sort the glob results to ensure a consistent ordering of
                #   Kconfig symbols, which indirectly ensures a consistent
                #   ordering in e.g. .config files
                filenames = sorted(iglob(join(self._srctree_prefix, pattern)))

                if not filenames and t0 in _OBL_SOURCE_TOKENS:
                    raise KconfigError(
                        "{}:{}: '{}' not found (in '{}'). Check that "
                        "environment variables are set correctly (e.g. "
                        "$srctree, which is {}). Also note that unset "
                        "environment variables expand to the empty string."
                        .format(self.filename, self.linenr, pattern,
                                self._line.strip(),
                                "set to '{}'".format(self.srctree)
                                    if self.srctree else "unset or blank"))

                for filename in filenames:
                    self._enter_file(filename)
                    prev = self._parse_block(None, parent, prev)
                    self._leave_file()

            elif t0 is end_token:
                # Reached the end of the block. Terminate the final node and
                # return it.

                if self._tokens[1] is not None:
                    self._trailing_tokens_error()

                prev.next = None
                return prev

            elif t0 is _T_IF:
                node = MenuNode()
                node.item = node.prompt = None
                node.parent = parent
                node.dep = self._expect_expr_and_eol()

                self._parse_block(_T_ENDIF, node, node)
                node.list = node.next

                prev.next = prev = node

            elif t0 is _T_MENU:
                node = MenuNode()
                node.kconfig = self
                node.item = t0  # _T_MENU == MENU
                node.is_menuconfig = True
                node.prompt = (self._expect_str_and_eol(), self.y)
                node.visibility = self.y
                node.parent = parent
                node.filename = self.filename
                node.linenr = self.linenr
                node.include_path = self._include_path

                self.menus.append(node)

                self._parse_props(node)
                self._parse_block(_T_ENDMENU, node, node)
                node.list = node.next

                prev.next = prev = node

            elif t0 is _T_COMMENT:
                node = MenuNode()
                node.kconfig = self
                node.item = t0  # _T_COMMENT == COMMENT
                node.is_menuconfig = False
                node.prompt = (self._expect_str_and_eol(), self.y)
                node.list = None
                node.parent = parent
                node.filename = self.filename
                node.linenr = self.linenr
                node.include_path = self._include_path

                self.comments.append(node)

                self._parse_props(node)

                prev.next = prev = node

            elif t0 is _T_CHOICE:
                if self._tokens[1] is None:
                    choice = Choice()
                    choice.direct_dep = self.n
                else:
                    # Named choice
                    name = self._expect_str_and_eol()
                    choice = self.named_choices.get(name)
                    if not choice:
                        choice = Choice()
                        choice.name = name
                        choice.direct_dep = self.n
                        self.named_choices[name] = choice

                self.choices.append(choice)

                node = MenuNode()
                node.kconfig = choice.kconfig = self
                node.item = choice
                node.is_menuconfig = True
                node.prompt = node.help = None
                node.parent = parent
                node.filename = self.filename
                node.linenr = self.linenr
                node.include_path = self._include_path

                choice.nodes.append(node)

                self._parse_props(node)
                self._parse_block(_T_ENDCHOICE, node, node)
                node.list = node.next

                prev.next = prev = node

            elif t0 is _T_MAINMENU:
                self.top_node.prompt = (self._expect_str_and_eol(), self.y)

            else:
                # A valid endchoice/endif/endmenu is caught by the 'end_token'
                # check above
                self._parse_error(
                    "no corresponding 'choice'" if t0 is _T_ENDCHOICE else
                    "no corresponding 'if'"     if t0 is _T_ENDIF else
                    "no corresponding 'menu'"   if t0 is _T_ENDMENU else
                    "unrecognized construct")

        # End of file reached. Return the last node.

        if end_token:
            raise KconfigError(
                "error: expected '{}' at end of '{}'"
                .format("endchoice" if end_token is _T_ENDCHOICE else
                        "endif"     if end_token is _T_ENDIF else
                        "endmenu",
                        self.filename))

        return prev

    def _parse_cond(self):
        # Parses an optional 'if <expr>' construct and returns the parsed
        # <expr>, or self.y if the next token is not _T_IF

        expr = self._parse_expr(True) if self._check_token(_T_IF) else self.y

        if self._tokens[self._tokens_i] is not None:
            self._trailing_tokens_error()

        return expr

    def _parse_props(self, node):
        # Parses and adds properties to the MenuNode 'node' (type, 'prompt',
        # 'default's, etc.) Properties are later copied up to symbols and
        # choices in a separate pass after parsing, in e.g.
        # _add_props_to_sym().
        #
        # An older version of this code added properties directly to symbols
        # and choices instead of to their menu nodes (and handled dependency
        # propagation simultaneously), but that loses information on where a
        # property is added when a symbol or choice is defined in multiple
        # locations. Some Kconfig configuration systems rely heavily on such
        # symbols, and better docs can be generated by keeping track of where
        # properties are added.
        #
        # node:
        #   The menu node we're parsing properties on

        # Dependencies from 'depends on'. Will get propagated to the properties
        # below.
        node.dep = self.y

        while self._next_line():
            t0 = self._tokens[0]

            if t0 in _TYPE_TOKENS:
                # Relies on '_T_BOOL is BOOL', etc., to save a conversion
                self._set_type(node.item, t0)
                if self._tokens[1] is not None:
                    self._parse_prompt(node)

            elif t0 is _T_DEPENDS:
                if not self._check_token(_T_ON):
                    self._parse_error("expected 'on' after 'depends'")

                node.dep = self._make_and(node.dep,
                                          self._expect_expr_and_eol())

            elif t0 is _T_HELP:
                self._parse_help(node)

            elif t0 is _T_SELECT:
                if node.item.__class__ is not Symbol:
                    self._parse_error("only symbols can select")

                node.selects.append((self._expect_nonconst_sym(),
                                     self._parse_cond()))

            elif t0 is None:
                # Blank line
                continue

            elif t0 is _T_DEFAULT:
                node.defaults.append((self._parse_expr(False),
                                      self._parse_cond()))

            elif t0 in _DEF_TOKEN_TO_TYPE:
                self._set_type(node.item, _DEF_TOKEN_TO_TYPE[t0])
                node.defaults.append((self._parse_expr(False),
                                      self._parse_cond()))

            elif t0 is _T_PROMPT:
                self._parse_prompt(node)

            elif t0 is _T_RANGE:
                node.ranges.append((self._expect_sym(), self._expect_sym(),
                                    self._parse_cond()))

            elif t0 is _T_IMPLY:
                if node.item.__class__ is not Symbol:
                    self._parse_error("only symbols can imply")

                node.implies.append((self._expect_nonconst_sym(),
                                     self._parse_cond()))

            elif t0 is _T_VISIBLE:
                if not self._check_token(_T_IF):
                    self._parse_error("expected 'if' after 'visible'")

                node.visibility = self._make_and(node.visibility,
                                                 self._expect_expr_and_eol())

            elif t0 is _T_OPTION:
                if self._check_token(_T_ENV):
                    if not self._check_token(_T_EQUAL):
                        self._parse_error("expected '=' after 'env'")

                    env_var = self._expect_str_and_eol()
                    node.item.env_var = env_var

                    if env_var in os.environ:
                        node.defaults.append(
                            (self._lookup_const_sym(os.environ[env_var]),
                             self.y))
                    else:
                        self._warn("{1} has 'option env=\"{0}\"', "
                                   "but the environment variable {0} is not "
                                   "set".format(node.item.name, env_var),
                                   self.filename, self.linenr)

                    if env_var != node.item.name:
                        self._warn("Kconfiglib expands environment variables "
                                   "in strings directly, meaning you do not "
                                   "need 'option env=...' \"bounce\" symbols. "
                                   "For compatibility with the C tools, "
                                   "rename {} to {} (so that the symbol name "
                                   "matches the environment variable name)."
                                   .format(node.item.name, env_var),
                                   self.filename, self.linenr)

                elif self._check_token(_T_DEFCONFIG_LIST):
                    if not self.defconfig_list:
                        self.defconfig_list = node.item
                    else:
                        self._warn("'option defconfig_list' set on multiple "
                                   "symbols ({0} and {1}). Only {0} will be "
                                   "used.".format(self.defconfig_list.name,
                                                  node.item.name),
                                   self.filename, self.linenr)

                elif self._check_token(_T_MODULES):
                    # To reduce warning spam, only warn if 'option modules' is
                    # set on some symbol that isn't MODULES, which should be
                    # safe. I haven't run into any projects that make use
                    # modules besides the kernel yet, and there it's likely to
                    # keep being called "MODULES".
                    if node.item is not self.modules:
                        self._warn("the 'modules' option is not supported. "
                                   "Let me know if this is a problem for you, "
                                   "as it wouldn't be that hard to implement. "
                                   "Note that modules are supported -- "
                                   "Kconfiglib just assumes the symbol name "
                                   "MODULES, like older versions of the C "
                                   "implementation did when 'option modules' "
                                   "wasn't used.",
                                   self.filename, self.linenr)

                elif self._check_token(_T_ALLNOCONFIG_Y):
                    if node.item.__class__ is not Symbol:
                        self._parse_error("the 'allnoconfig_y' option is only "
                                          "valid for symbols")

                    node.item.is_allnoconfig_y = True

                else:
                    self._parse_error("unrecognized option")

            elif t0 is _T_OPTIONAL:
                if node.item.__class__ is not Choice:
                    self._parse_error('"optional" is only valid for choices')

                node.item.is_optional = True

            else:
                # Reuse the tokens for the non-property line later
                self._reuse_tokens = True
                return

    def _set_type(self, sc, new_type):
        # Sets the type of 'sc' (symbol or choice) to 'new_type'

        # UNKNOWN is falsy
        if sc.orig_type and sc.orig_type is not new_type:
            self._warn("{} defined with multiple types, {} will be used"
                       .format(sc.name_and_loc, TYPE_TO_STR[new_type]))

        sc.orig_type = new_type

    def _parse_prompt(self, node):
        # 'prompt' properties override each other within a single definition of
        # a symbol, but additional prompts can be added by defining the symbol
        # multiple times

        if node.prompt:
            self._warn(node.item.name_and_loc +
                       " defined with multiple prompts in single location")

        prompt = self._tokens[1]
        self._tokens_i = 2

        if prompt.__class__ is not str:
            self._parse_error("expected prompt string")

        if prompt != prompt.strip():
            self._warn(node.item.name_and_loc +
                       " has leading or trailing whitespace in its prompt")

            # This avoid issues for e.g. reStructuredText documentation, where
            # '*prompt *' is invalid
            prompt = prompt.strip()

        node.prompt = (prompt, self._parse_cond())

    def _parse_help(self, node):
        if node.help is not None:
            self._warn(node.item.name_and_loc + " defined with more than "
                       "one help text -- only the last one will be used")

        # Micro-optimization. This code is pretty hot.
        readline = self._readline

        # Find first non-blank (not all-space) line and get its
        # indentation

        while 1:
            line = readline()
            self.linenr += 1
            if not line:
                self._empty_help(node, line)
                return
            if not line.isspace():
                break

        len_ = len  # Micro-optimization

        # Use a separate 'expline' variable here and below to avoid stomping on
        # any tabs people might've put deliberately into the first line after
        # the help text
        expline = line.expandtabs()
        indent = len_(expline) - len_(expline.lstrip())
        if not indent:
            self._empty_help(node, line)
            return

        # The help text goes on till the first non-blank line with less indent
        # than the first line

        # Add the first line
        lines = [expline[indent:]]
        add_line = lines.append  # Micro-optimization

        while 1:
            line = readline()
            if line.isspace():
                # No need to preserve the exact whitespace in these
                add_line("\n")
            elif not line:
                # End of file
                break
            else:
                expline = line.expandtabs()
                if len_(expline) - len_(expline.lstrip()) < indent:
                    break
                add_line(expline[indent:])

        self.linenr += len_(lines)
        node.help = "".join(lines).rstrip()
        if line:
            self._line_after_help(line)

    def _empty_help(self, node, line):
        self._warn(node.item.name_and_loc +
                   " has 'help' but empty help text")
        node.help = ""
        if line:
            self._line_after_help(line)

    def _parse_expr(self, transform_m):
        # Parses an expression from the tokens in Kconfig._tokens using a
        # simple top-down approach. See the module docstring for the expression
        # format.
        #
        # transform_m:
        #   True if m should be rewritten to m && MODULES. See the
        #   Kconfig.eval_string() documentation.

        # Grammar:
        #
        #   expr:     and_expr ['||' expr]
        #   and_expr: factor ['&&' and_expr]
        #   factor:   <symbol> ['='/'!='/'<'/... <symbol>]
        #             '!' factor
        #             '(' expr ')'
        #
        # It helps to think of the 'expr: and_expr' case as a single-operand OR
        # (no ||), and of the 'and_expr: factor' case as a single-operand AND
        # (no &&). Parsing code is always a bit tricky.

        # Mind dump: parse_factor() and two nested loops for OR and AND would
        # work as well. The straightforward implementation there gives a
        # (op, (op, (op, A, B), C), D) parse for A op B op C op D. Representing
        # expressions as (op, [list of operands]) instead goes nicely with that
        # version, but is wasteful for short expressions and complicates
        # expression evaluation and other code that works on expressions (more
        # complicated code likely offsets any performance gain from less
        # recursion too). If we also try to optimize the list representation by
        # merging lists when possible (e.g. when ANDing two AND expressions),
        # we end up allocating a ton of lists instead of reusing expressions,
        # which is bad.

        and_expr = self._parse_and_expr(transform_m)

        # Return 'and_expr' directly if we have a "single-operand" OR.
        # Otherwise, parse the expression on the right and make an OR node.
        # This turns A || B || C || D into (OR, A, (OR, B, (OR, C, D))).
        return and_expr if not self._check_token(_T_OR) else \
            (OR, and_expr, self._parse_expr(transform_m))

    def _parse_and_expr(self, transform_m):
        factor = self._parse_factor(transform_m)

        # Return 'factor' directly if we have a "single-operand" AND.
        # Otherwise, parse the right operand and make an AND node. This turns
        # A && B && C && D into (AND, A, (AND, B, (AND, C, D))).
        return factor if not self._check_token(_T_AND) else \
            (AND, factor, self._parse_and_expr(transform_m))

    def _parse_factor(self, transform_m):
        token = self._tokens[self._tokens_i]
        self._tokens_i += 1

        if token.__class__ is Symbol:
            # Plain symbol or relation

            if self._tokens[self._tokens_i] not in _RELATIONS:
                # Plain symbol

                # For conditional expressions ('depends on <expr>',
                # '... if <expr>', etc.), m is rewritten to m && MODULES.
                if transform_m and token is self.m:
                    return (AND, self.m, self.modules)

                return token

            # Relation
            #
            # _T_EQUAL, _T_UNEQUAL, etc., deliberately have the same values as
            # EQUAL, UNEQUAL, etc., so we can just use the token directly
            self._tokens_i += 1
            return (self._tokens[self._tokens_i - 1], token,
                    self._expect_sym())

        if token is _T_NOT:
            # token == _T_NOT == NOT
            return (token, self._parse_factor(transform_m))

        if token is _T_OPEN_PAREN:
            expr_parse = self._parse_expr(transform_m)
            if self._check_token(_T_CLOSE_PAREN):
                return expr_parse

        self._parse_error("malformed expression")

    #
    # Caching and invalidation
    #

    def _build_dep(self):
        # Populates the Symbol/Choice._dependents sets, which contain all other
        # items (symbols and choices) that immediately depend on the item in
        # the sense that changing the value of the item might affect the value
        # of the dependent items. This is used for caching/invalidation.
        #
        # The calculated sets might be larger than necessary as we don't do any
        # complex analysis of the expressions.

