aboutsummaryrefslogtreecommitdiffstats
path: root/include/wchar.h
blob: 280bd0698f86465f560c5d7cfe547f0af578f67c (plain) (blame)
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
/**
 * slibc — Yet another C library
 * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef _WCHAR_H
#define _WCHAR_H
#include <slibc/version.h>
#include <slibc/features.h>
#ifndef __PORTABLE /* `wchar_t` is not portable. */



/**
 * `NULL`'s canonical header is <stddef.h>
 */
#ifndef NULL
# define NULL  ((void*)0)
#endif


#define __NEED_size_t
#define __NEED_wchar_t
#define __NEED_wint_t

#include <bits/types.h>


/**
 * End of a wide-character stream
 */
#ifndef WEOF
# if __WCHAR_BIT == __CHAR_BIT
#  define WEOF  -1
# elif __WCHAR_BIT == __SHORT_BIT
#  define WEOF  -1
# elif __WCHAR_BIT == __INT_BIT
#  define WEOF  -1
# elif __WCHAR_BIT == __LONG_BIT
#  define WEOF  -1L
# else
#  define WEOF  -1LL
# endif
#endif


/**
 * `wchar_t` version of `strlen`.
 * 
 * @param   str  The string.
 * @return       The number of `wchar_t`:s before the
 *               first NUL character.
 */
size_t wcslen(const wchar_t*)
  __GCC_ONLY(__attribute__((__nonnull__, __warn_unused_result__, __pure__)));

/**
 * `wchar_t` version of `strnlen`.
 * 
 * @param   str     The string.
 * @param   maxlen  The number of bytes to inspect, at most.
 * @return          The number of `wchar_t`:s before the
 *                  first NUL character. `maxlen` if no
 *                  NUL character was found.
 */
size_t wcsnlen(const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __pure__)));



/**
 * Override a memory segment with a repeated wide character.
 * 
 * @param   segment  The beginning of the memory segment.
 * @param   c        The wide character.
 * @param   size     The number of wide characters in the memory segment.
 * @return           `segment` is returned.
 */
wchar_t* wmemset(wchar_t*, wchar_t, size_t);

/**
 * Copy a memory segment to another, non-overlapping, segment.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   size     The number of wide characters to copy.
 * @return           `whither` is returned.
 */
wchar_t* wmemcpy(wchar_t* restrict, const wchar_t* restrict, size_t);

#if defined(__GNU_SOURCE)
/**
 * Copy a memory segment to another, non-overlapping, segment.
 * 
 * This is a GNU extension.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   size     The number of wide characters to copy.
 * @return           `whither + size` is returned.
 */
wchar_t* wmempcpy(wchar_t* restrict, const wchar_t* restrict, size_t);

/**
 * Copy a memory segment to another, possibly overlapping, segment.
 * 
 * This is a GNU extension.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   size     The number of wide characters to copy.
 * @return           `whither` is returned.
 */
wchar_t* wmemmove(wchar_t*, const wchar_t*, size_t);

# if defined(__SLIBC_SOURCE)
/**
 * Copy a memory segment to another, possibly overlapping, segment.
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   size     The number of wide characters to copy.
 * @return           `whither + size` is returned.
 */
wchar_t* wmempmove(wchar_t*, const wchar_t*, size_t);
# endif
#endif

#if defined(__SLIBC_SOURCE)
/**
 * Copy a memory segment to another, non-overlapping, segment,
 * but stop if a specific character is encountered.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   c        The character to stop at if encountered.
 * @param   size     The maximum number of wide characters to copy.
 * @return           `NULL` if `c` was not encountered, otherwise
 *                   the possition of `c` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied characters; the address of
 *                   one character passed the last written character.
 */
wchar_t* wmemccpy(wchar_t* restrict, const wchar_t* restrict, wchar_t, size_t);

