summaryrefslogtreecommitdiff
path: root/class.c
blob: 76f4ef8622ed7ccfc9e395cba9af4b4307c10f2b (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
/**********************************************************************

  class.c -

  $Author$
  created at: Tue Aug 10 15:05:44 JST 1993

  Copyright (C) 1993-2007 Yukihiro Matsumoto

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

/*!
 * \defgroup class Classes and their hierarchy.
 * \par Terminology
 * - class: same as in Ruby.
 * - singleton class: class for a particular object
 * - eigenclass: = singleton class
 * - metaclass: class of a class. metaclass is a kind of singleton class.
 * - metametaclass: class of a metaclass.
 * - meta^(n)-class: class of a meta^(n-1)-class.
 * - attached object: A singleton class knows its unique instance.
 *   The instance is called the attached object for the singleton class.
 * \{
 */

#include "ruby/ruby.h"
#include "ruby/st.h"
#include "method.h"
#include "constant.h"
#include "vm_core.h"
#include <ctype.h>

extern st_table *rb_class_tbl;
static ID id_attached;

/**
 * Allocates a struct RClass for a new class.
 *
 * \param flags     initial value for basic.flags of the returned class.
 * \param klass     the class of the returned class.
 * \return          an uninitialized Class object.
 * \pre  \p klass must refer \c Class class or an ancestor of Class.
 * \pre  \code (flags | T_CLASS) != 0  \endcode
 * \post the returned class can safely be \c #initialize 'd.
 *
 * \note this function is not Class#allocate.
 */
static VALUE
class_alloc(VALUE flags, VALUE klass)
{
    rb_classext_t *ext = ALLOC(rb_classext_t);
    NEWOBJ(obj, struct RClass);
    OBJSETUP(obj, klass, flags);
    obj->ptr = ext;
    RCLASS_IV_TBL(obj) = 0;
    RCLASS_CONST_TBL(obj) = 0;
    RCLASS_M_TBL(obj) = 0;
    RCLASS_SUPER(obj) = 0;
    RCLASS_IV_INDEX_TBL(obj) = 0;
    return (VALUE)obj;
}


/*!
 * A utility function that wraps class_alloc.
 *
 * allocates a class and initializes safely.
 * \param super     a class from which the new class derives.
 * \return          a class object.
 * \pre  \a super must be a class.
 * \post the metaclass of the new class is Class.
 */
VALUE
rb_class_boot(VALUE super)
{
    VALUE klass = class_alloc(T_CLASS, rb_cClass);

    RCLASS_SUPER(klass) = super;
    RCLASS_M_TBL(klass) = st_init_numtable();

    OBJ_INFECT(klass, super);
    return (VALUE)klass;
}


/*!
 * Ensures a class can be derived from super.
 *
 * \param super a reference to an object.
 * \exception TypeError if \a super is not a Class or \a super is a singleton class.
 */
void
rb_check_inheritable(VALUE super)
{
    if (TYPE(super) != T_CLASS) {
	rb_raise(rb_eTypeError, "superclass must be a Class (%s given)",
		 rb_obj_classname(super));
    }
    if (RBASIC(super)->flags & FL_SINGLETON) {
	rb_raise(rb_eTypeError, "can't make subclass of singleton class");
    }
    if (super == rb_cClass) {
	rb_raise(rb_eTypeError, "can't make subclass of Class");
    }
}


/*!
 * Creates a new class.
 * \param super     a class from which the new class derives.
 * \exception TypeError \a super is not inheritable.
 * \exception TypeError \a super is the Class class.
 */
VALUE
rb_class_new(VALUE super)
{
    Check_Type(super, T_CLASS);
    rb_check_inheritable(super);
    return rb_class_boot(super);
}

struct clone_method_data {
    st_table *tbl;
    VALUE klass;
};

VALUE rb_iseq_clone(VALUE iseqval, VALUE newcbase);

static int
clone_method(ID mid, const rb_method_entry_t *me, struct clone_method_data *data)
{
    if (me->def && me->def->type == VM_METHOD_TYPE_ISEQ) {
	VALUE newiseqval = rb_iseq_clone(me->def->body.iseq->self, data->klass);
	rb_iseq_t *iseq;
	GetISeqPtr(newiseqval, iseq);
	rb_add_method(data->klass, mid, VM_METHOD_TYPE_ISEQ, iseq, me->flag);
    }
    else {
	rb_method_entry_set(data->klass, mid, me, me->flag);
    }
    return ST_CONTINUE;
}

static int
clone_const(ID key, const rb_const_entry_t *ce, st_table *tbl)
{
    rb_const_entry_t *nce = ALLOC(rb_const_entry_t);
    *nce = *ce;
    st_insert(tbl, key, (st_data_t)nce);
    return ST_CONTINUE;
}

/* :nodoc: */
VALUE
rb_mod_init_copy(VALUE clone, VALUE orig)
{
    rb_obj_init_copy(clone, orig);
    if (!FL_TEST(CLASS_OF(clone), FL_SINGLETON)) {
	RBASIC(clone)->klass = rb_singleton_class_clone(orig);
	rb_singleton_class_attached(RBASIC(clone)->klass, (VALUE)clone);
    }
    RCLASS_SUPER(clone) = RCLASS_SUPER(orig);
    if (RCLASS_IV_TBL(orig)) {
	st_data_t id;