        depend_on = _depend_on  # Micro-optimization

        # Only calculate _dependents for defined symbols. Constant and
        # undefined symbols could theoretically be selected/implied, but it
        # wouldn't change their value, so it's not a true dependency.
        for sym in self.unique_defined_syms:
            # Symbols depend on the following:

            # The prompt conditions
            for node in sym.nodes:
                if node.prompt:
                    depend_on(sym, node.prompt[1])

            # The default values and their conditions
            for value, cond in sym.defaults:
                depend_on(sym, value)
                depend_on(sym, cond)

            # The reverse and weak reverse dependencies
            depend_on(sym, sym.rev_dep)
            depend_on(sym, sym.weak_rev_dep)

            # The ranges along with their conditions
            for low, high, cond in sym.ranges:
                depend_on(sym, low)
                depend_on(sym, high)
                depend_on(sym, cond)

            # The direct dependencies. This is usually redundant, as the direct
            # dependencies get propagated to properties, but it's needed to get
            # invalidation solid for 'imply', which only checks the direct
            # dependencies (even if there are no properties to propagate it
            # to).
            depend_on(sym, sym.direct_dep)

            # In addition to the above, choice symbols depend on the choice
            # they're in, but that's handled automatically since the Choice is
            # propagated to the conditions of the properties before
            # _build_dep() runs.

        for choice in self.unique_choices:
            # Choices depend on the following:

            # The prompt conditions
            for node in choice.nodes:
                if node.prompt:
                    depend_on(choice, node.prompt[1])

            # The default symbol conditions
            for _, cond in choice.defaults:
                depend_on(choice, cond)

    def _add_choice_deps(self):
        # Choices also depend on the choice symbols themselves, because the
        # y-mode selection of the choice might change if a choice symbol's
        # visibility changes.
        #
        # We add these dependencies separately after dependency loop detection.
        # The invalidation algorithm can handle the resulting
        # <choice symbol> <-> <choice> dependency loops, but they make loop
        # detection awkward.

        for choice in self.unique_choices:
            for sym in choice.syms:
                sym._dependents.add(choice)

    def _invalidate_all(self):
        # Undefined symbols never change value and don't need to be
        # invalidated, so we can just iterate over defined symbols.
        # Invalidating constant symbols would break things horribly.
        for sym in self.unique_defined_syms:
            sym._invalidate()

        for choice in self.unique_choices:
            choice._invalidate()

    #
    # Post-parsing menu tree processing, including dependency propagation and
    # implicit submenu creation
    #

    def _finalize_node(self, node, visible_if):
        # Finalizes a menu node and its children:
        #
        #  - Copies properties from menu nodes up to their contained
        #    symbols/choices
        #
        #  - Propagates dependencies from parent to child nodes
        #
        #  - Creates implicit menus (see kconfig-language.txt)
        #
        #  - Removes 'if' nodes
        #
        #  - Sets 'choice' types and registers choice symbols
        #
        # menu_finalize() in the C implementation is similar.
        #
        # node:
        #   The menu node to finalize. This node and its children will have
        #   been finalized when the function returns, and any implicit menus
        #   will have been created.
        #
        # visible_if:
        #   Dependencies from 'visible if' on parent menus. These are added to
        #   the prompts of symbols and choices.

        if node.item.__class__ is Symbol:
            # Copy defaults, ranges, selects, and implies to the Symbol
            self._add_props_to_sym(node)

            # Find any items that should go in an implicit menu rooted at the
            # symbol
            cur = node
            while cur.next and _auto_menu_dep(node, cur.next):
                # This makes implicit submenu creation work recursively, with
                # implicit menus inside implicit menus
                self._finalize_node(cur.next, visible_if)
                cur = cur.next
                cur.parent = node

            if cur is not node:
                # Found symbols that should go in an implicit submenu. Tilt
                # them up above us.
                node.list = node.next
                node.next = cur.next
                cur.next = None

        elif node.list:
            # The menu node is a choice, menu, or if. Finalize each child node.

            if node.item is MENU:
                visible_if = self._make_and(visible_if, node.visibility)

            # Propagate the menu node's dependencies to each child menu node.
            #
            # This needs to go before the recursive _finalize_node() call so
            # that implicit submenu creation can look ahead at dependencies.
            self._propagate_deps(node, visible_if)

            # Finalize the children
            cur = node.list
            while cur:
                self._finalize_node(cur, visible_if)
                cur = cur.next

        if node.list:
            # node's children have been individually finalized. Do final steps
            # to finalize this "level" in the menu tree.
            _flatten(node.list)
            _remove_ifs(node)

        # Empty choices (node.list None) are possible, so this needs to go
        # outside
        if node.item.__class__ is Choice:
            # Add the node's non-node-specific properties to the choice, like
            # _add_props_to_sym() does
            choice = node.item
            choice.direct_dep = self._make_or(choice.direct_dep, node.dep)
            choice.defaults += node.defaults

            _finalize_choice(node)

    def _propagate_deps(self, node, visible_if):
        # Propagates 'node's dependencies to its child menu nodes

        # If the parent node holds a Choice, we use the Choice itself as the
        # parent dependency. This makes sense as the value (mode) of the choice
        # limits the visibility of the contained choice symbols. The C
        # implementation works the same way.
        #
        # Due to the similar interface, Choice works as a drop-in replacement
        # for Symbol here.
        basedep = node.item if node.item.__class__ is Choice else node.dep

        cur = node.list
        while cur:
            dep = cur.dep = self._make_and(cur.dep, basedep)

            if cur.item.__class__ in _SYMBOL_CHOICE:
                # Propagate 'visible if' and dependencies to the prompt
                if cur.prompt:
                    cur.prompt = (cur.prompt[0],
                                  self._make_and(
                                      cur.prompt[1],
                                      self._make_and(visible_if, dep)))

                # Propagate dependencies to defaults
                if cur.defaults:
                    cur.defaults = [(default, self._make_and(cond, dep))
                                    for default, cond in cur.defaults]

                # Propagate dependencies to ranges
                if cur.ranges:
                    cur.ranges = [(low, high, self._make_and(cond, dep))
                                  for low, high, cond in cur.ranges]

                # Propagate dependencies to selects
                if cur.selects:
                    cur.selects = [(target, self._make_and(cond, dep))
                                   for target, cond in cur.selects]

                # Propagate dependencies to implies
                if cur.implies:
                    cur.implies = [(target, self._make_and(cond, dep))
                                   for target, cond in cur.implies]

            elif cur.prompt:  # Not a symbol/choice
                # Propagate dependencies to the prompt. 'visible if' is only
                # propagated to symbols/choices.
                cur.prompt = (cur.prompt[0],
                              self._make_and(cur.prompt[1], dep))

            cur = cur.next

    def _add_props_to_sym(self, node):
        # Copies properties from the menu node 'node' up to its contained
        # symbol, and adds (weak) reverse dependencies to selected/implied
        # symbols.
        #
        # This can't be rolled into _propagate_deps(), because that function
        # traverses the menu tree roughly breadth-first, meaning properties on
        # symbols defined in multiple locations could end up in the wrong
        # order.

        sym = node.item

        # See the Symbol class docstring
        sym.direct_dep = self._make_or(sym.direct_dep, node.dep)

        sym.defaults += node.defaults
        sym.ranges += node.ranges
        sym.selects += node.selects
        sym.implies += node.implies

        # Modify the reverse dependencies of the selected symbol
        for target, cond in node.selects:
            target.rev_dep = self._make_or(
                target.rev_dep,
                self._make_and(sym, cond))

        # Modify the weak reverse dependencies of the implied
        # symbol
        for target, cond in node.implies:
            target.weak_rev_dep = self._make_or(
                target.weak_rev_dep,
                self._make_and(sym, cond))

    #
    # Misc.
    #

    def _check_sym_sanity(self):
        # Checks various symbol properties that are handiest to check after
        # parsing. Only generates errors and warnings.

        def num_ok(sym, type_):
            # Returns True if the (possibly constant) symbol 'sym' is valid as a value
            # for a symbol of type type_ (INT or HEX)

            # 'not sym.nodes' implies a constant or undefined symbol, e.g. a plain
            # "123"
            if not sym.nodes:
                return _is_base_n(sym.name, _TYPE_TO_BASE[type_])

            return sym.orig_type is type_

        for sym in self.unique_defined_syms:
            if sym.orig_type in _BOOL_TRISTATE:
                # A helper function could be factored out here, but keep it
                # speedy/straightforward

                for target_sym, _ in sym.selects:
                    if target_sym.orig_type not in _BOOL_TRISTATE_UNKNOWN:
                        self._warn("{} selects the {} symbol {}, which is not "
                                   "bool or tristate"
                                   .format(sym.name_and_loc,
                                           TYPE_TO_STR[target_sym.orig_type],
                                           target_sym.name_and_loc))

                for target_sym, _ in sym.implies:
                    if target_sym.orig_type not in _BOOL_TRISTATE_UNKNOWN:
                        self._warn("{} implies the {} symbol {}, which is not "
                                   "bool or tristate"
                                   .format(sym.name_and_loc,
                                           TYPE_TO_STR[target_sym.orig_type],
                                           target_sym.name_and_loc))

            elif sym.orig_type:  # STRING/INT/HEX
                for default, _ in sym.defaults:
                    if default.__class__ is not Symbol:
                        raise KconfigError(
                            "the {} symbol {} has a malformed default {} -- "
                            "expected a single symbol"
                            .format(TYPE_TO_STR[sym.orig_type],
                                    sym.name_and_loc, expr_str(default)))

                    if sym.orig_type is STRING:
                        if not default.is_constant and not default.nodes and \
                           not default.name.isupper():
                            # 'default foo' on a string symbol could be either a symbol
                            # reference or someone leaving out the quotes. Guess that
                            # the quotes were left out if 'foo' isn't all-uppercase
                            # (and no symbol named 'foo' exists).
                            self._warn("style: quotes recommended around "
                                       "default value for string symbol "
                                       + sym.name_and_loc)

                    elif not num_ok(default, sym.orig_type):  # INT/HEX
                        self._warn("the {0} symbol {1} has a non-{0} default {2}"
                                   .format(TYPE_TO_STR[sym.orig_type],
                                           sym.name_and_loc,
                                           default.name_and_loc))

                if sym.selects or sym.implies:
                    self._warn("the {} symbol {} has selects or implies"
                               .format(TYPE_TO_STR[sym.orig_type],
                                       sym.name_and_loc))

            else:  # UNKNOWN
                self._warn("{} defined without a type"
                           .format(sym.name_and_loc))


            if sym.ranges:
                if sym.orig_type not in _INT_HEX:
                    self._warn(
                        "the {} symbol {} has ranges, but is not int or hex"
                        .format(TYPE_TO_STR[sym.orig_type],
                                sym.name_and_loc))
                else:
                    for low, high, _ in sym.ranges:
                        if not num_ok(low, sym.orig_type) or \
                           not num_ok(high, sym.orig_type):

                            self._warn("the {0} symbol {1} has a non-{0} "
                                       "range [{2}, {3}]"
                                       .format(TYPE_TO_STR[sym.orig_type],
                                               sym.name_and_loc,
                                               low.name_and_loc,
                                               high.name_and_loc))

    def _check_choice_sanity(self):
        # Checks various choice properties that are handiest to check after
        # parsing. Only generates errors and warnings.

        def warn_select_imply(sym, expr, expr_type):
            msg = "the choice symbol {} is {} by the following symbols, but " \
                  "select/imply has no effect on choice symbols" \
                  .format(sym.name_and_loc, expr_type)

            # si = select/imply
            for si in split_expr(expr, OR):
                msg += "\n - " + split_expr(si, AND)[0].name_and_loc

            self._warn(msg)

        for choice in self.unique_choices:
            if choice.orig_type not in _BOOL_TRISTATE:
                self._warn("{} defined with type {}"
                           .format(choice.name_and_loc,
                                   TYPE_TO_STR[choice.orig_type]))

            for node in choice.nodes:
                if node.prompt:
                    break
            else:
                self._warn(choice.name_and_loc + " defined without a prompt")

            for default, _ in choice.defaults:
                if default.__class__ is not Symbol:
                    raise KconfigError(
                        "{} has a malformed default {}"
                        .format(choice.name_and_loc, expr_str(default)))

                if default.choice is not choice:
                    self._warn("the default selection {} of {} is not "
                               "contained in the choice"
                               .format(default.name_and_loc,
                                       choice.name_and_loc))

            for sym in choice.syms:
                if sym.defaults:
                    self._warn("default on the choice symbol {} will have "
                               "no effect, as defaults do not affect choice "
                               "symbols".format(sym.name_and_loc))

                if sym.rev_dep is not sym.kconfig.n:
                    warn_select_imply(sym, sym.rev_dep, "selected")

                if sym.weak_rev_dep is not sym.kconfig.n:
                    warn_select_imply(sym, sym.weak_rev_dep, "implied")

                for node in sym.nodes:
                    if node.parent.item is choice:
                        if not node.prompt:
                            self._warn("the choice symbol {} has no prompt"
                                       .format(sym.name_and_loc))

                    elif node.prompt:
                        self._warn("the choice symbol {} is defined with a "
                                   "prompt outside the choice"
                                   .format(sym.name_and_loc))

    def _parse_error(self, msg):
        raise KconfigError("{}error: couldn't parse '{}': {}".format(
            "" if self.filename is None else
                "{}:{}: ".format(self.filename, self.linenr),
            self._line.strip(), msg))

    def _trailing_tokens_error(self):
        self._parse_error("extra tokens at end of line")

    def _open(self, filename, mode):
        # open() wrapper:
        #
        # - Enable universal newlines mode on Python 2 to ease
        #   interoperability between Linux and Windows. It's already the
        #   default on Python 3.
        #
        #   The "U" flag would currently work for both Python 2 and 3, but it's
        #   deprecated on Python 3, so play it future-safe.
        #
        #   io.open() defaults to universal newlines on Python 2 (and is an
        #   alias for open() on Python 3), but it returns 'unicode' strings and
        #   slows things down:
        #
        #     Parsing x86 Kconfigs on Python 2
        #
        #     with open(..., "rU"):
        #
        #       real  0m0.930s
        #       user  0m0.905s
        #       sys   0m0.025s
        #
        #     with io.open():
        #
        #       real  0m1.069s
        #       user  0m1.040s
        #       sys   0m0.029s
        #
        #   There's no appreciable performance difference between "r" and
        #   "rU" for parsing performance on Python 2.
        #
        # - For Python 3, force the encoding. Forcing the encoding on Python 2
        #   turns strings into Unicode strings, which gets messy. Python 2
        #   doesn't decode regular strings anyway.
        return open(filename, "rU" if mode == "r" else mode) if _IS_PY2 else \
               open(filename, mode, encoding=self._encoding)

    def _check_undef_syms(self):
        # Prints warnings for all references to undefined symbols within the
        # Kconfig files

        def is_num(s):
            # Returns True if the string 's' looks like a number.
            #
            # Internally, all operands in Kconfig are symbols, only undefined symbols
            # (which numbers usually are) get their name as their value.
            #
            # Only hex numbers that start with 0x/0X are classified as numbers.
            # Otherwise, symbols whose names happen to contain only the letters A-F
            # would trigger false positives.

            try:
                int(s)
            except ValueError:
                if not s.startswith(("0x", "0X")):
                    return False

                try:
                    int(s, 16)
                except ValueError:
                    return False

            return True

        for sym in (self.syms.viewvalues if _IS_PY2 else self.syms.values)():
            # - sym.nodes empty means the symbol is undefined (has no
            #   definition locations)
            #
            # - Due to Kconfig internals, numbers show up as undefined Kconfig
            #   symbols, but shouldn't be flagged
            #
            # - The MODULES symbol always exists
            if not sym.nodes and not is_num(sym.name) and \
               sym.name != "MODULES":

                msg = "undefined symbol {}:".format(sym.name)
                for node in self.node_iter():
                    if sym in node.referenced:
                        msg += "\n\n- Referenced at {}:{}:\n\n{}" \
                               .format(node.filename, node.linenr, node)
                self._warn(msg)

    def _warn(self, msg, filename=None, linenr=None):
        # For printing general warnings

        if not self.warn:
            return

        msg = "warning: " + msg
        if filename is not None:
            msg = "{}:{}: {}".format(filename, linenr, msg)

        self.warnings.append(msg)
        if self.warn_to_stderr:
            sys.stderr.write(msg + "\n")


class Symbol(object):
    """
    Represents a configuration symbol:

      (menu)config FOO
          ...