/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * but stop if a specific character is encountered.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   c        The character to stop at if encountered.
 * @param   size     The maximum number of wide characters to copy.
 * @return           `NULL` if `c` was not encountered, otherwise
 *                   the possition of `c` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied characters; the address of
 *                   one character passed the last written character.
 */
wchar_t* wmemcmove(wchar_t*, const wchar_t*, wchar_t, size_t);
#endif

/**
 * Copy a memory segment to another, non-overlapping, segment,
 * stop when a NUL wide character is encountered.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @return           `whither` is returned.
 */
wchar_t* wcscpy(wchar_t* restrict, const wchar_t* restrict)
  __GCC_ONLY(__attribute__((__returns_nonnull__, __nonnull__)));

#if defined(__SLIBC_SOURCE) || defined(__GNU_SOURCE)
/**
 * Copy a memory segment to another, non-overlapping, segment,
 * stop when a NUL wide character is encountered.
 * 
 * This is a GNU-compliant slibc extension.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @return           `whither + wcslen(whence)` is returned.
 */
wchar_t* wcpcpy(wchar_t* restrict, const wchar_t* restrict)
  __GCC_ONLY(__attribute__((__returns_nonnull__, __nonnull__)));
#endif

#if defined(__SLIBC_SOURCE)
/**
 * Copy a memory segment to another, non-overlapping, segment,
 * stop when a NUL wide character or a specified wide character
 * is encountered.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   c        The stop character.
 * @return           `NULL` if `c` was not encountered, otherwise
 *                   the position of `c` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied characters; the address of
 *                   one character passed the last written non-NUL
 *                   character.
 */
wchar_t* wcsccpy(wchar_t* restrict, const wchar_t* restrict, wchar_t)
  __GCC_ONLY(__attribute__((__nonnull__)));

/**
 * Copy a memory segment to another, non-overlapping, segment,
 * stop when a NUL wide character or a specified substring is encountered.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   str      The substring, ignored if `NULL`.
 * @return           `NULL` if `str` was not encountered, otherwise
 *                   the position of `str` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied characters; the address of
 *                   one character passed the last written non-NUL
 *                   character.
 */
wchar_t* wcsstrcpy(wchar_t* restrict, const wchar_t* restrict, const wchar_t* restrict)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2))));
#endif

/**
 * Copy a memory segment to another, non-overlapping, segment,
 * stop when a NUL wide character is encountered.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `whither` is returned.
 */
wchar_t* wcsncpy(wchar_t* restrict, const wchar_t* restrict, size_t)
  __GCC_ONLY(__attribute__((__returns_nonnull__, __nonnull__)));

#if defined(__GNU_SOURCE)
/**
 * Copy a memory segment to another, non-overlapping, segment,
 * stop when a NUL wide character is encountered.
 * 
 * This is a GNU extension.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `whither` plus the number of written characters,
 *                   excluding NUL characters, is returned.
 */
wchar_t* wcpncpy(wchar_t* restrict, const wchar_t* restrict, size_t)
  __GCC_ONLY(__attribute__((__returns_nonnull__, __nonnull__)));

# if defined(__SLIBC_SOURCE)
/**
 * Copy a memory segment to another, non-overlapping, segment,
 * stop when a NUL wide character or a specified wide character
 * is encountered.
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   c        The stop character.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `NULL` if `c` was not encountered, otherwise
 *                   the position of `c` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied characters; the address of
 *                   one character passed the last written non-NUL
 *                   character.
 */
wchar_t* wcscncpy(wchar_t* restrict, const wchar_t* restrict, wchar_t, size_t)
  __GCC_ONLY(__attribute__((__nonnull__)));

/**
 * Copy a memory segment to another, non-overlapping, segment,
 * stop when a NUL wide character or a specified substring is encountered.
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   str      The substring, ignored if `NULL`.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `NULL` if `str` was not encountered, otherwise
 *                   the position of `str` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied chartacters; the address of
 *                   one character passed the last written non-NUL
 *                   character.
 */
wchar_t* wcsstrncpy(wchar_t* restrict, const wchar_t* restrict, const wchar_t* restrict, size_t)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2))));
# endif
#endif

