summaryrefslogtreecommitdiff
path: root/struct.c
blob: 7085042b43c2b32c4f8e96b8f087d776287191d1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
/**********************************************************************

  struct.c -

  $Author$
  created at: Tue Mar 22 18:44:30 JST 1995

  Copyright (C) 1993-2007 Yukihiro Matsumoto

**********************************************************************/

#include "id.h"
#include "internal.h"
#include "internal/class.h"
#include "internal/error.h"
#include "internal/hash.h"
#include "internal/object.h"
#include "internal/proc.h"
#include "internal/struct.h"
#include "internal/symbol.h"
#include "transient_heap.h"
#include "vm_core.h"
#include "builtin.h"

/* only for struct[:field] access */
enum {
    AREF_HASH_UNIT = 5,
    AREF_HASH_THRESHOLD = 10
};

VALUE rb_cStruct;
static ID id_members, id_back_members, id_keyword_init;

static VALUE struct_alloc(VALUE);

static inline VALUE
struct_ivar_get(VALUE c, ID id)
{
    VALUE orig = c;
    VALUE ivar = rb_attr_get(c, id);

    if (!NIL_P(ivar))
        return ivar;

    for (;;) {
        c = rb_class_superclass(c);
        if (c == 0 || c == rb_cStruct)
            return Qnil;
        RUBY_ASSERT(RB_TYPE_P(c, T_CLASS));
        ivar = rb_attr_get(c, id);
        if (!NIL_P(ivar)) {
            return rb_ivar_set(orig, id, ivar);
        }
    }
}

VALUE
rb_struct_s_keyword_init(VALUE klass)
{
    return struct_ivar_get(klass, id_keyword_init);
}

VALUE
rb_struct_s_members(VALUE klass)
{
    VALUE members = struct_ivar_get(klass, id_members);

    if (NIL_P(members)) {
        rb_raise(rb_eTypeError, "uninitialized struct");
    }
    if (!RB_TYPE_P(members, T_ARRAY)) {
        rb_raise(rb_eTypeError, "corrupted struct");
    }
    return members;
}

VALUE
rb_struct_members(VALUE s)
{
    VALUE members = rb_struct_s_members(rb_obj_class(s));

    if (RSTRUCT_LEN(s) != RARRAY_LEN(members)) {
        rb_raise(rb_eTypeError, "struct size differs (%ld required %ld given)",
                 RARRAY_LEN(members), RSTRUCT_LEN(s));
    }
    return members;
}

static long
struct_member_pos_ideal(VALUE name, long mask)
{
    /* (id & (mask/2)) * 2 */
    return (SYM2ID(name) >> (ID_SCOPE_SHIFT - 1)) & mask;
}

static long
struct_member_pos_probe(long prev, long mask)
{
    /* (((prev/2) * AREF_HASH_UNIT + 1) & (mask/2)) * 2 */
    return (prev * AREF_HASH_UNIT + 2) & mask;
}

static VALUE
struct_set_members(VALUE klass, VALUE /* frozen hidden array */ members)
{
    VALUE back;
    const long members_length = RARRAY_LEN(members);

    if (members_length <= AREF_HASH_THRESHOLD) {
        back = members;
    }
    else {
        long i, j, mask = 64;
        VALUE name;

        while (mask < members_length * AREF_HASH_UNIT) mask *= 2;

        back = rb_ary_hidden_new(mask + 1);
        rb_ary_store(back, mask, INT2FIX(members_length));
        mask -= 2;			  /* mask = (2**k-1)*2 */

        for (i=0; i < members_length; i++) {
            name = RARRAY_AREF(members, i);

            j = struct_member_pos_ideal(name, mask);

            for (;;) {
                if (!RTEST(RARRAY_AREF(back, j))) {
                    rb_ary_store(back, j, name);
                    rb_ary_store(back, j + 1, INT2FIX(i));
                    break;
                }
                j = struct_member_pos_probe(j, mask);
            }
        }
        OBJ_FREEZE_RAW(back);
    }
    rb_ivar_set(klass, id_members, members);
    rb_ivar_set(klass, id_back_members, back);

    return members;
}

static inline int
struct_member_pos(VALUE s, VALUE name)
{
    VALUE back = struct_ivar_get(rb_obj_class(s), id_back_members);
    long j, mask;

    if (UNLIKELY(NIL_P(back))) {
        rb_raise(rb_eTypeError, "uninitialized struct");
    }
    if (UNLIKELY(!RB_TYPE_P(back, T_ARRAY))) {
        rb_raise(rb_eTypeError, "corrupted struct");
    }

    mask = RARRAY_LEN(back);

    if (mask <= AREF_HASH_THRESHOLD) {
        if (UNLIKELY(RSTRUCT_LEN(s) != mask)) {
            rb_raise(rb_eTypeError,
                     "struct size differs (%ld required %ld given)",
                     mask, RSTRUCT_LEN(s));
        }
        for (j = 0; j < mask; j++) {
            if (RARRAY_AREF(back, j) == name)
                return (int)j;
        }
        return -1;
    }

    if (UNLIKELY(RSTRUCT_LEN(s) != FIX2INT(RARRAY_AREF(back, mask-1)))) {
        rb_raise(rb_eTypeError, "struct size differs (%d required %ld given)",
                 FIX2INT(RARRAY_AREF(back, mask-1)), RSTRUCT_LEN(s));
    }

    mask -= 3;
    j = struct_member_pos_ideal(name, mask);

    for (;;) {
        VALUE e = RARRAY_AREF(back, j);
        if (e == name)
            return FIX2INT(RARRAY_AREF(back, j + 1));
        if (!RTEST(e)) {
            return -1;
        }
        j = struct_member_pos_probe(j, mask);
    }
}

/*
 *  call-seq:
 *    StructClass::members -> array_of_symbols
 *
 *  Returns the member names of the Struct descendant as an array:
 *
 *     Customer = Struct.new(:name, :address, :zip)
 *     Customer.members # => [:name, :address, :zip]
 *
 */

static VALUE
rb_struct_s_members_m(VALUE klass)
{
    VALUE members = rb_struct_s_members(klass);

    return rb_ary_dup(members);
}

/*
 *  call-seq:
 *    members -> array_of_symbols
 *
 *  Returns the member names from +self+ as an array:
 *
 *     Customer = Struct.new(:name, :address, :zip)
 *     Customer.new.members # => [:name, :address, :zip]
 *
 *  Related: #to_a.
 */

static VALUE
rb_struct_members_m(VALUE obj)
{
    return rb_struct_s_members_m(rb_obj_class(obj));
}

VALUE
rb_struct_getmember(VALUE obj, ID id)
{
    VALUE slot = ID2SYM(id);
    int i = struct_member_pos(obj, slot);
    if (i != -1) {
        return RSTRUCT_GET(obj, i);
    }
    rb_name_err_raise("`%1$s' is not a struct member", obj, ID2SYM(id));