    The following attributes are available. They should be viewed as read-only,
    and some are implemented through @property magic (but are still efficient
    to access due to internal caching).

    Note: Prompts, help texts, and locations are stored in the Symbol's
    MenuNode(s) rather than in the Symbol itself. Check the MenuNode class and
    the Symbol.nodes attribute. This organization matches the C tools.

    name:
      The name of the symbol, e.g. "FOO" for 'config FOO'.

    type:
      The type of the symbol. One of BOOL, TRISTATE, STRING, INT, HEX, UNKNOWN.
      UNKNOWN is for undefined symbols, (non-special) constant symbols, and
      symbols defined without a type.

      When running without modules (MODULES having the value n), TRISTATE
      symbols magically change type to BOOL. This also happens for symbols
      within choices in "y" mode. This matches the C tools, and makes sense for
      menuconfig-like functionality.

    orig_type:
      The type as given in the Kconfig file, without any magic applied. Used
      when printing the symbol.

    tri_value:
      The tristate value of the symbol as an integer. One of 0, 1, 2,
      representing n, m, y. Always 0 (n) for non-bool/tristate symbols.

      This is the symbol value that's used outside of relation expressions
      (A, !A, A && B, A || B).

    str_value:
      The value of the symbol as a string. Gives the value for string/int/hex
      symbols. For bool/tristate symbols, gives "n", "m", or "y".

      This is the symbol value that's used in relational expressions
      (A = B, A != B, etc.)

      Gotcha: For int/hex symbols, the exact format of the value is often
      preserved (e.g. when writing a .config file), hence why you can't get it
      directly as an int. Do int(int_sym.str_value) or
      int(hex_sym.str_value, 16) to get the integer value.

    user_value:
      The user value of the symbol. None if no user value has been assigned
      (via Kconfig.load_config() or Symbol.set_value()).

      Holds 0, 1, or 2 for bool/tristate symbols, and a string for the other
      symbol types.

      WARNING: Do not assign directly to this. It will break things. Use
      Symbol.set_value().

    assignable:
      A tuple containing the tristate user values that can currently be
      assigned to the symbol (that would be respected), ordered from lowest (0,
      representing n) to highest (2, representing y). This corresponds to the
      selections available in the menuconfig interface. The set of assignable
      values is calculated from the symbol's visibility and selects/implies.

      Returns the empty set for non-bool/tristate symbols and for symbols with
      visibility n. The other possible values are (0, 2), (0, 1, 2), (1, 2),
      (1,), and (2,). A (1,) or (2,) result means the symbol is visible but
      "locked" to m or y through a select, perhaps in combination with the
      visibility. menuconfig represents this as -M- and -*-, respectively.

      For string/hex/int symbols, check if Symbol.visibility is non-0 (non-n)
      instead to determine if the value can be changed.

      Some handy 'assignable' idioms:

        # Is 'sym' an assignable (visible) bool/tristate symbol?
        if sym.assignable:
            # What's the highest value it can be assigned? [-1] in Python
            # gives the last element.
            sym_high = sym.assignable[-1]

            # The lowest?
            sym_low = sym.assignable[0]

            # Can the symbol be set to at least m?
            if sym.assignable[-1] >= 1:
                ...

        # Can the symbol be set to m?
        if 1 in sym.assignable:
            ...

    visibility:
      The visibility of the symbol. One of 0, 1, 2, representing n, m, y. See
      the module documentation for an overview of symbol values and visibility.

    config_string:
      The .config assignment string that would get written out for the symbol
      by Kconfig.write_config(). Returns the empty string if no .config
      assignment would get written out.

      In general, visible symbols, symbols with (active) defaults, and selected
      symbols get written out. This includes all non-n-valued bool/tristate
      symbols, and all visible string/int/hex symbols.

      Symbols with the (no longer needed) 'option env=...' option generate no
      configuration output, and neither does the special
      'option defconfig_list' symbol.

      Tip: This field is useful when generating custom configuration output,
      even for non-.config-like formats. To write just the symbols that would
      get written out to .config files, do this:

        if sym.config_string:
            *Write symbol, e.g. by looking sym.str_value*

      This is a superset of the symbols written out by write_autoconf().
      That function skips all n-valued symbols.

      There usually won't be any great harm in just writing all symbols either,
      though you might get some special symbols and possibly some "redundant"
      n-valued symbol entries in there.

    name_and_loc:
      Holds a string like

        "MY_SYMBOL (defined at foo/Kconfig:12, bar/Kconfig:14)"

      , giving the name of the symbol and its definition location(s).

      If the symbol is undefined, the location is given as "(undefined)".

    nodes:
      A list of MenuNodes for this symbol. Will contain a single MenuNode for
      most symbols. Undefined and constant symbols have an empty nodes list.
      Symbols defined in multiple locations get one node for each location.

    choice:
      Holds the parent Choice for choice symbols, and None for non-choice
      symbols. Doubles as a flag for whether a symbol is a choice symbol.

    defaults:
      List of (default, cond) tuples for the symbol's 'default' properties. For
      example, 'default A && B if C || D' is represented as
      ((AND, A, B), (OR, C, D)). If no condition was given, 'cond' is
      self.kconfig.y.

      Note that 'depends on' and parent dependencies are propagated to
      'default' conditions.

    selects:
      List of (symbol, cond) tuples for the symbol's 'select' properties. For
      example, 'select A if B && C' is represented as (A, (AND, B, C)). If no
      condition was given, 'cond' is self.kconfig.y.

      Note that 'depends on' and parent dependencies are propagated to 'select'
      conditions.

    implies:
      Like 'selects', for imply.

    ranges:
      List of (low, high, cond) tuples for the symbol's 'range' properties. For
      example, 'range 1 2 if A' is represented as (1, 2, A). If there is no
      condition, 'cond' is self.kconfig.y.

      Note that 'depends on' and parent dependencies are propagated to 'range'
      conditions.

      Gotcha: 1 and 2 above will be represented as (undefined) Symbols rather
      than plain integers. Undefined symbols get their name as their string
      value, so this works out. The C tools work the same way.

    orig_defaults:
    orig_selects:
    orig_implies:
    orig_ranges:
      See the corresponding attributes on the MenuNode class.

    rev_dep:
      Reverse dependency expression from other symbols selecting this symbol.
      Multiple selections get ORed together. A condition on a select is ANDed
      with the selecting symbol.

      For example, if A has 'select FOO' and B has 'select FOO if C', then
      FOO's rev_dep will be (OR, A, (AND, B, C)).

    weak_rev_dep:
      Like rev_dep, for imply.

    direct_dep:
      The direct ('depends on') dependencies for the symbol, or self.kconfig.y
      if there are no direct dependencies.

      This attribute includes any dependencies from surrounding menus and ifs.
      Those get propagated to the direct dependencies, and the resulting direct
      dependencies in turn get propagated to the conditions of all properties.

      If the symbol is defined in multiple locations, the dependencies from the
      different locations get ORed together.

    referenced:
      A set() with all symbols and choices referenced in the properties and
      property conditions of the symbol.

      Also includes dependencies from surrounding menus and ifs, because those
      get propagated to the symbol (see the 'Intro to symbol values' section in
      the module docstring).

      Choices appear in the dependencies of choice symbols.

      For the following definitions, only B and not C appears in A's
      'referenced'. To get transitive references, you'll have to recursively
      expand 'references' until no new items appear.

        config A
                bool
                depends on B

        config B
                bool
                depends on C

        config C
                bool

      See the Symbol.direct_dep attribute if you're only interested in the
      direct dependencies of the symbol (its 'depends on'). You can extract the
      symbols in it with the global expr_items() function.

    env_var:
      If the Symbol has an 'option env="FOO"' option, this contains the name
      ("FOO") of the environment variable. None for symbols without no
      'option env'.

      'option env="FOO"' acts like a 'default' property whose value is the
      value of $FOO.

      Symbols with 'option env' are never written out to .config files, even if
      they are visible. env_var corresponds to a flag called SYMBOL_AUTO in the
      C implementation.

    is_allnoconfig_y:
      True if the symbol has 'option allnoconfig_y' set on it. This has no
      effect internally (except when printing symbols), but can be checked by
      scripts.

    is_constant:
      True if the symbol is a constant (quoted) symbol.

    kconfig:
      The Kconfig instance this symbol is from.
    """
    __slots__ = (
        "_cached_assignable",
        "_cached_str_val",
        "_cached_tri_val",
        "_cached_vis",
        "_dependents",
        "_old_val",
        "_visited",
        "_was_set",
        "_write_to_conf",
        "choice",
        "defaults",
        "direct_dep",
        "env_var",
        "implies",
        "is_allnoconfig_y",
        "is_constant",
        "kconfig",
        "name",
        "nodes",
        "orig_type",
        "ranges",
        "rev_dep",
        "selects",
        "user_value",
        "weak_rev_dep",
    )

    #
    # Public interface
    #

    @property
    def type(self):
        """
        See the class documentation.
        """
        if self.orig_type is TRISTATE and \
           (self.choice and self.choice.tri_value == 2 or
            not self.kconfig.modules.tri_value):

            return BOOL

        return self.orig_type

    @property
    def str_value(self):
        """
        See the class documentation.
        """
        if self._cached_str_val is not None:
            return self._cached_str_val

        if self.orig_type in _BOOL_TRISTATE:
            # Also calculates the visibility, so invalidation safe
            self._cached_str_val = TRI_TO_STR[self.tri_value]
            return self._cached_str_val

        # As a quirk of Kconfig, undefined symbols get their name as their
        # string value. This is why things like "FOO = bar" work for seeing if
        # FOO has the value "bar".
        if not self.orig_type:  # UNKNOWN
            self._cached_str_val = self.name
            return self.name

        val = ""
        # Warning: See Symbol._rec_invalidate(), and note that this is a hidden
        # function call (property magic)
        vis = self.visibility

        self._write_to_conf = (vis != 0)

        if self.orig_type in _INT_HEX:
            # The C implementation checks the user value against the range in a
            # separate code path (post-processing after loading a .config).
            # Checking all values here instead makes more sense for us. It
            # requires that we check for a range first.

            base = _TYPE_TO_BASE[self.orig_type]

            # Check if a range is in effect
            for low_expr, high_expr, cond in self.ranges:
                if expr_value(cond):
                    has_active_range = True

                    # The zeros are from the C implementation running strtoll()
                    # on empty strings
                    low = int(low_expr.str_value, base) if \
                      _is_base_n(low_expr.str_value, base) else 0
                    high = int(high_expr.str_value, base) if \
                      _is_base_n(high_expr.str_value, base) else 0

                    break
            else:
                has_active_range = False

            # Defaults are used if the symbol is invisible, lacks a user value,
            # or has an out-of-range user value
            use_defaults = True

            if vis and self.user_value:
                user_val = int(self.user_value, base)
                if has_active_range and not low <= user_val <= high:
                    num2str = str if base == 10 else hex
                    self.kconfig._warn(
                        "user value {} on the {} symbol {} ignored due to "
                        "being outside the active range ([{}, {}]) -- falling "
                        "back on defaults"
                        .format(num2str(user_val), TYPE_TO_STR[self.orig_type],
                                self.name_and_loc,
                                num2str(low), num2str(high)))
                else:
                    # If the user value is well-formed and satisfies range
                    # contraints, it is stored in exactly the same form as
                    # specified in the assignment (with or without "0x", etc.)
                    val = self.user_value
                    use_defaults = False

            if use_defaults:
                # No user value or invalid user value. Look at defaults.

                # Used to implement the warning below
                has_default = False

                for sym, cond in self.defaults:
                    if expr_value(cond):
                        has_default = self._write_to_conf = True

                        val = sym.str_value

                        if _is_base_n(val, base):
                            val_num = int(val, base)
                        else:
                            val_num = 0  # strtoll() on empty string

                        break
                else:
                    val_num = 0  # strtoll() on empty string

                # This clamping procedure runs even if there's no default
                if has_active_range:
                    clamp = None
                    if val_num < low:
                        clamp = low
                    elif val_num > high:
                        clamp = high

                    if clamp is not None:
                        # The value is rewritten to a standard form if it is
                        # clamped
                        val = str(clamp) \
                              if self.orig_type is INT else \
                              hex(clamp)

                        if has_default:
                            num2str = str if base == 10 else hex
                            self.kconfig._warn(
                                "default value {} on {} clamped to {} due to "
                                "being outside the active range ([{}, {}])"
                                .format(val_num, self.name_and_loc,
                                        num2str(clamp), num2str(low),
                                        num2str(high)))

        elif self.orig_type is STRING:
            if vis and self.user_value is not None:
                # If the symbol is visible and has a user value, use that
                val = self.user_value
            else:
                # Otherwise, look at defaults
                for sym, cond in self.defaults:
                    if expr_value(cond):
                        val = sym.str_value
                        self._write_to_conf = True
                        break

        # env_var corresponds to SYMBOL_AUTO in the C implementation, and is
        # also set on the defconfig_list symbol there. Test for the
        # defconfig_list symbol explicitly instead here, to avoid a nonsensical
        # env_var setting and the defconfig_list symbol being printed
        # incorrectly. This code is pretty cold anyway.
        if self.env_var is not None or self is self.kconfig.defconfig_list:
            self._write_to_conf = False

        self._cached_str_val = val
        return val

    @property
    def tri_value(self):
        """
        See the class documentation.
        """
        if self._cached_tri_val is not None:
            return self._cached_tri_val

        if self.orig_type not in _BOOL_TRISTATE:
            if self.orig_type:  # != UNKNOWN
                # Would take some work to give the location here
                self.kconfig._warn(
                    "The {} symbol {} is being evaluated in a logical context "
                    "somewhere. It will always evaluate to n."
                    .format(TYPE_TO_STR[self.orig_type], self.name_and_loc))

            self._cached_tri_val = 0
            return 0

        # Warning: See Symbol._rec_invalidate(), and note that this is a hidden
        # function call (property magic)
        vis = self.visibility
        self._write_to_conf = (vis != 0)

        val = 0

        if not self.choice:
            # Non-choice symbol

            if vis and self.user_value is not None:
                # If the symbol is visible and has a user value, use that
                val = min(self.user_value, vis)

            else:
                # Otherwise, look at defaults and weak reverse dependencies
                # (implies)

                for default, cond in self.defaults:
                    dep_val = expr_value(cond)
                    if dep_val:
                        val = min(expr_value(default), dep_val)
                        if val:
                            self._write_to_conf = True
                        break

                # Weak reverse dependencies are only considered if our
                # direct dependencies are met
                dep_val = expr_value(self.weak_rev_dep)
                if dep_val and expr_value(self.direct_dep):
                    val = max(dep_val, val)
                    self._write_to_conf = True

            # Reverse (select-related) dependencies take precedence
            dep_val = expr_value(self.rev_dep)
            if dep_val:
                if expr_value(self.direct_dep) < dep_val:
                    self._warn_select_unsatisfied_deps()

                val = max(dep_val, val)
                self._write_to_conf = True

            # m is promoted to y for (1) bool symbols and (2) symbols with a
            # weak_rev_dep (from imply) of y
            if val == 1 and \
               (self.type is BOOL or expr_value(self.weak_rev_dep) == 2):
                val = 2

        elif vis == 2:
            # Visible choice symbol in y-mode choice. The choice mode limits
            # the visibility of choice symbols, so it's sufficient to just
            # check the visibility of the choice symbols themselves.
            val = 2 if self.choice.selection is self else 0

        elif vis and self.user_value:
            # Visible choice symbol in m-mode choice, with set non-0 user value
            val = 1

        self._cached_tri_val = val
        return val

    @property
    def assignable(self):
        """
        See the class documentation.
        """
        if self._cached_assignable is None:
            self._cached_assignable = self._assignable()
        return self._cached_assignable

    @property
    def visibility(self):
        """
        See the class documentation.
        """
        if self._cached_vis is None:
            self._cached_vis = _visibility(self)
        return self._cached_vis

    @property
    def config_string(self):
        """
        See the class documentation.
        """
        # _write_to_conf is determined when the value is calculated. This is a
        # hidden function call due to property magic.
        val = self.str_value
        if not self._write_to_conf:
            return ""

        if self.orig_type in _BOOL_TRISTATE:
            return "{}{}={}\n" \
                   .format(self.kconfig.config_prefix, self.name, val) \
                   if val != "n" else \
                   "# {}{} is not set\n" \
                   .format(self.kconfig.config_prefix, self.name)

        if self.orig_type in _INT_HEX:
            return "{}{}={}\n" \
                   .format(self.kconfig.config_prefix, self.name, val)

        # sym.orig_type is STRING
        return '{}{}="{}"\n' \
               .format(self.kconfig.config_prefix, self.name, escape(val))

    @property
    def name_and_loc(self):
        """
        See the class documentation.
        """
        return self.name + " " + _locs(self)

    def set_value(self, value):
        """
        Sets the user value of the symbol.