#if defined(__SLIBC_SOURCE)
/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * stop when a NUL wide character is encountered.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @return           `whither` is returned.
 */
wchar_t* wcsmove(wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__returns_nonnull__, __nonnull__)));

/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * stop when a NUL wide character is encountered.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @return           `whither + wcslen(whence)` is returned.
 */
wchar_t* wcpmove(wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__returns_nonnull__, __nonnull__)));

/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * stop when a NUL wide character or a specified wide character
 * is encountered.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   c        The stop character.
 * @return           `NULL` if `c` was not encountered, otherwise
 *                   the position of `c` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied characters; the address of
 *                   one character passed the last written non-NUL
 *                   character.
 */
wchar_t* wcscmove(wchar_t*, const wchar_t*, wchar_t)
  __GCC_ONLY(__attribute__((__nonnull__)));

/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * stop when a NUL wide character or a specified substring is encountered.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   str      The substring, ignored if `NULL`.
 * @return           `NULL` if `str` was not encountered, otherwise
 *                   the position of `str` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied characters; the address of
 *                   one character passed the last written non-NUL
 *                   character.
 */
wchar_t* wcsstrmove(wchar_t*, const wchar_t*, const wchar_t* restrict)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2))));

/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * stop when a NUL wide character is encountered.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `whither` is returned.
 */
wchar_t* wcsnmove(wchar_t*, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__returns_nonnull__, __nonnull__)));

# if defined(__GNU_SOURCE)
/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * stop when a NUL wide character is encountered.
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `whither` plus the number of written characters,
 *                   excluding NUL characters, is returned.
 */
wchar_t* wcpnmove(wchar_t*, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__returns_nonnull__, __nonnull__)));

/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * stop when a NUL wide character or a specified wide character
 * is encountered.
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   c        The stop character.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `NULL` if `c` was not encountered, otherwise
 *                   the position of `c` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied characters; the address of
 *                   one character passed the last written non-NUL
 *                   character.
 */
wchar_t* wcscnmove(wchar_t*, const wchar_t*, wchar_t, size_t)
  __GCC_ONLY(__attribute__((__nonnull__)));

/**
 * Copy a memory segment to another, possibly overlapping, segment,
 * stop when a NUL wide character or a specified substring is encountered.
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * 
 * @param   whither  The destination memory segment.
 * @param   whence   The source memory segment.
 * @param   str      The substring, ignored if `NULL`.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `NULL` if `str` was not encountered, otherwise
 *                   the position of `str` translated to `whither`,
 *                   that is, the address of `whither` plus the
 *                   number of copied chartacters; the address of
 *                   one character passed the last written non-NUL
 *                   character.
 */
wchar_t* wcsstrnmove(wchar_t*, const wchar_t*, const wchar_t* restrict, size_t)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2))));
# endif
#endif

/**
 * Concatenate a string to the end of another string.
 * The resulting strings must not overlap with the appended string.
 * 
 * The use of this function is often a bad idea.
 * 
 * @param   whither  The string to extend.
 * @param   whence   The string to append.
 * @return           `whither` is returned.
 */
wchar_t* wcscat(wchar_t* restrict whither, const wchar_t* restrict whence)
  __GCC_ONLY(__attribute__((__nonnull__)));

/* wcpcat does not exsits because use of it would be very inefficient. */

/**
 * Concatenate a string to the end of another string.
 * The resulting strings must not overlap with the appended string.
 * 
 * The use of this function is often a really bad idea.
 * 
 * @param   whither  The string to extend.
 * @param   whence   The string to append.
 * @param   maxlen   The maximum number of wide characters to copy.
 *                   NOTE that if the resulting string at least this
 *                   long, no NUL character will be written to `whither'.
 *                   On the otherhand, if the resultnig string is
 *                   shorter, `whither` will be filled with NUL characters
 *                   until this amount of characters have been written.
 * @return           `whither` is returned.
 */
wchar_t* wcsncat(wchar_t* restrict whither, const wchar_t* restrict whence, size_t maxlen)
  __GCC_ONLY(__attribute__((__nonnull__)));

