aboutsummaryrefslogblamecommitdiffstats
path: root/lib/compiler/src/cerl.erl
blob: 3d4b9ee0c6bc34d0fc4a2c2448a01a38a17148df (plain) (tree)
1
2
3
4
5
6
7
8
9
10
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
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
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
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

                   


                                                        




                                                                      
  



                                                                         
  









































































































                                                                        


                                         
                         
                    
                  
                   
                        
                                   
                                  
                             

                                                     
                      
                         
        
 
                                                                              
                                                                        
                                                        
 














                                  
                              
                                    









                                                                  
                                                                              
                                                                   
                                         
                                                               

                                                                

                                                             






























                                                                        
                     
             




                      

                       

















































                                                                      



                                                                               















                              
                      
                                

















































































































































                                                                      

                                          














































































































































































































































































































































































































































































































































































                                                                            
                                            








































































































                                                                        
                                                 

































































































                                                                        
                                                   


























































































































































































































































































































































































                                                                             

       













                                                                     
                                        
 


                          

                                                
                         
      
 


                                       










                                                             






                                                                           
                                                                   
 
                    
                                           
 

                                                                                          

                                                    
                     
                                   








                                                                                  
                                                                      








                                                                                  
                                                                              

                
                                                                      
        
 
                                                                       
 



                                                
 


                                      
 




                                                          

                                                         
 

                                                  
 

                                                          


                                                                        










































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































                                                                                   

                                            
                   

                                                                     


                                                     
                                                         




















































































































































































































































































































































































































































































































































































































































































































































































































































































                                                                             
          





























                                                                      
       






















































                                                                      
                                                    

































































































































                                                                          

                                

                                                                           
























































































































                                                                       


                                                                              
































































































































                                                                        

                                                      





















































































                                                              








































































                                                                         
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2001-2010. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%

%% =====================================================================
%% @doc Core Erlang abstract syntax trees.
%%
%% <p> This module defines an abstract data type for representing Core
%% Erlang source code as syntax trees.</p>
%%
%% <p>A recommended starting point for the first-time user is the
%% documentation of the function <a
%% href="#type-1"><code>type/1</code></a>.</p>
%%
%% <h3><b>NOTES:</b></h3>
%%
%% <p>This module deals with the composition and decomposition of
%% <em>syntactic</em> entities (as opposed to semantic ones); its
%% purpose is to hide all direct references to the data structures
%% used to represent these entities. With few exceptions, the
%% functions in this module perform no semantic interpretation of
%% their inputs, and in general, the user is assumed to pass
%% type-correct arguments - if this is not done, the effects are not
%% defined.</p>
%%
%% <p>Currently, the internal data structure used is the same as
%% the record-based data structures used traditionally in the Beam
%% compiler.</p>
%% 
%% <p>The internal representations of abstract syntax trees are
%% subject to change without notice, and should not be documented
%% outside this module. Furthermore, we do not give any guarantees on
%% how an abstract syntax tree may or may not be represented, <em>with
%% the following exceptions</em>: no syntax tree is represented by a
%% single atom, such as <code>none</code>, by a list constructor
%% <code>[X | Y]</code>, or by the empty list <code>[]</code>. This
%% can be relied on when writing functions that operate on syntax
%% trees.</p>
%%
%% @type cerl(). An abstract Core Erlang syntax tree.
%%
%% <p>Every abstract syntax tree has a <em>type</em>, given by the
%% function <a href="#type-1"><code>type/1</code></a>.  In addition,
%% each syntax tree has a list of <em>user annotations</em> (cf.  <a
%% href="#get_ann-1"><code>get_ann/1</code></a>), which are included
%% in the Core Erlang syntax.</p>

-module(cerl).

-export([abstract/1, add_ann/2, alias_pat/1, alias_var/1,
	 ann_abstract/2, ann_c_alias/3, ann_c_apply/3, ann_c_atom/2,
	 ann_c_call/4, ann_c_case/3, ann_c_catch/2, ann_c_char/2,
	 ann_c_clause/3, ann_c_clause/4, ann_c_cons/3, ann_c_float/2,
	 ann_c_fname/3, ann_c_fun/3, ann_c_int/2, ann_c_let/4,
	 ann_c_letrec/3, ann_c_module/4, ann_c_module/5, ann_c_nil/1,
	 ann_c_cons_skel/3, ann_c_tuple_skel/2, ann_c_primop/3,
	 ann_c_receive/2, ann_c_receive/4, ann_c_seq/3, ann_c_string/2,
	 ann_c_try/6, ann_c_tuple/2, ann_c_values/2, ann_c_var/2,
	 ann_make_data/3, ann_make_list/2, ann_make_list/3,
	 ann_make_data_skel/3, ann_make_tree/3, apply_args/1,
	 apply_arity/1, apply_op/1, atom_lit/1, atom_name/1, atom_val/1,
	 c_alias/2, c_apply/2, c_atom/1, c_call/3, c_case/2, c_catch/1,
	 c_char/1, c_clause/2, c_clause/3, c_cons/2, c_float/1,
	 c_fname/2, c_fun/2, c_int/1, c_let/3, c_letrec/2, c_module/3,
	 c_module/4, c_nil/0, c_cons_skel/2, c_tuple_skel/1, c_primop/2,
	 c_receive/1, c_receive/3, c_seq/2, c_string/1, c_try/5,
	 c_tuple/1, c_values/1, c_var/1, call_args/1, call_arity/1,
	 call_module/1, call_name/1, case_arg/1, case_arity/1,
	 case_clauses/1, catch_body/1, char_lit/1, char_val/1,
	 clause_arity/1, clause_body/1, clause_guard/1, clause_pats/1,
	 clause_vars/1, concrete/1, cons_hd/1, cons_tl/1, copy_ann/2,
	 data_arity/1, data_es/1, data_type/1, float_lit/1, float_val/1,
	 fname_arity/1, fname_id/1, fold_literal/1, from_records/1,
	 fun_arity/1, fun_body/1, fun_vars/1, get_ann/1, int_lit/1,
	 int_val/1, is_c_alias/1, is_c_apply/1, is_c_atom/1,
	 is_c_call/1, is_c_case/1, is_c_catch/1, is_c_char/1,
	 is_c_clause/1, is_c_cons/1, is_c_float/1, is_c_fname/1,
	 is_c_fun/1, is_c_int/1, is_c_let/1, is_c_letrec/1, is_c_list/1,
	 is_c_module/1, is_c_nil/1, is_c_primop/1, is_c_receive/1,
	 is_c_seq/1, is_c_string/1, is_c_try/1, is_c_tuple/1,
	 is_c_values/1, is_c_var/1, is_data/1, is_leaf/1, is_literal/1,
	 is_literal_term/1, is_print_char/1, is_print_string/1,
	 let_arg/1, let_arity/1, let_body/1, let_vars/1, letrec_body/1,
	 letrec_defs/1, letrec_vars/1, list_elements/1, list_length/1,
	 make_data/2, make_list/1, make_list/2, make_data_skel/2,
	 make_tree/2, meta/1, module_attrs/1, module_defs/1,
	 module_exports/1, module_name/1, module_vars/1,
	 pat_list_vars/1, pat_vars/1, primop_args/1, primop_arity/1,
	 primop_name/1, receive_action/1, receive_clauses/1,
	 receive_timeout/1, seq_arg/1, seq_body/1, set_ann/2,
	 string_lit/1, string_val/1, subtrees/1, to_records/1,
	 try_arg/1, try_body/1, try_vars/1, try_evars/1, try_handler/1,
	 tuple_arity/1, tuple_es/1, type/1, unfold_literal/1,
	 update_c_alias/3, update_c_apply/3, update_c_call/4,
	 update_c_case/3, update_c_catch/2, update_c_clause/4,
	 update_c_cons/3, update_c_cons_skel/3, update_c_fname/2,
	 update_c_fname/3, update_c_fun/3, update_c_let/4,
	 update_c_letrec/3, update_c_module/5, update_c_primop/3,
	 update_c_receive/4, update_c_seq/3, update_c_try/6,
	 update_c_tuple/2, update_c_tuple_skel/2, update_c_values/2,
	 update_c_var/2, update_data/3, update_list/2, update_list/3,
	 update_data_skel/3, update_tree/2, update_tree/3,
	 values_arity/1, values_es/1, var_name/1, c_binary/1,
	 update_c_binary/2, ann_c_binary/2, is_c_binary/1,
	 binary_segments/1, c_bitstr/3, c_bitstr/4, c_bitstr/5,
	 update_c_bitstr/5, update_c_bitstr/6, ann_c_bitstr/5,
	 ann_c_bitstr/6, is_c_bitstr/1, bitstr_val/1, bitstr_size/1,
	 bitstr_bitsize/1, bitstr_unit/1, bitstr_type/1,
	 bitstr_flags/1,

	 %% keep map exports here for now
	 c_map_pattern/1,
	 is_c_map/1,
	 map_es/1,
	 map_arg/1,
	 update_c_map/3,
	 c_map/1, is_c_map_empty/1,
	 ann_c_map/2, ann_c_map/3,
	 ann_c_map_pattern/2,
	 map_pair_op/1,map_pair_key/1,map_pair_val/1,
	 update_c_map_pair/4,
	 c_map_pair/2,
	 ann_c_map_pair/4
     ]).

-export_type([c_binary/0, c_bitstr/0, c_call/0, c_clause/0, c_cons/0, c_fun/0,
	      c_literal/0, c_map/0, c_map_pair/0, c_module/0, c_tuple/0,
	      c_values/0, c_var/0, cerl/0, var_name/0]).

-include("core_parse.hrl").

-type c_alias()   :: #c_alias{}.
-type c_apply()   :: #c_apply{}.
-type c_binary()  :: #c_binary{}.
-type c_bitstr()  :: #c_bitstr{}.
-type c_call()    :: #c_call{}.
-type c_case()    :: #c_case{}.
-type c_catch()   :: #c_catch{}.
-type c_clause()  :: #c_clause{}.
-type c_cons()    :: #c_cons{}.
-type c_fun()     :: #c_fun{}.
-type c_let()     :: #c_let{}.
-type c_letrec()  :: #c_letrec{}.
-type c_literal() :: #c_literal{}.
-type c_map()     :: #c_map{}.
-type c_map_pair() :: #c_map_pair{}.
-type c_module()  :: #c_module{}.
-type c_primop()  :: #c_primop{}.
-type c_receive() :: #c_receive{}.
-type c_seq()     :: #c_seq{}.
-type c_try()     :: #c_try{}.
-type c_tuple()   :: #c_tuple{}.
-type c_values()  :: #c_values{}.
-type c_var()     :: #c_var{}.

-type cerl() :: c_alias()  | c_apply()  | c_binary()  | c_bitstr()
              | c_call()   | c_case()   | c_catch()   | c_clause()  | c_cons()
              | c_fun()    | c_let()    | c_letrec()  | c_literal()
	      | c_map()    | c_map_pair()
	      | c_module() | c_primop() | c_receive() | c_seq()
              | c_try()    | c_tuple()  | c_values()  | c_var().

-type var_name() :: integer() | atom() | {atom(), integer()}.

%% =====================================================================
%% Representation (general)
%%
%% All nodes are represented by tuples of arity 2 or (generally)
%% greater, whose first element is an atom which uniquely identifies the
%% type of the node, and whose second element is a (proper) list of
%% annotation terms associated with the node - this is by default empty.
%%
%% For most node constructor functions, there are analogous functions
%% named 'ann_...', taking one extra argument 'As' (always the first
%% argument), specifying an annotation list at node creation time.
%% Similarly, there are also functions named 'update_...', taking one
%% extra argument 'Old', specifying a node from which all fields not
%% explicitly given as arguments should be copied (generally, this is
%% the annotation field only).
%% =====================================================================

%% @spec type(Node::cerl()) -> atom()
%%
%% @doc Returns the type tag of <code>Node</code>. Current node types
%% are:
%%	    
%% <p><center><table border="1">
%%  <tr>
%%    <td>alias</td>
%%    <td>apply</td>
%%    <td>binary</td>
%%    <td>bitstr</td>
%%    <td>call</td>
%%    <td>case</td>
%%    <td>catch</td>
%%    <td>clause</td>
%%  </tr><tr>
%%    <td>cons</td>
%%    <td>fun</td>
%%    <td>let</td>
%%    <td>letrec</td>
%%    <td>literal</td>
%%    <td>map</td>
%%    <td>map_pair</td>
%%    <td>module</td>
%%  </tr><tr>
%%    <td>primop</td>
%%    <td>receive</td>
%%    <td>seq</td>
%%    <td>try</td>
%%    <td>tuple</td>
%%    <td>values</td>
%%    <td>var</td>
%%  </tr>
%% </table></center></p>
%%
%% <p>Note: The name of the primary constructor function for a node
%% type is always the name of the type itself, prefixed by
%% "<code>c_</code>"; recognizer predicates are correspondingly
%% prefixed by "<code>is_c_</code>". Furthermore, to simplify
%% preservation of annotations (cf. <code>get_ann/1</code>), there are
%% analogous constructor functions prefixed by "<code>ann_c_</code>"
%% and "<code>update_c_</code>", for setting the annotation list of
%% the new node to either a specific value or to the annotations of an
%% existing node, respectively.</p>
%%
%% @see abstract/1
%% @see c_alias/2
%% @see c_apply/2
%% @see c_binary/1
%% @see c_bitstr/5
%% @see c_call/3
%% @see c_case/2
%% @see c_catch/1
%% @see c_clause/3
%% @see c_cons/2
%% @see c_fun/2
%% @see c_let/3
%% @see c_letrec/2
%% @see c_module/3
%% @see c_primop/2
%% @see c_receive/1
%% @see c_seq/2
%% @see c_try/3
%% @see c_tuple/1
%% @see c_values/1
%% @see c_var/1
%% @see get_ann/1
%% @see to_records/1
%% @see from_records/1
%% @see data_type/1
%% @see subtrees/1
%% @see meta/1

-type ctype() :: 'alias'   | 'apply'  | 'binary' | 'bitrst' | 'call' | 'case'
               | 'catch'   | 'clause' | 'cons'   | 'fun'    | 'let'  | 'letrec'
               | 'literal' | 'map'  | 'map_pair' | 'module' | 'primop'
               | 'receive' | 'seq'    | 'try'    | 'tuple'  | 'values' | 'var'.

-spec type(cerl()) -> ctype().

type(#c_alias{}) -> alias;
type(#c_apply{}) -> apply;
type(#c_binary{}) -> binary;
type(#c_bitstr{}) -> bitstr;
type(#c_call{}) -> call;
type(#c_case{}) -> 'case';
type(#c_catch{}) -> 'catch';
type(#c_clause{}) -> clause;
type(#c_cons{}) -> cons;
type(#c_fun{}) -> 'fun';
type(#c_let{}) -> 'let';
type(#c_letrec{}) -> letrec;
type(#c_literal{}) -> literal;
type(#c_map{}) -> map;
type(#c_map_pair{}) -> map_pair;
type(#c_module{}) -> module;
type(#c_primop{}) -> primop;
type(#c_receive{}) -> 'receive';
type(#c_seq{}) -> seq;
type(#c_try{}) -> 'try';
type(#c_tuple{}) -> tuple;
type(#c_values{}) -> values;
type(#c_var{}) -> var.


%% @spec is_leaf(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is a leaf node,
%% otherwise <code>false</code>. The current leaf node types are
%% <code>literal</code> and <code>var</code>.
%%
%% <p>Note: all literals (cf. <code>is_literal/1</code>) are leaf
%% nodes, even if they represent structured (constant) values such as
%% <code>{foo, [bar, baz]}</code>. Also note that variables are leaf
%% nodes but not literals.</p>
%%
%% @see type/1
%% @see is_literal/1

-spec is_leaf(cerl()) -> boolean().

is_leaf(Node) ->
    case type(Node) of
	literal -> true;
	var -> true;
	_ -> false
    end.


%% @spec get_ann(cerl()) -> [term()]
%%
%% @doc Returns the list of user annotations associated with a syntax
%% tree node. For a newly created node, this is the empty list. The
%% annotations may be any terms.
%%
%% @see set_ann/2

-spec get_ann(cerl()) -> [term()].

get_ann(Node) ->
    element(2, Node).


%% @spec set_ann(Node::cerl(), Annotations::[term()]) -> cerl()
%%
%% @doc Sets the list of user annotations of <code>Node</code> to
%% <code>Annotations</code>.
%%
%% @see get_ann/1
%% @see add_ann/2
%% @see copy_ann/2

-spec set_ann(cerl(), [term()]) -> cerl().

set_ann(Node, List) ->
    setelement(2, Node, List).


%% @spec add_ann(Annotations::[term()], Node::cerl()) -> cerl()
%%
%% @doc Appends <code>Annotations</code> to the list of user
%% annotations of <code>Node</code>.
%%
%% <p>Note: this is equivalent to <code>set_ann(Node, Annotations ++
%% get_ann(Node))</code>, but potentially more efficient.</p>
%%
%% @see get_ann/1
%% @see set_ann/2

-spec add_ann([term()], cerl()) -> cerl().

add_ann(Terms, Node) ->
    set_ann(Node, Terms ++ get_ann(Node)).


%% @spec copy_ann(Source::cerl(), Target::cerl()) -> cerl()
%%
%% @doc Copies the list of user annotations from <code>Source</code>
%% to <code>Target</code>.
%%
%% <p>Note: this is equivalent to <code>set_ann(Target,
%% get_ann(Source))</code>, but potentially more efficient.</p>
%%
%% @see get_ann/1
%% @see set_ann/2

-spec copy_ann(cerl(), cerl()) -> cerl().

copy_ann(Source, Target) ->
    set_ann(Target, get_ann(Source)).


%% @spec abstract(Term::term()) -> cerl()
%%
%% @doc Creates a syntax tree corresponding to an Erlang term.
%% <code>Term</code> must be a literal term, i.e., one that can be
%% represented as a source code literal. Thus, it may not contain a
%% process identifier, port, reference, binary or function value as a
%% subterm.
%%
%% <p>Note: This is a constant time operation.</p>
%%
%% @see ann_abstract/2
%% @see concrete/1
%% @see is_literal/1
%% @see is_literal_term/1

-spec abstract(term()) -> c_literal().

abstract(T) ->
    #c_literal{val = T}.