	if (RCLASS_IV_TBL(clone)) {
	    st_free_table(RCLASS_IV_TBL(clone));
	}
	RCLASS_IV_TBL(clone) = st_copy(RCLASS_IV_TBL(orig));
	CONST_ID(id, "__classpath__");
	st_delete(RCLASS_IV_TBL(clone), &id, 0);
	CONST_ID(id, "__classid__");
	st_delete(RCLASS_IV_TBL(clone), &id, 0);
    }
    if (RCLASS_CONST_TBL(orig)) {
	if (RCLASS_CONST_TBL(clone)) {
	    rb_free_const_table(RCLASS_CONST_TBL(clone));
	}
	RCLASS_CONST_TBL(clone) = st_init_numtable();
	st_foreach(RCLASS_CONST_TBL(orig), clone_const, (st_data_t)RCLASS_CONST_TBL(clone));
    }
    if (RCLASS_M_TBL(orig)) {
	struct clone_method_data data;

	if (RCLASS_M_TBL(clone)) {
	    rb_free_m_table(RCLASS_M_TBL(clone));
	}
	data.tbl = RCLASS_M_TBL(clone) = st_init_numtable();
	data.klass = clone;
	st_foreach(RCLASS_M_TBL(orig), clone_method,
		   (st_data_t)&data);
    }

    return clone;
}

/* :nodoc: */
VALUE
rb_class_init_copy(VALUE clone, VALUE orig)
{
    if (orig == rb_cBasicObject) {
	rb_raise(rb_eTypeError, "can't copy the root class");
    }
    if (RCLASS_SUPER(clone) != 0 || clone == rb_cBasicObject) {
	rb_raise(rb_eTypeError, "already initialized class");
    }
    if (FL_TEST(orig, FL_SINGLETON)) {
	rb_raise(rb_eTypeError, "can't copy singleton class");
    }
    return rb_mod_init_copy(clone, orig);
}

VALUE
rb_singleton_class_clone(VALUE obj)
{
    VALUE klass = RBASIC(obj)->klass;

    if (!FL_TEST(klass, FL_SINGLETON))
	return klass;
    else {
	struct clone_method_data data;
	/* copy singleton(unnamed) class */
	VALUE clone = class_alloc((RBASIC(klass)->flags & ~(FL_MARK)), 0);

	if (BUILTIN_TYPE(obj) == T_CLASS) {
	    RBASIC(clone)->klass = (VALUE)clone;
	}
	else {
	    RBASIC(clone)->klass = rb_singleton_class_clone(klass);
	}

	RCLASS_SUPER(clone) = RCLASS_SUPER(klass);
	if (RCLASS_IV_TBL(klass)) {
	    RCLASS_IV_TBL(clone) = st_copy(RCLASS_IV_TBL(klass));
	}
	if (RCLASS_CONST_TBL(klass)) {
	    RCLASS_CONST_TBL(clone) = st_init_numtable();
	    st_foreach(RCLASS_CONST_TBL(klass), clone_const, (st_data_t)RCLASS_CONST_TBL(clone));
	}
	RCLASS_M_TBL(clone) = st_init_numtable();
	data.tbl = RCLASS_M_TBL(clone);
	data.klass = (VALUE)clone;
	st_foreach(RCLASS_M_TBL(klass), clone_method,
		   (st_data_t)&data);
	rb_singleton_class_attached(RBASIC(clone)->klass, (VALUE)clone);
	FL_SET(clone, FL_SINGLETON);
	return (VALUE)clone;
    }
}

/*!
 * Attach a object to a singleton class.
 * @pre \a klass is the singleton class of \a obj.
 */
void
rb_singleton_class_attached(VALUE klass, VALUE obj)
{
    if (FL_TEST(klass, FL_SINGLETON)) {
	if (!RCLASS_IV_TBL(klass)) {
	    RCLASS_IV_TBL(klass) = st_init_numtable();
	}
	st_insert(RCLASS_IV_TBL(klass), id_attached, obj);
    }
}



#define METACLASS_OF(k) RBASIC(k)->klass

/*!
 * whether k is a meta^(n)-class of Class class
 * @retval 1 if \a k is a meta^(n)-class of Class class (n >= 0)
 * @retval 0 otherwise
 */
#define META_CLASS_OF_CLASS_CLASS_P(k)  (METACLASS_OF(k) == (k))


/*!
 * ensures \a klass belongs to its own eigenclass.
 * @return the eigenclass of \a klass
 * @post \a klass belongs to the returned eigenclass.
 *       i.e. the attached object of the eigenclass is \a klass.
 * @note this macro creates a new eigenclass if necessary.
 */
#define ENSURE_EIGENCLASS(klass) \
 (rb_ivar_get(METACLASS_OF(klass), id_attached) == (klass) ? METACLASS_OF(klass) : make_metaclass(klass))


/*!
 * Creates a metaclass of \a klass
 * \param klass     a class
 * \return          created metaclass for the class
 * \pre \a klass is a Class object
 * \pre \a klass has no singleton class.
 * \post the class of \a klass is the returned class.
 * \post the returned class is meta^(n+1)-class when \a klass is a meta^(n)-klass for n >= 0
 */
static inline VALUE
make_metaclass(VALUE klass)
{
    VALUE super;
    VALUE metaclass = rb_class_boot(Qundef);

    FL_SET(metaclass, FL_SINGLETON);
    rb_singleton_class_attached(metaclass, klass);

    if (META_CLASS_OF_CLASS_CLASS_P(klass)) {
	METACLASS_OF(klass) = METACLASS_OF(metaclass) = metaclass;
    }
    else {
	VALUE tmp = METACLASS_OF(klass); /* for a meta^(n)-class klass, tmp is meta^(n)-class of Class class */
	METACLASS_OF(klass) = metaclass;
	METACLASS_OF(metaclass) = ENSURE_EIGENCLASS(tmp);
    }

    super = RCLASS_SUPER(klass);
    while (RB_TYPE_P(super, T_ICLASS)) super = RCLASS_SUPER(super);
    RCLASS_SUPER(metaclass) = super ? ENSURE_EIGENCLASS(super) : rb_cClass;