/* wcpncat does not exsits because use of it would be very inefficient. */


#if defined(__SLIBC_SOURCE) || defined(__GNU_SOURCE)
/**
 * Duplicate a string.
 * 
 * This is a GNU-compliant slibc extension.
 * 
 * @param   string  The string to duplicate.
 * @return          The new string. `NULL` is returned on error
 *                  and `errno` is set to indicate the error.
 * 
 * @throws  ENOMEM  The process could not allocate sufficient amount of memory.
 */
wchar_t* wcsdup(const wchar_t*)
  __GCC_ONLY(__attribute__((__malloc__, __nonnull__, __warn_unused_result__)));
#endif

#if defined(__SLIBC_SOURCE)
# if defined(__GNU_SOURCE)
/**
 * Duplicate a string.
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * 
 * @param   string  The string to duplicate.
 * @param   maxlen  Truncate the string to this length, if it is longer.
 *                  A NUL wide character is guaranteed to always be
 *                  written upon successful completion.
 * @return          The new string. `NULL` is returned on error
 *                  and `errno` is set to indicate the error.
 * 
 * @throws  ENOMEM  The process could not allocate sufficient amount of memory.
 */
wchar_t* wcsndup(const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__malloc__, __nonnull__, __warn_unused_result__)));
# endif

/**
 * Duplicate a memory segment.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   segment  The memory segment to duplicate.
 * @param   size     The size of the memory segment.
 * @return           The new segment. `NULL` is returned on error
 *                   and `errno` is set to indicate the error.
 * 
 * @throws  ENOMEM  The process could not allocate sufficient amount of memory.
 */
wchar_t* wmemdup(const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__malloc__, __nonnull__, __warn_unused_result__)));

# if defined(__GNUC__)
#  if defined(__GNU_SOURCE)
/**
 * Duplicate a string, using dymanic stack allocation (`alloca`).
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * This macro is only available when using GCC.
 * 
 * @param   string:const wchar_t*  The string to duplicate.
 * @return  :size_t                The new string. There is no way to
 *                                 detect whether the allocation failed.
 */
#   define wcsdupa(string)					\
  ({								\
    const char* __s = (string);					\
    size_t __n = wcslen(__s) + 1;				\
    wchar_t* __r = __builtin_alloca(__n * sizeof(char));	\
    wmemcpy(__r, __s, __n);					\
  })

/**
 * Duplicate a string, using dymanic stack allocation (`alloca`).
 * 
 * This is a slibc extension added for completeness.
 * It is only available if GNU extensions are available.
 * This macro is only available when using GCC.
 * 
 * @param   string:const wchar_t*  The string to duplicate.
 * @param   maxlen:size_t          Truncate the string to this length, if it is longer.
 *                                 A NUL byte is guaranteed to always be written.
 * @return  :size_t                The new string. There is no way to
 *                                 detect whether the allocation failed.
 */
#   define wstrndupa(string, maxlen)				\
  ({								\
    const char* __s = (string);					\
    size_t __n = wcsnlen(__s, (maxlen)) + 1;			\
    wchar_t* __r = __builtin_alloca(__n * sizeof(wchar_t));	\
    wmemcpy(__r, __s, __n);					\
  })
#  endif

/**
 * Duplicate a memory segment, using dymanic stack allocation (`alloca`).
 * 
 * This is a slibc extension added for completeness.
 * This macro is only available when using GCC.
 * 
 * @param   segment:const wchar_t*  The memory segment to duplicate.
 * @param   size:size_t             The size of the memory segment.
 * @return  :size_t                 The new segment. There is no way to
 *                                  detect whether the allocation failed.
 */
#  define wmemdupa(segment, size)				\
  ({								\
    size_t __n = (size);					\
    wchar_t* __r = __builtin_alloca(__n * sizeof(wchar_t));	\
    wmemcpy(__r, (segmetn), __n);				\
  })
# endif
#endif