        Equal in effect to assigning the value to the symbol within a .config
        file. For bool and tristate symbols, use the 'assignable' attribute to
        check which values can currently be assigned. Setting values outside
        'assignable' will cause Symbol.user_value to differ from
        Symbol.str/tri_value (be truncated down or up).

        Setting a choice symbol to 2 (y) sets Choice.user_selection to the
        choice symbol in addition to setting Symbol.user_value.
        Choice.user_selection is considered when the choice is in y mode (the
        "normal" mode).

        Other symbols that depend (possibly indirectly) on this symbol are
        automatically recalculated to reflect the assigned value.

        value:
          The user value to give to the symbol. For bool and tristate symbols,
          n/m/y can be specified either as 0/1/2 (the usual format for tristate
          values in Kconfiglib) or as one of the strings "n", "m", or "y". For
          other symbol types, pass a string.

          Note that the value for an int/hex symbol is passed as a string, e.g.
          "123" or "0x0123". The format of this string is preserved in the
          output.

          Values that are invalid for the type (such as "foo" or 1 (m) for a
          BOOL or "0x123" for an INT) are ignored and won't be stored in
          Symbol.user_value. Kconfiglib will print a warning by default for
          invalid assignments, and set_value() will return False.

        Returns True if the value is valid for the type of the symbol, and
        False otherwise. This only looks at the form of the value. For BOOL and
        TRISTATE symbols, check the Symbol.assignable attribute to see what
        values are currently in range and would actually be reflected in the
        value of the symbol. For other symbol types, check whether the
        visibility is non-n.
        """
        if self.orig_type in _BOOL_TRISTATE and value in STR_TO_TRI:
            value = STR_TO_TRI[value]

        # If the new user value matches the old, nothing changes, and we can
        # avoid invalidating cached values.
        #
        # This optimization is skipped for choice symbols: Setting a choice
        # symbol's user value to y might change the state of the choice, so it
        # wouldn't be safe (symbol user values always match the values set in a
        # .config file or via set_value(), and are never implicitly updated).
        if value == self.user_value and not self.choice:
            self._was_set = True
            return True

        # Check if the value is valid for our type
        if not (self.orig_type is BOOL     and value in (2, 0)     or
                self.orig_type is TRISTATE and value in TRI_TO_STR or
                value.__class__ is str and
                (self.orig_type is STRING                        or
                 self.orig_type is INT and _is_base_n(value, 10) or
                 self.orig_type is HEX and _is_base_n(value, 16)
                                       and int(value, 16) >= 0)):

            # Display tristate values as n, m, y in the warning
            self.kconfig._warn(
                "the value {} is invalid for {}, which has type {} -- "
                "assignment ignored"
                .format(TRI_TO_STR[value] if value in TRI_TO_STR else
                            "'{}'".format(value),
                        self.name_and_loc, TYPE_TO_STR[self.orig_type]))

            return False

        self.user_value = value
        self._was_set = True

        if self.choice and value == 2:
            # Setting a choice symbol to y makes it the user selection of the
            # choice. Like for symbol user values, the user selection is not
            # guaranteed to match the actual selection of the choice, as
            # dependencies come into play.
            self.choice.user_selection = self
            self.choice._was_set = True
            self.choice._rec_invalidate()
        else:
            self._rec_invalidate_if_has_prompt()

        return True

    def unset_value(self):
        """
        Removes any user value from the symbol, as if the symbol had never
        gotten a user value via Kconfig.load_config() or Symbol.set_value().
        """
        if self.user_value is not None:
            self.user_value = None
            self._rec_invalidate_if_has_prompt()

    @property
    def referenced(self):
        """
        See the class documentation.
        """
        return {item for node in self.nodes for item in node.referenced}

    @property
    def orig_defaults(self):
        """
        See the class documentation.
        """
        return [d for node in self.nodes for d in node.orig_defaults]

    @property
    def orig_selects(self):
        """
        See the class documentation.
        """
        return [s for node in self.nodes for s in node.orig_selects]

    @property
    def orig_implies(self):
        """
        See the class documentation.
        """
        return [i for node in self.nodes for i in node.orig_implies]

    @property
    def orig_ranges(self):
        """
        See the class documentation.
        """
        return [r for node in self.nodes for r in node.orig_ranges]

    def __repr__(self):
        """
        Returns a string with information about the symbol (including its name,
        value, visibility, and location(s)) when it is evaluated on e.g. the
        interactive Python prompt.
        """
        fields = ["symbol " + self.name, TYPE_TO_STR[self.type]]
        add = fields.append

        for node in self.nodes:
            if node.prompt:
                add('"{}"'.format(node.prompt[0]))

        # Only add quotes for non-bool/tristate symbols
        add("value " + (self.str_value if self.orig_type in _BOOL_TRISTATE
                        else '"{}"'.format(self.str_value)))

        if not self.is_constant:
            # These aren't helpful to show for constant symbols

            if self.user_value is not None:
                # Only add quotes for non-bool/tristate symbols
                add("user value " + (TRI_TO_STR[self.user_value]
                                     if self.orig_type in _BOOL_TRISTATE
                                     else '"{}"'.format(self.user_value)))

            add("visibility " + TRI_TO_STR[self.visibility])

            if self.choice:
                add("choice symbol")

            if self.is_allnoconfig_y:
                add("allnoconfig_y")

            if self is self.kconfig.defconfig_list:
                add("is the defconfig_list symbol")

            if self.env_var is not None:
                add("from environment variable " + self.env_var)

            if self is self.kconfig.modules:
                add("is the modules symbol")

            add("direct deps " + TRI_TO_STR[expr_value(self.direct_dep)])

        if self.nodes:
            for node in self.nodes:
                add("{}:{}".format(node.filename, node.linenr))
        else:
            add("constant" if self.is_constant else "undefined")

        return "<{}>".format(", ".join(fields))

    def __str__(self):
        """
        Returns a string representation of the symbol when it is printed.
        Matches the Kconfig format, with any parent dependencies propagated to
        the 'depends on' condition.

        The string is constructed by joining the strings returned by
        MenuNode.__str__() for each of the symbol's menu nodes, so symbols
        defined in multiple locations will return a string with all
        definitions.

        The returned string does not end in a newline. An empty string is
        returned for undefined and constant symbols.
        """
        return self.custom_str(standard_sc_expr_str)

    def custom_str(self, sc_expr_str_fn):
        """
        Works like Symbol.__str__(), but allows a custom format to be used for
        all symbol/choice references. See expr_str().
        """
        return "\n\n".join(node.custom_str(sc_expr_str_fn)
                           for node in self.nodes)

    #
    # Private methods
    #

    def __init__(self):
        """
        Symbol constructor -- not intended to be called directly by Kconfiglib
        clients.
        """
        # These attributes are always set on the instance from outside and
        # don't need defaults:
        #   kconfig
        #   direct_dep
        #   is_constant
        #   name
        #   rev_dep
        #   weak_rev_dep

        # - UNKNOWN == 0
        # - _visited is used during tree iteration and dep. loop detection
        self.orig_type = self._visited = 0

        self.nodes = []

        self.defaults = []
        self.selects = []
        self.implies = []
        self.ranges = []

        self.user_value = \
        self.choice = \
        self.env_var = \
        self._cached_str_val = self._cached_tri_val = self._cached_vis = \
        self._cached_assignable = None

        # _write_to_conf is calculated along with the value. If True, the
        # Symbol gets a .config entry.

        self.is_allnoconfig_y = \
        self._was_set = \
        self._write_to_conf = False

        # See Kconfig._build_dep()
        self._dependents = set()

    def _assignable(self):
        # Worker function for the 'assignable' attribute

        if self.orig_type not in _BOOL_TRISTATE:
            return ()

        # Warning: See Symbol._rec_invalidate(), and note that this is a hidden
        # function call (property magic)
        vis = self.visibility
        if not vis:
            return ()

        rev_dep_val = expr_value(self.rev_dep)

        if vis == 2:
            if self.choice:
                return (2,)

            if not rev_dep_val:
                if self.type is BOOL or expr_value(self.weak_rev_dep) == 2:
                    return (0, 2)
                return (0, 1, 2)

            if rev_dep_val == 2:
                return (2,)

            # rev_dep_val == 1

            if self.type is BOOL or expr_value(self.weak_rev_dep) == 2:
                return (2,)
            return (1, 2)

        # vis == 1

        # Must be a tristate here, because bool m visibility gets promoted to y

        if not rev_dep_val:
            return (0, 1) if expr_value(self.weak_rev_dep) != 2 else (0, 2)

        if rev_dep_val == 2:
            return (2,)

        # vis == rev_dep_val == 1

        return (1,)

    def _invalidate(self):
        # Marks the symbol as needing to be recalculated

        self._cached_str_val = self._cached_tri_val = self._cached_vis = \
        self._cached_assignable = None

    def _rec_invalidate(self):
        # Invalidates the symbol and all items that (possibly) depend on it

        if self is self.kconfig.modules:
            # Invalidating MODULES has wide-ranging effects
            self.kconfig._invalidate_all()
        else:
            self._invalidate()

            for item in self._dependents:
                # _cached_vis doubles as a flag that tells us whether 'item'
                # has cached values, because it's calculated as a side effect
                # of calculating all other (non-constant) cached values.
                #
                # If item._cached_vis is None, it means there can't be cached
                # values on other items that depend on 'item', because if there
                # were, some value on 'item' would have been calculated and
                # item._cached_vis set as a side effect. It's therefore safe to
                # stop the invalidation at symbols with _cached_vis None.
                #
                # This approach massively speeds up scripts that set a lot of
                # values, vs simply invalidating all possibly dependent symbols
                # (even when you already have a list of all the dependent
                # symbols, because some symbols get huge dependency trees).
                #
                # This gracefully handles dependency loops too, which is nice
                # for choices, where the choice depends on the choice symbols
                # and vice versa.
                if item._cached_vis is not None:
                    item._rec_invalidate()

    def _rec_invalidate_if_has_prompt(self):
        # Invalidates the symbol and its dependent symbols, but only if the
        # symbol has a prompt. User values never have an effect on promptless
        # symbols, so we skip invalidation for them as an optimization.
        #
        # This also prevents constant (quoted) symbols from being invalidated
        # if set_value() is called on them, which would make them lose their
        # value and break things.
        #
        # Prints a warning if the symbol has no prompt. In some contexts (e.g.
        # when loading a .config files) assignments to promptless symbols are
        # normal and expected, so the warning can be disabled.

        for node in self.nodes:
            if node.prompt:
                self._rec_invalidate()
                return

        if self.kconfig._warn_assign_no_prompt:
            self.kconfig._warn(self.name_and_loc + " has no prompt, meaning "
                               "user values have no effect on it")

    def _str_default(self):
        # write_min_config() helper function. Returns the value the symbol
        # would get from defaults if it didn't have a user value. Uses exactly
        # the same algorithm as the C implementation (though a bit cleaned up),
        # for compatibility.

        if self.orig_type in _BOOL_TRISTATE:
            val = 0

            # Defaults, selects, and implies do not affect choice symbols
            if not self.choice:
                for default, cond in self.defaults:
                    cond_val = expr_value(cond)
                    if cond_val:
                        val = min(expr_value(default), cond_val)
                        break

                val = max(expr_value(self.rev_dep),
                          expr_value(self.weak_rev_dep),
                          val)

                # Transpose mod to yes if type is bool (possibly due to modules
                # being disabled)
                if val == 1 and self.type is BOOL:
                    val = 2

            return TRI_TO_STR[val]

        if self.orig_type:  # STRING/INT/HEX
            for default, cond in self.defaults:
                if expr_value(cond):
                    return default.str_value

        return ""

    def _warn_select_unsatisfied_deps(self):
        # Helper for printing an informative warning when a symbol with
        # unsatisfied direct dependencies (dependencies from 'depends on', ifs,
        # and menus) is selected by some other symbol. Also warn if a symbol
        # whose direct dependencies evaluate to m is selected to y.

        msg = "{} has direct dependencies {} with value {}, but is " \
              "currently being {}-selected by the following symbols:" \
              .format(self.name_and_loc, expr_str(self.direct_dep),
                      TRI_TO_STR[expr_value(self.direct_dep)],
                      TRI_TO_STR[expr_value(self.rev_dep)])

        # The reverse dependencies from each select are ORed together
        for select in split_expr(self.rev_dep, OR):
            if expr_value(select) <= expr_value(self.direct_dep):
                # Only include selects that exceed the direct dependencies
                continue

            # - 'select A if B' turns into A && B
            # - 'select A' just turns into A
            #
            # In both cases, we can split on AND and pick the first operand
            selecting_sym = split_expr(select, AND)[0]

            msg += "\n - {}, with value {}, direct dependencies {} " \
                   "(value: {})" \
                   .format(selecting_sym.name_and_loc,
                           selecting_sym.str_value,
                           expr_str(selecting_sym.direct_dep),
                           TRI_TO_STR[expr_value(selecting_sym.direct_dep)])

            if select.__class__ is tuple:
                msg += ", and select condition {} (value: {})" \
                       .format(expr_str(select[2]),
                               TRI_TO_STR[expr_value(select[2])])

        self.kconfig._warn(msg)


class Choice(object):
    """
    Represents a choice statement:

      choice
          ...
      endchoice

    The following attributes are available on Choice instances. They should be
    treated as read-only, and some are implemented through @property magic (but
    are still efficient to access due to internal caching).