    OBJ_INFECT(metaclass, RCLASS_SUPER(metaclass));

    return metaclass;
}

/*!
 * Creates a singleton class for \a obj.
 * \pre \a obj must not a immediate nor a special const.
 * \pre \a obj must not a Class object.
 * \pre \a obj has no singleton class.
 */
static inline VALUE
make_singleton_class(VALUE obj)
{
    VALUE orig_class = RBASIC(obj)->klass;
    VALUE klass = rb_class_boot(orig_class);

    FL_SET(klass, FL_SINGLETON);
    RBASIC(obj)->klass = klass;
    rb_singleton_class_attached(klass, obj);

    METACLASS_OF(klass) = METACLASS_OF(rb_class_real(orig_class));
    return klass;
}


static VALUE
boot_defclass(const char *name, VALUE super)
{
    extern st_table *rb_class_tbl;
    VALUE obj = rb_class_boot(super);
    ID id = rb_intern(name);

    rb_name_class(obj, id);
    st_add_direct(rb_class_tbl, id, obj);
    rb_const_set((rb_cObject ? rb_cObject : obj), id, obj);
    return obj;
}

void
Init_class_hierarchy(void)
{
    id_attached = rb_intern("__attached__");

    rb_cBasicObject = boot_defclass("BasicObject", 0);
    rb_cObject = boot_defclass("Object", rb_cBasicObject);
    rb_cModule = boot_defclass("Module", rb_cObject);
    rb_cClass =  boot_defclass("Class",  rb_cModule);

    RBASIC(rb_cClass)->klass
	= RBASIC(rb_cModule)->klass
	= RBASIC(rb_cObject)->klass
	= RBASIC(rb_cBasicObject)->klass
	= rb_cClass;
}


/*!
 * \internal
 * Creates a new *singleton class* for an object.
 *
 * \pre \a obj has no singleton class.
 * \note DO NOT USE the function in an extension libraries. Use \ref rb_singleton_class.
 * \param obj     An object.
 * \param unused  ignored.
 * \return        The singleton class of the object.
 */
VALUE
rb_make_metaclass(VALUE obj, VALUE unused)
{
    if (BUILTIN_TYPE(obj) == T_CLASS) {
	return make_metaclass(obj);
    }
    else {
	return make_singleton_class(obj);
    }
}


/*!
 * Defines a new class.
 * \param id     ignored
 * \param super  A class from which the new class will derive. NULL means \c Object class.
 * \return       the created class
 * \throw TypeError if super is not a \c Class object.
 *
 * \note the returned class will not be associated with \a id.
 *       You must explicitly set a class name if necessary.
 */
VALUE
rb_define_class_id(ID id, VALUE super)
{
    VALUE klass;

    if (!super) super = rb_cObject;
    klass = rb_class_new(super);
    rb_make_metaclass(klass, RBASIC(super)->klass);

    return klass;
}


/*!
 * Calls Class#inherited.
 * \param super  A class which will be called #inherited.
 *               NULL means Object class.
 * \param klass  A Class object which derived from \a super
 * \return the value \c Class#inherited's returns
 * \pre Each of \a super and \a klass must be a \c Class object.
 */
VALUE
rb_class_inherited(VALUE super, VALUE klass)
{
    ID inherited;
    if (!super) super = rb_cObject;
    CONST_ID(inherited, "inherited");
    return rb_funcall(super, inherited, 1, klass);
}



/*!
 * Defines a top-level class.
 * \param name   name of the class
 * \param super  a class from which the new class will derive.
 *               NULL means \c Object class.
 * \return the created class
 * \throw TypeError if the constant name \a name is already taken but
 *                  the constant is not a \c Class.
 * \throw NameError if the class is already defined but the class can not
 *                  be reopened because its superclass is not \a super.
 * \post top-level constant named \a name refers the returned class.
 *
 * \note if a class named \a name is already defined and its superclass is
 *       \a super, the function just returns the defined class.
 */
VALUE
rb_define_class(const char *name, VALUE super)
{
    VALUE klass;
    ID id;

    id = rb_intern(name);
    if (rb_const_defined(rb_cObject, id)) {
	klass = rb_const_get(rb_cObject, id);
	if (TYPE(klass) != T_CLASS) {
	    rb_raise(rb_eTypeError, "%s is not a class", name);
	}
	if (rb_class_real(RCLASS_SUPER(klass)) != super) {
	    rb_raise(rb_eTypeError, "superclass mismatch for class %s", name);
	}
	return klass;
    }
    if (!super) {
	rb_warn("no super class for `%s', Object assumed", name);
    }
    klass = rb_define_class_id(id, super);
    st_add_direct(rb_class_tbl, id, klass);
    rb_name_class(klass, id);
    rb_const_set(rb_cObject, id, klass);
    rb_class_inherited(super, klass);

    return klass;
}


/*!
 * Defines a class under the namespace of \a outer.
 * \param outer  a class which contains the new class.
 * \param name   name of the new class
 * \param super  a class from which the new class will derive.
 *               NULL means \c Object class.
 * \return the created class
 * \throw TypeError if the constant name \a name is already taken but
 *                  the constant is not a \c Class.
 * \throw NameError if the class is already defined but the class can not
 *                  be reopened because its superclass is not \a super.
 * \post top-level constant named \a name refers the returned class.
 *
 * \note if a class named \a name is already defined and its superclass is
 *       \a super, the function just returns the defined class.
 */
VALUE
rb_define_class_under(VALUE outer, const char *name, VALUE super)
{
    return rb_define_class_id_under(outer, rb_intern(name), super);
}


