utfrune.c 1.2 KB

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  1. /*
  2. * The authors of this software are Rob Pike and Ken Thompson.
  3. * Copyright (c) 2002 by Lucent Technologies.
  4. * Permission to use, copy, modify, and distribute this software for any
  5. * purpose without fee is hereby granted, provided that this entire notice
  6. * is included in all copies of any software which is or includes a copy
  7. * or modification of this software and in all copies of the supporting
  8. * documentation for such software.
  9. * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED
  10. * WARRANTY. IN PARTICULAR, NEITHER THE AUTHORS NOR LUCENT TECHNOLOGIES MAKE ANY
  11. * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY
  12. * OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.
  13. */
  14. #include <stdarg.h>
  15. #include <string.h>
  16. #include "third_party/utf/utf.h"
  17. #include "third_party/utf/utfdef.h"
  18. const
  19. char*
  20. utfrune(const char *s, Rune c)
  21. {
  22. long c1;
  23. Rune r;
  24. int n;
  25. if(c < Runesync) /* not part of utf sequence */
  26. return strchr(s, c);
  27. for(;;) {
  28. c1 = *(uchar*)s;
  29. if(c1 < Runeself) { /* one byte rune */
  30. if(c1 == 0)
  31. return 0;
  32. if(c1 == c)
  33. return s;
  34. s++;
  35. continue;
  36. }
  37. n = chartorune(&r, s);
  38. if(r == c)
  39. return s;
  40. s += n;
  41. }
  42. return 0;
  43. }