%% @spec ann_abstract(Annotations::[term()], Term::term()) -> cerl()
%% @see abstract/1

-spec ann_abstract([term()], term()) -> c_literal().

ann_abstract(As, T) ->
    #c_literal{val = T, anno = As}.


%% @spec is_literal_term(Term::term()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Term</code> can be
%% represented as a literal, otherwise <code>false</code>. This
%% function takes time proportional to the size of <code>Term</code>.
%%
%% @see abstract/1

-spec is_literal_term(term()) -> boolean().

is_literal_term(T) when is_integer(T) -> true;
is_literal_term(T) when is_float(T) -> true;
is_literal_term(T) when is_atom(T) -> true;
is_literal_term([]) -> true;
is_literal_term([H | T]) ->
    is_literal_term(H) andalso is_literal_term(T);
is_literal_term(T) when is_tuple(T) ->
    is_literal_term_list(tuple_to_list(T));
is_literal_term(B) when is_bitstring(B) -> true;
is_literal_term(M) when is_map(M) ->
    is_literal_term_list(maps:to_list(M));
is_literal_term(_) ->
    false.

-spec is_literal_term_list([term()]) -> boolean().

is_literal_term_list([T | Ts]) ->
    case is_literal_term(T) of
	true ->
	    is_literal_term_list(Ts);
	false ->
	    false
    end;
is_literal_term_list([]) ->
    true.


%% @spec concrete(Node::cerl()) -> term()
%%
%% @doc Returns the Erlang term represented by a syntax tree.  An
%% exception is thrown if <code>Node</code> does not represent a
%% literal term.
%%
%% <p>Note: This is a constant time operation.</p>
%%
%% @see abstract/1
%% @see is_literal/1

%% Because the normal tuple and list constructor operations always
%% return a literal if the arguments are literals, 'concrete' and
%% 'is_literal' never need to traverse the structure.

-spec concrete(c_literal()) -> term().

concrete(#c_literal{val = V}) ->
    V.


%% @spec is_literal(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> represents a
%% literal term, otherwise <code>false</code>. This function returns
%% <code>true</code> if and only if the value of
%% <code>concrete(Node)</code> is defined.
%%
%% <p>Note: This is a constant time operation.</p>
%%
%% @see abstract/1
%% @see concrete/1
%% @see fold_literal/1

-spec is_literal(cerl()) -> boolean().

is_literal(#c_literal{}) ->
    true;
is_literal(_) ->
    false.


%% @spec fold_literal(Node::cerl()) -> cerl()
%%
%% @doc Assures that literals have a compact representation. This is
%% occasionally useful if <code>c_cons_skel/2</code>,
%% <code>c_tuple_skel/1</code> or <code>unfold_literal/1</code> were
%% used in the construction of <code>Node</code>, and you want to revert
%% to the normal "folded" representation of literals. If
%% <code>Node</code> represents a tuple or list constructor, its
%% elements are rewritten recursively, and the node is reconstructed
%% using <code>c_cons/2</code> or <code>c_tuple/1</code>, respectively;
%% otherwise, <code>Node</code> is not changed.
%%
%% @see is_literal/1
%% @see c_cons_skel/2
%% @see c_tuple_skel/1
%% @see c_cons/2
%% @see c_tuple/1
%% @see unfold_literal/1

-spec fold_literal(cerl()) -> cerl().

fold_literal(Node) ->
    case type(Node) of
	tuple ->
	    update_c_tuple(Node, fold_literal_list(tuple_es(Node)));
	cons ->
	    update_c_cons(Node, fold_literal(cons_hd(Node)),
			  fold_literal(cons_tl(Node)));
	_ ->
	    Node    
    end.

fold_literal_list([E | Es]) ->
    [fold_literal(E) | fold_literal_list(Es)];
fold_literal_list([]) ->
    [].


%% @spec unfold_literal(Node::cerl()) -> cerl()
%%
%% @doc Assures that literals have a fully expanded representation. If
%% <code>Node</code> represents a literal tuple or list constructor, its
%% elements are rewritten recursively, and the node is reconstructed
%% using <code>c_cons_skel/2</code> or <code>c_tuple_skel/1</code>,
%% respectively; otherwise, <code>Node</code> is not changed. The {@link
%% fold_literal/1} can be used to revert to the normal compact
%% representation.
%%
%% @see is_literal/1
%% @see c_cons_skel/2
%% @see c_tuple_skel/1
%% @see c_cons/2
%% @see c_tuple/1
%% @see fold_literal/1

-spec unfold_literal(cerl()) -> cerl().

unfold_literal(Node) ->
    case type(Node) of
	literal ->
	    copy_ann(Node, unfold_concrete(concrete(Node)));
	_ ->
	    Node
    end.

unfold_concrete(Val) ->
    case Val of
	_ when is_tuple(Val) ->
	    c_tuple_skel(unfold_concrete_list(tuple_to_list(Val)));
	[H|T] ->
	    c_cons_skel(unfold_concrete(H), unfold_concrete(T));
	_ ->
	    abstract(Val)
    end.

unfold_concrete_list([E | Es]) ->
    [unfold_concrete(E) | unfold_concrete_list(Es)];
unfold_concrete_list([]) ->
    [].


%% ---------------------------------------------------------------------

%% @spec c_module(Name::cerl(), Exports, Definitions) -> cerl()
%%
%%     Exports = [cerl()]
%%     Definitions = [{cerl(), cerl()}]
%%
%% @equiv c_module(Name, Exports, [], Definitions)

-spec c_module(cerl(), [cerl()], [{cerl(), cerl()}]) -> c_module().

c_module(Name, Exports, Es) ->
    #c_module{name = Name, exports = Exports, attrs = [], defs = Es}.


%% @spec c_module(Name::cerl(), Exports, Attributes, Definitions) ->
%%           cerl()
%%
%%     Exports = [cerl()]
%%     Attributes = [{cerl(), cerl()}]
%%     Definitions = [{cerl(), cerl()}]
%%
%% @doc Creates an abstract module definition. The result represents
%% <pre>
%%   module <em>Name</em> [<em>E1</em>, ..., <em>Ek</em>]
%%     attributes [<em>K1</em> = <em>T1</em>, ...,
%%                 <em>Km</em> = <em>Tm</em>]
%%     <em>V1</em> = <em>F1</em>
%%     ...
%%     <em>Vn</em> = <em>Fn</em>
%%   end</pre>
%%
%% if <code>Exports</code> = <code>[E1, ..., Ek]</code>,
%% <code>Attributes</code> = <code>[{K1, T1}, ..., {Km, Tm}]</code>,
%% and <code>Definitions</code> = <code>[{V1, F1}, ..., {Vn,
%% Fn}]</code>.
%%
%% <p><code>Name</code> and all the <code>Ki</code> must be atom
%% literals, and all the <code>Ti</code> must be constant literals. All
%% the <code>Vi</code> and <code>Ei</code> must have type
%% <code>var</code> and represent function names. All the
%% <code>Fi</code> must have type <code>'fun'</code>.</p>
%%
%% @see c_module/3
%% @see module_name/1
%% @see module_exports/1
%% @see module_attrs/1
%% @see module_defs/1
%% @see module_vars/1
%% @see ann_c_module/4
%% @see ann_c_module/5
%% @see update_c_module/5
%% @see c_atom/1
%% @see c_var/1
%% @see c_fun/2
%% @see is_literal/1

-spec c_module(cerl(), [cerl()], [{cerl(), cerl()}], [{cerl(), cerl()}]) ->
        c_module().

c_module(Name, Exports, Attrs, Es) ->
    #c_module{name = Name, exports = Exports, attrs = Attrs, defs = Es}.


%% @spec ann_c_module(As::[term()], Name::cerl(), Exports,
%%                    Definitions) -> cerl()
%%
%%     Exports = [cerl()]
%%     Definitions = [{cerl(), cerl()}]
%%
%% @see c_module/3
%% @see ann_c_module/5

-spec ann_c_module([term()], cerl(), [cerl()], [{cerl(), cerl()}]) ->
        c_module().

ann_c_module(As, Name, Exports, Es) ->
    #c_module{name = Name, exports = Exports, attrs = [], defs = Es,
	      anno = As}.


%% @spec ann_c_module(As::[term()], Name::cerl(), Exports,
%%                    Attributes, Definitions) -> cerl()
%%
%%     Exports = [cerl()]
%%     Attributes = [{cerl(), cerl()}]
%%     Definitions = [{cerl(), cerl()}]
%%
%% @see c_module/4
%% @see ann_c_module/4

-spec ann_c_module([term()], cerl(), [cerl()],
		   [{cerl(), cerl()}], [{cerl(), cerl()}]) -> c_module().

ann_c_module(As, Name, Exports, Attrs, Es) ->
    #c_module{name = Name, exports = Exports, attrs = Attrs, defs = Es,
	      anno = As}.


%% @spec update_c_module(Old::cerl(), Name::cerl(), Exports,
%%                       Attributes, Definitions) -> cerl()
%%
%%     Exports = [cerl()]
%%     Attributes = [{cerl(), cerl()}]
%%     Definitions = [{cerl(), cerl()}]
%%
%% @see c_module/4

-spec update_c_module(c_module(), cerl(), [cerl()],
		      [{cerl(), cerl()}], [{cerl(), cerl()}]) -> c_module().

update_c_module(Node, Name, Exports, Attrs, Es) ->
    #c_module{name = Name, exports = Exports, attrs = Attrs, defs = Es,
	      anno = get_ann(Node)}.


%% @spec is_c_module(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% module definition, otherwise <code>false</code>.
%%
%% @see type/1

-spec is_c_module(cerl()) -> boolean().

is_c_module(#c_module{}) ->
    true;
is_c_module(_) ->
    false.


%% @spec module_name(Node::cerl()) -> cerl()
%%
%% @doc Returns the name subtree of an abstract module definition.
%%
%% @see c_module/4

-spec module_name(c_module()) -> cerl().

module_name(Node) ->
    Node#c_module.name.


%% @spec module_exports(Node::cerl()) -> [cerl()]
%%
%% @doc Returns the list of exports subtrees of an abstract module
%% definition.
%%
%% @see c_module/4

-spec module_exports(c_module()) -> [cerl()].

module_exports(Node) ->
    Node#c_module.exports.


%% @spec module_attrs(Node::cerl()) -> [{cerl(), cerl()}]
%%
%% @doc Returns the list of pairs of attribute key/value subtrees of
%% an abstract module definition.
%%
%% @see c_module/4

-spec module_attrs(c_module()) -> [{cerl(), cerl()}].

module_attrs(Node) ->
    Node#c_module.attrs.


%% @spec module_defs(Node::cerl()) -> [{cerl(), cerl()}]
%%
%% @doc Returns the list of function definitions of an abstract module
%% definition.
%%
%% @see c_module/4

-spec module_defs(c_module()) -> [{cerl(), cerl()}].

module_defs(Node) ->
    Node#c_module.defs.


%% @spec module_vars(Node::cerl()) -> [cerl()]
%%
%% @doc Returns the list of left-hand side function variable subtrees
%% of an abstract module definition.
%%
%% @see c_module/4

-spec module_vars(c_module()) -> [cerl()].

module_vars(Node) ->
    [F || {F, _} <- module_defs(Node)].


%% ---------------------------------------------------------------------

%% @spec c_int(Value::integer()) -> cerl()
%%
%% @doc Creates an abstract integer literal. The lexical
%% representation is the canonical decimal numeral of
%% <code>Value</code>.
%%
%% @see ann_c_int/2
%% @see is_c_int/1
%% @see int_val/1
%% @see int_lit/1
%% @see c_char/1

-spec c_int(integer()) -> c_literal().

c_int(Value) ->
    #c_literal{val = Value}.


%% @spec ann_c_int(As::[term()], Value::integer()) -> cerl()
%% @see c_int/1

-spec ann_c_int([term()], integer()) -> c_literal().

ann_c_int(As, Value) ->
    #c_literal{val = Value, anno = As}.


%% @spec is_c_int(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> represents an
%% integer literal, otherwise <code>false</code>.
%% @see c_int/1

-spec is_c_int(cerl()) -> boolean().

is_c_int(#c_literal{val = V}) when is_integer(V) ->
    true;
is_c_int(_) ->
    false.


%% @spec int_val(cerl()) -> integer()
%%
%% @doc Returns the value represented by an integer literal node.
%% @see c_int/1

-spec int_val(c_literal()) -> integer().

int_val(Node) ->
    Node#c_literal.val.


%% @spec int_lit(cerl()) -> string()
%%
%% @doc Returns the numeral string represented by an integer literal
%% node.
%% @see c_int/1

-spec int_lit(c_literal()) -> string().

int_lit(Node) ->
    integer_to_list(int_val(Node)).


%% ---------------------------------------------------------------------

%% @spec c_float(Value::float()) -> cerl()
%%
%% @doc Creates an abstract floating-point literal.  The lexical
%% representation is the decimal floating-point numeral of
%% <code>Value</code>.
%%
%% @see ann_c_float/2
%% @see is_c_float/1
%% @see float_val/1
%% @see float_lit/1

%% Note that not all floating-point numerals can be represented with
%% full precision.

-spec c_float(float()) -> c_literal().

c_float(Value) ->
    #c_literal{val = Value}.


%% @spec ann_c_float(As::[term()], Value::float()) -> cerl()
%% @see c_float/1

-spec ann_c_float([term()], float()) -> c_literal().

ann_c_float(As, Value) ->
    #c_literal{val = Value, anno = As}.


%% @spec is_c_float(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> represents a
%% floating-point literal, otherwise <code>false</code>.
%% @see c_float/1

-spec is_c_float(cerl()) -> boolean().

is_c_float(#c_literal{val = V}) when is_float(V) ->
    true;
is_c_float(_) ->
    false.


%% @spec float_val(cerl()) -> float()
%%
%% @doc Returns the value represented by a floating-point literal
%% node.
%% @see c_float/1

-spec float_val(c_literal()) -> float().

float_val(Node) ->
    Node#c_literal.val.


%% @spec float_lit(cerl()) -> string()
%%
%% @doc Returns the numeral string represented by a floating-point
%% literal node.
%% @see c_float/1

-spec float_lit(c_literal()) -> string().

float_lit(Node) ->
    float_to_list(float_val(Node)).


%% ---------------------------------------------------------------------

%% @spec c_atom(Name) -> cerl()
%%	    Name = atom() | string()
%%
%% @doc Creates an abstract atom literal.  The print name of the atom
%% is the character sequence represented by <code>Name</code>.
%%
%% <p>Note: passing a string as argument to this function causes a
%% corresponding atom to be created for the internal representation.</p>
%%
%% @see ann_c_atom/2
%% @see is_c_atom/1
%% @see atom_val/1
%% @see atom_name/1
%% @see atom_lit/1

-spec c_atom(atom() | string()) -> c_literal().

c_atom(Name) when is_atom(Name) ->
    #c_literal{val = Name};
c_atom(Name) ->
    #c_literal{val = list_to_atom(Name)}.


%% @spec ann_c_atom(As::[term()], Name) -> cerl()
%%	    Name = atom() | string()
%% @see c_atom/1

-spec ann_c_atom([term()], atom() | string()) -> c_literal().

ann_c_atom(As, Name) when is_atom(Name) ->
    #c_literal{val = Name, anno = As};
ann_c_atom(As, Name) ->
    #c_literal{val = list_to_atom(Name), anno = As}.


%% @spec is_c_atom(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> represents an
%% atom literal, otherwise <code>false</code>.
%%
%% @see c_atom/1

-spec is_c_atom(cerl()) -> boolean().

is_c_atom(#c_literal{val = V}) when is_atom(V) ->
    true;
is_c_atom(_) ->
    false.

%% @spec atom_val(cerl()) -> atom()
%%
%% @doc Returns the value represented by an abstract atom.
%%
%% @see c_atom/1

-spec atom_val(c_literal()) -> atom().

atom_val(Node) ->
    Node#c_literal.val.


%% @spec atom_name(cerl()) -> string()
%%
%% @doc Returns the printname of an abstract atom.
%%
%% @see c_atom/1

-spec atom_name(c_literal()) -> string().

atom_name(Node) ->
    atom_to_list(atom_val(Node)).


%% @spec atom_lit(cerl()) -> string()
%%
%% @doc Returns the literal string represented by an abstract
%% atom. This always includes surrounding single-quote characters.
%%
%% <p>Note that an abstract atom may have several literal
%% representations, and that the representation yielded by this
%% function is not fixed; e.g.,
%% <code>atom_lit(c_atom("a\012b"))</code> could yield the string
%% <code>"\'a\\nb\'"</code>.</p>
%%
%% @see c_atom/1

%% TODO: replace the use of the unofficial 'write_string/2'.

-spec atom_lit(cerl()) -> nonempty_string().

atom_lit(Node) ->
    io_lib:write_string(atom_name(Node), $'). %' stupid Emacs.


%% ---------------------------------------------------------------------

%% @spec c_char(Value) -> cerl()
%%
%%    Value = char() | integer()
%%
%% @doc Creates an abstract character literal. If the local
%% implementation of Erlang defines <code>char()</code> as a subset of
%% <code>integer()</code>, this function is equivalent to
%% <code>c_int/1</code>. Otherwise, if the given value is an integer,
%% it will be converted to the character with the corresponding
%% code. The lexical representation of a character is
%% "<code>$<em>Char</em></code>", where <code>Char</code> is a single
%% printing character or an escape sequence.
%%
%% @see c_int/1
%% @see c_string/1
%% @see ann_c_char/2
%% @see is_c_char/1
%% @see char_val/1
%% @see char_lit/1
%% @see is_print_char/1

-spec c_char(non_neg_integer()) -> c_literal().

c_char(Value) when is_integer(Value), Value >= 0 ->
    #c_literal{val = Value}.


%% @spec ann_c_char(As::[term()], Value::char()) -> cerl()
%% @see c_char/1

-spec ann_c_char([term()], char()) -> c_literal().

ann_c_char(As, Value) ->
    #c_literal{val = Value, anno = As}.


%% @spec is_c_char(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> may represent a
%% character literal, otherwise <code>false</code>.
%%
%% <p>If the local implementation of Erlang defines
%% <code>char()</code> as a subset of <code>integer()</code>, then
%% <code>is_c_int(<em>Node</em>)</code> will also yield
%% <code>true</code>.</p>
%%
%% @see c_char/1
%% @see is_print_char/1

-spec is_c_char(c_literal()) -> boolean().

is_c_char(#c_literal{val = V}) when is_integer(V), V >= 0 ->
    is_char_value(V);
is_c_char(_) ->
    false.