/**
 * Compare two memory segments alphabetically in a case sensitive manner.
 * 
 * @param   a     A negative value is returned if this is the lesser.
 * @param   b     A positive value is returned if this is the lesser.
 * @param   size  The size of the segments.
 * @return        Zero is returned if `a` and `b` are equal, otherwise,
 *                see the specifications for `a` and `b`.
 */
int wmemcmp(const wchar_t*, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __pure__)));

#if defined(__SLIBC_SOURCE)
/**
 * Compare two memory segments alphabetically in a case insensitive manner.
 * 
 * This is a slibc extension added because it was useful
 * in implementing slibc itself.
 * 
 * @param   a     A negative value is returned if this is the lesser.
 * @param   b     A positive value is returned if this is the lesser.
 * @param   size  The size of the segments.
 * @return        Zero is returned if `a` and `b` are equal, otherwise,
 *                see the specifications for `a` and `b`.
 */
int wmemcasecmp(const wchar_t*, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __pure__)));
#endif

/**
 * Compare two strings alphabetically in a case sensitive manner.
 * 
 * @param   a  A negative value is returned if this is the lesser.
 * @param   b  A positive value is returned if this is the lesser.
 * @return     Zero is returned if `a` and `b` are equal, otherwise,
 *             see the specifications for `a` and `b`.
 */
int wcscmp(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));

#if defined(__GNU_SOURCE) || defined(__SLIBC_SOURCE)
/**
 * Compare two strings alphabetically in a case insensitive manner.
 * Be aware, only ASCII characters are case insensitive, non-ASCII
 * characters are case sensitive.
 * 
 * This is a GNU-compliant slibc extension.
 * 
 * @param   a  A negative value is returned if this is the lesser.
 * @param   b  A positive value is returned if this is the lesser.
 * @return     Zero is returned if `a` and `b` are equal, otherwise,
 *             see the specifications for `a` and `b`.
 */
int wcscasecmp(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));

/**
 * Compare two strings alphabetically in a case sensitive manner.
 * 
 * This is a GNU-compliant slibc extension.
 * 
 * @param   a       A negative value is returned if this is the lesser.
 * @param   b       A positive value is returned if this is the lesser.
 * @param   length  The maximum number of characters to compare.
 * @return          Zero is returned if `a` and `b` are equal, otherwise,
 *                  see the specifications for `a` and `b`.
 */
int wcsncmp(const wchar_t*, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));

/**
 * Compare two strings alphabetically in a case insensitive manner.
 * Be aware, only ASCII characters are case insensitive, non-ASCII
 * characters are case sensitive.
 * 
 * This is a GNU-compliant slibc extension.
 * 
 * @param   a       A negative value is returned if this is the lesser.
 * @param   b       A positive value is returned if this is the lesser.
 * @param   length  The maximum number of characters to compare.
 * @return          Zero is returned if `a` and `b` are equal, otherwise,
 *                  see the specifications for `a` and `b`.
 */
int wcsncasecmp(const wchar_t*, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
#endif


/**
 * Find the first occurrence of a wide character
 * in a memory segment.
 * 
 * @param   segment  The memory segment to search.
 * @param   c        The sought after character.
 * @param   size     The size of the memory segment.
 * @return           Pointer to the first occurrence of `c`,
 *                   `NULL` if none were found.
 */
wchar_t* wmemchr(const wchar_t*, wchar_t, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __pure__)));
#ifdef __CONST_CORRECT
# define wmemchr(...)  (__const_correct(wmemchr, __VA_ARGS__))
#endif

#if defined(__SLIBC_SOURCE)
/**
 * Find the first occurrence of a wide character in a
 * memory segment. The memory segment must be known to
 * contain the sought after character.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   segment  The memory segment to search.
 * @param   c        The sought after character.
 * @return           Pointer to the first occurrence of `c`.
 */
wchar_t* rawwmemchr(const wchar_t*, wchar_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __returns_nonnull__, __nonnull__, __pure__)));
#ifdef __CONST_CORRECT
# define rawwmemchr(...)  (__const_correct(rawwmemchr, __VA_ARGS__))
#endif