    UNREACHABLE_RETURN(Qnil);
}

static void
rb_struct_modify(VALUE s)
{
    rb_check_frozen(s);
}

static VALUE
anonymous_struct(VALUE klass)
{
    VALUE nstr;

    nstr = rb_class_new(klass);
    rb_make_metaclass(nstr, RBASIC(klass)->klass);
    rb_class_inherited(klass, nstr);
    return nstr;
}

static VALUE
new_struct(VALUE name, VALUE super)
{
    /* old style: should we warn? */
    ID id;
    name = rb_str_to_str(name);
    if (!rb_is_const_name(name)) {
        rb_name_err_raise("identifier %1$s needs to be constant",
                          super, name);
    }
    id = rb_to_id(name);
    if (rb_const_defined_at(super, id)) {
        rb_warn("redefining constant %"PRIsVALUE"::%"PRIsVALUE, super, name);
        rb_mod_remove_const(super, ID2SYM(id));
    }
    return rb_define_class_id_under(super, id, super);
}

NORETURN(static void invalid_struct_pos(VALUE s, VALUE idx));

static void
define_aref_method(VALUE nstr, VALUE name, VALUE off)
{
    rb_add_method_optimized(nstr, SYM2ID(name), OPTIMIZED_METHOD_TYPE_STRUCT_AREF, FIX2UINT(off), METHOD_VISI_PUBLIC);
}

static void
define_aset_method(VALUE nstr, VALUE name, VALUE off)
{
    rb_add_method_optimized(nstr, SYM2ID(name), OPTIMIZED_METHOD_TYPE_STRUCT_ASET, FIX2UINT(off), METHOD_VISI_PUBLIC);
}

static VALUE
rb_struct_s_inspect(VALUE klass)
{
    VALUE inspect = rb_class_name(klass);
    if (RTEST(rb_struct_s_keyword_init(klass))) {
        rb_str_cat_cstr(inspect, "(keyword_init: true)");
    }
    return inspect;
}

#if 0 /* for RDoc */

/*
 * call-seq:
 *   StructClass::keyword_init? -> true or falsy value
 *
 * Returns +true+ if the class was initialized with <tt>keyword_init: true</tt>.
 * Otherwise returns +nil+ or +false+.
 *
 * Examples:
 *   Foo = Struct.new(:a)
 *   Foo.keyword_init? # => nil
 *   Bar = Struct.new(:a, keyword_init: true)
 *   Bar.keyword_init? # => true
 *   Baz = Struct.new(:a, keyword_init: false)
 *   Baz.keyword_init? # => false
 */
static VALUE
rb_struct_s_keyword_init_p(VALUE obj)
{
}
#endif

#define rb_struct_s_keyword_init_p rb_struct_s_keyword_init

static VALUE
setup_struct(VALUE nstr, VALUE members)
{
    long i, len;

    members = struct_set_members(nstr, members);

    rb_define_alloc_func(nstr, struct_alloc);
    rb_define_singleton_method(nstr, "new", rb_class_new_instance_pass_kw, -1);
    rb_define_singleton_method(nstr, "[]", rb_class_new_instance_pass_kw, -1);
    rb_define_singleton_method(nstr, "members", rb_struct_s_members_m, 0);
    rb_define_singleton_method(nstr, "inspect", rb_struct_s_inspect, 0);
    rb_define_singleton_method(nstr, "keyword_init?", rb_struct_s_keyword_init_p, 0);

    len = RARRAY_LEN(members);
    for (i=0; i< len; i++) {
        VALUE sym = RARRAY_AREF(members, i);
        ID id = SYM2ID(sym);
        VALUE off = LONG2NUM(i);

        define_aref_method(nstr, sym, off);
        define_aset_method(nstr, ID2SYM(rb_id_attrset(id)), off);
    }

    return nstr;
}

VALUE
rb_struct_alloc_noinit(VALUE klass)
{
    return struct_alloc(klass);
}

static VALUE
struct_make_members_list(va_list ar)
{
    char *mem;
    VALUE ary, list = rb_ident_hash_new();
    st_table *tbl = RHASH_TBL_RAW(list);

    RBASIC_CLEAR_CLASS(list);
    OBJ_WB_UNPROTECT(list);
    while ((mem = va_arg(ar, char*)) != 0) {
        VALUE sym = rb_sym_intern_ascii_cstr(mem);
        if (st_insert(tbl, sym, Qtrue)) {
            rb_raise(rb_eArgError, "duplicate member: %s", mem);
        }
    }
    ary = rb_hash_keys(list);
    st_clear(tbl);
    RBASIC_CLEAR_CLASS(ary);
    OBJ_FREEZE_RAW(ary);
    return ary;
}

static VALUE
struct_define_without_accessor(VALUE outer, const char *class_name, VALUE super, rb_alloc_func_t alloc, VALUE members)
{
    VALUE klass;

    if (class_name) {
        if (outer) {
            klass = rb_define_class_under(outer, class_name, super);
        }
        else {
            klass = rb_define_class(class_name, super);
        }
    }
    else {
        klass = anonymous_struct(super);
    }

    struct_set_members(klass, members);

    if (alloc) {
        rb_define_alloc_func(klass, alloc);
    }
    else {
        rb_define_alloc_func(klass, struct_alloc);
    }

    return klass;
}

VALUE
rb_struct_define_without_accessor_under(VALUE outer, const char *class_name, VALUE super, rb_alloc_func_t alloc, ...)
{
    va_list ar;
    VALUE members;

    va_start(ar, alloc);
    members = struct_make_members_list(ar);
    va_end(ar);

    return struct_define_without_accessor(outer, class_name, super, alloc, members);
}

VALUE
rb_struct_define_without_accessor(const char *class_name, VALUE super, rb_alloc_func_t alloc, ...)
{
    va_list ar;
    VALUE members;

    va_start(ar, alloc);
    members = struct_make_members_list(ar);
    va_end(ar);

    return struct_define_without_accessor(0, class_name, super, alloc, members);
}

VALUE
rb_struct_define(const char *name, ...)
{
    va_list ar;
    VALUE st, ary;

    va_start(ar, name);
    ary = struct_make_members_list(ar);
    va_end(ar);

    if (!name) st = anonymous_struct(rb_cStruct);
    else st = new_struct(rb_str_new2(name), rb_cStruct);
    return setup_struct(st, ary);
}