/*!
 * Defines a class under the namespace of \a outer.
 * \param outer  a class which contains the new class.
 * \param id     name of the new class
 * \param super  a class from which the new class will derive.
 *               NULL means \c Object class.
 * \return the created class
 * \throw TypeError if the constant name \a name is already taken but
 *                  the constant is not a \c Class.
 * \throw NameError if the class is already defined but the class can not
 *                  be reopened because its superclass is not \a super.
 * \post top-level constant named \a name refers the returned class.
 *
 * \note if a class named \a name is already defined and its superclass is
 *       \a super, the function just returns the defined class.
 */
VALUE
rb_define_class_id_under(VALUE outer, ID id, VALUE super)
{
    VALUE klass;

    if (rb_const_defined_at(outer, id)) {
	klass = rb_const_get_at(outer, id);
	if (TYPE(klass) != T_CLASS) {
	    rb_raise(rb_eTypeError, "%s is not a class", rb_id2name(id));
	}
	if (rb_class_real(RCLASS_SUPER(klass)) != super) {
	    rb_name_error(id, "%s is already defined", rb_id2name(id));
	}
	return klass;
    }
    if (!super) {
	rb_warn("no super class for `%s::%s', Object assumed",
		rb_class2name(outer), rb_id2name(id));
    }
    klass = rb_define_class_id(id, super);
    rb_set_class_path_string(klass, outer, rb_id2str(id));
    rb_const_set(outer, id, klass);
    rb_class_inherited(super, klass);
    rb_gc_register_mark_object(klass);

    return klass;
}

VALUE
rb_module_new(void)
{
    VALUE mdl = class_alloc(T_MODULE, rb_cModule);

    RCLASS_M_TBL(mdl) = st_init_numtable();

    return (VALUE)mdl;
}

VALUE
rb_define_module_id(ID id)
{
    VALUE mdl;

    mdl = rb_module_new();
    rb_name_class(mdl, id);

    return mdl;
}

VALUE
rb_define_module(const char *name)
{
    VALUE module;
    ID id;

    id = rb_intern(name);
    if (rb_const_defined(rb_cObject, id)) {
	module = rb_const_get(rb_cObject, id);
	if (TYPE(module) == T_MODULE)
	    return module;
	rb_raise(rb_eTypeError, "%s is not a module", rb_obj_classname(module));
    }
    module = rb_define_module_id(id);
    st_add_direct(rb_class_tbl, id, module);
    rb_const_set(rb_cObject, id, module);

    return module;
}

VALUE
rb_define_module_under(VALUE outer, const char *name)
{
    return rb_define_module_id_under(outer, rb_intern(name));
}

VALUE
rb_define_module_id_under(VALUE outer, ID id)
{
    VALUE module;

    if (rb_const_defined_at(outer, id)) {
	module = rb_const_get_at(outer, id);
	if (TYPE(module) == T_MODULE)
	    return module;
	rb_raise(rb_eTypeError, "%s::%s is not a module",
		 rb_class2name(outer), rb_obj_classname(module));
    }
    module = rb_define_module_id(id);
    rb_const_set(outer, id, module);
    rb_set_class_path_string(module, outer, rb_id2str(id));
    rb_gc_register_mark_object(module);

    return module;
}

static VALUE
include_class_new(VALUE module, VALUE super)
{
    VALUE klass = class_alloc(T_ICLASS, rb_cClass);

    if (BUILTIN_TYPE(module) == T_ICLASS) {
	module = RBASIC(module)->klass;
    }
    if (!RCLASS_IV_TBL(module)) {
	RCLASS_IV_TBL(module) = st_init_numtable();
    }
    if (!RCLASS_CONST_TBL(module)) {
	RCLASS_CONST_TBL(module) = st_init_numtable();
    }
    RCLASS_IV_TBL(klass) = RCLASS_IV_TBL(module);
    RCLASS_CONST_TBL(klass) = RCLASS_CONST_TBL(module);
    RCLASS_M_TBL(klass) = RCLASS_M_TBL(module);
    RCLASS_SUPER(klass) = super;
    if (TYPE(module) == T_ICLASS) {
	RBASIC(klass)->klass = RBASIC(module)->klass;
    }
    else {
	RBASIC(klass)->klass = module;
    }
    OBJ_INFECT(klass, module);
    OBJ_INFECT(klass, super);

    return (VALUE)klass;
}

void
rb_include_module(VALUE klass, VALUE module)
{
    VALUE p, c;
    int changed = 0;

    rb_frozen_class_p(klass);
    if (!OBJ_UNTRUSTED(klass)) {
	rb_secure(4);
    }

    if (TYPE(module) != T_MODULE) {
	Check_Type(module, T_MODULE);
    }

    OBJ_INFECT(klass, module);
    c = klass;
    while (module) {
	int superclass_seen = FALSE;

	if (RCLASS_M_TBL(klass) == RCLASS_M_TBL(module))
	    rb_raise(rb_eArgError, "cyclic include detected");
	/* ignore if the module included already in superclasses */
	for (p = RCLASS_SUPER(klass); p; p = RCLASS_SUPER(p)) {
	    switch (BUILTIN_TYPE(p)) {
	      case T_ICLASS:
		if (RCLASS_M_TBL(p) == RCLASS_M_TBL(module)) {
		    if (!superclass_seen) {
			c = p;  /* move insertion point */
		    }
		    goto skip;
		}
		break;
	      case T_CLASS:
		superclass_seen = TRUE;
		break;
	    }
	}
	c = RCLASS_SUPER(c) = include_class_new(module, RCLASS_SUPER(c));
	if (RMODULE_M_TBL(module) && RMODULE_M_TBL(module)->num_entries)
	    changed = 1;
      skip:
	module = RCLASS_SUPER(module);
    }
    if (changed) rb_clear_cache();
}

/*
 *  call-seq:
 *     mod.included_modules -> array
 *
 *  Returns the list of modules included in <i>mod</i>.
 *
 *     module Mixin
 *     end
 *
 *     module Outer
 *       include Mixin
 *     end
 *
 *     Mixin.included_modules   #=> []
 *     Outer.included_modules   #=> [Mixin]
 */