%% @spec is_print_char(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> may represent a
%% "printing" character, otherwise <code>false</code>. (Cf.
%% <code>is_c_char/1</code>.)  A "printing" character has either a
%% given graphical representation, or a "named" escape sequence such
%% as "<code>\n</code>". Currently, only ISO 8859-1 (Latin-1)
%% character values are recognized.
%%
%% @see c_char/1
%% @see is_c_char/1

-spec is_print_char(cerl()) -> boolean().

is_print_char(#c_literal{val = V}) when is_integer(V), V >= 0 ->
    is_print_char_value(V);
is_print_char(_) ->
    false.


%% @spec char_val(cerl()) -> char()
%%
%% @doc Returns the value represented by an abstract character literal.
%%
%% @see c_char/1

-spec char_val(c_literal()) -> char().

char_val(Node) ->
    Node#c_literal.val.


%% @spec char_lit(cerl()) -> string()
%%
%% @doc Returns the literal string represented by an abstract
%% character. This includes a leading <code>$</code>
%% character. Currently, all characters that are not in the set of ISO
%% 8859-1 (Latin-1) "printing" characters will be escaped.
%%
%% @see c_char/1

-spec char_lit(c_literal()) -> nonempty_string().

char_lit(Node) ->
    io_lib:write_char(char_val(Node)).


%% ---------------------------------------------------------------------

%% @spec c_string(Value::string()) -> cerl()
%%
%% @doc Creates an abstract string literal. Equivalent to creating an
%% abstract list of the corresponding character literals
%% (cf. <code>is_c_string/1</code>), but is typically more
%% efficient. The lexical representation of a string is
%% "<code>"<em>Chars</em>"</code>", where <code>Chars</code> is a
%% sequence of printing characters or spaces.
%%
%% @see c_char/1
%% @see ann_c_string/2
%% @see is_c_string/1
%% @see string_val/1
%% @see string_lit/1
%% @see is_print_string/1

-spec c_string(string()) -> c_literal().

c_string(Value) ->
    #c_literal{val = Value}.


%% @spec ann_c_string(As::[term()], Value::string()) -> cerl()
%% @see c_string/1

-spec ann_c_string([term()], string()) -> c_literal().

ann_c_string(As, Value) ->
    #c_literal{val = Value, anno = As}.


%% @spec is_c_string(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> may represent a
%% string literal, otherwise <code>false</code>. Strings are defined
%% as lists of characters; see <code>is_c_char/1</code> for details.
%%
%% @see c_string/1
%% @see is_c_char/1
%% @see is_print_string/1

-spec is_c_string(cerl()) -> boolean().

is_c_string(#c_literal{val = V}) ->
    is_char_list(V);
is_c_string(_) ->
    false.


%% @spec is_print_string(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> may represent a
%% string literal containing only "printing" characters, otherwise
%% <code>false</code>. See <code>is_c_string/1</code> and
%% <code>is_print_char/1</code> for details. Currently, only ISO
%% 8859-1 (Latin-1) character values are recognized.
%%
%% @see c_string/1
%% @see is_c_string/1
%% @see is_print_char/1

-spec is_print_string(cerl()) -> boolean().

is_print_string(#c_literal{val = V}) ->
    is_print_char_list(V);
is_print_string(_) ->
    false.


%% @spec string_val(cerl()) -> string()
%%
%% @doc Returns the value represented by an abstract string literal.
%%
%% @see c_string/1

-spec string_val(c_literal()) -> string().

string_val(Node) ->
    Node#c_literal.val.


%% @spec string_lit(cerl()) -> string()
%%
%% @doc Returns the literal string represented by an abstract string.
%% This includes surrounding double-quote characters
%% <code>"..."</code>. Currently, characters that are not in the set
%% of ISO 8859-1 (Latin-1) "printing" characters will be escaped,
%% except for spaces.
%%
%% @see c_string/1

-spec string_lit(c_literal()) -> nonempty_string().

string_lit(Node) ->
    io_lib:write_string(string_val(Node)).


%% ---------------------------------------------------------------------

%% @spec c_nil() -> cerl()
%%
%% @doc Creates an abstract empty list. The result represents
%% "<code>[]</code>". The empty list is traditionally called "nil".
%%
%% @see ann_c_nil/1
%% @see is_c_list/1
%% @see c_cons/2

-spec c_nil() -> c_literal().

c_nil() ->
    #c_literal{val = []}.


%% @spec ann_c_nil(As::[term()]) -> cerl()
%% @see c_nil/0

-spec ann_c_nil([term()]) -> c_literal().

ann_c_nil(As) ->
    #c_literal{val = [], anno = As}.


%% @spec is_c_nil(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% empty list, otherwise <code>false</code>.

-spec is_c_nil(cerl()) -> boolean().

is_c_nil(#c_literal{val = []}) ->
    true;
is_c_nil(_) ->
    false.


%% ---------------------------------------------------------------------

%% @spec c_cons(Head::cerl(), Tail::cerl()) -> cerl()
%%
%% @doc Creates an abstract list constructor. The result represents
%% "<code>[<em>Head</em> | <em>Tail</em>]</code>". Note that if both
%% <code>Head</code> and <code>Tail</code> have type
%% <code>literal</code>, then the result will also have type
%% <code>literal</code>, and annotations on <code>Head</code> and
%% <code>Tail</code> are lost.
%%
%% <p>Recall that in Erlang, the tail element of a list constructor is
%% not necessarily a list.</p>
%%
%% @see ann_c_cons/3
%% @see update_c_cons/3
%% @see c_cons_skel/2
%% @see is_c_cons/1
%% @see cons_hd/1
%% @see cons_tl/1
%% @see is_c_list/1
%% @see c_nil/0
%% @see list_elements/1
%% @see list_length/1
%% @see make_list/2

%% *Always* collapse literals.

-spec c_cons(cerl(), cerl()) -> c_literal() | c_cons().

c_cons(#c_literal{val = Head}, #c_literal{val = Tail}) ->
    #c_literal{val = [Head | Tail]};
c_cons(Head, Tail) ->
    #c_cons{hd = Head, tl = Tail}.


%% @spec ann_c_cons(As::[term()], Head::cerl(), Tail::cerl()) -> cerl()
%% @see c_cons/2

-spec ann_c_cons([term()], cerl(), cerl()) -> c_literal() | c_cons().

ann_c_cons(As, #c_literal{val = Head}, #c_literal{val = Tail}) ->
    #c_literal{val = [Head | Tail], anno = As};
ann_c_cons(As, Head, Tail) ->
    #c_cons{hd = Head, tl = Tail, anno = As}.


%% @spec update_c_cons(Old::cerl(), Head::cerl(), Tail::cerl()) ->
%%           cerl()
%% @see c_cons/2

-spec update_c_cons(c_literal() | c_cons(), cerl(), cerl()) ->
        c_literal() | c_cons().

update_c_cons(Node, #c_literal{val = Head}, #c_literal{val = Tail}) ->
    #c_literal{val = [Head | Tail], anno = get_ann(Node)};
update_c_cons(Node, Head, Tail) ->
    #c_cons{hd = Head, tl = Tail, anno = get_ann(Node)}.


%% @spec c_cons_skel(Head::cerl(), Tail::cerl()) -> cerl()
%%
%% @doc Creates an abstract list constructor skeleton. Does not fold
%% constant literals, i.e., the result always has type
%% <code>cons</code>, representing "<code>[<em>Head</em> |
%% <em>Tail</em>]</code>".
%%
%% <p>This function is occasionally useful when it is necessary to have
%% annotations on the subnodes of a list constructor node, even when the
%% subnodes are constant literals. Note however that
%% <code>is_literal/1</code> will yield <code>false</code> and
%% <code>concrete/1</code> will fail if passed the result from this
%% function.</p>
%%
%% <p><code>fold_literal/1</code> can be used to revert a node to the
%% normal-form representation.</p>
%%
%% @see ann_c_cons_skel/3
%% @see update_c_cons_skel/3
%% @see c_cons/2
%% @see is_c_cons/1
%% @see is_c_list/1
%% @see c_nil/0
%% @see is_literal/1
%% @see fold_literal/1
%% @see concrete/1

%% *Never* collapse literals.

-spec c_cons_skel(cerl(), cerl()) -> c_cons().

c_cons_skel(Head, Tail) ->
    #c_cons{hd = Head, tl = Tail}.


%% @spec ann_c_cons_skel(As::[term()], Head::cerl(), Tail::cerl()) ->
%%           cerl()
%% @see c_cons_skel/2

-spec ann_c_cons_skel([term()], cerl(), cerl()) -> c_cons().

ann_c_cons_skel(As, Head, Tail) ->
    #c_cons{hd = Head, tl = Tail, anno = As}.


%% @spec update_c_cons_skel(Old::cerl(), Head::cerl(), Tail::cerl()) ->
%%           cerl()
%% @see c_cons_skel/2

-spec update_c_cons_skel(c_cons() | c_literal(), cerl(), cerl()) -> c_cons().

update_c_cons_skel(Node, Head, Tail) ->
    #c_cons{hd = Head, tl = Tail, anno = get_ann(Node)}.


%% @spec is_c_cons(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% list constructor, otherwise <code>false</code>.

-spec is_c_cons(cerl()) -> boolean().

is_c_cons(#c_cons{}) ->
    true;
is_c_cons(#c_literal{val = [_ | _]}) ->
    true;
is_c_cons(_) ->
    false.


%% @spec cons_hd(cerl()) -> cerl()
%%
%% @doc Returns the head subtree of an abstract list constructor.
%%
%% @see c_cons/2

-spec cons_hd(c_cons() | c_literal()) -> cerl().

cons_hd(#c_cons{hd = Head}) ->
    Head;
cons_hd(#c_literal{val = [Head | _]}) ->
    #c_literal{val = Head}.


%% @spec cons_tl(cerl()) -> cerl()
%%
%% @doc Returns the tail subtree of an abstract list constructor.
%%
%% <p>Recall that the tail does not necessarily represent a proper
%% list.</p>
%%
%% @see c_cons/2

-spec cons_tl(c_cons() | c_literal()) -> cerl().

cons_tl(#c_cons{tl = Tail}) ->
    Tail;
cons_tl(#c_literal{val = [_ | Tail]}) ->
    #c_literal{val = Tail}.


%% @spec is_c_list(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> represents a
%% proper list, otherwise <code>false</code>. A proper list is either
%% the empty list <code>[]</code>, or a cons cell <code>[<em>Head</em> |
%% <em>Tail</em>]</code>, where recursively <code>Tail</code> is a
%% proper list.
%% 
%% <p>Note: Because <code>Node</code> is a syntax tree, the actual
%% run-time values corresponding to its subtrees may often be partially
%% or completely unknown. Thus, if <code>Node</code> represents e.g.
%% "<code>[... | Ns]</code>" (where <code>Ns</code> is a variable), then
%% the function will return <code>false</code>, because it is not known
%% whether <code>Ns</code> will be bound to a list at run-time. If
%% <code>Node</code> instead represents e.g. "<code>[1, 2, 3]</code>" or
%% "<code>[A | []]</code>", then the function will return
%% <code>true</code>.</p>
%%
%% @see c_cons/2
%% @see c_nil/0
%% @see list_elements/1
%% @see list_length/1

-spec is_c_list(cerl()) -> boolean().

is_c_list(#c_cons{tl = Tail}) ->
    is_c_list(Tail);
is_c_list(#c_literal{val = V}) ->
    is_proper_list(V);
is_c_list(_) ->
    false.

is_proper_list([_ | Tail]) ->
    is_proper_list(Tail);
is_proper_list([]) ->
    true;
is_proper_list(_) ->
    false.

%% @spec list_elements(cerl()) -> [cerl()]
%%
%% @doc Returns the list of element subtrees of an abstract list.
%% <code>Node</code> must represent a proper list. E.g., if
%% <code>Node</code> represents "<code>[<em>X1</em>, <em>X2</em> |
%% [<em>X3</em>, <em>X4</em> | []]</code>", then
%% <code>list_elements(Node)</code> yields the list <code>[X1, X2, X3,
%% X4]</code>.
%%
%% @see c_cons/2
%% @see c_nil/1
%% @see is_c_list/1
%% @see list_length/1
%% @see make_list/2

-spec list_elements(c_cons() | c_literal()) -> [cerl()].

list_elements(#c_cons{hd = Head, tl = Tail}) ->
    [Head | list_elements(Tail)];
list_elements(#c_literal{val = V}) ->
    abstract_list(V).

abstract_list([X | Xs]) ->
    [abstract(X) | abstract_list(Xs)];
abstract_list([]) ->
    [].


%% @spec list_length(Node::cerl()) -> integer()
%%
%% @doc Returns the number of element subtrees of an abstract list.
%% <code>Node</code> must represent a proper list. E.g., if
%% <code>Node</code> represents "<code>[X1 | [X2, X3 | [X4, X5,
%% X6]]]</code>", then <code>list_length(Node)</code> returns the
%% integer 6.
%%
%% <p>Note: this is equivalent to
%% <code>length(list_elements(Node))</code>, but potentially more
%% efficient.</p>
%%
%% @see c_cons/2
%% @see c_nil/1
%% @see is_c_list/1
%% @see list_elements/1

-spec list_length(c_cons() | c_literal()) -> non_neg_integer().

list_length(L) ->
    list_length(L, 0).

list_length(#c_cons{tl = Tail}, A) ->
    list_length(Tail, A + 1);
list_length(#c_literal{val = V}, A) ->
    A + length(V).


%% @spec make_list(List) -> Node
%% @equiv make_list(List, none)

-spec make_list([cerl()]) -> cerl().

make_list(List) ->
    ann_make_list([], List).


%% @spec make_list(List::[cerl()], Tail) -> cerl()
%%
%%	    Tail = cerl() | none
%%
%% @doc Creates an abstract list from the elements in <code>List</code>
%% and the optional <code>Tail</code>. If <code>Tail</code> is
%% <code>none</code>, the result will represent a nil-terminated list,
%% otherwise it represents "<code>[... | <em>Tail</em>]</code>".
%%
%% @see c_cons/2
%% @see c_nil/0
%% @see ann_make_list/3
%% @see update_list/3
%% @see list_elements/1

-spec make_list([cerl()], cerl() | 'none') -> cerl().

make_list(List, Tail) ->
    ann_make_list([], List, Tail).


%% @spec update_list(Old::cerl(), List::[cerl()]) -> cerl()
%% @equiv update_list(Old, List, none)

-spec update_list(cerl(), [cerl()]) -> cerl().

update_list(Node, List) ->
    ann_make_list(get_ann(Node), List).


%% @spec update_list(Old::cerl(), List::[cerl()], Tail) -> cerl()
%%
%%	    Tail = cerl() | none
%%
%% @see make_list/2
%% @see update_list/2

-spec update_list(cerl(), [cerl()], cerl() | 'none') -> cerl().

update_list(Node, List, Tail) ->
    ann_make_list(get_ann(Node), List, Tail).


%% @spec ann_make_list(As::[term()], List::[cerl()]) -> cerl()
%% @equiv ann_make_list(As, List, none)

-spec ann_make_list([term()], [cerl()]) -> cerl().

ann_make_list(As, List) ->
    ann_make_list(As, List, none).


%% @spec ann_make_list(As::[term()], List::[cerl()], Tail) -> cerl()
%%
%%	    Tail = cerl() | none
%%
%% @see make_list/2
%% @see ann_make_list/2

-spec ann_make_list([term()], [cerl()], cerl() | 'none') -> cerl().

ann_make_list(As, [H | T], Tail) ->
    ann_c_cons(As, H, make_list(T, Tail));    % `c_cons' folds literals
ann_make_list(As, [], none) ->
    ann_c_nil(As);
ann_make_list(_, [], Node) ->
    Node.


%% ---------------------------------------------------------------------
%% maps

%% @spec is_c_map(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% map constructor, otherwise <code>false</code>.

-spec is_c_map(cerl()) -> boolean().

is_c_map(#c_map{}) ->
    true;
is_c_map(#c_literal{val = V}) when is_map(V) ->
    true;
is_c_map(_) ->
    false.

-spec map_es(c_map()) -> [c_map_pair()].

map_es(#c_map{es = Es}) ->
    Es.

-spec map_arg(c_map()) -> c_map() | c_literal().

map_arg(#c_map{arg=M}) ->
    M.

-spec c_map([c_map_pair()]) -> c_map().

c_map(Pairs) ->
    ann_c_map([], Pairs).

-spec c_map_pattern([c_map_pair()]) -> c_map().

c_map_pattern(Pairs) ->
    #c_map{es=Pairs, is_pat=true}.

-spec ann_c_map_pattern([term()], [c_map_pair()]) -> c_map().

ann_c_map_pattern(As, Pairs) ->
    #c_map{anno=As, es=Pairs, is_pat=true}.

-spec is_c_map_empty(c_map() | c_literal()) -> boolean().

is_c_map_empty(#c_map{ es=[] }) -> true;
is_c_map_empty(#c_literal{val=M}) when is_map(M),map_size(M) =:= 0 -> true;
is_c_map_empty(_) -> false.

-spec ann_c_map([term()], [c_map_pair()]) -> c_map() | c_literal().

ann_c_map(As, Es) ->
    ann_c_map(As, #c_literal{val=#{}}, Es).

-spec ann_c_map([term()], c_map() | c_literal(), [c_map_pair()]) -> c_map() | c_literal().

ann_c_map(As,#c_literal{val=M},Es) when is_map(M) ->
    fold_map_pairs(As,Es,M);
ann_c_map(As,M,Es) ->
    #c_map{arg=M, es=Es, anno=As }.

fold_map_pairs(As,[],M) -> #c_literal{anno=As,val=M};
%% M#{ K => V}
fold_map_pairs(As,[#c_map_pair{op=#c_literal{val=assoc},key=Ck,val=Cv}=E|Es],M) ->
    case is_lit_list([Ck,Cv]) of
	true ->
	    [K,V] = lit_list_vals([Ck,Cv]),
	    fold_map_pairs(As,Es,maps:put(K,V,M));
	false ->
	    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
    end;
%% M#{ K := V}
fold_map_pairs(As,[#c_map_pair{op=#c_literal{val=exact},key=Ck,val=Cv}=E|Es],M) ->
    case is_lit_list([Ck,Cv]) of
	true ->
	    [K,V] = lit_list_vals([Ck,Cv]),
	    case maps:is_key(K,M) of
		true -> fold_map_pairs(As,Es,maps:put(K,V,M));
		false ->
		    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
	    end;
	false ->
	    #c_map{arg=#c_literal{val=M,anno=As}, es=[E|Es], anno=As }
    end.