/**
 * Find the last occurrence of a wide character in
 * a memory segment.
 * 
 * For improved performace, use this function instead
 * of `wcssrchr` if you already know the length of the
 * string.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   segment  The memory segment to search.
 * @param   c        The sought after character.
 * @param   size     The size of the memory segment.
 * @return           Pointer to the last occurrence of `c`,
 *                   `NULL` if none were found.
 */
wchar_t* wmemrchr(const wchar_t*, wchar_t, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __pure__)));
# ifdef __CONST_CORRECT
#  define wmemrchr(...)  (__const_correct(wmemrchr, __VA_ARGS__))
# endif
#endif

/**
 * Find the first occurrence of a wide character in a string.
 * 
 * @param   string  The string to search.
 *                  The terminating NUL character is
 *                  considered a part of the string.
 * @param   c       The sought after character.
 * @return          Pointer to the first occurrence of `c`,
 *                  `NULL` if none were found.
 */
wchar_t* wcschr(const wchar_t*, wchar_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
#ifdef __CONST_CORRECT
# define wcschr(...)  (__const_correct(wcschr, __VA_ARGS__))
#endif

#if defined(__GNU_SOURCE)
/**
 * Find the first occurrence of a wide character in a
 * string, or if there is no such character, the end of
 * the string.
 * 
 * This is a GNU-compliant slibc extension.
 * 
 * @param   string  The string to search.
 *                  The terminating NUL character is
 *                  considered a part of the string.
 * @param   c       The sought after character.
 * @return          Pointer to the first occurrence of `c`,
 *                  Pointer to the terminating NUL character
 *                  if none were found.
 */
wchar_t* wcschrnul(const wchar_t*, wchar_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __returns_nonnull__, __nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define wcschrnul(...)  (__const_correct(wcschrnul, __VA_ARGS__))
# endif
#endif

/**
 * Find the last occurrence of a wide character in a string.
 * 
 * For improved performace, use `wmemrchr` instead of
 * this function if you already know the length of the
 * string.
 * 
 * @param   string  The string to search.
 *                  The terminating NUL character is
 *                  considered a part of the string.
 * @param   c       The sought after character.
 * @return          Pointer to the last occurrence of `c`,
 *                  `NULL` if none were found.
 */
wchar_t* wcsrchr(const wchar_t*, wchar_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
#ifdef __CONST_CORRECT
# define wcsrchr(...)  (__const_correct(wcsrchr, __VA_ARGS__))
#endif


/**
 * This function is identical to `wcsstr`.
 */
wchar_t* wcswcs(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)))
  __deprecated("Use 'wcsstr' instead.");
#ifdef __CONST_CORRECT
# define wcswcs(...)  (__const_correct(wcswcs, __VA_ARGS__))
#endif

/**
 * Finds the first occurrence of a substring.
 * This search is case sensitive.
 * 
 * @param   haystack  The string to search.
 * @param   needle    The sought after substring.
 * @return            Pointer to the first occurrence of the
 *                    substring, `NULL` if not found.
 */
wchar_t* wcsstr(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
#ifdef __CONST_CORRECT
# define wcsstr(...)  (__const_correct(wcsstr, __VA_ARGS__))
#endif

#if defined(__SLIBC_SOURCE)
/**
 * Finds the first occurrence of a substring.
 * This search is case insensitive.
 * 
 * This is a slibc extension.
 * 
 * @param   haystack  The string to search.
 * @param   needle    The sought after substring.
 * @return            Pointer to the first occurrence of the
 *                    substring, `NULL` if not found.
 */
wchar_t* wcscasestr(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define wcscasestr(...)  (__const_correct(wcscasestr, __VA_ARGS__))
# endif