VALUE
rb_mod_included_modules(VALUE mod)
{
    VALUE ary = rb_ary_new();
    VALUE p;

    for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
	if (BUILTIN_TYPE(p) == T_ICLASS) {
	    rb_ary_push(ary, RBASIC(p)->klass);
	}
    }
    return ary;
}

/*
 *  call-seq:
 *     mod.include?(module)    -> true or false
 *
 *  Returns <code>true</code> if <i>module</i> is included in
 *  <i>mod</i> or one of <i>mod</i>'s ancestors.
 *
 *     module A
 *     end
 *     class B
 *       include A
 *     end
 *     class C < B
 *     end
 *     B.include?(A)   #=> true
 *     C.include?(A)   #=> true
 *     A.include?(A)   #=> false
 */

VALUE
rb_mod_include_p(VALUE mod, VALUE mod2)
{
    VALUE p;

    Check_Type(mod2, T_MODULE);
    for (p = RCLASS_SUPER(mod); p; p = RCLASS_SUPER(p)) {
	if (BUILTIN_TYPE(p) == T_ICLASS) {
	    if (RBASIC(p)->klass == mod2) return Qtrue;
	}
    }
    return Qfalse;
}

/*
 *  call-seq:
 *     mod.ancestors -> array
 *
 *  Returns a list of modules included in <i>mod</i> (including
 *  <i>mod</i> itself).
 *
 *     module Mod
 *       include Math
 *       include Comparable
 *     end
 *
 *     Mod.ancestors    #=> [Mod, Comparable, Math]
 *     Math.ancestors   #=> [Math]
 */

VALUE
rb_mod_ancestors(VALUE mod)
{
    VALUE p, ary = rb_ary_new();

    for (p = mod; p; p = RCLASS_SUPER(p)) {
	if (FL_TEST(p, FL_SINGLETON))
	    continue;
	if (BUILTIN_TYPE(p) == T_ICLASS) {
	    rb_ary_push(ary, RBASIC(p)->klass);
	}
	else {
	    rb_ary_push(ary, p);
	}
    }
    return ary;
}

#define VISI(x) ((x)&NOEX_MASK)
#define VISI_CHECK(x,f) (VISI(x) == (f))

static int
ins_methods_push(ID name, long type, VALUE ary, long visi)
{
    if (type == -1) return ST_CONTINUE;

    switch (visi) {
      case NOEX_PRIVATE:
      case NOEX_PROTECTED:
      case NOEX_PUBLIC:
	visi = (type == visi);
	break;
      default:
	visi = (type != NOEX_PRIVATE);
	break;
    }
    if (visi) {
	rb_ary_push(ary, ID2SYM(name));
    }
    return ST_CONTINUE;
}

static int
ins_methods_i(ID name, long type, VALUE ary)
{
    return ins_methods_push(name, type, ary, -1); /* everything but private */
}

static int
ins_methods_prot_i(ID name, long type, VALUE ary)
{
    return ins_methods_push(name, type, ary, NOEX_PROTECTED);
}

static int
ins_methods_priv_i(ID name, long type, VALUE ary)
{
    return ins_methods_push(name, type, ary, NOEX_PRIVATE);
}

static int
ins_methods_pub_i(ID name, long type, VALUE ary)
{
    return ins_methods_push(name, type, ary, NOEX_PUBLIC);
}

static int
method_entry(ID key, const rb_method_entry_t *me, st_table *list)
{
    long type;

    if (key == ID_ALLOCATOR) {
	return ST_CONTINUE;
    }

    if (!st_lookup(list, key, 0)) {
	if (UNDEFINED_METHOD_ENTRY_P(me)) {
	    type = -1; /* none */
	}
	else {
	    type = VISI(me->flag);
	}
	st_add_direct(list, key, type);
    }
    return ST_CONTINUE;
}

static VALUE
class_instance_method_list(int argc, VALUE *argv, VALUE mod, int obj, int (*func) (ID, long, VALUE))
{
    VALUE ary;
    int recur;
    st_table *list;

    if (argc == 0) {
	recur = TRUE;
    }
    else {
	VALUE r;
	rb_scan_args(argc, argv, "01", &r);
	recur = RTEST(r);
    }

    list = st_init_numtable();
    for (; mod; mod = RCLASS_SUPER(mod)) {
	st_foreach(RCLASS_M_TBL(mod), method_entry, (st_data_t)list);
	if (BUILTIN_TYPE(mod) == T_ICLASS) continue;
	if (obj && FL_TEST(mod, FL_SINGLETON)) continue;
	if (!recur) break;
    }
    ary = rb_ary_new();
    st_foreach(list, func, ary);
    st_free_table(list);

    return ary;
}

/*
 *  call-seq:
 *     mod.instance_methods(include_super=true)   -> array
 *
 *  Returns an array containing the names of the public and protected instance
 *  methods in the receiver. For a module, these are the public and protected methods;
 *  for a class, they are the instance (not singleton) methods. With no
 *  argument, or with an argument that is <code>false</code>, the
 *  instance methods in <i>mod</i> are returned, otherwise the methods
 *  in <i>mod</i> and <i>mod</i>'s superclasses are returned.
 *
 *     module A
 *       def method1()  end
 *     end
 *     class B
 *       def method2()  end
 *     end
 *     class C < B
 *       def method3()  end
 *     end
 *
 *     A.instance_methods                #=> [:method1]
 *     B.instance_methods(false)         #=> [:method2]
 *     C.instance_methods(false)         #=> [:method3]
 *     C.instance_methods(true).length   #=> 43
 */

VALUE
rb_class_instance_methods(int argc, VALUE *argv, VALUE mod)
{
    return class_instance_method_list(argc, argv, mod, 0, ins_methods_i);
}