    Note: Prompts, help texts, and locations are stored in the Choice's
    MenuNode(s) rather than in the Choice itself. Check the MenuNode class and
    the Choice.nodes attribute. This organization matches the C tools.

    name:
      The name of the choice, e.g. "FOO" for 'choice FOO', or None if the
      Choice has no name.

    type:
      The type of the choice. One of BOOL, TRISTATE, UNKNOWN. UNKNOWN is for
      choices defined without a type where none of the contained symbols have a
      type either (otherwise the choice inherits the type of the first symbol
      defined with a type).

      When running without modules (CONFIG_MODULES=n), TRISTATE choices
      magically change type to BOOL. This matches the C tools, and makes sense
      for menuconfig-like functionality.

    orig_type:
      The type as given in the Kconfig file, without any magic applied. Used
      when printing the choice.

    tri_value:
      The tristate value (mode) of the choice. A choice can be in one of three
      modes:

        0 (n) - The choice is disabled and no symbols can be selected. For
                visible choices, this mode is only possible for choices with
                the 'optional' flag set (see kconfig-language.txt).

        1 (m) - Any number of choice symbols can be set to m, the rest will
                be n.

        2 (y) - One symbol will be y, the rest n.

      Only tristate choices can be in m mode. The visibility of the choice is
      an upper bound on the mode, and the mode in turn is an upper bound on the
      visibility of the choice symbols.

      To change the mode, use Choice.set_value().

      Implementation note:
        The C tools internally represent choices as a type of symbol, with
        special-casing in many code paths. This is why there is a lot of
        similarity to Symbol. The value (mode) of a choice is really just a
        normal symbol value, and an implicit reverse dependency forces its
        lower bound to m for visible non-optional choices (the reverse
        dependency is 'm && <visibility>').

        Symbols within choices get the choice propagated as a dependency to
        their properties. This turns the mode of the choice into an upper bound
        on e.g. the visibility of choice symbols, and explains the gotcha
        related to printing choice symbols mentioned in the module docstring.

        Kconfiglib uses a separate Choice class only because it makes the code
        and interface less confusing (especially in a user-facing interface).
        Corresponding attributes have the same name in the Symbol and Choice
        classes, for consistency and compatibility.

    str_value:
      Like choice.tri_value, but gives the value as one of the strings
      "n", "m", or "y"

    user_value:
      The value (mode) selected by the user through Choice.set_value(). Either
      0, 1, or 2, or None if the user hasn't selected a mode. See
      Symbol.user_value.

      WARNING: Do not assign directly to this. It will break things. Use
      Choice.set_value() instead.

    assignable:
      See the symbol class documentation. Gives the assignable values (modes).

    selection:
      The Symbol instance of the currently selected symbol. None if the Choice
      is not in y mode or has no selected symbol (due to unsatisfied
      dependencies on choice symbols).

      WARNING: Do not assign directly to this. It will break things. Call
      sym.set_value(2) on the choice symbol you want to select instead.

    user_selection:
      The symbol selected by the user (by setting it to y). Ignored if the
      choice is not in y mode, but still remembered so that the choice "snaps
      back" to the user selection if the mode is changed back to y. This might
      differ from 'selection' due to unsatisfied dependencies.

      WARNING: Do not assign directly to this. It will break things. Call
      sym.set_value(2) on the choice symbol to be selected instead.

    visibility:
      See the Symbol class documentation. Acts on the value (mode).

    name_and_loc:
      Holds a string like

        "<choice MY_CHOICE> (defined at foo/Kconfig:12)"

      , giving the name of the choice and its definition location(s). If the
      choice has no name (isn't defined with 'choice MY_CHOICE'), then it will
      be shown as "<choice>" before the list of locations (always a single one
      in that case).

    syms:
      List of symbols contained in the choice.

      Obscure gotcha: If a symbol depends on the previous symbol within a
      choice so that an implicit menu is created, it won't be a choice symbol,
      and won't be included in 'syms'.

    nodes:
      A list of MenuNodes for this choice. In practice, the list will probably
      always contain a single MenuNode, but it is possible to give a choice a
      name and define it in multiple locations.

    defaults:
      List of (symbol, cond) tuples for the choice's 'defaults' properties. For
      example, 'default A if B && C' is represented as (A, (AND, B, C)). If
      there is no condition, 'cond' is self.kconfig.y.

      Note that 'depends on' and parent dependencies are propagated to
      'default' conditions.

    orig_defaults:
      See the corresponding attribute on the MenuNode class.

    direct_dep:
      See Symbol.direct_dep.

    referenced:
      A set() with all symbols referenced in the properties and property
      conditions of the choice.

      Also includes dependencies from surrounding menus and ifs, because those
      get propagated to the choice (see the 'Intro to symbol values' section in
      the module docstring).

    is_optional:
      True if the choice has the 'optional' flag set on it and can be in
      n mode.

    kconfig:
      The Kconfig instance this choice is from.
    """
    __slots__ = (
        "_cached_assignable",
        "_cached_selection",
        "_cached_vis",
        "_dependents",
        "_visited",
        "_was_set",
        "defaults",
        "direct_dep",
        "is_constant",
        "is_optional",
        "kconfig",
        "name",
        "nodes",
        "orig_type",
        "syms",
        "user_selection",
        "user_value",
    )

    #
    # Public interface
    #

    @property
    def type(self):
        """
        Returns the type of the choice. See Symbol.type.
        """
        if self.orig_type is TRISTATE and not self.kconfig.modules.tri_value:
            return BOOL
        return self.orig_type

    @property
    def str_value(self):
        """
        See the class documentation.
        """
        return TRI_TO_STR[self.tri_value]

    @property
    def tri_value(self):
        """
        See the class documentation.
        """
        # This emulates a reverse dependency of 'm && visibility' for
        # non-optional choices, which is how the C implementation does it

        val = 0 if self.is_optional else 1

        if self.user_value is not None:
            val = max(val, self.user_value)

        # Warning: See Symbol._rec_invalidate(), and note that this is a hidden
        # function call (property magic)
        val = min(val, self.visibility)

        # Promote m to y for boolean choices
        return 2 if val == 1 and self.type is BOOL else val

    @property
    def assignable(self):
        """
        See the class documentation.
        """
        if self._cached_assignable is None:
            self._cached_assignable = self._assignable()
        return self._cached_assignable

    @property
    def visibility(self):
        """
        See the class documentation.
        """
        if self._cached_vis is None:
            self._cached_vis = _visibility(self)
        return self._cached_vis

    @property
    def name_and_loc(self):
        """
        See the class documentation.
        """
        # Reuse the expression format, which is '<choice (name, if any)>'.
        return standard_sc_expr_str(self) + " " + _locs(self)

    @property
    def selection(self):
        """
        See the class documentation.
        """
        if self._cached_selection is _NO_CACHED_SELECTION:
            self._cached_selection = self._selection()
        return self._cached_selection

    def set_value(self, value):
        """
        Sets the user value (mode) of the choice. Like for Symbol.set_value(),
        the visibility might truncate the value. Choices without the 'optional'
        attribute (is_optional) can never be in n mode, but 0/"n" is still
        accepted since it's not a malformed value (though it will have no
        effect).

        Returns True if the value is valid for the type of the choice, and
        False otherwise. This only looks at the form of the value. Check the
        Choice.assignable attribute to see what values are currently in range
        and would actually be reflected in the mode of the choice.
        """
        if value in STR_TO_TRI:
            value = STR_TO_TRI[value]

        if value == self.user_value:
            # We know the value must be valid if it was successfully set
            # previously
            self._was_set = True
            return True

        if not (self.orig_type is BOOL     and value in (2, 0) or
                self.orig_type is TRISTATE and value in TRI_TO_STR):

            # Display tristate values as n, m, y in the warning
            self.kconfig._warn(
                "the value {} is invalid for {}, which has type {} -- "
                "assignment ignored"
                .format(TRI_TO_STR[value] if value in TRI_TO_STR else
                            "'{}'".format(value),
                        self.name_and_loc, TYPE_TO_STR[self.orig_type]))

            return False

        self.user_value = value
        self._was_set = True
        self._rec_invalidate()

        return True

    def unset_value(self):
        """
        Resets the user value (mode) and user selection of the Choice, as if
        the user had never touched the mode or any of the choice symbols.
        """
        if self.user_value is not None or self.user_selection:
            self.user_value = self.user_selection = None
            self._rec_invalidate()

    @property
    def referenced(self):
        """
        See the class documentation.
        """
        return {item for node in self.nodes for item in node.referenced}

    @property
    def orig_defaults(self):
        """
        See the class documentation.
        """
        return [d for node in self.nodes for d in node.orig_defaults]

    def __repr__(self):
        """
        Returns a string with information about the choice when it is evaluated
        on e.g. the interactive Python prompt.
        """
        fields = ["choice " + self.name if self.name else "choice",
                  TYPE_TO_STR[self.type]]
        add = fields.append

        for node in self.nodes:
            if node.prompt:
                add('"{}"'.format(node.prompt[0]))

        add("mode " + self.str_value)

        if self.user_value is not None:
            add('user mode {}'.format(TRI_TO_STR[self.user_value]))

        if self.selection:
            add("{} selected".format(self.selection.name))

        if self.user_selection:
            user_sel_str = "{} selected by user" \
                           .format(self.user_selection.name)

            if self.selection is not self.user_selection:
                user_sel_str += " (overridden)"

            add(user_sel_str)

        add("visibility " + TRI_TO_STR[self.visibility])

        if self.is_optional:
            add("optional")

        for node in self.nodes:
            add("{}:{}".format(node.filename, node.linenr))

        return "<{}>".format(", ".join(fields))

    def __str__(self):
        """
        Returns a string representation of the choice when it is printed.
        Matches the Kconfig format (though without the contained choice
        symbols), with any parent dependencies propagated to the 'depends on'
        condition.

        The returned string does not end in a newline.

        See Symbol.__str__() as well.
        """
        return self.custom_str(standard_sc_expr_str)

    def custom_str(self, sc_expr_str_fn):
        """
        Works like Choice.__str__(), but allows a custom format to be used for
        all symbol/choice references. See expr_str().
        """
        return "\n\n".join(node.custom_str(sc_expr_str_fn)
                           for node in self.nodes)

    #
    # Private methods
    #

    def __init__(self):
        """
        Choice constructor -- not intended to be called directly by Kconfiglib
        clients.
        """
        # These attributes are always set on the instance from outside and
        # don't need defaults:
        #   direct_dep
        #   kconfig

        # - UNKNOWN == 0
        # - _visited is used during dep. loop detection
        self.orig_type = self._visited = 0

        self.nodes = []

        self.syms = []
        self.defaults = []

        self.name = \
        self.user_value = self.user_selection = \
        self._cached_vis = self._cached_assignable = None

        self._cached_selection = _NO_CACHED_SELECTION

        # is_constant is checked by _depend_on(). Just set it to avoid having
        # to special-case choices.
        self.is_constant = self.is_optional = False

        # See Kconfig._build_dep()
        self._dependents = set()

    def _assignable(self):
        # Worker function for the 'assignable' attribute

        # Warning: See Symbol._rec_invalidate(), and note that this is a hidden
        # function call (property magic)
        vis = self.visibility

        if not vis:
            return ()

        if vis == 2:
            if not self.is_optional:
                return (2,) if self.type is BOOL else (1, 2)
            return (0, 2) if self.type is BOOL else (0, 1, 2)

        # vis == 1

        return (0, 1) if self.is_optional else (1,)

    def _selection(self):
        # Worker function for the 'selection' attribute

        # Warning: See Symbol._rec_invalidate(), and note that this is a hidden
        # function call (property magic)
        if self.tri_value != 2:
            # Not in y mode, so no selection
            return None

        # Use the user selection if it's visible
        if self.user_selection and self.user_selection.visibility:
            return self.user_selection

        # Otherwise, check if we have a default
        return self._selection_from_defaults()

    def _selection_from_defaults(self):
        # Check if we have a default
        for sym, cond in self.defaults:
            # The default symbol must be visible too
            if expr_value(cond) and sym.visibility:
                return sym

        # Otherwise, pick the first visible symbol, if any
        for sym in self.syms:
            if sym.visibility:
                return sym

        # Couldn't find a selection
        return None

    def _invalidate(self):
        self._cached_vis = self._cached_assignable = None
        self._cached_selection = _NO_CACHED_SELECTION

    def _rec_invalidate(self):
        # See Symbol._rec_invalidate()

        self._invalidate()

        for item in self._dependents:
            if item._cached_vis is not None:
                item._rec_invalidate()


class MenuNode(object):
    """
    Represents a menu node in the configuration. This corresponds to an entry
    in e.g. the 'make menuconfig' interface, though non-visible choices, menus,
    and comments also get menu nodes. If a symbol or choice is defined in
    multiple locations, it gets one menu node for each location.

    The top-level menu node, corresponding to the implicit top-level menu, is
    available in Kconfig.top_node.

    The menu nodes for a Symbol or Choice can be found in the
    Symbol/Choice.nodes attribute. Menus and comments are represented as plain
    menu nodes, with their text stored in the prompt attribute (prompt[0]).
    This mirrors the C implementation.

    The following attributes are available on MenuNode instances. They should
    be viewed as read-only.

    item:
      Either a Symbol, a Choice, or one of the constants MENU and COMMENT.
      Menus and comments are represented as plain menu nodes. Ifs are collapsed
      (matching the C implementation) and do not appear in the final menu tree.

    next:
      The following menu node. None if there is no following node.

    list:
      The first child menu node. None if there are no children.

      Choices and menus naturally have children, but Symbols can also have
      children because of menus created automatically from dependencies (see
      kconfig-language.txt).

    parent:
      The parent menu node. None if there is no parent.

    prompt:
      A (string, cond) tuple with the prompt for the menu node and its
      conditional expression (which is self.kconfig.y if there is no
      condition). None if there is no prompt.

      For symbols and choices, the prompt is stored in the MenuNode rather than
      the Symbol or Choice instance. For menus and comments, the prompt holds
      the text.

    defaults:
      The 'default' properties for this particular menu node. See
      symbol.defaults.

      When evaluating defaults, you should use Symbol/Choice.defaults instead,
      as it include properties from all menu nodes (a symbol/choice can have
      multiple definition locations/menu nodes). MenuNode.defaults is meant for
      documentation generation.

    selects:
      Like MenuNode.defaults, for selects.

    implies:
      Like MenuNode.defaults, for implies.

    ranges:
      Like MenuNode.defaults, for ranges.

    orig_prompt:
    orig_defaults:
    orig_selects:
    orig_implies:
    orig_ranges:
      These work the like the corresponding attributes without orig_*, but omit
      any dependencies propagated from 'depends on' and surrounding 'if's (the
      direct dependencies, stored in MenuNode.dep).

      One use for this is generating less cluttered documentation, by only
      showing the direct dependencies in one place.

    help:
      The help text for the menu node for Symbols and Choices. None if there is
      no help text. Always stored in the node rather than the Symbol or Choice.
      It is possible to have a separate help text at each location if a symbol
      is defined in multiple locations.

      Trailing whitespace (including a final newline) is stripped from the help
      text. This was not the case before Kconfiglib 10.21.0, where the format
      was undocumented.

    dep:
      The direct ('depends on') dependencies for the menu node, or
      self.kconfig.y if there are no direct dependencies.

      This attribute includes any dependencies from surrounding menus and ifs.
      Those get propagated to the direct dependencies, and the resulting direct
      dependencies in turn get propagated to the conditions of all properties.

      If a symbol or choice is defined in multiple locations, only the
      properties defined at a particular location get the corresponding
      MenuNode.dep dependencies propagated to them.

    visibility:
      The 'visible if' dependencies for the menu node (which must represent a
      menu), or self.kconfig.y if there are no 'visible if' dependencies.
      'visible if' dependencies are recursively propagated to the prompts of
      symbols and choices within the menu.

    referenced:
      A set() with all symbols and choices referenced in the properties and
      property conditions of the menu node.