/**
 * Finds the first occurrence of a substring.
 * This search is case sensitive.
 * 
 * This is a slibc extension added for because it was useful
 * in implementing slibc itself.
 * 
 * @param   haystack  The string to search.
 * @param   needle    The sought after substring.
 * @param   maxlen    The maximum number of character to search.
 * @return            Pointer to the first occurrence of the
 *                    substring, `NULL` if not found.
 */
wchar_t* wcsnstr(const wchar_t*, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define wcsnstr(...)  (__const_correct(wcsnstr, __VA_ARGS__))
# endif

/**
 * Finds the first occurrence of a substring.
 * This search is case insensitive.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   haystack  The string to search.
 * @param   needle    The sought after substring.
 * @param   maxlen    The maximum number of character to search.
 * @return            Pointer to the first occurrence of the
 *                    substring, `NULL` if not found.
 */
wchar_t* wcsncasestr(const wchar_t*, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define wcsncasestr(...)  (__const_correct(wcsncasestr, __VA_ARGS__))
# endif

/**
 * Finds the first occurrence of a substring.
 * This search is case sensitive.
 * It must already be known that such a substring exists.
 * 
 * This is a slibc extension.
 * 
 * @param   haystack  The string to search.
 * @param   needle    The sought after substring.
 * @return            Pointer to the first occurrence of the substring.
 */
wchar_t* rawwcsstr(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __returns_nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define rawwcsstr(...)  (__const_correct(rawwcsstr, __VA_ARGS__))
# endif

/**
 * Finds the first occurrence of a substring.
 * This search is case insensitive.
 * It must already be known that such a substring exists.
 * 
 * This is a slibc extension.
 * 
 * @param   haystack  The string to search.
 * @param   needle    The sought after substring.
 * @return            Pointer to the first occurrence of the substring.
 */
wchar_t* rawwcscasestr(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __returns_nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define rawwcscasestr(...)  (__const_correct(rawwcscasestr, __VA_ARGS__))
# endif

/**
 * Finds the first occurrence of a substring.
 * This search is case insensitive.
 * 
 * This is a slibc extension added because it was useful
 * in implementing slibc itself.
 * 
 * @param   haystack         The string to search.
 * @param   haystack_length  The number of character to search.
 * @param   needle           The sought after substring.
 * @param   needle_length    The length of `needle`.
 * @return                   Pointer to the first occurrence of
 *                           the substring, `NULL` if not found.
 */
wchar_t* wmemcasemem(const wchar_t*, size_t, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __pure__)));
# ifdef __CONST_CORRECT
#  define wmemcasemem(...)  (__const_correct(wmemcasemem, __VA_ARGS__))
# endif

/**
 * Check whether a string starts with a specific string.
 * This check is case sensitive.
 * 
 * This is a slibc extension.
 * 
 * @param   string   The string to inspect.
 * @param   desired  The desired beginning of the string.
 * @return           `string` if `string` begins with
 *                   `desired`, `NULL` otherwise.
 */
wchar_t* wcsstarts(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define wcsstarts(...)  (__const_correct(wcsstarts, __VA_ARGS__))
# endif

/**
 * Check whether a string ends with a specific string.
 * This check is case sensitive.
 * 
 * This is a slibc extension.
 * 
 * @param   string   The string to inspect.
 * @param   desired  The desired ending of the string.
 * @return           The `string`, where `desired` beings if
 *                   `string` ends with `desired`, `NULL` otherwise.
 */
wchar_t* wcsends(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define wcsends(...)  (__const_correct(wcsends, __VA_ARGS__))
# endif

/**
 * Check whether a string starts with a specific string.
 * This check is case insensitive.
 * 
 * This is a slibc extension.
 * 
 * @param   string   The string to inspect.
 * @param   desired  The desired beginning of the string.
 * @return           `string` if `string` begins with
 *                   `desired`, `NULL` otherwise.
 */
wchar_t* wcscasestarts(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define wcscasestarts(...)  (__const_correct(wcscasestarts, __VA_ARGS__))
# endif