VALUE
rb_struct_define_under(VALUE outer, const char *name, ...)
{
    va_list ar;
    VALUE ary;

    va_start(ar, name);
    ary = struct_make_members_list(ar);
    va_end(ar);

    return setup_struct(rb_define_class_under(outer, name, rb_cStruct), ary);
}

/*
 *  call-seq:
 *    Struct.new(*member_names, keyword_init: false){|Struct_subclass| ... } -> Struct_subclass
 *    Struct.new(class_name, *member_names, keyword_init: false){|Struct_subclass| ... } -> Struct_subclass
 *    Struct_subclass.new(*member_names) -> Struct_subclass_instance
 *    Struct_subclass.new(**member_names) -> Struct_subclass_instance
 *
 *  <tt>Struct.new</tt> returns a new subclass of +Struct+.  The new subclass:
 *
 *  - May be anonymous, or may have the name given by +class_name+.
 *  - May have members as given by +member_names+.
 *  - May have initialization via ordinary arguments (the default)
 *    or via keyword arguments (if <tt>keyword_init: true</tt> is given).
 *
 *  The new subclass has its own method <tt>::new</tt>; thus:
 *
 *    Foo = Struct.new('Foo', :foo, :bar) # => Struct::Foo
 *    f = Foo.new(0, 1)                   # => #<struct Struct::Foo foo=0, bar=1>
 *
 *  <b>\Class Name</b>
 *
 *  With string argument +class_name+,
 *  returns a new subclass of +Struct+ named <tt>Struct::<em>class_name</em></tt>:
 *
 *    Foo = Struct.new('Foo', :foo, :bar) # => Struct::Foo
 *    Foo.name                            # => "Struct::Foo"
 *    Foo.superclass                      # => Struct
 *
 *  Without string argument +class_name+,
 *  returns a new anonymous subclass of +Struct+:
 *
 *    Struct.new(:foo, :bar).name # => nil
 *
 *  <b>Block</b>
 *
 *  With a block given, the created subclass is yielded to the block:
 *
 *    Customer = Struct.new('Customer', :name, :address) do |new_class|
 *      p "The new subclass is #{new_class}"
 *      def greeting
 *        "Hello #{name} at #{address}"
 *      end
 *    end           # => Struct::Customer
 *    dave = Customer.new('Dave', '123 Main')
 *    dave # =>     #<struct Struct::Customer name="Dave", address="123 Main">
 *    dave.greeting # => "Hello Dave at 123 Main"
 *
 *  Output, from <tt>Struct.new</tt>:
 *
 *    "The new subclass is Struct::Customer"
 *
 *  <b>Member Names</b>
 *
 *  \Symbol arguments +member_names+
 *  determines the members of the new subclass:
 *
 *    Struct.new(:foo, :bar).members        # => [:foo, :bar]
 *    Struct.new('Foo', :foo, :bar).members # => [:foo, :bar]
 *
 *  The new subclass has instance methods corresponding to +member_names+:
 *
 *    Foo = Struct.new('Foo', :foo, :bar)
 *    Foo.instance_methods(false) # => [:foo, :bar, :foo=, :bar=]
 *    f = Foo.new                 # => #<struct Struct::Foo foo=nil, bar=nil>
 *    f.foo                       # => nil
 *    f.foo = 0                   # => 0
 *    f.bar                       # => nil
 *    f.bar = 1                   # => 1
 *    f                           # => #<struct Struct::Foo foo=0, bar=1>
 *
 *  <b>Singleton Methods</b>
 *
 *  A subclass returned by Struct.new has these singleton methods:
 *
 *  - \Method <tt>::new </tt> creates an instance of the subclass:
 *
 *      Foo.new          # => #<struct Struct::Foo foo=nil, bar=nil>
 *      Foo.new(0)       # => #<struct Struct::Foo foo=0, bar=nil>
 *      Foo.new(0, 1)    # => #<struct Struct::Foo foo=0, bar=1>
 *      Foo.new(0, 1, 2) # Raises ArgumentError: struct size differs
 *
 *    \Method <tt>::[]</tt> is an alias for method <tt>::new</tt>.
 *
 *  - \Method <tt>:inspect</tt> returns a string representation of the subclass:
 *
 *      Foo.inspect
 *      # => "Struct::Foo"
 *
 *  - \Method <tt>::members</tt> returns an array of the member names:
 *
 *      Foo.members # => [:foo, :bar]
 *
 *  <b>Keyword Argument</b>
 *
 *  By default, the arguments for initializing an instance of the new subclass
 *  are ordinary arguments (not keyword arguments).
 *  With optional keyword argument <tt>keyword_init: true</tt>,
 *  the new subclass is initialized with keyword arguments:
 *
 *    # Without keyword_init: true.
 *    Foo = Struct.new('Foo', :foo, :bar)
 *    Foo                     # => Struct::Foo
 *    Foo.new(0, 1)           # => #<struct Struct::Foo foo=0, bar=1>
 *    # With keyword_init: true.
 *    Bar = Struct.new(:foo, :bar, keyword_init: true)
 *    Bar # =>                # => Bar(keyword_init: true)
 *    Bar.new(bar: 1, foo: 0) # => #<struct Bar foo=0, bar=1>
 *
 */

static VALUE
rb_struct_s_def(int argc, VALUE *argv, VALUE klass)
{
    VALUE name, rest, keyword_init = Qnil;
    long i;
    VALUE st;
    st_table *tbl;
    VALUE opt;

    argc = rb_scan_args(argc, argv, "1*:", NULL, NULL, &opt);
    name = argv[0];
    if (SYMBOL_P(name)) {
        name = Qnil;
    }
    else {
        --argc;
        ++argv;
    }

    if (!NIL_P(opt)) {
        static ID keyword_ids[1];

        if (!keyword_ids[0]) {
            keyword_ids[0] = rb_intern("keyword_init");
        }
        rb_get_kwargs(opt, keyword_ids, 0, 1, &keyword_init);
        if (keyword_init == Qundef) {
            keyword_init = Qnil;
        }
        else if (RTEST(keyword_init)) {
            keyword_init = Qtrue;
        }
    }

    rest = rb_ident_hash_new();
    RBASIC_CLEAR_CLASS(rest);
    OBJ_WB_UNPROTECT(rest);
    tbl = RHASH_TBL_RAW(rest);
    for (i=0; i<argc; i++) {
        VALUE mem = rb_to_symbol(argv[i]);
        if (rb_is_attrset_sym(mem)) {
            rb_raise(rb_eArgError, "invalid struct member: %"PRIsVALUE, mem);
        }
        if (st_insert(tbl, mem, Qtrue)) {
            rb_raise(rb_eArgError, "duplicate member: %"PRIsVALUE, mem);
        }
    }
    rest = rb_hash_keys(rest);
    st_clear(tbl);
    RBASIC_CLEAR_CLASS(rest);
    OBJ_FREEZE_RAW(rest);
    if (NIL_P(name)) {
        st = anonymous_struct(klass);
    }
    else {
        st = new_struct(name, klass);
    }
    setup_struct(st, rest);
    rb_ivar_set(st, id_keyword_init, keyword_init);
    if (rb_block_given_p()) {
        rb_mod_module_eval(0, 0, st);
    }

    return st;
}

static long
num_members(VALUE klass)
{
    VALUE members;
    members = struct_ivar_get(klass, id_members);
    if (!RB_TYPE_P(members, T_ARRAY)) {
        rb_raise(rb_eTypeError, "broken members");
    }
    return RARRAY_LEN(members);
}