      Also includes dependencies inherited from surrounding menus and ifs.
      Choices appear in the dependencies of choice symbols.

    is_menuconfig:
      Set to True if the children of the menu node should be displayed in a
      separate menu. This is the case for the following items:

        - Menus (node.item == MENU)

        - Choices

        - Symbols defined with the 'menuconfig' keyword. The children come from
          implicitly created submenus, and should be displayed in a separate
          menu rather than being indented.

      'is_menuconfig' is just a hint on how to display the menu node. It's
      ignored internally by Kconfiglib, except when printing symbols.

    filename/linenr:
      The location where the menu node appears. The filename is relative to
      $srctree (or to the current directory if $srctree isn't set), except
      absolute paths are used for paths outside $srctree.

    include_path:
      A tuple of (filename, linenr) tuples, giving the locations of the
      'source' statements via which the Kconfig file containing this menu node
      was included. The first element is the location of the 'source' statement
      in the top-level Kconfig file passed to Kconfig.__init__(), etc.

      Note that the Kconfig file of the menu node itself isn't included. Check
      'filename' and 'linenr' for that.

    kconfig:
      The Kconfig instance the menu node is from.
    """
    __slots__ = (
        "dep",
        "filename",
        "help",
        "include_path",
        "is_menuconfig",
        "item",
        "kconfig",
        "linenr",
        "list",
        "next",
        "parent",
        "prompt",
        "visibility",

        # Properties
        "defaults",
        "selects",
        "implies",
        "ranges",
    )

    def __init__(self):
        # Properties defined on this particular menu node. A local 'depends on'
        # only applies to these, in case a symbol is defined in multiple
        # locations.
        self.defaults = []
        self.selects = []
        self.implies = []
        self.ranges = []

    @property
    def orig_prompt(self):
        """
        See the class documentation.
        """
        if not self.prompt:
            return None
        return (self.prompt[0], self._strip_dep(self.prompt[1]))

    @property
    def orig_defaults(self):
        """
        See the class documentation.
        """
        return [(default, self._strip_dep(cond))
                for default, cond in self.defaults]

    @property
    def orig_selects(self):
        """
        See the class documentation.
        """
        return [(select, self._strip_dep(cond))
                for select, cond in self.selects]

    @property
    def orig_implies(self):
        """
        See the class documentation.
        """
        return [(imply, self._strip_dep(cond))
                for imply, cond in self.implies]

    @property
    def orig_ranges(self):
        """
        See the class documentation.
        """
        return [(low, high, self._strip_dep(cond))
                for low, high, cond in self.ranges]

    @property
    def referenced(self):
        """
        See the class documentation.
        """
        # self.dep is included to catch dependencies from a lone 'depends on'
        # when there are no properties to propagate it to
        res = expr_items(self.dep)

        if self.prompt:
            res |= expr_items(self.prompt[1])

        if self.item is MENU:
            res |= expr_items(self.visibility)

        for value, cond in self.defaults:
            res |= expr_items(value)
            res |= expr_items(cond)

        for value, cond in self.selects:
            res.add(value)
            res |= expr_items(cond)

        for value, cond in self.implies:
            res.add(value)
            res |= expr_items(cond)

        for low, high, cond in self.ranges:
            res.add(low)
            res.add(high)
            res |= expr_items(cond)

        return res

    def __repr__(self):
        """
        Returns a string with information about the menu node when it is
        evaluated on e.g. the interactive Python prompt.
        """
        fields = []
        add = fields.append

        if self.item.__class__ is Symbol:
            add("menu node for symbol " + self.item.name)

        elif self.item.__class__ is Choice:
            s = "menu node for choice"
            if self.item.name is not None:
                s += " " + self.item.name
            add(s)

        elif self.item is MENU:
            add("menu node for menu")

        else:  # self.item is COMMENT
            add("menu node for comment")

        if self.prompt:
            add('prompt "{}" (visibility {})'.format(
                self.prompt[0], TRI_TO_STR[expr_value(self.prompt[1])]))

        if self.item.__class__ is Symbol and self.is_menuconfig:
            add("is menuconfig")

        add("deps " + TRI_TO_STR[expr_value(self.dep)])

        if self.item is MENU:
            add("'visible if' deps " + TRI_TO_STR[expr_value(self.visibility)])

        if self.item.__class__ in _SYMBOL_CHOICE and self.help is not None:
            add("has help")

        if self.list:
            add("has child")

        if self.next:
            add("has next")

        add("{}:{}".format(self.filename, self.linenr))

        return "<{}>".format(", ".join(fields))

    def __str__(self):
        """
        Returns a string representation of the menu node. Matches the Kconfig
        format, with any parent dependencies propagated to the 'depends on'
        condition.

        The output could (almost) be fed back into a Kconfig parser to redefine
        the object associated with the menu node. See the module documentation
        for a gotcha related to choice symbols.

        For symbols and choices with multiple menu nodes (multiple definition
        locations), properties that aren't associated with a particular menu
        node are shown on all menu nodes ('option env=...', 'optional' for
        choices, etc.).

        The returned string does not end in a newline.
        """
        return self.custom_str(standard_sc_expr_str)

    def custom_str(self, sc_expr_str_fn):
        """
        Works like MenuNode.__str__(), but allows a custom format to be used
        for all symbol/choice references. See expr_str().
        """
        return self._menu_comment_node_str(sc_expr_str_fn) \
               if self.item in _MENU_COMMENT else \
               self._sym_choice_node_str(sc_expr_str_fn)

    def _menu_comment_node_str(self, sc_expr_str_fn):
        s = '{} "{}"'.format("menu" if self.item is MENU else "comment",
                             self.prompt[0])

        if self.dep is not self.kconfig.y:
            s += "\n\tdepends on {}".format(expr_str(self.dep, sc_expr_str_fn))

        if self.item is MENU and self.visibility is not self.kconfig.y:
            s += "\n\tvisible if {}".format(expr_str(self.visibility,
                                                     sc_expr_str_fn))

        return s

    def _sym_choice_node_str(self, sc_expr_str_fn):
        def indent_add(s):
            lines.append("\t" + s)

        def indent_add_cond(s, cond):
            if cond is not self.kconfig.y:
                s += " if " + expr_str(cond, sc_expr_str_fn)
            indent_add(s)

        sc = self.item

        if sc.__class__ is Symbol:
            lines = [("menuconfig " if self.is_menuconfig else "config ")
                     + sc.name]
        else:
            lines = ["choice " + sc.name if sc.name else "choice"]

        if sc.orig_type and not self.prompt:  # sc.orig_type != UNKNOWN
            # If there's a prompt, we'll use the '<type> "prompt"' shorthand
            # instead
            indent_add(TYPE_TO_STR[sc.orig_type])

        if self.prompt:
            if sc.orig_type:
                prefix = TYPE_TO_STR[sc.orig_type]
            else:
                # Symbol defined without a type (which generates a warning)
                prefix = "prompt"

            indent_add_cond(prefix + ' "{}"'.format(escape(self.prompt[0])),
                            self.orig_prompt[1])

        if sc.__class__ is Symbol:
            if sc.is_allnoconfig_y:
                indent_add("option allnoconfig_y")

            if sc is sc.kconfig.defconfig_list:
                indent_add("option defconfig_list")

            if sc.env_var is not None:
                indent_add('option env="{}"'.format(sc.env_var))

            if sc is sc.kconfig.modules:
                indent_add("option modules")

            for low, high, cond in self.orig_ranges:
                indent_add_cond(
                    "range {} {}".format(sc_expr_str_fn(low),
                                         sc_expr_str_fn(high)),
                    cond)

        for default, cond in self.orig_defaults:
            indent_add_cond("default " + expr_str(default, sc_expr_str_fn),
                            cond)

        if sc.__class__ is Choice and sc.is_optional:
            indent_add("optional")

        if sc.__class__ is Symbol:
            for select, cond in self.orig_selects:
                indent_add_cond("select " + sc_expr_str_fn(select), cond)

            for imply, cond in self.orig_implies:
                indent_add_cond("imply " + sc_expr_str_fn(imply), cond)

        if self.dep is not sc.kconfig.y:
            indent_add("depends on " + expr_str(self.dep, sc_expr_str_fn))

        if self.help is not None:
            indent_add("help")
            for line in self.help.splitlines():
                indent_add("  " + line)

        return "\n".join(lines)

    def _strip_dep(self, expr):
        # Helper function for removing MenuNode.dep from 'expr'. Uses two
        # pieces of internal knowledge: (1) Expressions are reused rather than
        # copied, and (2) the direct dependencies always appear at the end.

        # ... if dep -> ... if y
        if self.dep is expr:
            return self.kconfig.y

        # (AND, X, dep) -> X
        if expr.__class__ is tuple and expr[0] is AND and expr[2] is self.dep:
            return expr[1]

        return expr


class Variable(object):
    """
    Represents a preprocessor variable/function.

    The following attributes are available:

    name:
      The name of the variable.

    value:
      The unexpanded value of the variable.

    expanded_value:
      The expanded value of the variable. For simple variables (those defined
      with :=), this will equal 'value'. Accessing this property will raise a
      KconfigError if the expansion seems to be stuck in a loop.

      Accessing this field is the same as calling expanded_value_w_args() with
      no arguments. I hadn't considered function arguments when adding it. It
      is retained for backwards compatibility though.

    is_recursive:
      True if the variable is recursive (defined with =).
    """
    __slots__ = (
        "_n_expansions",
        "is_recursive",
        "kconfig",
        "name",
        "value",
    )

    @property
    def expanded_value(self):
        """
        See the class documentation.
        """
        return self.expanded_value_w_args()

    def expanded_value_w_args(self, *args):
        """
        Returns the expanded value of the variable/function. Any arguments
        passed will be substituted for $(1), $(2), etc.

        Raises a KconfigError if the expansion seems to be stuck in a loop.
        """
        return self.kconfig._fn_val((self.name,) + args)

    def __repr__(self):
        return "<variable {}, {}, value '{}'>" \
               .format(self.name,
                       "recursive" if self.is_recursive else "immediate",
                       self.value)


class KconfigError(Exception):
    """
    Exception raised for Kconfig-related errors.

    KconfigError and KconfigSyntaxError are the same class. The
    KconfigSyntaxError alias is only maintained for backwards compatibility.
    """

KconfigSyntaxError = KconfigError  # Backwards compatibility


class InternalError(Exception):
    "Never raised. Kept around for backwards compatibility."


# Workaround:
#
# If 'errno' and 'strerror' are set on IOError, then __str__() always returns
# "[Errno <errno>] <strerror>", ignoring any custom message passed to the
# constructor. By defining our own subclass, we can use a custom message while
# also providing 'errno', 'strerror', and 'filename' to scripts.
class _KconfigIOError(IOError):
    def __init__(self, ioerror, msg):
        self.msg = msg
        super(_KconfigIOError, self).__init__(
            ioerror.errno, ioerror.strerror, ioerror.filename)

    def __str__(self):
        return self.msg


#
# Public functions
#


def expr_value(expr):
    """
    Evaluates the expression 'expr' to a tristate value. Returns 0 (n), 1 (m),
    or 2 (y).

    'expr' must be an already-parsed expression from a Symbol, Choice, or
    MenuNode property. To evaluate an expression represented as a string, use
    Kconfig.eval_string().

    Passing subexpressions of expressions to this function works as expected.
    """
    if expr.__class__ is not tuple:
        return expr.tri_value

    if expr[0] is AND:
        v1 = expr_value(expr[1])
        # Short-circuit the n case as an optimization (~5% faster
        # allnoconfig.py and allyesconfig.py, as of writing)
        return 0 if not v1 else min(v1, expr_value(expr[2]))

    if expr[0] is OR:
        v1 = expr_value(expr[1])
        # Short-circuit the y case as an optimization
        return 2 if v1 == 2 else max(v1, expr_value(expr[2]))

    if expr[0] is NOT:
        return 2 - expr_value(expr[1])

    # Relation
    #
    # Implements <, <=, >, >= comparisons as well. These were added to
    # kconfig in 31847b67 (kconfig: allow use of relations other than
    # (in)equality).

    rel, v1, v2 = expr

    # If both operands are strings...
    if v1.orig_type is STRING and v2.orig_type is STRING:
        # ...then compare them lexicographically
        comp = _strcmp(v1.str_value, v2.str_value)
    else:
        # Otherwise, try to compare them as numbers
        try:
            comp = _sym_to_num(v1) - _sym_to_num(v2)
        except ValueError:
            # Fall back on a lexicographic comparison if the operands don't
            # parse as numbers
            comp = _strcmp(v1.str_value, v2.str_value)

    return 2*(comp == 0 if rel is EQUAL else
              comp != 0 if rel is UNEQUAL else
              comp <  0 if rel is LESS else
              comp <= 0 if rel is LESS_EQUAL else
              comp >  0 if rel is GREATER else
              comp >= 0)


def standard_sc_expr_str(sc):
    """
    Standard symbol/choice printing function. Uses plain Kconfig syntax, and
    displays choices as <choice> (or <choice NAME>, for named choices).

    See expr_str().
    """
    if sc.__class__ is Symbol:
        if sc.is_constant and sc.name not in STR_TO_TRI:
            return '"{}"'.format(escape(sc.name))
        return sc.name

    return "<choice {}>".format(sc.name) if sc.name else "<choice>"


def expr_str(expr, sc_expr_str_fn=standard_sc_expr_str):
    """
    Returns the string representation of the expression 'expr', as in a Kconfig
    file.

    Passing subexpressions of expressions to this function works as expected.

    sc_expr_str_fn (default: standard_sc_expr_str):
      This function is called for every symbol/choice (hence "sc") appearing in
      the expression, with the symbol/choice as the argument. It is expected to
      return a string to be used for the symbol/choice.

      This can be used e.g. to turn symbols/choices into links when generating
      documentation, or for printing the value of each symbol/choice after it.

      Note that quoted values are represented as constants symbols
      (Symbol.is_constant == True).
    """
    if expr.__class__ is not tuple:
        return sc_expr_str_fn(expr)

    if expr[0] is AND:
        return "{} && {}".format(_parenthesize(expr[1], OR, sc_expr_str_fn),
                                 _parenthesize(expr[2], OR, sc_expr_str_fn))

    if expr[0] is OR:
        # This turns A && B || C && D into "(A && B) || (C && D)", which is
        # redundant, but more readable
        return "{} || {}".format(_parenthesize(expr[1], AND, sc_expr_str_fn),
                                 _parenthesize(expr[2], AND, sc_expr_str_fn))

    if expr[0] is NOT:
        if expr[1].__class__ is tuple:
            return "!({})".format(expr_str(expr[1], sc_expr_str_fn))
        return "!" + sc_expr_str_fn(expr[1])  # Symbol

    # Relation
    #
    # Relation operands are always symbols (quoted strings are constant
    # symbols)
    return "{} {} {}".format(sc_expr_str_fn(expr[1]), REL_TO_STR[expr[0]],
                             sc_expr_str_fn(expr[2]))


def expr_items(expr):
    """
    Returns a set() of all items (symbols and choices) that appear in the
    expression 'expr'.

    Passing subexpressions of expressions to this function works as expected.
    """
    res = set()

    def rec(subexpr):
        if subexpr.__class__ is tuple:
            # AND, OR, NOT, or relation

            rec(subexpr[1])

            # NOTs only have a single operand
            if subexpr[0] is not NOT:
                rec(subexpr[2])

        else:
            # Symbol or choice
            res.add(subexpr)

    rec(expr)
    return res


def split_expr(expr, op):
    """
    Returns a list containing the top-level AND or OR operands in the
    expression 'expr', in the same (left-to-right) order as they appear in
    the expression.