/**
 * Check whether a string ends with a specific string.
 * This check is case insensitive.
 * 
 * This is a slibc extension.
 * 
 * @param   string   The string to inspect.
 * @param   desired  The desired ending of the string.
 * @return           The `string`, where `desired` beings if
 *                   `string` ends with `desired`, `NULL` otherwise.
 */
wchar_t* wcscaseends(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
# ifdef __CONST_CORRECT
#  define wcscaseends(...)  (__const_correct(wcscaseends, __VA_ARGS__))
# endif
#endif

#if defined(__GNU_SOURCE) || defined(__SLIBC_SOURCE)
/**
 * Finds the first occurrence of a substring.
 * This search is case sensitive.
 * 
 * This is a slibc extension added for completeness,
 * and because it was it was useful in implementing
 * slibc itself.
 * 
 * @param   haystack         The string to search.
 * @param   haystack_length  The number of character to search.
 * @param   needle           The sought after substring.
 * @param   needle_length    The length of `needle`.
 * @return                   Pointer to the first occurrence of
 *                           the substring, `NULL` if not found.
 */
wchar_t* wmemmem(const wchar_t*, size_t, const wchar_t*, size_t)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __pure__)));
# ifdef __CONST_CORRECT
#  define wmemmem(...)  (__const_correct(wmemmem, __VA_ARGS__))
# endif
#endif


/* TODO Add case right-to-left substring searching functions. */


/**
 * Returns length of the initial substring
 * that consists entirely of a set of specified
 * wide characters.
 * 
 * @param   string   The string.
 * @param   skipset  Characters allowed in the substring.
 * @return           The length of the substring.
 */
size_t wcsspn(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));

/**
 * Returns length of the initial substring
 * that consists entirely of the complement
 * of a set of specified wide characters.
 * 
 * @param   string   The string.
 * @param   stopset  Characters disallowed in the substring.
 * @return           The length of the substring.
 */
size_t wcscspn(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));

/**
 * This function works like `strcspn`,
 * except it returns the pointer to the
 * location of the first found non-matching
 * wide character.
 * 
 * @param   string   The string.
 * @param   stopset  Bytes disallowed in the substring.
 * @return           A pointer to the first occurrence in
 *                   `string` of a character found in `stopset`.
 *                   `NULL` is returned if none is found.
 */
wchar_t* wcspbrk(const wchar_t*, const wchar_t*)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__, __pure__)));
#ifdef __CONST_CORRECT
# define wcspbrk(...)  (__const_correct(wcspbrk, __VA_ARGS__))
#endif


/**
 * Tokenise a string.
 * 
 * @param   string      The string to tokenise on the first,
 *                      `NULL` on subsequent calls.
 *                      All characters found in `delimiters` will
 *                      be overriden with NUL characters.
 * @param   delimiters  Delimiting characters.
 * @param   state       Pointer to a `char*` that the function
 *                      can use to keep track of its state.
 *                      It is reasonable to make it point to `NULL`
 *                      on the first call.
 * @return              The next non-empty string that does not
 *                      contain a byte from `delimiters`. The
 *                      returned string will be as long as possible.
 *                      `NULL` is returned the search as reached
 *                      the end of the string, and there therefore
 *                      are no more tokens.
 */
wchar_t* wcstok(wchar_t* restrict, const wchar_t* restrict, wchar_t** restrict)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(2, 3))));

#if defined(__SLIBC_SOURCE)
/**
 * Tokenise a string.
 * 
 * This is a slibc extension.
 * 
 * @param   string      Pointer to the string to tokenise on the first call,
 *                      will be updated to keep track of the state.
 *                      All characters found in `delimiters` will
 *                      be overriden with NUL characters.
 * @param   delimiters  Delimiting characters.
 * @return              The next, possibly empty, string that does
 *                      not contain a byte from `delimiters`. The
 *                      returned string will be as long as possible.
 *                      `NULL` is returned the search as reached
 *                      the end of the string, and there therefore
 *                      are no more tokens.
 */
wchar_t* wcssep(wchar_t** restrict, const wchar_t* restrict)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__)));
#endif



#endif
#endif