/*
 *  call-seq:
 *     mod.protected_instance_methods(include_super=true)   -> array
 *
 *  Returns a list of the protected instance methods defined in
 *  <i>mod</i>. If the optional parameter is not <code>false</code>, the
 *  methods of any ancestors are included.
 */

VALUE
rb_class_protected_instance_methods(int argc, VALUE *argv, VALUE mod)
{
    return class_instance_method_list(argc, argv, mod, 0, ins_methods_prot_i);
}

/*
 *  call-seq:
 *     mod.private_instance_methods(include_super=true)    -> array
 *
 *  Returns a list of the private instance methods defined in
 *  <i>mod</i>. If the optional parameter is not <code>false</code>, the
 *  methods of any ancestors are included.
 *
 *     module Mod
 *       def method1()  end
 *       private :method1
 *       def method2()  end
 *     end
 *     Mod.instance_methods           #=> [:method2]
 *     Mod.private_instance_methods   #=> [:method1]
 */

VALUE
rb_class_private_instance_methods(int argc, VALUE *argv, VALUE mod)
{
    return class_instance_method_list(argc, argv, mod, 0, ins_methods_priv_i);
}

/*
 *  call-seq:
 *     mod.public_instance_methods(include_super=true)   -> array
 *
 *  Returns a list of the public instance methods defined in <i>mod</i>.
 *  If the optional parameter is not <code>false</code>, the methods of
 *  any ancestors are included.
 */

VALUE
rb_class_public_instance_methods(int argc, VALUE *argv, VALUE mod)
{
    return class_instance_method_list(argc, argv, mod, 0, ins_methods_pub_i);
}

/*
 *  call-seq:
 *     obj.methods    -> array
 *
 *  Returns a list of the names of public and protected methods of
 *  <i>obj</i>. This will include all the methods accessible in
 *  <i>obj</i>'s ancestors.
 *
 *     class Klass
 *       def kMethod()
 *       end
 *     end
 *     k = Klass.new
 *     k.methods[0..9]    #=> [:kMethod, :freeze, :nil?, :is_a?,
 *                        #    :class, :instance_variable_set,
 *                        #    :methods, :extend, :__send__, :instance_eval]
 *     k.methods.length   #=> 42
 */

VALUE
rb_obj_methods(int argc, VALUE *argv, VALUE obj)
{
  retry:
    if (argc == 0) {
	VALUE args[1];

	args[0] = Qtrue;
	return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_i);
    }
    else {
	VALUE recur;

	rb_scan_args(argc, argv, "1", &recur);
	if (RTEST(recur)) {
	    argc = 0;
	    goto retry;
	}
	return rb_obj_singleton_methods(argc, argv, obj);
    }
}

/*
 *  call-seq:
 *     obj.protected_methods(all=true)   -> array
 *
 *  Returns the list of protected methods accessible to <i>obj</i>. If
 *  the <i>all</i> parameter is set to <code>false</code>, only those methods
 *  in the receiver will be listed.
 */

VALUE
rb_obj_protected_methods(int argc, VALUE *argv, VALUE obj)
{
    return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_prot_i);
}

/*
 *  call-seq:
 *     obj.private_methods(all=true)   -> array
 *
 *  Returns the list of private methods accessible to <i>obj</i>. If
 *  the <i>all</i> parameter is set to <code>false</code>, only those methods
 *  in the receiver will be listed.
 */

VALUE
rb_obj_private_methods(int argc, VALUE *argv, VALUE obj)
{
    return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_priv_i);
}

/*
 *  call-seq:
 *     obj.public_methods(all=true)   -> array
 *
 *  Returns the list of public methods accessible to <i>obj</i>. If
 *  the <i>all</i> parameter is set to <code>false</code>, only those methods
 *  in the receiver will be listed.
 */

VALUE
rb_obj_public_methods(int argc, VALUE *argv, VALUE obj)
{
    return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_pub_i);
}

/*
 *  call-seq:
 *     obj.singleton_methods(all=true)    -> array
 *
 *  Returns an array of the names of singleton methods for <i>obj</i>.
 *  If the optional <i>all</i> parameter is true, the list will include
 *  methods in modules included in <i>obj</i>.
 *  Only public and protected singleton methods are returned.
 *
 *     module Other
 *       def three() end
 *     end
 *
 *     class Single
 *       def Single.four() end
 *     end
 *
 *     a = Single.new
 *
 *     def a.one()
 *     end
 *
 *     class << a
 *       include Other
 *       def two()
 *       end
 *     end
 *
 *     Single.singleton_methods    #=> [:four]
 *     a.singleton_methods(false)  #=> [:two, :one]
 *     a.singleton_methods         #=> [:two, :one, :three]
 */

VALUE
rb_obj_singleton_methods(int argc, VALUE *argv, VALUE obj)
{
    VALUE recur, ary, klass;
    st_table *list;

    if (argc == 0) {
	recur = Qtrue;
    }
    else {
	rb_scan_args(argc, argv, "01", &recur);
    }
    klass = CLASS_OF(obj);
    list = st_init_numtable();
    if (klass && FL_TEST(klass, FL_SINGLETON)) {
	st_foreach(RCLASS_M_TBL(klass), method_entry, (st_data_t)list);
	klass = RCLASS_SUPER(klass);
    }
    if (RTEST(recur)) {
	while (klass && (FL_TEST(klass, FL_SINGLETON) || TYPE(klass) == T_ICLASS)) {
	    st_foreach(RCLASS_M_TBL(klass), method_entry, (st_data_t)list);
	    klass = RCLASS_SUPER(klass);
	}
    }
    ary = rb_ary_new();
    st_foreach(list, ins_methods_i, ary);
    st_free_table(list);