    This can be handy e.g. for splitting (weak) reverse dependencies
    from 'select' and 'imply' into individual selects/implies.

    op:
      Either AND to get AND operands, or OR to get OR operands.

      (Having this as an operand might be more future-safe than having two
      hardcoded functions.)


    Pseudo-code examples:

      split_expr( A                    , OR  )  ->  [A]
      split_expr( A && B               , OR  )  ->  [A && B]
      split_expr( A || B               , OR  )  ->  [A, B]
      split_expr( A || B               , AND )  ->  [A || B]
      split_expr( A || B || (C && D)   , OR  )  ->  [A, B, C && D]

      # Second || is not at the top level
      split_expr( A || (B && (C || D)) , OR )  ->  [A, B && (C || D)]

      # Parentheses don't matter as long as we stay at the top level (don't
      # encounter any non-'op' nodes)
      split_expr( (A || B) || C        , OR )  ->  [A, B, C]
      split_expr( A || (B || C)        , OR )  ->  [A, B, C]
    """
    res = []

    def rec(subexpr):
        if subexpr.__class__ is tuple and subexpr[0] is op:
            rec(subexpr[1])
            rec(subexpr[2])
        else:
            res.append(subexpr)

    rec(expr)
    return res


def escape(s):
    r"""
    Escapes the string 's' in the same fashion as is done for display in
    Kconfig format and when writing strings to a .config file. " and \ are
    replaced by \" and \\, respectively.
    """
    # \ must be escaped before " to avoid double escaping
    return s.replace("\\", r"\\").replace('"', r'\"')


def unescape(s):
    r"""
    Unescapes the string 's'. \ followed by any character is replaced with just
    that character. Used internally when reading .config files.
    """
    return _unescape_sub(r"\1", s)

# unescape() helper
_unescape_sub = re.compile(r"\\(.)").sub


def standard_kconfig(description=None):
    """
    Argument parsing helper for tools that take a single optional Kconfig file
    argument (default: Kconfig). Returns the Kconfig instance for the parsed
    configuration. Uses argparse internally.

    Exits with sys.exit() (which raises SystemExit) on errors.

    description (default: None):
      The 'description' passed to argparse.ArgumentParser().
      argparse.RawDescriptionHelpFormatter is used, so formatting is preserved.
    """
    import argparse

    parser = argparse.ArgumentParser(
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description=description)

    parser.add_argument(
        "kconfig",
        metavar="KCONFIG",
        default="Kconfig",
        nargs="?",
        help="Top-level Kconfig file (default: Kconfig)")

    return Kconfig(parser.parse_args().kconfig, suppress_traceback=True)


def standard_config_filename():
    """
    Helper for tools. Returns the value of KCONFIG_CONFIG (which specifies the
    .config file to load/save) if it is set, and ".config" otherwise.

    Calling load_config() with filename=None might give the behavior you want,
    without having to use this function.
    """
    return os.getenv("KCONFIG_CONFIG", ".config")


def load_allconfig(kconf, filename):
    """
    Use Kconfig.load_allconfig() instead, which was added in Kconfiglib 13.4.0.
    Supported for backwards compatibility. Might be removed at some point after
    a long period of deprecation warnings.
    """
    allconfig = os.getenv("KCONFIG_ALLCONFIG")
    if allconfig is None:
        return

    def std_msg(e):
        # "Upcasts" a _KconfigIOError to an IOError, removing the custom
        # __str__() message. The standard message is better here.
        #
        # This might also convert an OSError to an IOError in obscure cases,
        # but it's probably not a big deal. The distinction is shaky (see
        # PEP-3151).
        return IOError(e.errno, e.strerror, e.filename)

    old_warn_assign_override = kconf.warn_assign_override
    old_warn_assign_redun = kconf.warn_assign_redun
    kconf.warn_assign_override = kconf.warn_assign_redun = False

    if allconfig in ("", "1"):
        try:
            print(kconf.load_config(filename, False))
        except EnvironmentError as e1:
            try:
                print(kconf.load_config("all.config", False))
            except EnvironmentError as e2:
                sys.exit("error: KCONFIG_ALLCONFIG is set, but neither {} "
                         "nor all.config could be opened: {}, {}"
                         .format(filename, std_msg(e1), std_msg(e2)))
    else:
        try:
            print(kconf.load_config(allconfig, False))
        except EnvironmentError as e:
            sys.exit("error: KCONFIG_ALLCONFIG is set to '{}', which "
                     "could not be opened: {}"
                     .format(allconfig, std_msg(e)))

    kconf.warn_assign_override = old_warn_assign_override
    kconf.warn_assign_redun = old_warn_assign_redun


#
# Internal functions
#


def _visibility(sc):
    # Symbols and Choices have a "visibility" that acts as an upper bound on
    # the values a user can set for them, corresponding to the visibility in
    # e.g. 'make menuconfig'. This function calculates the visibility for the
    # Symbol or Choice 'sc' -- the logic is nearly identical.

    vis = 0

    for node in sc.nodes:
        if node.prompt:
            vis = max(vis, expr_value(node.prompt[1]))

    if sc.__class__ is Symbol and sc.choice:
        if sc.choice.orig_type is TRISTATE and \
           sc.orig_type is not TRISTATE and sc.choice.tri_value != 2:
            # Non-tristate choice symbols are only visible in y mode
            return 0

        if sc.orig_type is TRISTATE and vis == 1 and sc.choice.tri_value == 2:
            # Choice symbols with m visibility are not visible in y mode
            return 0

    # Promote m to y if we're dealing with a non-tristate (possibly due to
    # modules being disabled)
    if vis == 1 and sc.type is not TRISTATE:
        return 2

    return vis


def _depend_on(sc, expr):
    # Adds 'sc' (symbol or choice) as a "dependee" to all symbols in 'expr'.
    # Constant symbols in 'expr' are skipped as they can never change value
    # anyway.

    if expr.__class__ is tuple:
        # AND, OR, NOT, or relation

        _depend_on(sc, expr[1])

        # NOTs only have a single operand
        if expr[0] is not NOT:
            _depend_on(sc, expr[2])

    elif not expr.is_constant:
        # Non-constant symbol, or choice
        expr._dependents.add(sc)


def _parenthesize(expr, type_, sc_expr_str_fn):
    # expr_str() helper. Adds parentheses around expressions of type 'type_'.

    if expr.__class__ is tuple and expr[0] is type_:
        return "({})".format(expr_str(expr, sc_expr_str_fn))
    return expr_str(expr, sc_expr_str_fn)


def _ordered_unique(lst):
    # Returns 'lst' with any duplicates removed, preserving order. This hacky
    # version seems to be a common idiom. It relies on short-circuit evaluation
    # and set.add() returning None, which is falsy.

    seen = set()
    seen_add = seen.add
    return [x for x in lst if x not in seen and not seen_add(x)]


def _is_base_n(s, n):
    try:
        int(s, n)
        return True
    except ValueError:
        return False


def _strcmp(s1, s2):
    # strcmp()-alike that returns -1, 0, or 1

    return (s1 > s2) - (s1 < s2)


def _sym_to_num(sym):
    # expr_value() helper for converting a symbol to a number. Raises
    # ValueError for symbols that can't be converted.

    # For BOOL and TRISTATE, n/m/y count as 0/1/2. This mirrors 9059a3493ef
    # ("kconfig: fix relational operators for bool and tristate symbols") in
    # the C implementation.
    return sym.tri_value if sym.orig_type in _BOOL_TRISTATE else \
           int(sym.str_value, _TYPE_TO_BASE[sym.orig_type])


def _touch_dep_file(path, sym_name):
    # If sym_name is MY_SYM_NAME, touches my/sym/name.h. See the sync_deps()
    # docstring.

    sym_path = path + os.sep + sym_name.lower().replace("_", os.sep) + ".h"
    sym_path_dir = dirname(sym_path)
    if not exists(sym_path_dir):
        os.makedirs(sym_path_dir, 0o755)

    # A kind of truncating touch, mirroring the C tools
    os.close(os.open(
        sym_path, os.O_WRONLY | os.O_CREAT | os.O_TRUNC, 0o644))


def _save_old(path):
    # See write_config()

    def copy(src, dst):
        # Import as needed, to save some startup time
        import shutil
        shutil.copyfile(src, dst)

    if islink(path):
        # Preserve symlinks
        copy_fn = copy
    elif hasattr(os, "replace"):
        # Python 3 (3.3+) only. Best choice when available, because it
        # removes <filename>.old on both *nix and Windows.
        copy_fn = os.replace
    elif os.name == "posix":
        # Removes <filename>.old on POSIX systems
        copy_fn = os.rename
    else:
        # Fall back on copying
        copy_fn = copy

    try:
        copy_fn(path, path + ".old")
    except Exception:
        # Ignore errors from 'path' missing as well as other errors.
        # <filename>.old file is usually more of a nice-to-have, and not worth
        # erroring out over e.g. if <filename>.old happens to be a directory or
        # <filename> is something like /dev/null.
        pass


def _locs(sc):
    # Symbol/Choice.name_and_loc helper. Returns the "(defined at ...)" part of
    # the string. 'sc' is a Symbol or Choice.

    if sc.nodes:
        return "(defined at {})".format(
            ", ".join("{0.filename}:{0.linenr}".format(node)
                      for node in sc.nodes))

    return "(undefined)"


# Menu manipulation


def _expr_depends_on(expr, sym):
    # Reimplementation of expr_depends_symbol() from mconf.c. Used to determine
    # if a submenu should be implicitly created. This also influences which
    # items inside choice statements are considered choice items.

    if expr.__class__ is not tuple:
        return expr is sym

    if expr[0] in _EQUAL_UNEQUAL:
        # Check for one of the following:
        # sym = m/y, m/y = sym, sym != n, n != sym

        left, right = expr[1:]

        if right is sym:
            left, right = right, left
        elif left is not sym:
            return False

        return (expr[0] is EQUAL and right is sym.kconfig.m or
                                     right is sym.kconfig.y) or \
               (expr[0] is UNEQUAL and right is sym.kconfig.n)

    return expr[0] is AND and \
           (_expr_depends_on(expr[1], sym) or
            _expr_depends_on(expr[2], sym))


def _auto_menu_dep(node1, node2):
    # Returns True if node2 has an "automatic menu dependency" on node1. If
    # node2 has a prompt, we check its condition. Otherwise, we look directly
    # at node2.dep.

    return _expr_depends_on(node2.prompt[1] if node2.prompt else node2.dep,
                            node1.item)


def _flatten(node):
    # "Flattens" menu nodes without prompts (e.g. 'if' nodes and non-visible
    # symbols with children from automatic menu creation) so that their
    # children appear after them instead. This gives a clean menu structure
    # with no unexpected "jumps" in the indentation.
    #
    # Do not flatten promptless choices (which can appear "legitimately" if a
    # named choice is defined in multiple locations to add on symbols). It
    # looks confusing, and the menuconfig already shows all choice symbols if
    # you enter the choice at some location with a prompt.

    while node:
        if node.list and not node.prompt and \
           node.item.__class__ is not Choice:

            last_node = node.list
            while 1:
                last_node.parent = node.parent
                if not last_node.next:
                    break
                last_node = last_node.next

            last_node.next = node.next
            node.next = node.list
            node.list = None

        node = node.next


def _remove_ifs(node):
    # Removes 'if' nodes (which can be recognized by MenuNode.item being None),
    # which are assumed to already have been flattened. The C implementation
    # doesn't bother to do this, but we expose the menu tree directly, and it
    # makes it nicer to work with.

    cur = node.list
    while cur and not cur.item:
        cur = cur.next

    node.list = cur

    while cur:
        next = cur.next
        while next and not next.item:
            next = next.next

        # Equivalent to
        #
        #   cur.next = next
        #   cur = next
        #
        # due to tricky Python semantics. The order matters.
        cur.next = cur = next


def _finalize_choice(node):
    # Finalizes a choice, marking each symbol whose menu node has the choice as
    # the parent as a choice symbol, and automatically determining types if not
    # specified.

    choice = node.item

    cur = node.list
    while cur:
        if cur.item.__class__ is Symbol:
            cur.item.choice = choice
            choice.syms.append(cur.item)
        cur = cur.next

    # If no type is specified for the choice, its type is that of
    # the first choice item with a specified type
    if not choice.orig_type:
        for item in choice.syms:
            if item.orig_type:
                choice.orig_type = item.orig_type
                break

    # Each choice item of UNKNOWN type gets the type of the choice
    for sym in choice.syms:
        if not sym.orig_type:
            sym.orig_type = choice.orig_type


def _check_dep_loop_sym(sym, ignore_choice):
    # Detects dependency loops using depth-first search on the dependency graph
    # (which is calculated earlier in Kconfig._build_dep()).
    #
    # Algorithm:
    #
    #  1. Symbols/choices start out with _visited = 0, meaning unvisited.
    #
    #  2. When a symbol/choice is first visited, _visited is set to 1, meaning
    #     "visited, potentially part of a dependency loop". The recursive
    #     search then continues from the symbol/choice.
    #
    #  3. If we run into a symbol/choice X with _visited already set to 1,
    #     there's a dependency loop. The loop is found on the call stack by
    #     recording symbols while returning ("on the way back") until X is seen
    #     again.
    #
    #  4. Once a symbol/choice and all its dependencies (or dependents in this
    #     case) have been checked recursively without detecting any loops, its
    #     _visited is set to 2, meaning "visited, not part of a dependency
    #     loop".
    #
    #     This saves work if we run into the symbol/choice again in later calls
    #     to _check_dep_loop_sym(). We just return immediately.
    #
    # Choices complicate things, as every choice symbol depends on every other
    # choice symbol in a sense. When a choice is "entered" via a choice symbol
    # X, we visit all choice symbols from the choice except X, and prevent
    # immediately revisiting the choice with a flag (ignore_choice).
    #
    # Maybe there's a better way to handle this (different flags or the
    # like...)

    if not sym._visited:
        # sym._visited == 0, unvisited

        sym._visited = 1

        for dep in sym._dependents:
            # Choices show up in Symbol._dependents when the choice has the
            # symbol in a 'prompt' or 'default' condition (e.g.
            # 'default ... if SYM').
            #
            # Since we aren't entering the choice via a choice symbol, all
            # choice symbols need to be checked, hence the None.
            loop = _check_dep_loop_choice(dep, None) \
                   if dep.__class__ is Choice \
                   else _check_dep_loop_sym(dep, False)

            if loop:
                # Dependency loop found
                return _found_dep_loop(loop, sym)

        if sym.choice and not ignore_choice:
            loop = _check_dep_loop_choice(sym.choice, sym)
            if loop:
                # Dependency loop found
                return _found_dep_loop(loop, sym)

        # The symbol is not part of a dependency loop
        sym._visited = 2

        # No dependency loop found
        return None

    if sym._visited == 2:
        # The symbol was checked earlier and is already known to not be part of
        # a dependency loop
        return None

    # sym._visited == 1, found a dependency loop. Return the symbol as the
    # first element in it.
    return (sym,)


def _check_dep_loop_choice(choice, skip):
    if not choice._visited:
        # choice._visited == 0, unvisited

        choice._visited = 1

        # Check for loops involving choice symbols. If we came here via a
        # choice symbol, skip that one, as we'd get a false positive
        # '<sym FOO> -> <choice> -> <sym FOO>' loop otherwise.
        for sym in choice.syms:
            if sym is not skip:
                # Prevent the choice from being immediately re-entered via the
                # "is a choice symbol" path by passing True
                loop = _check_dep_loop_sym(sym, True)
                if loop:
                    # Dependency loop found
                    return _found_dep_loop(loop, choice)