/*
 */

struct struct_hash_set_arg {
    VALUE self;
    VALUE unknown_keywords;
};

static int rb_struct_pos(VALUE s, VALUE *name);

static int
struct_hash_set_i(VALUE key, VALUE val, VALUE arg)
{
    struct struct_hash_set_arg *args = (struct struct_hash_set_arg *)arg;
    int i = rb_struct_pos(args->self, &key);
    if (i < 0) {
        if (NIL_P(args->unknown_keywords)) {
            args->unknown_keywords = rb_ary_new();
        }
        rb_ary_push(args->unknown_keywords, key);
    }
    else {
        rb_struct_modify(args->self);
        RSTRUCT_SET(args->self, i, val);
    }
    return ST_CONTINUE;
}

static VALUE
rb_struct_initialize_m(int argc, const VALUE *argv, VALUE self)
{
    VALUE klass = rb_obj_class(self);
    rb_struct_modify(self);
    long n = num_members(klass);
    if (argc == 0) {
        rb_mem_clear((VALUE *)RSTRUCT_CONST_PTR(self), n);
        return Qnil;
    }

    bool keyword_init = false;
    switch (rb_struct_s_keyword_init(klass)) {
      default:
        if (argc > 1 || !RB_TYPE_P(argv[0], T_HASH)) {
            rb_raise(rb_eArgError, "wrong number of arguments (given %d, expected 0)", argc);
        }
        keyword_init = true;
        break;
      case Qfalse:
        break;
      case Qnil:
        if (argc > 1 || !RB_TYPE_P(argv[0], T_HASH)) {
            break;
        }
        keyword_init = rb_keyword_given_p();
        break;
    }
    if (keyword_init) {
        struct struct_hash_set_arg arg;
        rb_mem_clear((VALUE *)RSTRUCT_CONST_PTR(self), n);
        arg.self = self;
        arg.unknown_keywords = Qnil;
        rb_hash_foreach(argv[0], struct_hash_set_i, (VALUE)&arg);
        if (arg.unknown_keywords != Qnil) {
            rb_raise(rb_eArgError, "unknown keywords: %s",
                     RSTRING_PTR(rb_ary_join(arg.unknown_keywords, rb_str_new2(", "))));
        }
    }
    else {
        if (n < argc) {
            rb_raise(rb_eArgError, "struct size differs");
        }
        for (long i=0; i<argc; i++) {
            RSTRUCT_SET(self, i, argv[i]);
        }
        if (n > argc) {
            rb_mem_clear((VALUE *)RSTRUCT_CONST_PTR(self)+argc, n-argc);
        }
    }
    return Qnil;
}

VALUE
rb_struct_initialize(VALUE self, VALUE values)
{
    rb_struct_initialize_m(RARRAY_LENINT(values), RARRAY_CONST_PTR(values), self);
    RB_GC_GUARD(values);
    return Qnil;
}

static VALUE *
struct_heap_alloc(VALUE st, size_t len)
{
    VALUE *ptr = rb_transient_heap_alloc((VALUE)st, sizeof(VALUE) * len);

    if (ptr) {
        RSTRUCT_TRANSIENT_SET(st);
        return ptr;
    }
    else {
        RSTRUCT_TRANSIENT_UNSET(st);
        return ALLOC_N(VALUE, len);
    }
}

#if USE_TRANSIENT_HEAP
void
rb_struct_transient_heap_evacuate(VALUE obj, int promote)
{
    if (RSTRUCT_TRANSIENT_P(obj)) {
        const VALUE *old_ptr = rb_struct_const_heap_ptr(obj);
        VALUE *new_ptr;
        long len = RSTRUCT_LEN(obj);

        if (promote) {
            new_ptr = ALLOC_N(VALUE, len);
            FL_UNSET_RAW(obj, RSTRUCT_TRANSIENT_FLAG);
        }
        else {
            new_ptr = struct_heap_alloc(obj, len);
        }
        MEMCPY(new_ptr, old_ptr, VALUE, len);
        RSTRUCT(obj)->as.heap.ptr = new_ptr;
    }
}
#endif

static VALUE
struct_alloc(VALUE klass)
{
    long n;
    NEWOBJ_OF(st, struct RStruct, klass, T_STRUCT | (RGENGC_WB_PROTECTED_STRUCT ? FL_WB_PROTECTED : 0));

    n = num_members(klass);

    if (0 < n && n <= RSTRUCT_EMBED_LEN_MAX) {
        RBASIC(st)->flags &= ~RSTRUCT_EMBED_LEN_MASK;
        RBASIC(st)->flags |= n << RSTRUCT_EMBED_LEN_SHIFT;
        rb_mem_clear((VALUE *)st->as.ary, n);
    }
    else {
        st->as.heap.ptr = struct_heap_alloc((VALUE)st, n);
        rb_mem_clear((VALUE *)st->as.heap.ptr, n);
        st->as.heap.len = n;
    }

    return (VALUE)st;
}

VALUE
rb_struct_alloc(VALUE klass, VALUE values)
{
    return rb_class_new_instance(RARRAY_LENINT(values), RARRAY_CONST_PTR(values), klass);
}

VALUE
rb_struct_new(VALUE klass, ...)
{
    VALUE tmpargs[16], *mem = tmpargs;
    int size, i;
    va_list args;

    size = rb_long2int(num_members(klass));
    if (size > numberof(tmpargs)) {
        tmpargs[0] = rb_ary_hidden_new(size);
        mem = RARRAY_PTR(tmpargs[0]);
    }
    va_start(args, klass);
    for (i=0; i<size; i++) {
        mem[i] = va_arg(args, VALUE);
    }
    va_end(args);

    return rb_class_new_instance(size, mem, klass);
}

static VALUE
struct_enum_size(VALUE s, VALUE args, VALUE eobj)
{
    return rb_struct_size(s);
}

/*
 *  call-seq:
 *    each {|value| ... } -> self
 *    each -> enumerator
 *
 *  Calls the given block with the value of each member; returns +self+:
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe.each {|value| p value }
 *
 *  Output:
 *
 *    "Joe Smith"
 *    "123 Maple, Anytown NC"
 *    12345
 *
 *  Returns an Enumerator if no block is given.
 *
 *  Related: #each_pair.
 */

static VALUE
rb_struct_each(VALUE s)
{
    long i;