    return ary;
}

/*!
 * \}
 */
/*!
 * \defgroup defmethod Defining methods
 * There are some APIs to define a method from C.
 * These API takes a C function as a method body.
 *
 * \par Method body functions
 * Method body functions must return a VALUE and
 * can be one of the following form:
 * <dl>
 * <dt>Fixed number of parameters</dt>
 * <dd>
 *     This form is a normal C function, excepting it takes
 *     a receiver object as the first argument.
 *
 *     \code
 *     static VALUE my_method(VALUE self, VALUE x, VALUE y);
 *     \endcode
 * </dd>
 * <dt>argc and argv style</dt>
 * <dd>
 *     This form takes three parameters: \a argc, \a argv and \a self.
 *     \a self is the receiver. \a argc is the number of arguments.
 *     \a argv is a pointer to an array of the arguments.
 *
 *     \code
 *     static VALUE my_method(int argc, VALUE *argv, VALUE self);
 *     \endcode
 * </dd>
 * <dt>Ruby array style</dt>
 * <dd>
 *     This form takes two parameters: self and args.
 *     \a self is the receiver. \a args is an Array object which
 *     contains the arguments.
 *
 *     \code
 *     static VALUE my_method(VALUE self, VALUE args);
 *     \endcode
 * </dd>
 *
 * \par Number of parameters
 * Method defining APIs takes the number of parameters which the
 * method will takes. This number is called \a argc.
 * \a argc can be:
 * <dl>
 * <dt>zero or positive number</dt>
 * <dd>This means the method body function takes a fixed number of parameters</dd>
 * <dt>-1</dt>
 * <dd>This means the method body function is "argc and argv" style.</dd>
 * <dt>-2</dt>
 * <dd>This means the method body function is "self and args" style.</dd>
 * </dl>
 * \{
 */

void
rb_define_method_id(VALUE klass, ID mid, VALUE (*func)(ANYARGS), int argc)
{
    rb_add_method_cfunc(klass, mid, func, argc, NOEX_PUBLIC);
}

void
rb_define_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
{
    rb_add_method_cfunc(klass, rb_intern(name), func, argc, NOEX_PUBLIC);
}

void
rb_define_protected_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
{
    rb_add_method_cfunc(klass, rb_intern(name), func, argc, NOEX_PROTECTED);
}

void
rb_define_private_method(VALUE klass, const char *name, VALUE (*func)(ANYARGS), int argc)
{
    rb_add_method_cfunc(klass, rb_intern(name), func, argc, NOEX_PRIVATE);
}

void
rb_undef_method(VALUE klass, const char *name)
{
    rb_add_method(klass, rb_intern(name), VM_METHOD_TYPE_UNDEF, 0, NOEX_UNDEF);
}

/*!
 * \}
 */
/*!
 * \addtogroup class
 * \{
 */

#define SPECIAL_SINGLETON(x,c) do {\
    if (obj == (x)) {\
	return (c);\
    }\
} while (0)


/*!
 * \internal
 * Returns the singleton class of \a obj. Creates it if necessary.
 *
 * \note DO NOT expose the returned singleton class to
 *       outside of class.c.
 *       Use \ref rb_singleton_class instead for
 *       consistency of the metaclass hierarchy.
 */
static VALUE
singleton_class_of(VALUE obj)
{
    VALUE klass;

    if (FIXNUM_P(obj) || SYMBOL_P(obj)) {
	rb_raise(rb_eTypeError, "can't define singleton");
    }
    if (rb_special_const_p(obj)) {
	SPECIAL_SINGLETON(Qnil, rb_cNilClass);
	SPECIAL_SINGLETON(Qfalse, rb_cFalseClass);
	SPECIAL_SINGLETON(Qtrue, rb_cTrueClass);
	rb_bug("unknown immediate %p", (void *)obj);
    }

    if (FL_TEST(RBASIC(obj)->klass, FL_SINGLETON) &&
	rb_ivar_get(RBASIC(obj)->klass, id_attached) == obj) {
	klass = RBASIC(obj)->klass;
    }
    else {
	klass = rb_make_metaclass(obj, RBASIC(obj)->klass);
    }

    if (OBJ_TAINTED(obj)) {
	OBJ_TAINT(klass);
    }
    else {
	FL_UNSET(klass, FL_TAINT);
    }
    if (OBJ_UNTRUSTED(obj)) {
	OBJ_UNTRUST(klass);
    }
    else {
	FL_UNSET(klass, FL_UNTRUSTED);
    }
    if (OBJ_FROZEN(obj)) OBJ_FREEZE(klass);

    return klass;
}


/*!
 * Returns the singleton class of \a obj. Creates it if necessary.
 *
 * \param obj an arbitrary object.
 * \throw TypeError if \a obj is a Fixnum or a Symbol.
 * \return the singleton class.
 *
 * \post \a obj has its own singleton class.
 * \post if \a obj is a class,
 *       the returned singleton class also has its own
 *       singleton class in order to keep consistency of the
 *       inheritance structure of metaclasses.
 * \note a new singleton class will be created
 *       if \a obj does not have it.
 * \note the singleton classes for nil, true and false are:
 *       NilClass, TrueClass and FalseClass.
 */
VALUE
rb_singleton_class(VALUE obj)
{
    VALUE klass = singleton_class_of(obj);

    /* ensures an exposed class belongs to its own eigenclass */
    if (TYPE(obj) == T_CLASS) (void)ENSURE_EIGENCLASS(klass);

    return klass;
}

/*!
 * \}
 */

/*!
 * \addtogroup defmethod
 * \{
 */

/*!
 * Defines a singleton method for \a obj.
 * \param obj    an arbitrary object
 * \param name   name of the singleton method
 * \param func   the method body
 * \param argc   the number of parameters, or -1 or -2. see \ref defmethod.
 */
void
rb_define_singleton_method(VALUE obj, const char *name, VALUE (*func)(ANYARGS), int argc)
{
    rb_define_method(singleton_class_of(obj), name, func, argc);
}