-spec update_c_map(c_map(), cerl(), [cerl()]) -> c_map() | c_literal().

update_c_map(#c_map{is_pat=true}=Old, M, Es) ->
    Old#c_map{arg=M, es=Es};
update_c_map(#c_map{is_pat=false}=Old, M, Es) ->
    ann_c_map(get_ann(Old), M, Es).

map_pair_key(#c_map_pair{key=K}) -> K.
map_pair_val(#c_map_pair{val=V}) -> V.
map_pair_op(#c_map_pair{op=Op}) -> Op.

-spec c_map_pair(cerl(), cerl()) -> c_map_pair().

c_map_pair(Key,Val) ->
    #c_map_pair{op=#c_literal{val=assoc},key=Key,val=Val}.

-spec ann_c_map_pair([term()], cerl(), cerl(), cerl()) ->
        c_map_pair().

ann_c_map_pair(As,Op,K,V) ->
    #c_map_pair{op=Op, key = K, val=V, anno = As}.

update_c_map_pair(Old,Op,K,V) ->
    #c_map_pair{op=Op, key=K, val=V, anno = get_ann(Old)}.


%% ---------------------------------------------------------------------

%% @spec c_tuple(Elements::[cerl()]) -> cerl()
%%
%% @doc Creates an abstract tuple. If <code>Elements</code> is
%% <code>[E1, ..., En]</code>, the result represents
%% "<code>{<em>E1</em>, ..., <em>En</em>}</code>".  Note that if all
%% nodes in <code>Elements</code> have type <code>literal</code>, or if
%% <code>Elements</code> is empty, then the result will also have type
%% <code>literal</code> and annotations on nodes in
%% <code>Elements</code> are lost.
%%
%% <p>Recall that Erlang has distinct 1-tuples, i.e., <code>{X}</code>
%% is always distinct from <code>X</code> itself.</p>
%%
%% @see ann_c_tuple/2
%% @see update_c_tuple/2
%% @see is_c_tuple/1
%% @see tuple_es/1
%% @see tuple_arity/1
%% @see c_tuple_skel/1

%% *Always* collapse literals.

-spec c_tuple([cerl()]) -> c_tuple() | c_literal().

c_tuple(Es) ->
    case is_lit_list(Es) of
	false ->
	    #c_tuple{es = Es};
	true ->
	    #c_literal{val = list_to_tuple(lit_list_vals(Es))}
    end.


%% @spec ann_c_tuple(As::[term()], Elements::[cerl()]) -> cerl()
%% @see c_tuple/1

-spec ann_c_tuple([term()], [cerl()]) -> c_tuple() | c_literal().

ann_c_tuple(As, Es) ->
    case is_lit_list(Es) of
	false ->
	    #c_tuple{es = Es, anno = As};
	true ->
	    #c_literal{val = list_to_tuple(lit_list_vals(Es)), anno = As}
    end.


%% @spec update_c_tuple(Old::cerl(),  Elements::[cerl()]) -> cerl()
%% @see c_tuple/1

-spec update_c_tuple(c_tuple() | c_literal(), [cerl()]) -> c_tuple() | c_literal().

update_c_tuple(Node, Es) ->
    case is_lit_list(Es) of
	false ->
	    #c_tuple{es = Es, anno = get_ann(Node)};
	true ->
	    #c_literal{val = list_to_tuple(lit_list_vals(Es)),
		       anno = get_ann(Node)}
    end.


%% @spec c_tuple_skel(Elements::[cerl()]) -> cerl()
%%
%% @doc Creates an abstract tuple skeleton. Does not fold constant
%% literals, i.e., the result always has type <code>tuple</code>,
%% representing "<code>{<em>E1</em>, ..., <em>En</em>}</code>", if
%% <code>Elements</code> is <code>[E1, ..., En]</code>.
%% 
%% <p>This function is occasionally useful when it is necessary to have
%% annotations on the subnodes of a tuple node, even when all the
%% subnodes are constant literals. Note however that
%% <code>is_literal/1</code> will yield <code>false</code> and
%% <code>concrete/1</code> will fail if passed the result from this
%% function.</p>
%%
%% <p><code>fold_literal/1</code> can be used to revert a node to the
%% normal-form representation.</p>
%%
%% @see ann_c_tuple_skel/2
%% @see update_c_tuple_skel/2
%% @see c_tuple/1
%% @see tuple_es/1
%% @see is_c_tuple/1
%% @see is_literal/1
%% @see fold_literal/1
%% @see concrete/1

%% *Never* collapse literals.

-spec c_tuple_skel([cerl()]) -> c_tuple().

c_tuple_skel(Es) ->
    #c_tuple{es = Es}.


%% @spec ann_c_tuple_skel(As::[term()], Elements::[cerl()]) -> cerl()
%% @see c_tuple_skel/1

-spec ann_c_tuple_skel([term()], [cerl()]) -> c_tuple().

ann_c_tuple_skel(As, Es) ->
    #c_tuple{es = Es, anno = As}.


%% @spec update_c_tuple_skel(Old::cerl(), Elements::[cerl()]) -> cerl()
%% @see c_tuple_skel/1

-spec update_c_tuple_skel(c_tuple(), [cerl()]) -> c_tuple().

update_c_tuple_skel(Old, Es) ->
    #c_tuple{es = Es, anno = get_ann(Old)}.


%% @spec is_c_tuple(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% tuple, otherwise <code>false</code>.
%%
%% @see c_tuple/1

-spec is_c_tuple(cerl()) -> boolean().

is_c_tuple(#c_tuple{}) ->
    true;
is_c_tuple(#c_literal{val = V}) when is_tuple(V) ->
    true;
is_c_tuple(_) ->
    false.


%% @spec tuple_es(cerl()) -> [cerl()]
%%
%% @doc Returns the list of element subtrees of an abstract tuple.
%%
%% @see c_tuple/1

-spec tuple_es(c_tuple() | c_literal()) -> [cerl()].

tuple_es(#c_tuple{es = Es}) ->
    Es;
tuple_es(#c_literal{val = V}) ->
    make_lit_list(tuple_to_list(V)).


%% @spec tuple_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of element subtrees of an abstract tuple.
%%
%% <p>Note: this is equivalent to <code>length(tuple_es(Node))</code>,
%% but potentially more efficient.</p>
%%
%% @see tuple_es/1
%% @see c_tuple/1

-spec tuple_arity(c_tuple() | c_literal()) -> non_neg_integer().

tuple_arity(#c_tuple{es = Es}) ->
    length(Es);
tuple_arity(#c_literal{val = V}) when is_tuple(V) ->
    tuple_size(V).


%% ---------------------------------------------------------------------

%% @spec c_var(Name::var_name()) -> cerl()
%%
%%     var_name() = integer() | atom() | {atom(), integer()}
%%
%% @doc Creates an abstract variable. A variable is identified by its
%% name, given by the <code>Name</code> parameter.
%%
%% <p>If a name is given by a single atom, it should either be a
%% "simple" atom which does not need to be single-quoted in Erlang, or
%% otherwise its print name should correspond to a proper Erlang
%% variable, i.e., begin with an uppercase character or an
%% underscore. Names on the form <code>{A, N}</code> represent
%% function name variables "<code><em>A</em>/<em>N</em></code>"; these
%% are special variables which may be bound only in the function
%% definitions of a module or a <code>letrec</code>.  They may not be
%% bound in <code>let</code> expressions and cannot occur in clause
%% patterns. The atom <code>A</code> in a function name may be any
%% atom; the integer <code>N</code> must be nonnegative. The functions
%% <code>c_fname/2</code> etc. are utilities for handling function
%% name variables.</p>
%%
%% <p>When printing variable names, they must have the form of proper
%% Core Erlang variables and function names. E.g., a name represented
%% by an integer such as <code>42</code> could be formatted as
%% "<code>_42</code>", an atom <code>'Xxx'</code> simply as
%% "<code>Xxx</code>", and an atom <code>foo</code> as
%% "<code>_foo</code>". However, one must assure that any two valid
%% distinct names are never mapped to the same strings.  Tuples such
%% as <code>{foo, 2}</code> representing function names can simply by
%% formatted as "<code>'foo'/2</code>", with no risk of conflicts.</p>
%%
%% @see ann_c_var/2
%% @see update_c_var/2
%% @see is_c_var/1
%% @see var_name/1
%% @see c_fname/2
%% @see c_module/4
%% @see c_letrec/2

-spec c_var(var_name()) -> c_var().

c_var(Name) ->
    #c_var{name = Name}.


%% @spec ann_c_var(As::[term()], Name::var_name()) -> cerl()
%%
%% @see c_var/1

-spec ann_c_var([term()], var_name()) -> c_var().

ann_c_var(As, Name) ->
    #c_var{name = Name, anno = As}.

%% @spec update_c_var(Old::cerl(), Name::var_name()) -> cerl()
%%
%% @see c_var/1

-spec update_c_var(c_var(), var_name()) -> c_var().

update_c_var(Node, Name) ->
    #c_var{name = Name, anno = get_ann(Node)}.


%% @spec is_c_var(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% variable, otherwise <code>false</code>.
%%
%% @see c_var/1

-spec is_c_var(cerl()) -> boolean().

is_c_var(#c_var{}) ->
    true;
is_c_var(_) ->
    false.


%% @spec c_fname(Name::atom(), Arity::integer()) -> cerl()
%% @equiv c_var({Name, Arity})
%% @see fname_id/1
%% @see fname_arity/1
%% @see is_c_fname/1
%% @see ann_c_fname/3
%% @see update_c_fname/3

-spec c_fname(atom(), non_neg_integer()) -> c_var().

c_fname(Atom, Arity) ->
    c_var({Atom, Arity}).


%% @spec ann_c_fname(As::[term()], Name::atom(), Arity::integer()) ->
%%           cerl()
%% @equiv ann_c_var(As, {Atom, Arity})
%% @see c_fname/2

-spec ann_c_fname([term()], atom(), non_neg_integer()) -> c_var().

ann_c_fname(As, Atom, Arity) ->
    ann_c_var(As, {Atom, Arity}).


%% @spec update_c_fname(Old::cerl(), Name::atom()) -> cerl()
%% @doc Like <code>update_c_fname/3</code>, but takes the arity from
%% <code>Node</code>.
%% @see update_c_fname/3
%% @see c_fname/2

-spec update_c_fname(c_var(), atom()) -> c_var().

update_c_fname(#c_var{name = {_, Arity}, anno = As}, Atom) ->
    #c_var{name = {Atom, Arity}, anno = As}.


%% @spec update_c_fname(Old::cerl(), Name::atom(), Arity::integer()) ->
%%           cerl()
%% @equiv update_c_var(Old, {Atom, Arity})
%% @see update_c_fname/2
%% @see c_fname/2

-spec update_c_fname(c_var(), atom(), integer()) -> c_var().

update_c_fname(Node, Atom, Arity) ->
    update_c_var(Node, {Atom, Arity}).


%% @spec is_c_fname(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% function name variable, otherwise <code>false</code>.
%%
%% @see c_fname/2
%% @see c_var/1
%% @see c_var_name/1

-spec is_c_fname(cerl()) -> boolean().

is_c_fname(#c_var{name = {A, N}}) when is_atom(A), is_integer(N), N >= 0 ->
    true;
is_c_fname(_) ->
    false.


%% @spec var_name(cerl()) -> var_name()
%%
%% @doc Returns the name of an abstract variable.
%%
%% @see c_var/1

-spec var_name(c_var()) -> var_name().

var_name(Node) ->
    Node#c_var.name.


%% @spec fname_id(cerl()) -> atom()
%%
%% @doc Returns the identifier part of an abstract function name
%% variable.
%% 
%% @see fname_arity/1
%% @see c_fname/2

-spec fname_id(c_var()) -> atom().

fname_id(#c_var{name={A,_}}) ->
    A.


%% @spec fname_arity(cerl()) -> byte()
%%
%% @doc Returns the arity part of an abstract function name variable.
%%
%% @see fname_id/1
%% @see c_fname/2

-spec fname_arity(c_var()) -> byte().

fname_arity(#c_var{name={_,N}}) ->
    N.


%% ---------------------------------------------------------------------

%% @spec c_values(Elements::[cerl()]) -> cerl()
%%
%% @doc Creates an abstract value list. If <code>Elements</code> is
%% <code>[E1, ..., En]</code>, the result represents
%% "<code>&lt;<em>E1</em>, ..., <em>En</em>&gt;</code>".
%%
%% @see ann_c_values/2
%% @see update_c_values/2
%% @see is_c_values/1
%% @see values_es/1
%% @see values_arity/1

-spec c_values([cerl()]) -> c_values().

c_values(Es) ->
    #c_values{es = Es}.


%% @spec ann_c_values(As::[term()], Elements::[cerl()]) -> cerl()
%% @see c_values/1

-spec ann_c_values([term()], [cerl()]) -> c_values().

ann_c_values(As, Es) ->
    #c_values{es = Es, anno = As}.


%% @spec update_c_values(Old::cerl(), Elements::[cerl()]) -> cerl()
%% @see c_values/1

-spec update_c_values(c_values(), [cerl()]) -> c_values().

update_c_values(Node, Es) ->
    #c_values{es = Es, anno = get_ann(Node)}.


%% @spec is_c_values(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% value list; otherwise <code>false</code>.
%%
%% @see c_values/1

-spec is_c_values(cerl()) -> boolean().

is_c_values(#c_values{}) ->
    true;
is_c_values(_) ->
    false.


%% @spec values_es(cerl()) -> [cerl()]
%%
%% @doc Returns the list of element subtrees of an abstract value
%% list.
%%
%% @see c_values/1
%% @see values_arity/1

-spec values_es(c_values()) -> [cerl()].

values_es(Node) ->
    Node#c_values.es.


%% @spec values_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of element subtrees of an abstract value
%% list.
%% 
%% <p>Note: This is equivalent to
%% <code>length(values_es(Node))</code>, but potentially more
%% efficient.</p>
%%
%% @see c_values/1
%% @see values_es/1

-spec values_arity(c_values()) -> non_neg_integer().

values_arity(Node) ->
    length(values_es(Node)).


%% ---------------------------------------------------------------------

%% @spec c_binary(Segments::[cerl()]) -> cerl()
%%
%% @doc Creates an abstract binary-template. A binary object is a
%% sequence of 8-bit bytes. It is specified by zero or more bit-string
%% template <em>segments</em> of arbitrary lengths (in number of bits),
%% such that the sum of the lengths is evenly divisible by 8. If
%% <code>Segments</code> is <code>[S1, ..., Sn]</code>, the result
%% represents "<code>#{<em>S1</em>, ..., <em>Sn</em>}#</code>". All the
%% <code>Si</code> must have type <code>bitstr</code>.
%%
%% @see ann_c_binary/2
%% @see update_c_binary/2
%% @see is_c_binary/1
%% @see binary_segments/1
%% @see c_bitstr/5

-spec c_binary([cerl()]) -> c_binary().

c_binary(Segments) ->
    #c_binary{segments = Segments}.


%% @spec ann_c_binary(As::[term()], Segments::[cerl()]) -> cerl()
%% @see c_binary/1

-spec ann_c_binary([term()], [cerl()]) -> c_binary().

ann_c_binary(As, Segments) ->
    #c_binary{segments = Segments, anno = As}.


%% @spec update_c_binary(Old::cerl(), Segments::[cerl()]) -> cerl()
%% @see c_binary/1

-spec update_c_binary(c_binary(), [cerl()]) -> c_binary().

update_c_binary(Node, Segments) ->
    #c_binary{segments = Segments, anno = get_ann(Node)}.


%% @spec is_c_binary(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% binary-template; otherwise <code>false</code>.
%%
%% @see c_binary/1

-spec is_c_binary(cerl()) -> boolean().

is_c_binary(#c_binary{}) ->
    true;
is_c_binary(_) ->
    false.


%% @spec binary_segments(cerl()) -> [cerl()]
%%
%% @doc Returns the list of segment subtrees of an abstract
%% binary-template.
%%
%% @see c_binary/1
%% @see c_bitstr/5

-spec binary_segments(c_binary()) -> [cerl()].

binary_segments(Node) ->
    Node#c_binary.segments.


%% @spec c_bitstr(Value::cerl(), Size::cerl(), Unit::cerl(),
%%                Type::cerl(), Flags::cerl()) -> cerl()
%%
%% @doc Creates an abstract bit-string template. These can only occur as
%% components of an abstract binary-template (see {@link c_binary/1}).
%% The result represents "<code>#&lt;<em>Value</em>&gt;(<em>Size</em>,
%% <em>Unit</em>, <em>Type</em>, <em>Flags</em>)</code>", where
%% <code>Unit</code> must represent a positive integer constant,
%% <code>Type</code> must represent a constant atom (one of
%% <code>'integer'</code>, <code>'float'</code>, or
%% <code>'binary'</code>), and <code>Flags</code> must represent a
%% constant list <code>"[<em>F1</em>, ..., <em>Fn</em>]"</code> where
%% all the <code>Fi</code> are atoms.
%% 
%% @see c_binary/1
%% @see ann_c_bitstr/6
%% @see update_c_bitstr/6
%% @see is_c_bitstr/1
%% @see bitstr_val/1
%% @see bitstr_size/1
%% @see bitstr_unit/1
%% @see bitstr_type/1
%% @see bitstr_flags/1

-spec c_bitstr(cerl(), cerl(), cerl(), cerl(), cerl()) -> c_bitstr().

c_bitstr(Val, Size, Unit, Type, Flags) ->
    #c_bitstr{val = Val, size = Size, unit = Unit, type = Type,
	      flags = Flags}.


%% @spec c_bitstr(Value::cerl(), Size::cerl(), Type::cerl(),
%%                Flags::cerl()) -> cerl()
%% @equiv c_bitstr(Value, Size, abstract(1), Type, Flags)

-spec c_bitstr(cerl(), cerl(), cerl(), cerl()) -> c_bitstr().

c_bitstr(Val, Size, Type, Flags) ->
    c_bitstr(Val, Size, abstract(1), Type, Flags).