    RETURN_SIZED_ENUMERATOR(s, 0, 0, struct_enum_size);
    for (i=0; i<RSTRUCT_LEN(s); i++) {
        rb_yield(RSTRUCT_GET(s, i));
    }
    return s;
}

/*
 *  call-seq:
 *    each_pair {|(name, value)| ... } -> self
 *    each_pair -> enumerator
 *
 *  Calls the given block with each member name/value pair; returns +self+:
 *
 *    Customer = Struct.new(:name, :address, :zip) # => Customer
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe.each_pair {|(name, value)| p "#{name} => #{value}" }
 *
 *  Output:
 *
 *    "name => Joe Smith"
 *    "address => 123 Maple, Anytown NC"
 *    "zip => 12345"
 *
 *  Returns an Enumerator if no block is given.
 *
 *  Related: #each.
 *
 */

static VALUE
rb_struct_each_pair(VALUE s)
{
    VALUE members;
    long i;

    RETURN_SIZED_ENUMERATOR(s, 0, 0, struct_enum_size);
    members = rb_struct_members(s);
    if (rb_block_pair_yield_optimizable()) {
        for (i=0; i<RSTRUCT_LEN(s); i++) {
            VALUE key = rb_ary_entry(members, i);
            VALUE value = RSTRUCT_GET(s, i);
            rb_yield_values(2, key, value);
        }
    }
    else {
        for (i=0; i<RSTRUCT_LEN(s); i++) {
            VALUE key = rb_ary_entry(members, i);
            VALUE value = RSTRUCT_GET(s, i);
            rb_yield(rb_assoc_new(key, value));
        }
    }
    return s;
}

static VALUE
inspect_struct(VALUE s, VALUE dummy, int recur)
{
    VALUE cname = rb_class_path(rb_obj_class(s));
    VALUE members, str = rb_str_new2("#<struct ");
    long i, len;
    char first = RSTRING_PTR(cname)[0];

    if (recur || first != '#') {
        rb_str_append(str, cname);
    }
    if (recur) {
        return rb_str_cat2(str, ":...>");
    }

    members = rb_struct_members(s);
    len = RSTRUCT_LEN(s);

    for (i=0; i<len; i++) {
        VALUE slot;
        ID id;

        if (i > 0) {
            rb_str_cat2(str, ", ");
        }
        else if (first != '#') {
            rb_str_cat2(str, " ");
        }
        slot = RARRAY_AREF(members, i);
        id = SYM2ID(slot);
        if (rb_is_local_id(id) || rb_is_const_id(id)) {
            rb_str_append(str, rb_id2str(id));
        }
        else {
            rb_str_append(str, rb_inspect(slot));
        }
        rb_str_cat2(str, "=");
        rb_str_append(str, rb_inspect(RSTRUCT_GET(s, i)));
    }
    rb_str_cat2(str, ">");

    return str;
}

/*
 *  call-seq:
 *    inspect -> string
 *
 *  Returns a string representation of +self+:
 *
 *    Customer = Struct.new(:name, :address, :zip) # => Customer
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe.inspect # => "#<struct Customer name=\"Joe Smith\", address=\"123 Maple, Anytown NC\", zip=12345>"
 *
 *  Struct#to_s is an alias for Struct#inspect.
 *
 */

static VALUE
rb_struct_inspect(VALUE s)
{
    return rb_exec_recursive(inspect_struct, s, 0);
}

/*
 *  call-seq:
 *    to_a     -> array
 *
 *  Returns the values in +self+ as an array:
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe.to_a # => ["Joe Smith", "123 Maple, Anytown NC", 12345]
 *
 *  Struct#values and Struct#deconstruct are aliases for Struct#to_a.
 *
 *  Related: #members.
 */

static VALUE
rb_struct_to_a(VALUE s)
{
    return rb_ary_new4(RSTRUCT_LEN(s), RSTRUCT_CONST_PTR(s));
}

/*
 *  call-seq:
 *    to_h -> hash
 *    to_h {|name, value| ... } -> hash
 *
 *  Returns a hash containing the name and value for each member:
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    h = joe.to_h
 *    h # => {:name=>"Joe Smith", :address=>"123 Maple, Anytown NC", :zip=>12345}
 *
 *  If a block is given, it is called with each name/value pair;
 *  the block should return a 2-element array whose elements will become
 *  a key/value pair in the returned hash:
 *
 *    h = joe.to_h{|name, value| [name.upcase, value.to_s.upcase]}
 *    h # => {:NAME=>"JOE SMITH", :ADDRESS=>"123 MAPLE, ANYTOWN NC", :ZIP=>"12345"}
 *
 *  Raises ArgumentError if the block returns an inappropriate value.
 *
 */

static VALUE
rb_struct_to_h(VALUE s)
{
    VALUE h = rb_hash_new_with_size(RSTRUCT_LEN(s));
    VALUE members = rb_struct_members(s);
    long i;
    int block_given = rb_block_given_p();

    for (i=0; i<RSTRUCT_LEN(s); i++) {
        VALUE k = rb_ary_entry(members, i), v = RSTRUCT_GET(s, i);
        if (block_given)
            rb_hash_set_pair(h, rb_yield_values(2, k, v));
        else
            rb_hash_aset(h, k, v);
    }
    return h;
}

/*
 *  call-seq:
 *    deconstruct_keys(array_of_names) -> hash
 *
 *  Returns a hash of the name/value pairs for the given member names.
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    h = joe.deconstruct_keys([:zip, :address])
 *    h # => {:zip=>12345, :address=>"123 Maple, Anytown NC"}
 *
 *  Returns all names and values if +array_of_names+ is +nil+:
 *
 *    h = joe.deconstruct_keys(nil)
 *    h # => {:name=>"Joseph Smith, Jr.", :address=>"123 Maple, Anytown NC", :zip=>12345}
 *
 */
static VALUE
rb_struct_deconstruct_keys(VALUE s, VALUE keys)
{
    VALUE h;
    long i;

    if (NIL_P(keys)) {
        return rb_struct_to_h(s);
    }
    if (UNLIKELY(!RB_TYPE_P(keys, T_ARRAY))) {
        rb_raise(rb_eTypeError,
                 "wrong argument type %"PRIsVALUE" (expected Array or nil)",
                 rb_obj_class(keys));

    }
    if (RSTRUCT_LEN(s) < RARRAY_LEN(keys)) {
        return rb_hash_new_with_size(0);
    }
    h = rb_hash_new_with_size(RARRAY_LEN(keys));
    for (i=0; i<RARRAY_LEN(keys); i++) {
        VALUE key = RARRAY_AREF(keys, i);
        int i = rb_struct_pos(s, &key);
        if (i < 0) {
            return h;
        }
        rb_hash_aset(h, key, RSTRUCT_GET(s, i));
    }
    return h;
}