/*!
 * Defines a module function for \a module.
 * \param module  an module or a class.
 * \param name    name of the function
 * \param func    the method body
 * \param argc    the number of parameters, or -1 or -2. see \ref defmethod.
 */
void
rb_define_module_function(VALUE module, const char *name, VALUE (*func)(ANYARGS), int argc)
{
    rb_define_private_method(module, name, func, argc);
    rb_define_singleton_method(module, name, func, argc);
}


/*!
 * Defines a global function
 * \param name    name of the function
 * \param func    the method body
 * \param argc    the number of parameters, or -1 or -2. see \ref defmethod.
 */
void
rb_define_global_function(const char *name, VALUE (*func)(ANYARGS), int argc)
{
    rb_define_module_function(rb_mKernel, name, func, argc);
}


/*!
 * Defines an alias of a method.
 * \param klass  the class which the original method belongs to
 * \param name1  a new name for the method
 * \param name2  the original name of the method
 */
void
rb_define_alias(VALUE klass, const char *name1, const char *name2)
{
    rb_alias(klass, rb_intern(name1), rb_intern(name2));
}

/*!
 * Defines (a) public accessor method(s) for an attribute.
 * \param klass  the class which the attribute will belongs to
 * \param name   name of the attribute
 * \param read   a getter method for the attribute will be defined if \a read is non-zero.
 * \param write  a setter method for the attribute will be defined if \a write is non-zero.
 */
void
rb_define_attr(VALUE klass, const char *name, int read, int write)
{
    rb_attr(klass, rb_intern(name), read, write, FALSE);
}

int
rb_obj_basic_to_s_p(VALUE obj)
{
    const rb_method_entry_t *me = rb_method_entry(CLASS_OF(obj), rb_intern("to_s"));
    if (me && me->def && me->def->type == VM_METHOD_TYPE_CFUNC &&
	me->def->body.cfunc.func == rb_any_to_s)
	return 1;
    return 0;
}

#include <stdarg.h>

int
rb_scan_args(int argc, const VALUE *argv, const char *fmt, ...)
{
    int i;
    const char *p = fmt;
    VALUE *var;
    va_list vargs;
    int f_var = 0, f_hash = 0, f_block = 0;
    int n_lead = 0, n_opt = 0, n_trail = 0, n_mand;
    int argi = 0;
    VALUE hash = Qnil;

    if (ISDIGIT(*p)) {
	n_lead = *p - '0';
	p++;
	if (ISDIGIT(*p)) {
	    n_opt = *p - '0';
	    p++;
	    if (ISDIGIT(*p)) {
		n_trail = *p - '0';
		p++;
		goto block_arg;
	    }
	}
    }
    if (*p == '*') {
	f_var = 1;
	p++;
	if (ISDIGIT(*p)) {
	    n_trail = *p - '0';
	    p++;
	}
    }
  block_arg:
    if (*p == ':') {
	f_hash = 1;
	p++;
    }
    if (*p == '&') {
	f_block = 1;
	p++;
    }
    if (*p != '\0') {
	rb_fatal("bad scan arg format: %s", fmt);
    }
    n_mand = n_lead + n_trail;

    if (argc < n_mand)
	goto argc_error;

    va_start(vargs, fmt);

    /* capture an option hash - phase 1: pop */
    if (f_hash && n_mand < argc) {
	VALUE last = argv[argc - 1];

	if (NIL_P(last)) {
	    /* nil is taken as an empty option hash only if it is not
	       ambiguous; i.e. '*' is not specified and arguments are
	       given more than sufficient */
	    if (!f_var && n_mand + n_opt < argc)
		argc--;
	}
	else {
	    hash = rb_check_convert_type(last, T_HASH, "Hash", "to_hash");
	    if (!NIL_P(hash))
		argc--;
	}
    }
    /* capture leading mandatory arguments */
    for (i = n_lead; i-- > 0; ) {
	var = va_arg(vargs, VALUE *);
	if (var) *var = argv[argi];
	argi++;
    }
    /* capture optional arguments */
    for (i = n_opt; i-- > 0; ) {
	var = va_arg(vargs, VALUE *);
	if (argi < argc - n_trail) {
	    if (var) *var = argv[argi];
	    argi++;
	}
	else {
	    if (var) *var = Qnil;
	}
    }
    /* capture variable length arguments */
    if (f_var) {
	int n_var = argc - argi - n_trail;

	var = va_arg(vargs, VALUE *);
	if (0 < n_var) {
	    if (var) *var = rb_ary_new4(n_var, &argv[argi]);
	    argi += n_var;
	}
	else {
	    if (var) *var = rb_ary_new();
	}
    }
    /* capture trailing mandatory arguments */
    for (i = n_trail; i-- > 0; ) {
	var = va_arg(vargs, VALUE *);
	if (var) *var = argv[argi];
	argi++;
    }
    /* capture an option hash - phase 2: assignment */
    if (f_hash) {
	var = va_arg(vargs, VALUE *);
	if (var) *var = hash;
    }
    /* capture iterator block */
    if (f_block) {
	var = va_arg(vargs, VALUE *);
	if (rb_block_given_p()) {
	    *var = rb_block_proc();
	}
	else {
	    *var = Qnil;
	}
    }
    va_end(vargs);

    if (argi < argc)
	goto argc_error;

    return argc;

  argc_error:
    if (0 < n_opt)
	rb_raise(rb_eArgError, "wrong number of arguments (%d for %d..%d%s)",
		 argc, n_mand, n_mand + n_opt, f_var ? "+" : "");
    else
	rb_raise(rb_eArgError, "wrong number of arguments (%d for %d%s)",
		 argc, n_mand, f_var ? "+" : "");
}

/*!
 * \}
 */