%% @spec c_bitstr(Value::cerl(), Type::cerl(),
%%                Flags::cerl()) -> cerl()
%% @equiv c_bitstr(Value, abstract(all), abstract(1), Type, Flags)

-spec c_bitstr(cerl(), cerl(), cerl()) -> c_bitstr().

c_bitstr(Val, Type, Flags) ->
    c_bitstr(Val, abstract(all), abstract(1), Type, Flags).


%% @spec ann_c_bitstr(As::[term()], Value::cerl(), Size::cerl(),
%%                    Unit::cerl(), Type::cerl(), Flags::cerl()) -> cerl()
%% @see c_bitstr/5
%% @see ann_c_bitstr/5

-spec ann_c_bitstr([term()], cerl(), cerl(), cerl(), cerl(), cerl()) ->
        c_bitstr().

ann_c_bitstr(As, Val, Size, Unit, Type, Flags) ->
    #c_bitstr{val = Val, size = Size, unit = Unit, type = Type,
	      flags = Flags, anno = As}.

%% @spec ann_c_bitstr(As::[term()], Value::cerl(), Size::cerl(),
%%                    Type::cerl(), Flags::cerl()) -> cerl()
%% @equiv ann_c_bitstr(As, Value, Size, abstract(1), Type, Flags)

-spec ann_c_bitstr([term()], cerl(), cerl(), cerl(), cerl()) -> c_bitstr().

ann_c_bitstr(As, Value, Size, Type, Flags) ->
    ann_c_bitstr(As, Value, Size, abstract(1), Type, Flags).


%% @spec update_c_bitstr(Old::cerl(), Value::cerl(), Size::cerl(),
%%           Unit::cerl(), Type::cerl(), Flags::cerl()) -> cerl()
%% @see c_bitstr/5
%% @see update_c_bitstr/5

-spec update_c_bitstr(c_bitstr(), cerl(), cerl(), cerl(), cerl(), cerl()) ->
        c_bitstr().

update_c_bitstr(Node, Val, Size, Unit, Type, Flags) ->
    #c_bitstr{val = Val, size = Size, unit = Unit, type = Type,
	     flags = Flags, anno = get_ann(Node)}.


%% @spec update_c_bitstr(Old::cerl(), Value::cerl(), Size::cerl(),
%%                       Type::cerl(), Flags::cerl()) -> cerl()
%% @equiv update_c_bitstr(Node, Value, Size, abstract(1), Type, Flags)

-spec update_c_bitstr(c_bitstr(), cerl(), cerl(), cerl(), cerl()) -> c_bitstr().

update_c_bitstr(Node, Value, Size, Type, Flags) ->
    update_c_bitstr(Node, Value, Size, abstract(1), Type, Flags).

%% @spec is_c_bitstr(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% bit-string template; otherwise <code>false</code>.
%%
%% @see c_bitstr/5

-spec is_c_bitstr(cerl()) -> boolean().

is_c_bitstr(#c_bitstr{}) ->
    true;
is_c_bitstr(_) ->
    false.


%% @spec bitstr_val(cerl()) -> cerl()
%%
%% @doc Returns the value subtree of an abstract bit-string template.
%%
%% @see c_bitstr/5

-spec bitstr_val(c_bitstr()) -> cerl().

bitstr_val(Node) ->
    Node#c_bitstr.val.


%% @spec bitstr_size(cerl()) -> cerl()
%%
%% @doc Returns the size subtree of an abstract bit-string template.
%%
%% @see c_bitstr/5

-spec bitstr_size(c_bitstr()) -> cerl().

bitstr_size(Node) ->
    Node#c_bitstr.size.


%% @spec bitstr_bitsize(cerl()) -> any | all | utf | integer()
%%
%% @doc Returns the total size in bits of an abstract bit-string
%% template. If the size field is an integer literal, the result is the
%% product of the size and unit values; if the size field is the atom
%% literal <code>all</code>, the atom <code>all</code> is returned.
%% If the size is not a literal, the atom <code>any</code> is returned.
%%
%% @see c_bitstr/5

-spec bitstr_bitsize(c_bitstr()) -> 'all' | 'any' | 'utf' | non_neg_integer().

bitstr_bitsize(Node) ->
    Size = Node#c_bitstr.size,
    case is_literal(Size) of
	true ->
	    case concrete(Size) of
		all ->
		    all;
		undefined ->
		     %% just an assertion below
		    "utf" ++ _ = atom_to_list(concrete(Node#c_bitstr.type)),
		    utf;
		S when is_integer(S) ->
		    S * concrete(Node#c_bitstr.unit)
	    end;
	false ->
	    any
    end.


%% @spec bitstr_unit(cerl()) -> cerl()
%%
%% @doc Returns the unit subtree of an abstract bit-string template.
%%
%% @see c_bitstr/5

-spec bitstr_unit(c_bitstr()) -> cerl().

bitstr_unit(Node) ->
    Node#c_bitstr.unit.


%% @spec bitstr_type(cerl()) -> cerl()
%%
%% @doc Returns the type subtree of an abstract bit-string template.
%%
%% @see c_bitstr/5

-spec bitstr_type(c_bitstr()) -> cerl().

bitstr_type(Node) ->
    Node#c_bitstr.type.


%% @spec bitstr_flags(cerl()) -> cerl()
%%
%% @doc Returns the flags subtree of an abstract bit-string template.
%%
%% @see c_bitstr/5

-spec bitstr_flags(c_bitstr()) -> cerl().

bitstr_flags(Node) ->
    Node#c_bitstr.flags.


%% ---------------------------------------------------------------------

%% @spec c_fun(Variables::[cerl()], Body::cerl()) -> cerl()
%%
%% @doc Creates an abstract fun-expression. If <code>Variables</code>
%% is <code>[V1, ..., Vn]</code>, the result represents "<code>fun
%% (<em>V1</em>, ..., <em>Vn</em>) -> <em>Body</em></code>". All the
%% <code>Vi</code> must have type <code>var</code>.
%%
%% @see ann_c_fun/3
%% @see update_c_fun/3
%% @see is_c_fun/1
%% @see fun_vars/1
%% @see fun_body/1
%% @see fun_arity/1

-spec c_fun([cerl()], cerl()) -> c_fun().

c_fun(Variables, Body) ->
    #c_fun{vars = Variables, body = Body}.


%% @spec ann_c_fun(As::[term()], Variables::[cerl()], Body::cerl()) ->
%%           cerl()
%% @see c_fun/2

-spec ann_c_fun([term()], [cerl()], cerl()) -> c_fun().

ann_c_fun(As, Variables, Body) ->
    #c_fun{vars = Variables, body = Body, anno = As}.


%% @spec update_c_fun(Old::cerl(), Variables::[cerl()],
%%                    Body::cerl()) -> cerl()
%% @see c_fun/2

-spec update_c_fun(c_fun(), [cerl()], cerl()) -> c_fun().

update_c_fun(Node, Variables, Body) ->
    #c_fun{vars = Variables, body = Body, anno = get_ann(Node)}.


%% @spec is_c_fun(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% fun-expression, otherwise <code>false</code>.
%%
%% @see c_fun/2

-spec is_c_fun(cerl()) -> boolean().

is_c_fun(#c_fun{}) ->
    true;		% Now this is fun!
is_c_fun(_) ->
    false.


%% @spec fun_vars(cerl()) -> [cerl()]
%%
%% @doc Returns the list of parameter subtrees of an abstract
%% fun-expression.
%%
%% @see c_fun/2
%% @see fun_arity/1

-spec fun_vars(c_fun()) -> [cerl()].

fun_vars(Node) ->
    Node#c_fun.vars.


%% @spec fun_body(cerl()) -> cerl()
%%
%% @doc Returns the body subtree of an abstract fun-expression.
%%
%% @see c_fun/2

-spec fun_body(c_fun()) -> cerl().

fun_body(Node) ->
    Node#c_fun.body.


%% @spec fun_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of parameter subtrees of an abstract
%% fun-expression.
%% 
%% <p>Note: this is equivalent to <code>length(fun_vars(Node))</code>,
%% but potentially more efficient.</p>
%%
%% @see c_fun/2
%% @see fun_vars/1

-spec fun_arity(c_fun()) -> non_neg_integer().

fun_arity(Node) ->
    length(fun_vars(Node)).


%% ---------------------------------------------------------------------

%% @spec c_seq(Argument::cerl(), Body::cerl()) -> cerl()
%%
%% @doc Creates an abstract sequencing expression. The result
%% represents "<code>do <em>Argument</em> <em>Body</em></code>".
%%
%% @see ann_c_seq/3
%% @see update_c_seq/3
%% @see is_c_seq/1
%% @see seq_arg/1
%% @see seq_body/1

-spec c_seq(cerl(), cerl()) -> c_seq().

c_seq(Argument, Body) ->
    #c_seq{arg = Argument, body = Body}.


%% @spec ann_c_seq(As::[term()], Argument::cerl(), Body::cerl()) ->
%%           cerl()
%% @see c_seq/2

-spec ann_c_seq([term()], cerl(), cerl()) -> c_seq().

ann_c_seq(As, Argument, Body) ->
    #c_seq{arg = Argument, body = Body, anno = As}.


%% @spec update_c_seq(Old::cerl(), Argument::cerl(), Body::cerl()) ->
%%           cerl()
%% @see c_seq/2

-spec update_c_seq(c_seq(), cerl(), cerl()) -> c_seq().

update_c_seq(Node, Argument, Body) ->
    #c_seq{arg = Argument, body = Body, anno = get_ann(Node)}.


%% @spec is_c_seq(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% sequencing expression, otherwise <code>false</code>.
%%
%% @see c_seq/2

-spec is_c_seq(cerl()) -> boolean().

is_c_seq(#c_seq{}) ->
    true;
is_c_seq(_) ->
    false.


%% @spec seq_arg(cerl()) -> cerl()
%%
%% @doc Returns the argument subtree of an abstract sequencing
%% expression.
%%
%% @see c_seq/2

-spec seq_arg(c_seq()) -> cerl().

seq_arg(Node) ->
    Node#c_seq.arg.


%% @spec seq_body(cerl()) -> cerl()
%%
%% @doc Returns the body subtree of an abstract sequencing expression.
%%
%% @see c_seq/2

-spec seq_body(c_seq()) -> cerl().

seq_body(Node) ->
    Node#c_seq.body.


%% ---------------------------------------------------------------------

%% @spec c_let(Variables::[cerl()], Argument::cerl(), Body::cerl()) ->
%%           cerl()
%%
%% @doc Creates an abstract let-expression. If <code>Variables</code>
%% is <code>[V1, ..., Vn]</code>, the result represents "<code>let
%% &lt;<em>V1</em>, ..., <em>Vn</em>&gt; = <em>Argument</em> in
%% <em>Body</em></code>".  All the <code>Vi</code> must have type
%% <code>var</code>.
%%
%% @see ann_c_let/4
%% @see update_c_let/4
%% @see is_c_let/1
%% @see let_vars/1
%% @see let_arg/1
%% @see let_body/1
%% @see let_arity/1

-spec c_let([cerl()], cerl(), cerl()) -> c_let().

c_let(Variables, Argument, Body) ->
    #c_let{vars = Variables, arg = Argument, body = Body}.


%% ann_c_let(As, Variables, Argument, Body) -> Node
%% @see c_let/3

-spec ann_c_let([term()], [cerl()], cerl(), cerl()) -> c_let().

ann_c_let(As, Variables, Argument, Body) ->
    #c_let{vars = Variables, arg = Argument, body = Body, anno = As}.


%% update_c_let(Old, Variables, Argument, Body) -> Node
%% @see c_let/3

-spec update_c_let(c_let(), [cerl()], cerl(), cerl()) -> c_let().

update_c_let(Node, Variables, Argument, Body) ->
    #c_let{vars = Variables, arg = Argument, body = Body,
	   anno = get_ann(Node)}.


%% @spec is_c_let(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% let-expression, otherwise <code>false</code>.
%%
%% @see c_let/3

-spec is_c_let(cerl()) -> boolean().

is_c_let(#c_let{}) ->
    true;
is_c_let(_) ->
    false.


%% @spec let_vars(cerl()) -> [cerl()]
%%
%% @doc Returns the list of left-hand side variables of an abstract
%% let-expression.
%%
%% @see c_let/3
%% @see let_arity/1

-spec let_vars(c_let()) -> [cerl()].

let_vars(Node) ->
    Node#c_let.vars.


%% @spec let_arg(cerl()) -> cerl()
%%
%% @doc Returns the argument subtree of an abstract let-expression.
%%
%% @see c_let/3

-spec let_arg(c_let()) -> cerl().

let_arg(Node) ->
    Node#c_let.arg.


%% @spec let_body(cerl()) -> cerl()
%%
%% @doc Returns the body subtree of an abstract let-expression.
%%
%% @see c_let/3

-spec let_body(c_let()) -> cerl().

let_body(Node) ->
    Node#c_let.body.


%% @spec let_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of left-hand side variables of an abstract
%% let-expression.
%% 
%% <p>Note: this is equivalent to <code>length(let_vars(Node))</code>,
%% but potentially more efficient.</p>
%%
%% @see c_let/3
%% @see let_vars/1

-spec let_arity(c_let()) -> non_neg_integer().

let_arity(Node) ->
    length(let_vars(Node)).


%% ---------------------------------------------------------------------

%% @spec c_letrec(Definitions::[{cerl(), cerl()}], Body::cerl()) ->
%%           cerl()
%%
%% @doc Creates an abstract letrec-expression. If
%% <code>Definitions</code> is <code>[{V1, F1}, ..., {Vn, Fn}]</code>,
%% the result represents "<code>letrec <em>V1</em> = <em>F1</em>
%% ... <em>Vn</em> = <em>Fn</em> in <em>Body</em></code>.  All the
%% <code>Vi</code> must have type <code>var</code> and represent
%% function names.  All the <code>Fi</code> must have type
%% <code>'fun'</code>.
%%
%% @see ann_c_letrec/3
%% @see update_c_letrec/3
%% @see is_c_letrec/1
%% @see letrec_defs/1
%% @see letrec_body/1
%% @see letrec_vars/1

-spec c_letrec([{cerl(), cerl()}], cerl()) -> c_letrec().

c_letrec(Defs, Body) ->
    #c_letrec{defs = Defs, body = Body}.


%% @spec ann_c_letrec(As::[term()], Definitions::[{cerl(), cerl()}],
%%                    Body::cerl()) -> cerl()
%% @see c_letrec/2

-spec ann_c_letrec([term()], [{cerl(), cerl()}], cerl()) -> c_letrec().

ann_c_letrec(As, Defs, Body) ->
    #c_letrec{defs = Defs, body = Body, anno = As}.


%% @spec update_c_letrec(Old::cerl(),
%%                       Definitions::[{cerl(), cerl()}],
%%                       Body::cerl()) -> cerl()
%% @see c_letrec/2

-spec update_c_letrec(c_letrec(), [{cerl(), cerl()}], cerl()) -> c_letrec().

update_c_letrec(Node, Defs, Body) ->
    #c_letrec{defs = Defs, body = Body, anno = get_ann(Node)}.


%% @spec is_c_letrec(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% letrec-expression, otherwise <code>false</code>.
%%
%% @see c_letrec/2

-spec is_c_letrec(cerl()) -> boolean().

is_c_letrec(#c_letrec{}) ->
    true;
is_c_letrec(_) ->
    false.


%% @spec letrec_defs(Node::cerl()) -> [{cerl(), cerl()}]
%%
%% @doc Returns the list of definitions of an abstract
%% letrec-expression. If <code>Node</code> represents "<code>letrec
%% <em>V1</em> = <em>F1</em> ... <em>Vn</em> = <em>Fn</em> in
%% <em>Body</em></code>", the returned value is <code>[{V1, F1}, ...,
%% {Vn, Fn}]</code>.
%%
%% @see c_letrec/2

-spec letrec_defs(c_letrec()) -> [{cerl(), cerl()}].

letrec_defs(Node) ->
    Node#c_letrec.defs.


%% @spec letrec_body(cerl()) -> cerl()
%%
%% @doc Returns the body subtree of an abstract letrec-expression.
%%
%% @see c_letrec/2

-spec letrec_body(c_letrec()) -> cerl().

letrec_body(Node) ->
    Node#c_letrec.body.


%% @spec letrec_vars(cerl()) -> [cerl()]
%%
%% @doc Returns the list of left-hand side function variable subtrees
%% of a letrec-expression. If <code>Node</code> represents
%% "<code>letrec <em>V1</em> = <em>F1</em> ... <em>Vn</em> =
%% <em>Fn</em> in <em>Body</em></code>", the returned value is
%% <code>[V1, ..., Vn]</code>.
%%
%% @see c_letrec/2

-spec letrec_vars(c_letrec()) -> [cerl()].

letrec_vars(Node) ->
    [F || {F, _} <- letrec_defs(Node)].


%% ---------------------------------------------------------------------

%% @spec c_case(Argument::cerl(), Clauses::[cerl()]) -> cerl()
%%
%% @doc Creates an abstract case-expression. If <code>Clauses</code>
%% is <code>[C1, ..., Cn]</code>, the result represents "<code>case
%% <em>Argument</em> of <em>C1</em> ... <em>Cn</em>
%% end</code>". <code>Clauses</code> must not be empty.
%%
%% @see ann_c_case/3
%% @see update_c_case/3
%% @see is_c_case/1
%% @see c_clause/3
%% @see case_arg/1
%% @see case_clauses/1
%% @see case_arity/1

-spec c_case(cerl(), [cerl()]) -> c_case().

c_case(Expr, Clauses) ->
    #c_case{arg = Expr, clauses = Clauses}.


%% @spec ann_c_case(As::[term()], Argument::cerl(),
%%                  Clauses::[cerl()]) -> cerl()
%% @see c_case/2

-spec ann_c_case([term()], cerl(), [cerl()]) -> c_case().

ann_c_case(As, Expr, Clauses) ->
    #c_case{arg = Expr, clauses = Clauses, anno = As}.


%% @spec update_c_case(Old::cerl(), Argument::cerl(),
%%                     Clauses::[cerl()]) -> cerl()
%% @see c_case/2

-spec update_c_case(c_case(), cerl(), [cerl()]) -> c_case().

update_c_case(Node, Expr, Clauses) ->
    #c_case{arg = Expr, clauses = Clauses, anno = get_ann(Node)}.


%% is_c_case(Node) -> boolean()
%%
%%	    Node = cerl()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% case-expression; otherwise <code>false</code>.
%%
%% @see c_case/2

-spec is_c_case(cerl()) -> boolean().

is_c_case(#c_case{}) ->
    true;
is_c_case(_) ->
    false.