        # The choice is not part of a dependency loop
        choice._visited = 2

        # No dependency loop found
        return None

    if choice._visited == 2:
        # The choice was checked earlier and is already known to not be part of
        # a dependency loop
        return None

    # choice._visited == 1, found a dependency loop. Return the choice as the
    # first element in it.
    return (choice,)


def _found_dep_loop(loop, cur):
    # Called "on the way back" when we know we have a loop

    # Is the symbol/choice 'cur' where the loop started?
    if cur is not loop[0]:
        # Nope, it's just a part of the loop
        return loop + (cur,)

    # Yep, we have the entire loop. Throw an exception that shows it.

    msg = "\nDependency loop\n" \
            "===============\n\n"

    for item in loop:
        if item is not loop[0]:
            msg += "...depends on "
            if item.__class__ is Symbol and item.choice:
                msg += "the choice symbol "

        msg += "{}, with definition...\n\n{}\n\n" \
               .format(item.name_and_loc, item)

        # Small wart: Since we reuse the already calculated
        # Symbol/Choice._dependents sets for recursive dependency detection, we
        # lose information on whether a dependency came from a 'select'/'imply'
        # condition or e.g. a 'depends on'.
        #
        # This might cause selecting symbols to "disappear". For example,
        # a symbol B having 'select A if C' gives a direct dependency from A to
        # C, since it corresponds to a reverse dependency of B && C.
        #
        # Always print reverse dependencies for symbols that have them to make
        # sure information isn't lost. I wonder if there's some neat way to
        # improve this.

        if item.__class__ is Symbol:
            if item.rev_dep is not item.kconfig.n:
                msg += "(select-related dependencies: {})\n\n" \
                       .format(expr_str(item.rev_dep))

            if item.weak_rev_dep is not item.kconfig.n:
                msg += "(imply-related dependencies: {})\n\n" \
                       .format(expr_str(item.rev_dep))

    msg += "...depends again on " + loop[0].name_and_loc

    raise KconfigError(msg)


def _decoding_error(e, filename, macro_linenr=None):
    # Gives the filename and context for UnicodeDecodeError's, which are a pain
    # to debug otherwise. 'e' is the UnicodeDecodeError object.
    #
    # If the decoding error is for the output of a $(shell,...) command,
    # macro_linenr holds the line number where it was run (the exact line
    # number isn't available for decoding errors in files).

    raise KconfigError(
        "\n"
        "Malformed {} in {}\n"
        "Context: {}\n"
        "Problematic data: {}\n"
        "Reason: {}".format(
            e.encoding,
            "'{}'".format(filename) if macro_linenr is None else
                "output from macro at {}:{}".format(filename, macro_linenr),
            e.object[max(e.start - 40, 0):e.end + 40],
            e.object[e.start:e.end],
            e.reason))


def _warn_verbose_deprecated(fn_name):
    sys.stderr.write(
        "Deprecation warning: {0}()'s 'verbose' argument has no effect. Since "
        "Kconfiglib 12.0.0, the message is returned from {0}() instead, "
        "and is always generated. Do e.g. print(kconf.{0}()) if you want to "
        "want to show a message like \"Loaded configuration '.config'\" on "
        "stdout. The old API required ugly hacks to reuse messages in "
        "configuration interfaces.\n".format(fn_name))


# Predefined preprocessor functions


def _filename_fn(kconf, _):
    return kconf.filename


def _lineno_fn(kconf, _):
    return str(kconf.linenr)


def _info_fn(kconf, _, msg):
    print("{}:{}: {}".format(kconf.filename, kconf.linenr, msg))

    return ""


def _warning_if_fn(kconf, _, cond, msg):
    if cond == "y":
        kconf._warn(msg, kconf.filename, kconf.linenr)

    return ""


def _error_if_fn(kconf, _, cond, msg):
    if cond == "y":
        raise KconfigError("{}:{}: {}".format(
            kconf.filename, kconf.linenr, msg))

    return ""


def _shell_fn(kconf, _, command):
    import subprocess  # Only import as needed, to save some startup time

    stdout, stderr = subprocess.Popen(
        command, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
    ).communicate()

    if not _IS_PY2:
        try:
            stdout = stdout.decode(kconf._encoding)
            stderr = stderr.decode(kconf._encoding)
        except UnicodeDecodeError as e:
            _decoding_error(e, kconf.filename, kconf.linenr)

    if stderr:
        kconf._warn("'{}' wrote to stderr: {}".format(
                        command, "\n".join(stderr.splitlines())),
                    kconf.filename, kconf.linenr)

    # Universal newlines with splitlines() (to prevent e.g. stray \r's in
    # command output on Windows), trailing newline removal, and
    # newline-to-space conversion.
    #
    # On Python 3 versions before 3.6, it's not possible to specify the
    # encoding when passing universal_newlines=True to Popen() (the 'encoding'
    # parameter was added in 3.6), so we do this manual version instead.
    return "\n".join(stdout.splitlines()).rstrip("\n").replace("\n", " ")

#
# Global constants
#

TRI_TO_STR = {
    0: "n",
    1: "m",
    2: "y",
}

STR_TO_TRI = {
    "n": 0,
    "m": 1,
    "y": 2,
}

# Constant representing that there's no cached choice selection. This is
# distinct from a cached None (no selection). Any object that's not None or a
# Symbol will do. We test this with 'is'.
_NO_CACHED_SELECTION = 0

# Are we running on Python 2?
_IS_PY2 = sys.version_info[0] < 3

try:
    _UNAME_RELEASE = os.uname()[2]
except AttributeError:
    # Only import as needed, to save some startup time
    import platform
    _UNAME_RELEASE = platform.uname()[2]

# The token and type constants below are safe to test with 'is', which is a bit
# faster (~30% faster on my machine, and a few % faster for total parsing
# time), even without assuming Python's small integer optimization (which
# caches small integer objects). The constants end up pointing to unique
# integer objects, and since we consistently refer to them via the names below,
# we always get the same object.
#
# Client code should use == though.

# Tokens, with values 1, 2, ... . Avoiding 0 simplifies some checks by making
# all tokens except empty strings truthy.
(
    _T_ALLNOCONFIG_Y,
    _T_AND,
    _T_BOOL,
    _T_CHOICE,
    _T_CLOSE_PAREN,
    _T_COMMENT,
    _T_CONFIG,
    _T_DEFAULT,
    _T_DEFCONFIG_LIST,
    _T_DEF_BOOL,
    _T_DEF_HEX,
    _T_DEF_INT,
    _T_DEF_STRING,
    _T_DEF_TRISTATE,
    _T_DEPENDS,
    _T_ENDCHOICE,
    _T_ENDIF,
    _T_ENDMENU,
    _T_ENV,
    _T_EQUAL,
    _T_GREATER,
    _T_GREATER_EQUAL,
    _T_HELP,
    _T_HEX,
    _T_IF,
    _T_IMPLY,
    _T_INT,
    _T_LESS,
    _T_LESS_EQUAL,
    _T_MAINMENU,
    _T_MENU,
    _T_MENUCONFIG,
    _T_MODULES,
    _T_NOT,
    _T_ON,
    _T_OPEN_PAREN,
    _T_OPTION,
    _T_OPTIONAL,
    _T_OR,
    _T_ORSOURCE,
    _T_OSOURCE,
    _T_PROMPT,
    _T_RANGE,
    _T_RSOURCE,
    _T_SELECT,
    _T_SOURCE,
    _T_STRING,
    _T_TRISTATE,
    _T_UNEQUAL,
    _T_VISIBLE,
) = range(1, 51)

# Keyword to token map, with the get() method assigned directly as a small
# optimization
_get_keyword = {
    "---help---":     _T_HELP,
    "allnoconfig_y":  _T_ALLNOCONFIG_Y,
    "bool":           _T_BOOL,
    "boolean":        _T_BOOL,
    "choice":         _T_CHOICE,
    "comment":        _T_COMMENT,
    "config":         _T_CONFIG,
    "def_bool":       _T_DEF_BOOL,
    "def_hex":        _T_DEF_HEX,
    "def_int":        _T_DEF_INT,
    "def_string":     _T_DEF_STRING,
    "def_tristate":   _T_DEF_TRISTATE,
    "default":        _T_DEFAULT,
    "defconfig_list": _T_DEFCONFIG_LIST,
    "depends":        _T_DEPENDS,
    "endchoice":      _T_ENDCHOICE,
    "endif":          _T_ENDIF,
    "endmenu":        _T_ENDMENU,
    "env":            _T_ENV,
    "grsource":       _T_ORSOURCE,  # Backwards compatibility
    "gsource":        _T_OSOURCE,   # Backwards compatibility
    "help":           _T_HELP,
    "hex":            _T_HEX,
    "if":             _T_IF,
    "imply":          _T_IMPLY,
    "int":            _T_INT,
    "mainmenu":       _T_MAINMENU,
    "menu":           _T_MENU,
    "menuconfig":     _T_MENUCONFIG,
    "modules":        _T_MODULES,
    "on":             _T_ON,
    "option":         _T_OPTION,
    "optional":       _T_OPTIONAL,
    "orsource":       _T_ORSOURCE,
    "osource":        _T_OSOURCE,
    "prompt":         _T_PROMPT,
    "range":          _T_RANGE,
    "rsource":        _T_RSOURCE,
    "select":         _T_SELECT,
    "source":         _T_SOURCE,
    "string":         _T_STRING,
    "tristate":       _T_TRISTATE,
    "visible":        _T_VISIBLE,
}.get

# The constants below match the value of the corresponding tokens to remove the
# need for conversion

# Node types
MENU    = _T_MENU
COMMENT = _T_COMMENT

# Expression types
AND           = _T_AND
OR            = _T_OR
NOT           = _T_NOT
EQUAL         = _T_EQUAL
UNEQUAL       = _T_UNEQUAL
LESS          = _T_LESS
LESS_EQUAL    = _T_LESS_EQUAL
GREATER       = _T_GREATER
GREATER_EQUAL = _T_GREATER_EQUAL

REL_TO_STR = {
    EQUAL:         "=",
    UNEQUAL:       "!=",
    LESS:          "<",
    LESS_EQUAL:    "<=",
    GREATER:       ">",
    GREATER_EQUAL: ">=",
}

# Symbol/choice types. UNKNOWN is 0 (falsy) to simplify some checks.
# Client code shouldn't rely on it though, as it was non-zero in
# older versions.
UNKNOWN  = 0
BOOL     = _T_BOOL
TRISTATE = _T_TRISTATE
STRING   = _T_STRING
INT      = _T_INT
HEX      = _T_HEX

TYPE_TO_STR = {
    UNKNOWN:  "unknown",
    BOOL:     "bool",
    TRISTATE: "tristate",
    STRING:   "string",
    INT:      "int",
    HEX:      "hex",
}

# Used in comparisons. 0 means the base is inferred from the format of the
# string.
_TYPE_TO_BASE = {
    HEX:      16,
    INT:      10,
    STRING:   0,
    UNKNOWN:  0,
}

# def_bool -> BOOL, etc.
_DEF_TOKEN_TO_TYPE = {
    _T_DEF_BOOL:     BOOL,
    _T_DEF_HEX:      HEX,
    _T_DEF_INT:      INT,
    _T_DEF_STRING:   STRING,
    _T_DEF_TRISTATE: TRISTATE,
}

# Tokens after which strings are expected. This is used to tell strings from
# constant symbol references during tokenization, both of which are enclosed in
# quotes.
#
# Identifier-like lexemes ("missing quotes") are also treated as strings after
# these tokens. _T_CHOICE is included to avoid symbols being registered for
# named choices.
_STRING_LEX = frozenset({
    _T_BOOL,
    _T_CHOICE,
    _T_COMMENT,
    _T_HEX,
    _T_INT,
    _T_MAINMENU,
    _T_MENU,
    _T_ORSOURCE,
    _T_OSOURCE,
    _T_PROMPT,
    _T_RSOURCE,
    _T_SOURCE,
    _T_STRING,
    _T_TRISTATE,
})

# Various sets for quick membership tests. Gives a single global lookup and
# avoids creating temporary dicts/tuples.

_TYPE_TOKENS = frozenset({
    _T_BOOL,
    _T_TRISTATE,
    _T_INT,
    _T_HEX,
    _T_STRING,
})

_SOURCE_TOKENS = frozenset({
    _T_SOURCE,
    _T_RSOURCE,
    _T_OSOURCE,
    _T_ORSOURCE,
})

_REL_SOURCE_TOKENS = frozenset({
    _T_RSOURCE,
    _T_ORSOURCE,
})

# Obligatory (non-optional) sources
_OBL_SOURCE_TOKENS = frozenset({
    _T_SOURCE,
    _T_RSOURCE,
})

_BOOL_TRISTATE = frozenset({
    BOOL,
    TRISTATE,
})

_BOOL_TRISTATE_UNKNOWN = frozenset({
    BOOL,
    TRISTATE,
    UNKNOWN,
})

_INT_HEX = frozenset({
    INT,
    HEX,
})

_SYMBOL_CHOICE = frozenset({
    Symbol,
    Choice,
})

_MENU_COMMENT = frozenset({
    MENU,
    COMMENT,
})

_EQUAL_UNEQUAL = frozenset({
    EQUAL,
    UNEQUAL,
})

_RELATIONS = frozenset({
    EQUAL,
    UNEQUAL,
    LESS,
    LESS_EQUAL,
    GREATER,
    GREATER_EQUAL,
})

# Helper functions for getting compiled regular expressions, with the needed
# matching function returned directly as a small optimization.
#
# Use ASCII regex matching on Python 3. It's already the default on Python 2.


def _re_match(regex):
    return re.compile(regex, 0 if _IS_PY2 else re.ASCII).match


def _re_search(regex):
    return re.compile(regex, 0 if _IS_PY2 else re.ASCII).search


# Various regular expressions used during parsing

# The initial token on a line. Also eats leading and trailing whitespace, so
# that we can jump straight to the next token (or to the end of the line if
# there is only one token).
#
# This regex will also fail to match for empty lines and comment lines.
#
# '$' is included to detect preprocessor variable assignments with macro
# expansions in the left-hand side.
_command_match = _re_match(r"\s*([A-Za-z0-9_$-]+)\s*")

# An identifier/keyword after the first token. Also eats trailing whitespace.
# '$' is included to detect identifiers containing macro expansions.
_id_keyword_match = _re_match(r"([A-Za-z0-9_$/.-]+)\s*")

# A fragment in the left-hand side of a preprocessor variable assignment. These
# are the portions between macro expansions ($(foo)). Macros are supported in
# the LHS (variable name).
_assignment_lhs_fragment_match = _re_match("[A-Za-z0-9_-]*")

# The assignment operator and value (right-hand side) in a preprocessor
# variable assignment
_assignment_rhs_match = _re_match(r"\s*(=|:=|\+=)\s*(.*)")

# Special characters/strings while expanding a macro ('(', ')', ',', and '$(')
_macro_special_search = _re_search(r"\(|\)|,|\$\(")

# Special characters/strings while expanding a string (quotes, '\', and '$(')
_string_special_search = _re_search(r'"|\'|\\|\$\(')

# Special characters/strings while expanding a symbol name. Also includes
# end-of-line, in case the macro is the last thing on the line.
_name_special_search = _re_search(r'[^A-Za-z0-9_$/.-]|\$\(|$')

# A valid right-hand side for an assignment to a string symbol in a .config
# file, including escaped characters. Extracts the contents.
_conf_string_match = _re_match(r'"((?:[^\\"]|\\.)*)"')