/* :nodoc: */
VALUE
rb_struct_init_copy(VALUE copy, VALUE s)
{
    long i, len;

    if (!OBJ_INIT_COPY(copy, s)) return copy;
    if (RSTRUCT_LEN(copy) != RSTRUCT_LEN(s)) {
        rb_raise(rb_eTypeError, "struct size mismatch");
    }

    for (i=0, len=RSTRUCT_LEN(copy); i<len; i++) {
        RSTRUCT_SET(copy, i, RSTRUCT_GET(s, i));
    }

    return copy;
}

static int
rb_struct_pos(VALUE s, VALUE *name)
{
    long i;
    VALUE idx = *name;

    if (SYMBOL_P(idx)) {
        return struct_member_pos(s, idx);
    }
    else if (RB_TYPE_P(idx, T_STRING)) {
        idx = rb_check_symbol(name);
        if (NIL_P(idx)) return -1;
        return struct_member_pos(s, idx);
    }
    else {
        long len;
        i = NUM2LONG(idx);
        len = RSTRUCT_LEN(s);
        if (i < 0) {
            if (i + len < 0) {
                *name = LONG2FIX(i);
                return -1;
            }
            i += len;
        }
        else if (len <= i) {
            *name = LONG2FIX(i);
            return -1;
        }
        return (int)i;
    }
}

static void
invalid_struct_pos(VALUE s, VALUE idx)
{
    if (FIXNUM_P(idx)) {
        long i = FIX2INT(idx), len = RSTRUCT_LEN(s);
        if (i < 0) {
            rb_raise(rb_eIndexError, "offset %ld too small for struct(size:%ld)",
                     i, len);
        }
        else {
            rb_raise(rb_eIndexError, "offset %ld too large for struct(size:%ld)",
                     i, len);
        }
    }
    else {
        rb_name_err_raise("no member '%1$s' in struct", s, idx);
    }
}

/*
 *  call-seq:
 *    struct[name] -> object
 *    struct[n] -> object
 *
 *  Returns a value from +self+.
 *
 *  With symbol or string argument +name+ given, returns the value for the named member:
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe[:zip] # => 12345
 *
 *  Raises NameError if +name+ is not the name of a member.
 *
 *  With integer argument +n+ given, returns <tt>self.values[n]</tt>
 *  if +n+ is in range;
 *  see Array@Array+Indexes:
 *
 *    joe[2]  # => 12345
 *    joe[-2] # => "123 Maple, Anytown NC"
 *
 *  Raises IndexError if +n+ is out of range.
 *
 */

VALUE
rb_struct_aref(VALUE s, VALUE idx)
{
    int i = rb_struct_pos(s, &idx);
    if (i < 0) invalid_struct_pos(s, idx);
    return RSTRUCT_GET(s, i);
}

/*
 *  call-seq:
 *    struct[name] = value -> value
 *    struct[n] = value -> value
 *
 *  Assigns a value to a member.
 *
 *  With symbol or string argument +name+ given, assigns the given +value+
 *  to the named member; returns +value+:
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe[:zip] = 54321 # => 54321
 *    joe # => #<struct Customer name="Joe Smith", address="123 Maple, Anytown NC", zip=54321>
 *
 *  Raises NameError if +name+ is not the name of a member.
 *
 *  With integer argument +n+ given, assigns the given +value+
 *  to the +n+-th member if +n+ is in range;
 *  see Array@Array+Indexes:
 *
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe[2] = 54321           # => 54321
 *    joe[-3] = 'Joseph Smith' # => "Joseph Smith"
 *    joe # => #<struct Customer name="Joseph Smith", address="123 Maple, Anytown NC", zip=54321>
 *
 *  Raises IndexError if +n+ is out of range.
 *
 */

VALUE
rb_struct_aset(VALUE s, VALUE idx, VALUE val)
{
    int i = rb_struct_pos(s, &idx);
    if (i < 0) invalid_struct_pos(s, idx);
    rb_struct_modify(s);
    RSTRUCT_SET(s, i, val);
    return val;
}

FUNC_MINIMIZED(VALUE rb_struct_lookup(VALUE s, VALUE idx));
NOINLINE(static VALUE rb_struct_lookup_default(VALUE s, VALUE idx, VALUE notfound));

VALUE
rb_struct_lookup(VALUE s, VALUE idx)
{
    return rb_struct_lookup_default(s, idx, Qnil);
}

static VALUE
rb_struct_lookup_default(VALUE s, VALUE idx, VALUE notfound)
{
    int i = rb_struct_pos(s, &idx);
    if (i < 0) return notfound;
    return RSTRUCT_GET(s, i);
}

static VALUE
struct_entry(VALUE s, long n)
{
    return rb_struct_aref(s, LONG2NUM(n));
}

/*
 *  call-seq:
 *    values_at(*integers) -> array
 *    values_at(integer_range) -> array
 *
 *  Returns an array of values from +self+.
 *
 *  With integer arguments +integers+ given,
 *  returns an array containing each value given by one of +integers+:
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe.values_at(0, 2)    # => ["Joe Smith", 12345]
 *    joe.values_at(2, 0)    # => [12345, "Joe Smith"]
 *    joe.values_at(2, 1, 0) # => [12345, "123 Maple, Anytown NC", "Joe Smith"]
 *    joe.values_at(0, -3)   # => ["Joe Smith", "Joe Smith"]
 *
 *  Raises IndexError if any of +integers+ is out of range;
 *  see Array@Array+Indexes.
 *
 *  With integer range argument +integer_range+ given,
 *  returns an array containing each value given by the elements of the range;
 *  fills with +nil+ values for range elements larger than the structure:
 *
 *    joe.values_at(0..2)
 *    # => ["Joe Smith", "123 Maple, Anytown NC", 12345]
 *    joe.values_at(-3..-1)
 *    # => ["Joe Smith", "123 Maple, Anytown NC", 12345]
 *    joe.values_at(1..4) # => ["123 Maple, Anytown NC", 12345, nil, nil]
 *
 *  Raises RangeError if any element of the range is negative and out of range;
 *  see Array@Array+Indexes.
 *
 */

static VALUE
rb_struct_values_at(int argc, VALUE *argv, VALUE s)
{
    return rb_get_values_at(s, RSTRUCT_LEN(s), argc, argv, struct_entry);
}