%% @spec case_arg(cerl()) -> cerl()
%%
%% @doc Returns the argument subtree of an abstract case-expression.
%%
%% @see c_case/2

-spec case_arg(c_case()) -> cerl().

case_arg(Node) ->
    Node#c_case.arg.


%% @spec case_clauses(cerl()) -> [cerl()]
%%
%% @doc Returns the list of clause subtrees of an abstract
%% case-expression.
%%
%% @see c_case/2
%% @see case_arity/1

-spec case_clauses(c_case()) -> [cerl()].

case_clauses(Node) ->
    Node#c_case.clauses.


%% @spec case_arity(Node::cerl()) -> integer()
%%
%% @doc Equivalent to
%% <code>clause_arity(hd(case_clauses(Node)))</code>, but potentially
%% more efficient.
%%
%% @see c_case/2
%% @see case_clauses/1
%% @see clause_arity/1

-spec case_arity(c_case()) -> non_neg_integer().

case_arity(Node) ->
    clause_arity(hd(case_clauses(Node))).


%% ---------------------------------------------------------------------

%% @spec c_clause(Patterns::[cerl()], Body::cerl()) -> cerl()
%% @equiv c_clause(Patterns, c_atom(true), Body)
%% @see c_atom/1

-spec c_clause([cerl()], cerl()) -> c_clause().

c_clause(Patterns, Body) ->
    c_clause(Patterns, c_atom(true), Body).


%% @spec c_clause(Patterns::[cerl()], Guard::cerl(), Body::cerl()) ->
%%           cerl()
%%
%% @doc Creates an an abstract clause. If <code>Patterns</code> is
%% <code>[P1, ..., Pn]</code>, the result represents
%% "<code>&lt;<em>P1</em>, ..., <em>Pn</em>&gt; when <em>Guard</em> ->
%% <em>Body</em></code>".
%%
%% @see c_clause/2
%% @see ann_c_clause/4
%% @see update_c_clause/4
%% @see is_c_clause/1
%% @see c_case/2
%% @see c_receive/3
%% @see clause_pats/1
%% @see clause_guard/1
%% @see clause_body/1
%% @see clause_arity/1
%% @see clause_vars/1

-spec c_clause([cerl()], cerl(), cerl()) -> c_clause().

c_clause(Patterns, Guard, Body) ->
    #c_clause{pats = Patterns, guard = Guard, body = Body}.


%% @spec ann_c_clause(As::[term()], Patterns::[cerl()],
%%                    Body::cerl()) -> cerl()
%% @equiv ann_c_clause(As, Patterns, c_atom(true), Body)
%% @see c_clause/3

-spec ann_c_clause([term()], [cerl()], cerl()) -> c_clause().

ann_c_clause(As, Patterns, Body) ->
    ann_c_clause(As, Patterns, c_atom(true), Body).


%% @spec ann_c_clause(As::[term()], Patterns::[cerl()], Guard::cerl(),
%%                    Body::cerl()) -> cerl()
%% @see ann_c_clause/3
%% @see c_clause/3

-spec ann_c_clause([term()], [cerl()], cerl(), cerl()) -> c_clause().

ann_c_clause(As, Patterns, Guard, Body) ->
    #c_clause{pats = Patterns, guard = Guard, body = Body, anno = As}.


%% @spec update_c_clause(Old::cerl(), Patterns::[cerl()],
%%                       Guard::cerl(), Body::cerl()) -> cerl()
%% @see c_clause/3

-spec update_c_clause(c_clause(), [cerl()], cerl(), cerl()) -> c_clause().

update_c_clause(Node, Patterns, Guard, Body) ->
    #c_clause{pats = Patterns, guard = Guard, body = Body,
	      anno = get_ann(Node)}.


%% @spec is_c_clause(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% clause, otherwise <code>false</code>.
%%
%% @see c_clause/3

-spec is_c_clause(cerl()) -> boolean().

is_c_clause(#c_clause{}) ->
    true;
is_c_clause(_) ->
    false.


%% @spec clause_pats(cerl()) -> [cerl()]
%%
%% @doc Returns the list of pattern subtrees of an abstract clause.
%%
%% @see c_clause/3
%% @see clause_arity/1

-spec clause_pats(c_clause()) -> [cerl()].

clause_pats(Node) ->
    Node#c_clause.pats.


%% @spec clause_guard(cerl()) -> cerl()
%%
%% @doc Returns the guard subtree of an abstract clause.
%% 
%% @see c_clause/3

-spec clause_guard(c_clause()) -> cerl().

clause_guard(Node) ->
    Node#c_clause.guard.


%% @spec clause_body(cerl()) -> cerl()
%%
%% @doc Returns the body subtree of an abstract clause.
%%
%% @see c_clause/3

-spec clause_body(c_clause()) -> cerl().

clause_body(Node) ->
    Node#c_clause.body.


%% @spec clause_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of pattern subtrees of an abstract clause.
%%
%% <p>Note: this is equivalent to
%% <code>length(clause_pats(Node))</code>, but potentially more
%% efficient.</p>
%%
%% @see c_clause/3
%% @see clause_pats/1

-spec clause_arity(c_clause()) -> non_neg_integer().

clause_arity(Node) ->
    length(clause_pats(Node)).


%% @spec clause_vars(cerl()) -> [cerl()]
%%
%% @doc Returns the list of all abstract variables in the patterns of
%% an abstract clause. The order of listing is not defined.
%%
%% @see c_clause/3
%% @see pat_list_vars/1

-spec clause_vars(c_clause()) -> [cerl()].

clause_vars(Clause) ->
    pat_list_vars(clause_pats(Clause)).


%% @spec pat_vars(Pattern::cerl()) -> [cerl()]
%%
%% @doc Returns the list of all abstract variables in a pattern. An
%% exception is thrown if <code>Node</code> does not represent a
%% well-formed Core Erlang clause pattern. The order of listing is not
%% defined.
%%
%% @see pat_list_vars/1
%% @see clause_vars/1

-spec pat_vars(cerl()) -> [cerl()].

pat_vars(Node) ->
    pat_vars(Node, []).

pat_vars(Node, Vs) ->
    case type(Node) of
	var ->
	    [Node | Vs];
	literal ->
	    Vs;
	cons ->
	    pat_vars(cons_hd(Node), pat_vars(cons_tl(Node), Vs));
	tuple ->
	    pat_list_vars(tuple_es(Node), Vs);
	map ->
	    pat_list_vars(map_es(Node), Vs);
	map_pair ->
	    %% map_pair_key is not a pattern var, excluded
	    pat_list_vars([map_pair_op(Node),map_pair_val(Node)],Vs);
	binary ->
	    pat_list_vars(binary_segments(Node), Vs);
	bitstr ->
	    %% bitstr_size is not a pattern var, excluded
	    pat_vars(bitstr_val(Node), Vs);
	alias ->
	    pat_vars(alias_pat(Node), [alias_var(Node) | Vs])
    end.


%% @spec pat_list_vars(Patterns::[cerl()]) -> [cerl()]
%%
%% @doc Returns the list of all abstract variables in the given
%% patterns. An exception is thrown if some element in
%% <code>Patterns</code> does not represent a well-formed Core Erlang
%% clause pattern. The order of listing is not defined.
%%
%% @see pat_vars/1
%% @see clause_vars/1

-spec pat_list_vars([cerl()]) -> [cerl()].

pat_list_vars(Ps) ->
    pat_list_vars(Ps, []).

pat_list_vars([P | Ps], Vs) ->
    pat_list_vars(Ps, pat_vars(P, Vs));
pat_list_vars([], Vs) ->
    Vs.


%% ---------------------------------------------------------------------

%% @spec c_alias(Variable::cerl(), Pattern::cerl()) -> cerl()
%%
%% @doc Creates an abstract pattern alias. The result represents
%% "<code><em>Variable</em> = <em>Pattern</em></code>".
%%
%% @see ann_c_alias/3
%% @see update_c_alias/3
%% @see is_c_alias/1
%% @see alias_var/1
%% @see alias_pat/1
%% @see c_clause/3

-spec c_alias(c_var(), cerl()) -> c_alias().

c_alias(Var, Pattern) ->
    #c_alias{var = Var, pat = Pattern}.


%% @spec ann_c_alias(As::[term()], Variable::cerl(),
%%                   Pattern::cerl()) -> cerl()
%% @see c_alias/2

-spec ann_c_alias([term()], c_var(), cerl()) -> c_alias().

ann_c_alias(As, Var, Pattern) ->
    #c_alias{var = Var, pat = Pattern, anno = As}.


%% @spec update_c_alias(Old::cerl(), Variable::cerl(),
%%                      Pattern::cerl()) -> cerl()
%% @see c_alias/2

-spec update_c_alias(c_alias(), cerl(), cerl()) -> c_alias().

update_c_alias(Node, Var, Pattern) ->
    #c_alias{var = Var, pat = Pattern, anno = get_ann(Node)}.


%% @spec is_c_alias(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% pattern alias, otherwise <code>false</code>.
%%
%% @see c_alias/2

-spec is_c_alias(cerl()) -> boolean().

is_c_alias(#c_alias{}) ->
    true;
is_c_alias(_) ->
    false.


%% @spec alias_var(cerl()) -> cerl()
%%
%% @doc Returns the variable subtree of an abstract pattern alias.
%%
%% @see c_alias/2

-spec alias_var(c_alias()) -> c_var().

alias_var(Node) ->
    Node#c_alias.var.


%% @spec alias_pat(cerl()) -> cerl()
%%
%% @doc Returns the pattern subtree of an abstract pattern alias.
%%
%% @see c_alias/2

-spec alias_pat(c_alias()) -> cerl().

alias_pat(Node) ->
    Node#c_alias.pat.


%% ---------------------------------------------------------------------

%% @spec c_receive(Clauses::[cerl()]) -> cerl()
%% @equiv c_receive(Clauses, c_atom(infinity), c_atom(true))
%% @see c_atom/1

-spec c_receive([cerl()]) -> c_receive().

c_receive(Clauses) ->
    c_receive(Clauses, c_atom(infinity), c_atom(true)).


%% @spec c_receive(Clauses::[cerl()], Timeout::cerl(),
%%                 Action::cerl()) -> cerl()
%%
%% @doc Creates an abstract receive-expression. If
%% <code>Clauses</code> is <code>[C1, ..., Cn]</code>, the result
%% represents "<code>receive <em>C1</em> ... <em>Cn</em> after
%% <em>Timeout</em> -> <em>Action</em> end</code>".
%%
%% @see c_receive/1
%% @see ann_c_receive/4
%% @see update_c_receive/4
%% @see is_c_receive/1
%% @see receive_clauses/1
%% @see receive_timeout/1
%% @see receive_action/1

-spec c_receive([cerl()], cerl(), cerl()) -> c_receive().

c_receive(Clauses, Timeout, Action) ->
    #c_receive{clauses = Clauses, timeout = Timeout, action = Action}.


%% @spec ann_c_receive(As::[term()], Clauses::[cerl()]) -> cerl()
%% @equiv ann_c_receive(As, Clauses, c_atom(infinity), c_atom(true))
%% @see c_receive/3
%% @see c_atom/1

-spec ann_c_receive([term()], [cerl()]) -> c_receive().

ann_c_receive(As, Clauses) ->
    ann_c_receive(As, Clauses, c_atom(infinity), c_atom(true)).


%% @spec ann_c_receive(As::[term()], Clauses::[cerl()],
%%                     Timeout::cerl(), Action::cerl()) -> cerl()
%% @see ann_c_receive/2
%% @see c_receive/3

-spec ann_c_receive([term()], [cerl()], cerl(), cerl()) -> c_receive().

ann_c_receive(As, Clauses, Timeout, Action) ->
    #c_receive{clauses = Clauses, timeout = Timeout, action = Action,
	       anno = As}.


%% @spec update_c_receive(Old::cerl(), Clauses::[cerl()],
%%                        Timeout::cerl(), Action::cerl()) -> cerl()
%% @see c_receive/3

-spec update_c_receive(c_receive(), [cerl()], cerl(), cerl()) -> c_receive().

update_c_receive(Node, Clauses, Timeout, Action) ->
    #c_receive{clauses = Clauses, timeout = Timeout, action = Action,
	       anno = get_ann(Node)}.


%% @spec is_c_receive(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% receive-expression, otherwise <code>false</code>.
%%
%% @see c_receive/3

-spec is_c_receive(cerl()) -> boolean().

is_c_receive(#c_receive{}) ->
    true;
is_c_receive(_) ->
    false.


%% @spec receive_clauses(cerl()) -> [cerl()]
%%
%% @doc Returns the list of clause subtrees of an abstract
%% receive-expression.
%%
%% @see c_receive/3

-spec receive_clauses(c_receive()) -> [cerl()].

receive_clauses(Node) ->
    Node#c_receive.clauses.


%% @spec receive_timeout(cerl()) -> cerl()
%%
%% @doc Returns the timeout subtree of an abstract receive-expression.
%%
%% @see c_receive/3

-spec receive_timeout(c_receive()) -> cerl().

receive_timeout(Node) ->
    Node#c_receive.timeout.


%% @spec receive_action(cerl()) -> cerl()
%%
%% @doc Returns the action subtree of an abstract receive-expression.
%%
%% @see c_receive/3

-spec receive_action(c_receive()) -> cerl().

receive_action(Node) ->
    Node#c_receive.action.


%% ---------------------------------------------------------------------

%% @spec c_apply(Operator::cerl(), Arguments::[cerl()]) -> cerl()
%%
%% @doc Creates an abstract function application. If
%% <code>Arguments</code> is <code>[A1, ..., An]</code>, the result
%% represents "<code>apply <em>Operator</em>(<em>A1</em>, ...,
%% <em>An</em>)</code>".
%%
%% @see ann_c_apply/3
%% @see update_c_apply/3
%% @see is_c_apply/1
%% @see apply_op/1
%% @see apply_args/1
%% @see apply_arity/1
%% @see c_call/3
%% @see c_primop/2

-spec c_apply(cerl(), [cerl()]) -> c_apply().

c_apply(Operator, Arguments) ->
    #c_apply{op = Operator, args = Arguments}.


%% @spec ann_c_apply(As::[term()], Operator::cerl(),
%%                   Arguments::[cerl()]) -> cerl()
%% @see c_apply/2

-spec ann_c_apply([term()], cerl(), [cerl()]) -> c_apply().

ann_c_apply(As, Operator, Arguments) ->
    #c_apply{op = Operator, args = Arguments, anno = As}.


%% @spec update_c_apply(Old::cerl(), Operator::cerl(),
%%                      Arguments::[cerl()]) -> cerl()
%% @see c_apply/2

-spec update_c_apply(c_apply(), cerl(), [cerl()]) -> c_apply().

update_c_apply(Node, Operator, Arguments) ->
    #c_apply{op = Operator, args = Arguments, anno = get_ann(Node)}.


%% @spec is_c_apply(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% function application, otherwise <code>false</code>.
%%
%% @see c_apply/2

-spec is_c_apply(cerl()) -> boolean().

is_c_apply(#c_apply{}) ->
    true;
is_c_apply(_) ->
    false.


%% @spec apply_op(cerl()) -> cerl()
%%
%% @doc Returns the operator subtree of an abstract function
%% application.
%%
%% @see c_apply/2

-spec apply_op(c_apply()) -> cerl().

apply_op(Node) ->
    Node#c_apply.op.


%% @spec apply_args(cerl()) -> [cerl()]
%%
%% @doc Returns the list of argument subtrees of an abstract function
%% application.
%%
%% @see c_apply/2
%% @see apply_arity/1

-spec apply_args(c_apply()) -> [cerl()].

apply_args(Node) ->
    Node#c_apply.args.


%% @spec apply_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of argument subtrees of an abstract
%% function application.
%%
%% <p>Note: this is equivalent to
%% <code>length(apply_args(Node))</code>, but potentially more
%% efficient.</p>
%%
%% @see c_apply/2
%% @see apply_args/1

-spec apply_arity(c_apply()) -> non_neg_integer().

apply_arity(Node) ->
    length(apply_args(Node)).


%% ---------------------------------------------------------------------

%% @spec c_call(Module::cerl(), Name::cerl(), Arguments::[cerl()]) ->
%%           cerl()
%%
%% @doc Creates an abstract inter-module call. If
%% <code>Arguments</code> is <code>[A1, ..., An]</code>, the result
%% represents "<code>call <em>Module</em>:<em>Name</em>(<em>A1</em>,
%% ..., <em>An</em>)</code>".
%%
%% @see ann_c_call/4
%% @see update_c_call/4
%% @see is_c_call/1
%% @see call_module/1
%% @see call_name/1
%% @see call_args/1
%% @see call_arity/1
%% @see c_apply/2
%% @see c_primop/2

-spec c_call(cerl(), cerl(), [cerl()]) -> c_call().

c_call(Module, Name, Arguments) ->
    #c_call{module = Module, name = Name, args = Arguments}.


%% @spec ann_c_call(As::[term()], Module::cerl(), Name::cerl(),
%%                  Arguments::[cerl()]) -> cerl()
%% @see c_call/3

-spec ann_c_call([term()], cerl(), cerl(), [cerl()]) -> c_call().

ann_c_call(As, Module, Name, Arguments) ->
    #c_call{module = Module, name = Name, args = Arguments, anno = As}.


%% @spec update_c_call(Old::cerl(), Module::cerl(), Name::cerl(),
%%                  Arguments::[cerl()]) -> cerl()
%% @see c_call/3

-spec update_c_call(cerl(), cerl(), cerl(), [cerl()]) -> c_call().

update_c_call(Node, Module, Name, Arguments) ->
    #c_call{module = Module, name = Name, args = Arguments,
	    anno = get_ann(Node)}.


%% @spec is_c_call(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% inter-module call expression; otherwise <code>false</code>.
%%
%% @see c_call/3

-spec is_c_call(cerl()) -> boolean().

is_c_call(#c_call{}) ->
    true;
is_c_call(_) ->
    false.


%% @spec call_module(cerl()) -> cerl()
%%
%% @doc Returns the module subtree of an abstract inter-module call.
%%
%% @see c_call/3

-spec call_module(c_call()) -> cerl().

call_module(Node) ->
    Node#c_call.module.


%% @spec call_name(cerl()) -> cerl()
%%
%% @doc Returns the name subtree of an abstract inter-module call.
%%
%% @see c_call/3

-spec call_name(c_call()) -> cerl().

call_name(Node) ->
    Node#c_call.name.


%% @spec call_args(cerl()) -> [cerl()]
%%
%% @doc Returns the list of argument subtrees of an abstract
%% inter-module call.
%%
%% @see c_call/3
%% @see call_arity/1

-spec call_args(c_call()) -> [cerl()].

call_args(Node) ->
    Node#c_call.args.


%% @spec call_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of argument subtrees of an abstract
%% inter-module call.
%%
%% <p>Note: this is equivalent to
%% <code>length(call_args(Node))</code>, but potentially more
%% efficient.</p>
%%
%% @see c_call/3
%% @see call_args/1

-spec call_arity(c_call()) -> non_neg_integer().

call_arity(Node) ->
    length(call_args(Node)).


%% ---------------------------------------------------------------------

%% @spec c_primop(Name::cerl(), Arguments::[cerl()]) -> cerl()
%%
%% @doc Creates an abstract primitive operation call. If
%% <code>Arguments</code> is <code>[A1, ..., An]</code>, the result
%% represents "<code>primop <em>Name</em>(<em>A1</em>, ...,
%% <em>An</em>)</code>". <code>Name</code> must be an atom literal.
%%
%% @see ann_c_primop/3
%% @see update_c_primop/3
%% @see is_c_primop/1
%% @see primop_name/1
%% @see primop_args/1
%% @see primop_arity/1
%% @see c_apply/2
%% @see c_call/3

-spec c_primop(cerl(), [cerl()]) -> c_primop().

c_primop(Name, Arguments) ->
    #c_primop{name = Name, args = Arguments}.


%% @spec ann_c_primop(As::[term()], Name::cerl(),
%%                    Arguments::[cerl()]) -> cerl()
%% @see c_primop/2

-spec ann_c_primop([term()], cerl(), [cerl()]) -> c_primop().

ann_c_primop(As, Name, Arguments) ->
    #c_primop{name = Name, args = Arguments, anno = As}.


%% @spec update_c_primop(Old::cerl(), Name::cerl(),
%%                       Arguments::[cerl()]) -> cerl()
%% @see c_primop/2

-spec update_c_primop(cerl(), cerl(), [cerl()]) -> c_primop().

update_c_primop(Node, Name, Arguments) ->
    #c_primop{name = Name, args = Arguments, anno = get_ann(Node)}.


%% @spec is_c_primop(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% primitive operation call, otherwise <code>false</code>.
%%
%% @see c_primop/2

-spec is_c_primop(cerl()) -> boolean().

is_c_primop(#c_primop{}) ->
    true;
is_c_primop(_) ->
    false.


%% @spec primop_name(cerl()) -> cerl()
%%
%% @doc Returns the name subtree of an abstract primitive operation
%% call.
%%
%% @see c_primop/2

-spec primop_name(c_primop()) -> cerl().

primop_name(Node) ->
    Node#c_primop.name.


%% @spec primop_args(cerl()) -> [cerl()]
%%
%% @doc Returns the list of argument subtrees of an abstract primitive
%% operation call.
%%
%% @see c_primop/2
%% @see primop_arity/1

-spec primop_args(c_primop()) -> [cerl()].

primop_args(Node) ->
    Node#c_primop.args.


%% @spec primop_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of argument subtrees of an abstract
%% primitive operation call.
%%
%% <p>Note: this is equivalent to
%% <code>length(primop_args(Node))</code>, but potentially more
%% efficient.</p>
%%
%% @see c_primop/2
%% @see primop_args/1

-spec primop_arity(c_primop()) -> non_neg_integer().

primop_arity(Node) ->
    length(primop_args(Node)).


%% ---------------------------------------------------------------------

%% @spec c_try(Argument::cerl(), Variables::[cerl()], Body::cerl(),
%%             ExceptionVars::[cerl()], Handler::cerl()) -> cerl()
%%
%% @doc Creates an abstract try-expression. If <code>Variables</code> is
%% <code>[V1, ..., Vn]</code> and <code>ExceptionVars</code> is
%% <code>[X1, ..., Xm]</code>, the result represents "<code>try
%% <em>Argument</em> of &lt;<em>V1</em>, ..., <em>Vn</em>&gt; ->
%% <em>Body</em> catch &lt;<em>X1</em>, ..., <em>Xm</em>&gt; ->
%% <em>Handler</em></code>". All the <code>Vi</code> and <code>Xi</code>
%% must have type <code>var</code>.
%%
%% @see ann_c_try/6
%% @see update_c_try/6
%% @see is_c_try/1
%% @see try_arg/1
%% @see try_vars/1
%% @see try_body/1
%% @see c_catch/1

-spec c_try(cerl(), [cerl()], cerl(), [cerl()], cerl()) -> c_try().

c_try(Expr, Vs, Body, Evs, Handler) ->
    #c_try{arg = Expr, vars = Vs, body = Body,
	   evars = Evs, handler = Handler}.


%% @spec ann_c_try(As::[term()], Expression::cerl(),
%%                 Variables::[cerl()], Body::cerl(),
%%                 EVars::[cerl()], Handler::cerl()) -> cerl()
%% @see c_try/3

-spec ann_c_try([term()], cerl(), [cerl()], cerl(), [cerl()], cerl()) ->
        c_try().

ann_c_try(As, Expr, Vs, Body, Evs, Handler) ->
    #c_try{arg = Expr, vars = Vs, body = Body,
	   evars = Evs, handler = Handler, anno = As}.


%% @spec update_c_try(Old::cerl(), Expression::cerl(),
%%                    Variables::[cerl()], Body::cerl(),
%%                    EVars::[cerl()], Handler::cerl()) -> cerl()
%% @see c_try/3

-spec update_c_try(c_try(), cerl(), [cerl()], cerl(), [cerl()], cerl()) ->
        c_try().

update_c_try(Node, Expr, Vs, Body, Evs, Handler) ->
    #c_try{arg = Expr, vars = Vs, body = Body,
	   evars = Evs, handler = Handler, anno = get_ann(Node)}.


%% @spec is_c_try(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% try-expression, otherwise <code>false</code>.
%%
%% @see c_try/3

-spec is_c_try(cerl()) -> boolean().

is_c_try(#c_try{}) ->
    true;
is_c_try(_) ->
    false.


%% @spec try_arg(cerl()) -> cerl()
%%
%% @doc Returns the expression subtree of an abstract try-expression.
%%
%% @see c_try/3

-spec try_arg(c_try()) -> cerl().

try_arg(Node) ->
    Node#c_try.arg.


%% @spec try_vars(cerl()) -> [cerl()]
%%
%% @doc Returns the list of success variable subtrees of an abstract
%% try-expression.
%%
%% @see c_try/3

-spec try_vars(c_try()) -> [cerl()].

try_vars(Node) ->
    Node#c_try.vars.


%% @spec try_body(cerl()) -> cerl()
%%
%% @doc Returns the success body subtree of an abstract try-expression.
%%
%% @see c_try/3

-spec try_body(c_try()) -> cerl().

try_body(Node) ->
    Node#c_try.body.


%% @spec try_evars(cerl()) -> [cerl()]
%%
%% @doc Returns the list of exception variable subtrees of an abstract
%% try-expression.
%%
%% @see c_try/3

-spec try_evars(c_try()) -> [cerl()].

try_evars(Node) ->
    Node#c_try.evars.


%% @spec try_handler(cerl()) -> cerl()
%%
%% @doc Returns the exception body subtree of an abstract
%% try-expression.
%%
%% @see c_try/3

-spec try_handler(c_try()) -> cerl().

try_handler(Node) ->
    Node#c_try.handler.


%% ---------------------------------------------------------------------

%% @spec c_catch(Body::cerl()) -> cerl()
%%
%% @doc Creates an abstract catch-expression. The result represents
%% "<code>catch <em>Body</em></code>".
%%
%% <p>Note: catch-expressions can be rewritten as try-expressions, and
%% will eventually be removed from Core Erlang.</p>
%%
%% @see ann_c_catch/2
%% @see update_c_catch/2
%% @see is_c_catch/1
%% @see catch_body/1
%% @see c_try/3

-spec c_catch(cerl()) -> c_catch().

c_catch(Body) ->
    #c_catch{body = Body}.


%% @spec ann_c_catch(As::[term()], Body::cerl()) -> cerl()
%% @see c_catch/1

-spec ann_c_catch([term()], cerl()) -> c_catch().

ann_c_catch(As, Body) ->
    #c_catch{body = Body, anno = As}.


%% @spec update_c_catch(Old::cerl(), Body::cerl()) -> cerl()
%% @see c_catch/1

-spec update_c_catch(c_catch(), cerl()) -> c_catch().

update_c_catch(Node, Body) ->
    #c_catch{body = Body, anno = get_ann(Node)}.


%% @spec is_c_catch(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> is an abstract
%% catch-expression, otherwise <code>false</code>.
%%
%% @see c_catch/1

-spec is_c_catch(cerl()) -> boolean().

is_c_catch(#c_catch{}) ->
    true;
is_c_catch(_) ->
    false.


%% @spec catch_body(Node::cerl()) -> cerl()
%%
%% @doc Returns the body subtree of an abstract catch-expression.
%%
%% @see c_catch/1

-spec catch_body(c_catch()) -> cerl().

catch_body(Node) ->
    Node#c_catch.body.


%% ---------------------------------------------------------------------

%% @spec to_records(Tree::cerl()) -> record(record_types())
%%
%% @doc Translates an abstract syntax tree to a corresponding explicit
%% record representation. The records are defined in the file
%% "<code>cerl.hrl</code>".
%%
%% @see type/1
%% @see from_records/1

-spec to_records(cerl()) -> cerl().

to_records(Node) ->
    Node.

%% @spec from_records(Tree::record(record_types())) -> cerl()
%%
%%     record_types() = c_alias | c_apply | c_call | c_case | c_catch |
%%                      c_clause | c_cons | c_fun | c_let |
%%                      c_letrec | c_lit | c_module | c_primop |
%%                      c_receive | c_seq | c_try | c_tuple |
%%                      c_values | c_var
%%
%% @doc Translates an explicit record representation to a
%% corresponding abstract syntax tree.  The records are defined in the
%% file "<code>core_parse.hrl</code>".
%%
%% @see type/1
%% @see to_records/1

-spec from_records(cerl()) -> cerl().

from_records(Node) ->
    Node.


%% ---------------------------------------------------------------------

%% @spec is_data(Node::cerl()) -> boolean()
%%
%% @doc Returns <code>true</code> if <code>Node</code> represents a
%% data constructor, otherwise <code>false</code>. Data constructors
%% are cons cells, tuples, and atomic literals.
%%
%% @see data_type/1
%% @see data_es/1
%% @see data_arity/1

-spec is_data(cerl()) -> boolean().

is_data(#c_literal{}) ->
    true;
is_data(#c_cons{}) ->
    true;
is_data(#c_tuple{}) ->
    true;
is_data(_) ->
    false.


%% @spec data_type(Node::cerl()) -> dtype()
%%
%%     dtype() = cons | tuple | {atomic, Value}
%%     Value = integer() | float() | atom() | []
%%
%% @doc Returns a type descriptor for a data constructor
%% node. (Cf. <code>is_data/1</code>.) This is mainly useful for
%% comparing types and for constructing new nodes of the same type
%% (cf. <code>make_data/2</code>). If <code>Node</code> represents an
%% integer, floating-point number, atom or empty list, the result is
%% <code>{atomic, Value}</code>, where <code>Value</code> is the value
%% of <code>concrete(Node)</code>, otherwise the result is either
%% <code>cons</code> or <code>tuple</code>.
%%
%% <p>Type descriptors can be compared for equality or order (in the
%% Erlang term order), but remember that floating-point values should
%% in general never be tested for equality.</p>
%%
%% @see is_data/1
%% @see make_data/2
%% @see type/1
%% @see concrete/1

-type value() :: integer() | float() | atom() | [].
-type dtype() :: 'cons' | 'tuple' | {'atomic', value()}.
-type c_lct() :: c_literal() | c_cons() | c_tuple().

-spec data_type(c_lct()) -> dtype().

data_type(#c_literal{val = V}) ->
    case V of
	[_ | _] ->
	    cons;
	_ when is_tuple(V) ->
	    tuple;
	_ ->
	    {atomic, V}
    end;
data_type(#c_cons{}) ->
    cons;
data_type(#c_tuple{}) ->
    tuple.

%% @spec data_es(Node::cerl()) -> [cerl()]
%%
%% @doc Returns the list of subtrees of a data constructor node. If
%% the arity of the constructor is zero, the result is the empty list.
%%
%% <p>Note: if <code>data_type(Node)</code> is <code>cons</code>, the
%% number of subtrees is exactly two. If <code>data_type(Node)</code>
%% is <code>{atomic, Value}</code>, the number of subtrees is
%% zero.</p>
%%
%% @see is_data/1
%% @see data_type/1
%% @see data_arity/1
%% @see make_data/2

-spec data_es(c_lct()) -> [cerl()].

data_es(#c_literal{val = V}) ->
    case V of
	[Head | Tail] ->
	    [#c_literal{val = Head}, #c_literal{val = Tail}];
	_ when is_tuple(V) ->
	    make_lit_list(tuple_to_list(V));
	_ ->
	    []
    end;
data_es(#c_cons{hd = H, tl = T}) ->
    [H, T];
data_es(#c_tuple{es = Es}) ->
    Es.

%% @spec data_arity(Node::cerl()) -> integer()
%%
%% @doc Returns the number of subtrees of a data constructor
%% node. This is equivalent to <code>length(data_es(Node))</code>, but
%% potentially more efficient.
%%
%% @see is_data/1
%% @see data_es/1

-spec data_arity(c_lct()) -> non_neg_integer().

data_arity(#c_literal{val = V}) ->
    case V of
	[_ | _] ->
	    2;
	_ when is_tuple(V) ->
	    tuple_size(V);
	_ ->
	    0
    end;
data_arity(#c_cons{}) ->
    2;
data_arity(#c_tuple{es = Es}) ->
    length(Es).


%% @spec make_data(Type::dtype(), Elements::[cerl()]) -> cerl()
%%
%% @doc Creates a data constructor node with the specified type and
%% subtrees. (Cf. <code>data_type/1</code>.)  An exception is thrown
%% if the length of <code>Elements</code> is invalid for the given
%% <code>Type</code>; see <code>data_es/1</code> for arity constraints
%% on constructor types.
%%
%% @see data_type/1
%% @see data_es/1
%% @see ann_make_data/3
%% @see update_data/3
%% @see make_data_skel/2

-spec make_data(dtype(), [cerl()]) -> c_lct().

make_data(CType, Es) ->
    ann_make_data([], CType, Es).


%% @spec ann_make_data(As::[term()], Type::dtype(),
%%                     Elements::[cerl()]) -> cerl()
%% @see make_data/2

-spec ann_make_data([term()], dtype(), [cerl()]) -> c_lct().

ann_make_data(As, {atomic, V}, []) -> #c_literal{val = V, anno = As};
ann_make_data(As, cons, [H, T]) -> ann_c_cons(As, H, T);
ann_make_data(As, tuple, Es) -> ann_c_tuple(As, Es).

%% @spec update_data(Old::cerl(), Type::dtype(),
%%                   Elements::[cerl()]) -> cerl()
%% @see make_data/2

-spec update_data(cerl(), dtype(), [cerl()]) -> c_lct().

update_data(Node, CType, Es) ->
    ann_make_data(get_ann(Node), CType, Es).


%% @spec make_data_skel(Type::dtype(), Elements::[cerl()]) -> cerl()
%%
%% @doc Like <code>make_data/2</code>, but analogous to
%% <code>c_tuple_skel/1</code> and <code>c_cons_skel/2</code>.
%%
%% @see ann_make_data_skel/3
%% @see update_data_skel/3
%% @see make_data/2
%% @see c_tuple_skel/1
%% @see c_cons_skel/2

-spec make_data_skel(dtype(), [cerl()]) -> c_lct().

make_data_skel(CType, Es) ->
    ann_make_data_skel([], CType, Es).


%% @spec ann_make_data_skel(As::[term()], Type::dtype(),
%%                          Elements::[cerl()]) -> cerl()
%% @see make_data_skel/2

-spec ann_make_data_skel([term()], dtype(), [cerl()]) -> c_lct().

ann_make_data_skel(As, {atomic, V}, []) -> #c_literal{val = V, anno = As};
ann_make_data_skel(As, cons, [H, T]) -> ann_c_cons_skel(As, H, T);
ann_make_data_skel(As, tuple, Es) -> ann_c_tuple_skel(As, Es).


%% @spec update_data_skel(Old::cerl(), Type::dtype(),
%%                        Elements::[cerl()]) -> cerl()
%% @see make_data_skel/2

-spec update_data_skel(cerl(), dtype(), [cerl()]) -> c_lct().

update_data_skel(Node, CType, Es) ->
    ann_make_data_skel(get_ann(Node), CType, Es).