/*
 *  call-seq:
 *    select {|value| ... } -> array
 *    select -> enumerator
 *
 *  With a block given, returns an array of values from +self+
 *  for which the block returns a truthy value:
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    a = joe.select {|value| value.is_a?(String) }
 *    a # => ["Joe Smith", "123 Maple, Anytown NC"]
 *    a = joe.select {|value| value.is_a?(Integer) }
 *    a # => [12345]
 *
 *  With no block given, returns an Enumerator.
 *
 *  Struct#filter is an alias for Struct#select.
 */

static VALUE
rb_struct_select(int argc, VALUE *argv, VALUE s)
{
    VALUE result;
    long i;

    rb_check_arity(argc, 0, 0);
    RETURN_SIZED_ENUMERATOR(s, 0, 0, struct_enum_size);
    result = rb_ary_new();
    for (i = 0; i < RSTRUCT_LEN(s); i++) {
        if (RTEST(rb_yield(RSTRUCT_GET(s, i)))) {
            rb_ary_push(result, RSTRUCT_GET(s, i));
        }
    }

    return result;
}

static VALUE
recursive_equal(VALUE s, VALUE s2, int recur)
{
    long i, len;

    if (recur) return Qtrue; /* Subtle! */
    len = RSTRUCT_LEN(s);
    for (i=0; i<len; i++) {
        if (!rb_equal(RSTRUCT_GET(s, i), RSTRUCT_GET(s2, i))) return Qfalse;
    }
    return Qtrue;
}


/*
 *  call-seq:
 *    self == other -> true or false
 *
 *  Returns  +true+ if and only if the following are true; otherwise returns +false+:
 *
 *  - <tt>other.class == self.class</tt>.
 *  - For each member name +name+, <tt>other.name == self.name</tt>.
 *
 *  Examples:
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe    = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe_jr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe_jr == joe # => true
 *    joe_jr[:name] = 'Joe Smith, Jr.'
 *    # => "Joe Smith, Jr."
 *    joe_jr == joe # => false
 */

static VALUE
rb_struct_equal(VALUE s, VALUE s2)
{
    if (s == s2) return Qtrue;
    if (!RB_TYPE_P(s2, T_STRUCT)) return Qfalse;
    if (rb_obj_class(s) != rb_obj_class(s2)) return Qfalse;
    if (RSTRUCT_LEN(s) != RSTRUCT_LEN(s2)) {
        rb_bug("inconsistent struct"); /* should never happen */
    }

    return rb_exec_recursive_paired(recursive_equal, s, s2, s2);
}

/*
 *  call-seq:
 *    hash -> integer
 *
 *  Returns the integer hash value for +self+.
 *
 *  Two structs of the same class and with the same content
 *  will have the same hash code (and will compare using Struct#eql?):
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe    = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe_jr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe.hash == joe_jr.hash # => true
 *    joe_jr[:name] = 'Joe Smith, Jr.'
 *    joe.hash == joe_jr.hash # => false
 *
 *  Related: Object#hash.
 */

static VALUE
rb_struct_hash(VALUE s)
{
    long i, len;
    st_index_t h;
    VALUE n;

    h = rb_hash_start(rb_hash(rb_obj_class(s)));
    len = RSTRUCT_LEN(s);
    for (i = 0; i < len; i++) {
        n = rb_hash(RSTRUCT_GET(s, i));
        h = rb_hash_uint(h, NUM2LONG(n));
    }
    h = rb_hash_end(h);
    return ST2FIX(h);
}

static VALUE
recursive_eql(VALUE s, VALUE s2, int recur)
{
    long i, len;

    if (recur) return Qtrue; /* Subtle! */
    len = RSTRUCT_LEN(s);
    for (i=0; i<len; i++) {
        if (!rb_eql(RSTRUCT_GET(s, i), RSTRUCT_GET(s2, i))) return Qfalse;
    }
    return Qtrue;
}

/*
 * call-seq:
 *   eql?(other) -> true or false
 *
 *  Returns +true+ if and only if the following are true; otherwise returns +false+:
 *
 *  - <tt>other.class == self.class</tt>.
 *  - For each member name +name+, <tt>other.name.eql?(self.name)</tt>.
 *
 *     Customer = Struct.new(:name, :address, :zip)
 *     joe    = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe_jr = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *     joe_jr.eql?(joe) # => true
 *     joe_jr[:name] = 'Joe Smith, Jr.'
 *     joe_jr.eql?(joe) # => false
 *
 *  Related: Object#==.
 */

static VALUE
rb_struct_eql(VALUE s, VALUE s2)
{
    if (s == s2) return Qtrue;
    if (!RB_TYPE_P(s2, T_STRUCT)) return Qfalse;
    if (rb_obj_class(s) != rb_obj_class(s2)) return Qfalse;
    if (RSTRUCT_LEN(s) != RSTRUCT_LEN(s2)) {
        rb_bug("inconsistent struct"); /* should never happen */
    }

    return rb_exec_recursive_paired(recursive_eql, s, s2, s2);
}

/*
 *  call-seq:
 *    size -> integer
 *
 *  Returns the number of members.
 *
 *    Customer = Struct.new(:name, :address, :zip)
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe.size #=> 3
 *
 *  Struct#length is an alias for Struct#size.
 */

VALUE
rb_struct_size(VALUE s)
{
    return LONG2FIX(RSTRUCT_LEN(s));
}

/*
 * call-seq:
 *   dig(name, *identifiers) -> object
 *   dig(n, *identifiers) -> object
 *
 *  Finds and returns an object among nested objects.
 *  The nested objects may be instances of various classes.
 *  See {Dig Methods}[rdoc-ref:dig_methods.rdoc].
 *
 *
 *  Given symbol or string argument +name+,
 *  returns the object that is specified by +name+ and +identifiers+:
 *
 *   Foo = Struct.new(:a)
 *   f = Foo.new(Foo.new({b: [1, 2, 3]}))
 *   f.dig(:a) # => #<struct Foo a={:b=>[1, 2, 3]}>
 *   f.dig(:a, :a) # => {:b=>[1, 2, 3]}
 *   f.dig(:a, :a, :b) # => [1, 2, 3]
 *   f.dig(:a, :a, :b, 0) # => 1
 *   f.dig(:b, 0) # => nil
 *
 *  Given integer argument +n+,
 *  returns the object that is specified by +n+ and +identifiers+:
 *
 *   f.dig(0) # => #<struct Foo a={:b=>[1, 2, 3]}>
 *   f.dig(0, 0) # => {:b=>[1, 2, 3]}
 *   f.dig(0, 0, :b) # => [1, 2, 3]
 *   f.dig(0, 0, :b, 0) # => 1
 *   f.dig(:b, 0) # => nil
 *
 */

static VALUE
rb_struct_dig(int argc, VALUE *argv, VALUE self)
{
    rb_check_arity(argc, 1, UNLIMITED_ARGUMENTS);
    self = rb_struct_lookup(self, *argv);
    if (!--argc) return self;
    ++argv;
    return rb_obj_dig(argc, argv, self, Qnil);
}