%% ---------------------------------------------------------------------

%% @spec subtrees(Node::cerl()) -> [[cerl()]]
%%
%% @doc Returns the grouped list of all subtrees of a node. If
%% <code>Node</code> is a leaf node (cf. <code>is_leaf/1</code>), this
%% is the empty list, otherwise the result is always a nonempty list,
%% containing the lists of subtrees of <code>Node</code>, in
%% left-to-right order as they occur in the printed program text, and
%% grouped by category. Often, each group contains only a single
%% subtree.
%%
%% <p>Depending on the type of <code>Node</code>, the size of some
%% groups may be variable (e.g., the group consisting of all the
%% elements of a tuple), while others always contain the same number
%% of elements - usually exactly one (e.g., the group containing the
%% argument expression of a case-expression). Note, however, that the
%% exact structure of the returned list (for a given node type) should
%% in general not be depended upon, since it might be subject to
%% change without notice.</p>
%%
%% <p>The function <code>subtrees/1</code> and the constructor functions
%% <code>make_tree/2</code> and <code>update_tree/2</code> can be a
%% great help if one wants to traverse a syntax tree, visiting all its
%% subtrees, but treat nodes of the tree in a uniform way in most or all
%% cases. Using these functions makes this simple, and also assures that
%% your code is not overly sensitive to extensions of the syntax tree
%% data type, because any node types not explicitly handled by your code
%% can be left to a default case.</p>
%%
%% <p>For example:
%% <pre>
%%   postorder(F, Tree) ->
%%       F(case subtrees(Tree) of
%%           [] -> Tree;
%%           List -> update_tree(Tree,
%%                               [[postorder(F, Subtree)
%%                                 || Subtree &lt;- Group]
%%                                || Group &lt;- List])
%%         end).
%% </pre>
%% maps the function <code>F</code> on <code>Tree</code> and all its
%% subtrees, doing a post-order traversal of the syntax tree. (Note
%% the use of <code>update_tree/2</code> to preserve annotations.) For
%% a simple function like:
%% <pre>
%%   f(Node) ->
%%       case type(Node) of
%%           atom -> atom("a_" ++ atom_name(Node));
%%           _ -> Node
%%       end.
%% </pre>
%% the call <code>postorder(fun f/1, Tree)</code> will yield a new
%% representation of <code>Tree</code> in which all atom names have
%% been extended with the prefix "a_", but nothing else (including
%% annotations) has been changed.</p>
%%
%% @see is_leaf/1
%% @see make_tree/2
%% @see update_tree/2

-spec subtrees(cerl()) -> [[cerl()]].

subtrees(T) ->
    case is_leaf(T) of
	true ->
	    [];
	false ->
	    case type(T) of
		values ->
		    [values_es(T)];
		binary ->
		    [binary_segments(T)];
		bitstr ->
		    [[bitstr_val(T)], [bitstr_size(T)],
		     [bitstr_unit(T)], [bitstr_type(T)],
		     [bitstr_flags(T)]];
		cons ->
		    [[cons_hd(T)], [cons_tl(T)]];
		tuple ->
		    [tuple_es(T)];
		map ->
		    [map_es(T)];
		map_pair ->
		    [[map_pair_op(T)],[map_pair_key(T)],[map_pair_val(T)]];
		'let' ->
		    [let_vars(T), [let_arg(T)], [let_body(T)]];
		seq ->
		    [[seq_arg(T)], [seq_body(T)]];
		apply ->
		    [[apply_op(T)], apply_args(T)];
		call ->
		    [[call_module(T)], [call_name(T)],
		     call_args(T)];
		primop ->
		    [[primop_name(T)], primop_args(T)];
		'case' ->
		    [[case_arg(T)], case_clauses(T)];
		clause ->
		    [clause_pats(T), [clause_guard(T)],
		     [clause_body(T)]];
		alias ->
		    [[alias_var(T)], [alias_pat(T)]];
		'fun' ->
		    [fun_vars(T), [fun_body(T)]];
		'receive' ->
		    [receive_clauses(T), [receive_timeout(T)],
		     [receive_action(T)]];
		'try' ->
		    [[try_arg(T)], try_vars(T), [try_body(T)],
		     try_evars(T), [try_handler(T)]];
		'catch' ->
		    [[catch_body(T)]];
		letrec ->
		    Es = unfold_tuples(letrec_defs(T)),
		    [Es, [letrec_body(T)]];
		module ->
		    As = unfold_tuples(module_attrs(T)),
		    Es = unfold_tuples(module_defs(T)),
		    [[module_name(T)], module_exports(T), As, Es]
	    end
    end.


%% @spec update_tree(Old::cerl(), Groups::[[cerl()]]) -> cerl()
%%
%% @doc Creates a syntax tree with the given subtrees, and the same
%% type and annotations as the <code>Old</code> node. This is
%% equivalent to <code>ann_make_tree(get_ann(Node), type(Node),
%% Groups)</code>, but potentially more efficient.
%%
%% @see update_tree/3
%% @see ann_make_tree/3
%% @see get_ann/1
%% @see type/1

-spec update_tree(cerl(), [[cerl()],...]) -> cerl().

update_tree(Node, Gs) ->
    ann_make_tree(get_ann(Node), type(Node), Gs).


%% @spec update_tree(Old::cerl(), Type::ctype(), Groups::[[cerl()]]) ->
%%           cerl()
%%
%% @doc Creates a syntax tree with the given type and subtrees, and
%% the same annotations as the <code>Old</code> node. This is
%% equivalent to <code>ann_make_tree(get_ann(Node), Type,
%% Groups)</code>, but potentially more efficient.
%%
%% @see update_tree/2
%% @see ann_make_tree/3
%% @see get_ann/1

-spec update_tree(cerl(), ctype(), [[cerl()],...]) -> cerl().

update_tree(Node, Type, Gs) ->
    ann_make_tree(get_ann(Node), Type, Gs).


%% @spec make_tree(Type::ctype(), Groups::[[cerl()]]) -> cerl()
%%
%% @doc Creates a syntax tree with the given type and subtrees.
%% <code>Type</code> must be a node type name
%% (cf. <code>type/1</code>) that does not denote a leaf node type
%% (cf. <code>is_leaf/1</code>).  <code>Groups</code> must be a
%% <em>nonempty</em> list of groups of syntax trees, representing the
%% subtrees of a node of the given type, in left-to-right order as
%% they would occur in the printed program text, grouped by category
%% as done by <code>subtrees/1</code>.
%%
%% <p>The result of <code>ann_make_tree(get_ann(Node), type(Node),
%% subtrees(Node))</code> (cf. <code>update_tree/2</code>) represents
%% the same source code text as the original <code>Node</code>,
%% assuming that <code>subtrees(Node)</code> yields a nonempty
%% list. However, it does not necessarily have the exact same data
%% representation as <code>Node</code>.</p>
%%
%% @see ann_make_tree/3
%% @see type/1
%% @see is_leaf/1
%% @see subtrees/1
%% @see update_tree/2

-spec make_tree(ctype(), [[cerl()],...]) -> cerl().

make_tree(Type, Gs) ->
    ann_make_tree([], Type, Gs).


%% @spec ann_make_tree(As::[term()], Type::ctype(),
%%                     Groups::[[cerl()]]) -> cerl()
%%
%% @doc Creates a syntax tree with the given annotations, type and
%% subtrees. See <code>make_tree/2</code> for details.
%%
%% @see make_tree/2

-spec ann_make_tree([term()], ctype(), [[cerl()],...]) -> cerl().

ann_make_tree(As, values, [Es]) -> ann_c_values(As, Es);
ann_make_tree(As, binary, [Ss]) -> ann_c_binary(As, Ss);
ann_make_tree(As, bitstr, [[V],[S],[U],[T],[Fs]]) ->
    ann_c_bitstr(As, V, S, U, T, Fs);
ann_make_tree(As, cons, [[H], [T]]) -> ann_c_cons(As, H, T);
ann_make_tree(As, tuple, [Es]) -> ann_c_tuple(As, Es);
ann_make_tree(As, map, [Es]) -> ann_c_map(As, Es);
ann_make_tree(As, map, [[A], Es]) -> ann_c_map(As, A, Es);
ann_make_tree(As, map_pair, [[Op], [K], [V]]) -> ann_c_map_pair(As, Op, K, V);
ann_make_tree(As, 'let', [Vs, [A], [B]]) -> ann_c_let(As, Vs, A, B);
ann_make_tree(As, seq, [[A], [B]]) -> ann_c_seq(As, A, B);
ann_make_tree(As, apply, [[Op], Es]) -> ann_c_apply(As, Op, Es);
ann_make_tree(As, call, [[M], [N], Es]) -> ann_c_call(As, M, N, Es);
ann_make_tree(As, primop, [[N], Es]) -> ann_c_primop(As, N, Es);
ann_make_tree(As, 'case', [[A], Cs]) -> ann_c_case(As, A, Cs);
ann_make_tree(As, clause, [Ps, [G], [B]]) -> ann_c_clause(As, Ps, G, B);
ann_make_tree(As, alias, [[V], [P]]) -> ann_c_alias(As, V, P);
ann_make_tree(As, 'fun', [Vs, [B]]) -> ann_c_fun(As, Vs, B);
ann_make_tree(As, 'receive', [Cs, [T], [A]]) ->
    ann_c_receive(As, Cs, T, A);
ann_make_tree(As, 'try', [[E], Vs, [B], Evs, [H]]) ->
    ann_c_try(As, E, Vs, B, Evs, H);
ann_make_tree(As, 'catch', [[B]]) -> ann_c_catch(As, B);
ann_make_tree(As, letrec, [Es, [B]]) ->
    ann_c_letrec(As, fold_tuples(Es), B);
ann_make_tree(As, module, [[N], Xs, Es, Ds]) ->
    ann_c_module(As, N, Xs, fold_tuples(Es), fold_tuples(Ds)).


%% ---------------------------------------------------------------------

%% @spec meta(Tree::cerl()) -> cerl()
%%
%% @doc Creates a meta-representation of a syntax tree. The result
%% represents an Erlang expression "<code><em>MetaTree</em></code>"
%% which, if evaluated, will yield a new syntax tree representing the
%% same source code text as <code>Tree</code> (although the actual
%% data representation may be different). The expression represented
%% by <code>MetaTree</code> is <em>implementation independent</em>
%% with regard to the data structures used by the abstract syntax tree
%% implementation.
%%
%% <p>Any node in <code>Tree</code> whose node type is
%% <code>var</code> (cf. <code>type/1</code>), and whose list of
%% annotations (cf. <code>get_ann/1</code>) contains the atom
%% <code>meta_var</code>, will remain unchanged in the resulting tree,
%% except that exactly one occurrence of <code>meta_var</code> is
%% removed from its annotation list.</p>
%%
%% <p>The main use of the function <code>meta/1</code> is to transform
%% a data structure <code>Tree</code>, which represents a piece of
%% program code, into a form that is <em>representation independent
%% when printed</em>. E.g., suppose <code>Tree</code> represents a
%% variable named "V". Then (assuming a function <code>print/1</code>
%% for printing syntax trees), evaluating
%% <code>print(abstract(Tree))</code> - simply using
%% <code>abstract/1</code> to map the actual data structure onto a
%% syntax tree representation - would output a string that might look
%% something like "<code>{var, ..., 'V'}</code>", which is obviously
%% dependent on the implementation of the abstract syntax trees. This
%% could e.g. be useful for caching a syntax tree in a file. However,
%% in some situations like in a program generator generator (with two
%% "generator"), it may be unacceptable.  Using
%% <code>print(meta(Tree))</code> instead would output a
%% <em>representation independent</em> syntax tree generating
%% expression; in the above case, something like
%% "<code>cerl:c_var('V')</code>".</p>
%%
%% <p>The implementation tries to generate compact code with respect
%% to literals and lists.</p>
%%
%% @see abstract/1
%% @see type/1
%% @see get_ann/1

-spec meta(cerl()) -> cerl().

meta(Node) ->
    %% First of all we check for metavariables:
    case type(Node) of
	var ->
	    case lists:member(meta_var, get_ann(Node)) of
		false ->
		    meta_0(var, Node);
		true ->
		    %% A meta-variable: remove the first found
		    %% 'meta_var' annotation, but otherwise leave
		    %% the node unchanged.
		    set_ann(Node, lists:delete(meta_var, get_ann(Node)))
	    end;
	Type ->
	    meta_0(Type, Node)
    end.

meta_0(Type, Node) ->
    case get_ann(Node) of
	[] ->
	    meta_1(Type, Node);
	As ->
	    meta_call(set_ann, [meta_1(Type, Node), abstract(As)])
    end.

meta_1(literal, Node) ->
    %% We handle atomic literals separately, to get a bit
    %% more compact code. For the rest, we use 'abstract'.
    case concrete(Node) of
	V when is_atom(V) ->
	    meta_call(c_atom, [Node]);
	V when is_integer(V) ->
	    meta_call(c_int, [Node]);
	V when is_float(V) ->
	    meta_call(c_float, [Node]);
	[] ->
	    meta_call(c_nil, []);
	_ ->
	    meta_call(abstract, [Node])
    end;
meta_1(var, Node) ->
    %% A normal variable or function name.
    meta_call(c_var, [abstract(var_name(Node))]);
meta_1(values, Node) ->
    meta_call(c_values,
	      [make_list(meta_list(values_es(Node)))]);
meta_1(binary, Node) ->
    meta_call(c_binary,
	      [make_list(meta_list(binary_segments(Node)))]);
meta_1(bitstr, Node) ->
    meta_call(c_bitstr,
	      [meta(bitstr_val(Node)),
	       meta(bitstr_size(Node)),
	       meta(bitstr_unit(Node)),
	       meta(bitstr_type(Node)),
	       meta(bitstr_flags(Node))]);
meta_1(cons, Node) ->
    %% The list is split up if some sublist has annotatations. If
    %% we get exactly one element, we generate a 'c_cons' call
    %% instead of 'make_list' to reconstruct the node.
    case split_list(Node) of
	{[H], Node1} ->
	    meta_call(c_cons, [meta(H), meta(Node1)]);
	{L, Node1} ->
	    meta_call(make_list,
		      [make_list(meta_list(L)), meta(Node1)])
    end;
meta_1(tuple, Node) ->
    meta_call(c_tuple,
	      [make_list(meta_list(tuple_es(Node)))]);
meta_1('let', Node) ->
    meta_call(c_let,
	      [make_list(meta_list(let_vars(Node))),
	       meta(let_arg(Node)), meta(let_body(Node))]);
meta_1(seq, Node) ->
    meta_call(c_seq,
	      [meta(seq_arg(Node)), meta(seq_body(Node))]);
meta_1(apply, Node) ->
    meta_call(c_apply,
	      [meta(apply_op(Node)),
	       make_list(meta_list(apply_args(Node)))]);
meta_1(call, Node) ->
    meta_call(c_call,
	      [meta(call_module(Node)), meta(call_name(Node)),
	       make_list(meta_list(call_args(Node)))]);
meta_1(primop, Node) ->
    meta_call(c_primop,
	      [meta(primop_name(Node)),
	       make_list(meta_list(primop_args(Node)))]);
meta_1('case', Node) ->
    meta_call(c_case,
	      [meta(case_arg(Node)),
	       make_list(meta_list(case_clauses(Node)))]);
meta_1(clause, Node) ->
    meta_call(c_clause,
	      [make_list(meta_list(clause_pats(Node))),
	       meta(clause_guard(Node)),
	       meta(clause_body(Node))]);
meta_1(alias, Node) ->
    meta_call(c_alias,
	      [meta(alias_var(Node)), meta(alias_pat(Node))]);
meta_1('fun', Node) ->
    meta_call(c_fun,
	      [make_list(meta_list(fun_vars(Node))),
	       meta(fun_body(Node))]);
meta_1('receive', Node) ->
    meta_call(c_receive,
	      [make_list(meta_list(receive_clauses(Node))),
	       meta(receive_timeout(Node)),
	       meta(receive_action(Node))]);
meta_1('try', Node) ->
    meta_call(c_try,
	      [meta(try_arg(Node)),
	       make_list(meta_list(try_vars(Node))),
	       meta(try_body(Node)),
	       make_list(meta_list(try_evars(Node))),
	       meta(try_handler(Node))]);
meta_1('catch', Node) ->
    meta_call(c_catch, [meta(catch_body(Node))]);
meta_1(letrec, Node) ->
    meta_call(c_letrec,
	      [make_list([c_tuple([meta(N), meta(F)])
			  || {N, F} <- letrec_defs(Node)]),
	       meta(letrec_body(Node))]);
meta_1(module, Node) ->
    meta_call(c_module,
	      [meta(module_name(Node)),
	       make_list(meta_list(module_exports(Node))),
	       make_list([c_tuple([meta(A), meta(V)])
			  || {A, V} <- module_attrs(Node)]),
	       make_list([c_tuple([meta(N), meta(F)])
			  || {N, F} <- module_defs(Node)])]).

meta_call(F, As) ->
    c_call(c_atom(?MODULE), c_atom(F), As).

meta_list([T | Ts]) ->
    [meta(T) | meta_list(Ts)];
meta_list([]) ->
    [].

split_list(Node) ->
    split_list(set_ann(Node, []), []).

split_list(Node, L) ->
    A = get_ann(Node),
    case type(Node) of
	cons when A =:= [] ->
	    split_list(cons_tl(Node), [cons_hd(Node) | L]);
	_ ->
	    {lists:reverse(L), Node}
    end.


%% ---------------------------------------------------------------------

%% General utilities

is_lit_list([#c_literal{} | Es]) ->
    is_lit_list(Es);
is_lit_list([_ | _]) ->
    false;
is_lit_list([]) ->
    true.

lit_list_vals([#c_literal{val = V} | Es]) ->
    [V | lit_list_vals(Es)];
lit_list_vals([]) ->
    [].

-spec make_lit_list([_]) -> [#c_literal{}].  % XXX: cerl() instead of _ ?

make_lit_list([V | Vs]) ->
    [#c_literal{val = V} | make_lit_list(Vs)];
make_lit_list([]) ->
    [].

%% The following tests are the same as done by 'io_lib:char_list' and
%% 'io_lib:printable_list', respectively, but for a single character.

is_char_value(V) when V >= $\000, V =< $\377 -> true;
is_char_value(_) -> false.

is_print_char_value(V) when V >= $\040, V =< $\176 -> true;
is_print_char_value(V) when V >= $\240, V =< $\377 -> true;
is_print_char_value(V) when V =:= $\b -> true;
is_print_char_value(V) when V =:= $\d -> true;
is_print_char_value(V) when V =:= $\e -> true;
is_print_char_value(V) when V =:= $\f -> true;
is_print_char_value(V) when V =:= $\n -> true;
is_print_char_value(V) when V =:= $\r -> true;
is_print_char_value(V) when V =:= $\s -> true;
is_print_char_value(V) when V =:= $\t -> true;
is_print_char_value(V) when V =:= $\v -> true;
is_print_char_value(V) when V =:= $\" -> true;
is_print_char_value(V) when V =:= $\' -> true;
is_print_char_value(V) when V =:= $\\ -> true;
is_print_char_value(_) -> false.

is_char_list([V | Vs]) when is_integer(V) ->
    is_char_value(V) andalso is_char_list(Vs);
is_char_list([]) ->
    true;
is_char_list(_) ->
    false.

is_print_char_list([V | Vs]) when is_integer(V) ->
    is_print_char_value(V) andalso is_print_char_list(Vs);
is_print_char_list([]) ->
    true;
is_print_char_list(_) ->
    false.

unfold_tuples([{X, Y} | Ps]) ->
    [X, Y | unfold_tuples(Ps)];
unfold_tuples([]) ->
    [].

fold_tuples([X, Y | Es]) ->
    [{X, Y} | fold_tuples(Es)];
fold_tuples([]) ->
    [].