/*
 *  Document-class: Struct
 *
 *  \Class \Struct provides a convenient way to create a simple class
 *  that can store and fetch values.
 *
 *  This example creates a subclass of +Struct+, <tt>Struct::Customer</tt>;
 *  the first argument, a string, is the name of the subclass;
 *  the other arguments, symbols, determine the _members_ of the new subclass.
 *
 *    Customer = Struct.new('Customer', :name, :address, :zip)
 *    Customer.name       # => "Struct::Customer"
 *    Customer.class      # => Class
 *    Customer.superclass # => Struct
 *
 *  Corresponding to each member are two methods, a writer and a reader,
 *  that store and fetch values:
 *
 *    methods = Customer.instance_methods false
 *    methods # => [:zip, :address=, :zip=, :address, :name, :name=]
 *
 *  An instance of the subclass may be created,
 *  and its members assigned values, via method <tt>::new</tt>:
 *
 *    joe = Customer.new("Joe Smith", "123 Maple, Anytown NC", 12345)
 *    joe # => #<struct Struct::Customer name="Joe Smith", address="123 Maple, Anytown NC", zip=12345>
 *
 *  The member values may be managed thus:
 *
 *    joe.name    # => "Joe Smith"
 *    joe.name = 'Joseph Smith'
 *    joe.name    # => "Joseph Smith"
 *
 *  And thus; note that member name may be expressed as either a string or a symbol:
 *
 *    joe[:name]  # => "Joseph Smith"
 *    joe[:name] = 'Joseph Smith, Jr.'
 *    joe['name'] # => "Joseph Smith, Jr."
 *
 *  See Struct::new.
 *
 *  == What's Here
 *
 *  First, what's elsewhere. \Class \Struct:
 *
 *  - Inherits from {class Object}[rdoc-ref:Object@What-27s+Here].
 *  - Includes {module Enumerable}[rdoc-ref:Enumerable@What-27s+Here],
 *    which provides dozens of additional methods.
 *
 *  Here, class \Struct provides methods that are useful for:
 *
 *  - {Creating a Struct Subclass}[rdoc-ref:Struct@Methods+for+Creating+a+Struct+Subclass]
 *  - {Querying}[rdoc-ref:Struct@Methods+for+Querying]
 *  - {Comparing}[rdoc-ref:Struct@Methods+for+Comparing]
 *  - {Fetching}[rdoc-ref:Struct@Methods+for+Fetching]
 *  - {Assigning}[rdoc-ref:Struct@Methods+for+Assigning]
 *  - {Iterating}[rdoc-ref:Struct@Methods+for+Iterating]
 *  - {Converting}[rdoc-ref:Struct@Methods+for+Converting]
 *
 *  === Methods for Creating a Struct Subclass
 *
 *  - ::new: Returns a new subclass of \Struct.
 *
 *  === Methods for Querying
 *
 *  - #hash: Returns the integer hash code.
 *  - #length, #size: Returns the number of members.
 *
 *  === Methods for Comparing
 *
 *  - #==: Returns whether a given object is equal to +self+, using <tt>==</tt>
 *    to compare member values.
 *  - #eql?: Returns whether a given object is equal to +self+,
 *    using <tt>eql?</tt> to compare member values.
 *
 *  === Methods for Fetching
 *
 *  - #[]: Returns the value associated with a given member name.
 *  - #to_a, #values, #deconstruct: Returns the member values in +self+ as an array.
 *  - #deconstruct_keys: Returns a hash of the name/value pairs
 *    for given member names.
 *  - #dig: Returns the object in nested objects that is specified
 *    by a given member name and additional arguments.
 *  - #members: Returns an array of the member names.
 *  - #select, #filter: Returns an array of member values from +self+,
 *    as selected by the given block.
 *  - #values_at: Returns an array containing values for given member names.
 *
 *  === Methods for Assigning
 *
 *  - #[]=: Assigns a given value to a given member name.
 *
 *  === Methods for Iterating
 *
 *  - #each: Calls a given block with each member name.
 *  - #each_pair: Calls a given block with each member name/value pair.
 *
 *  === Methods for Converting
 *
 *  - #inspect, #to_s: Returns a string representation of +self+.
 *  - #to_h: Returns a hash of the member name/value pairs in +self+.
 *
 */
void
InitVM_Struct(void)
{
    rb_cStruct = rb_define_class("Struct", rb_cObject);
    rb_include_module(rb_cStruct, rb_mEnumerable);

    rb_undef_alloc_func(rb_cStruct);
    rb_define_singleton_method(rb_cStruct, "new", rb_struct_s_def, -1);
#if 0 /* for RDoc */
    rb_define_singleton_method(rb_cStruct, "keyword_init?", rb_struct_s_keyword_init_p, 0);
    rb_define_singleton_method(rb_cStruct, "members", rb_struct_s_members_m, 0);
#endif

    rb_define_method(rb_cStruct, "initialize", rb_struct_initialize_m, -1);
    rb_define_method(rb_cStruct, "initialize_copy", rb_struct_init_copy, 1);

    rb_define_method(rb_cStruct, "==", rb_struct_equal, 1);
    rb_define_method(rb_cStruct, "eql?", rb_struct_eql, 1);
    rb_define_method(rb_cStruct, "hash", rb_struct_hash, 0);

    rb_define_method(rb_cStruct, "inspect", rb_struct_inspect, 0);
    rb_define_alias(rb_cStruct,  "to_s", "inspect");
    rb_define_method(rb_cStruct, "to_a", rb_struct_to_a, 0);
    rb_define_method(rb_cStruct, "to_h", rb_struct_to_h, 0);
    rb_define_method(rb_cStruct, "values", rb_struct_to_a, 0);
    rb_define_method(rb_cStruct, "size", rb_struct_size, 0);
    rb_define_method(rb_cStruct, "length", rb_struct_size, 0);

    rb_define_method(rb_cStruct, "each", rb_struct_each, 0);
    rb_define_method(rb_cStruct, "each_pair", rb_struct_each_pair, 0);
    rb_define_method(rb_cStruct, "[]", rb_struct_aref, 1);
    rb_define_method(rb_cStruct, "[]=", rb_struct_aset, 2);
    rb_define_method(rb_cStruct, "select", rb_struct_select, -1);
    rb_define_method(rb_cStruct, "filter", rb_struct_select, -1);
    rb_define_method(rb_cStruct, "values_at", rb_struct_values_at, -1);

    rb_define_method(rb_cStruct, "members", rb_struct_members_m, 0);
    rb_define_method(rb_cStruct, "dig", rb_struct_dig, -1);

    rb_define_method(rb_cStruct, "deconstruct", rb_struct_to_a, 0);
    rb_define_method(rb_cStruct, "deconstruct_keys", rb_struct_deconstruct_keys, 1);
}

#undef rb_intern
void
Init_Struct(void)
{
    id_members = rb_intern("__members__");
    id_back_members = rb_intern("__members_back__");
    id_keyword_init = rb_intern("__keyword_init__");

    InitVM(Struct);
}