New module 'mbsrchr'.

[gnulib.git] / lib / mbsrchr.c

diff --git a/lib/mbsrchr.c b/lib/mbsrchr.c
new file mode 100644 (file)
index 0000000..f3b2808
--- /dev/null
+++ b/lib/mbsrchr.c
@@ -0,0 +1,56 @@
+/* Searching a string for the last occurrence of a character.
+   Copyright (C) 2007 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2007.
+
+   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 2, 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, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <string.h>
+
+#if HAVE_MBRTOWC
+# include "mbuiter.h"
+#endif
+
+/* Locate the last single-byte character C in the character string STRING,
+   and return a pointer to it.  Return NULL if C is not found in STRING.  */
+char *
+mbsrchr (const char *string, int c)
+{
+#if HAVE_MBRTOWC
+  if (MB_CUR_MAX > 1
+      /* Optimization: We know that ASCII characters < 0x30 don't occur as
+        part of multibyte characters longer than 1 byte.  Hence, if c < 0x30,
+        the faster unibyte loop can be used.  */
+      && (unsigned char) c >= 0x30)
+    {
+      const char *result = NULL;
+      mbui_iterator_t iter;
+
+      for (mbui_init (iter, string);; mbui_advance (iter))
+       {
+         if (mb_len (mbui_cur (iter)) == 1
+             && (unsigned char) * mbui_cur_ptr (iter) == (unsigned char) c)
+           result = mbui_cur_ptr (iter);
+         if (!mbui_avail (iter))
+           break;
+       }
+      return (char *) result;
+    }
+  else
+#endif
+    return strrchr (string, c);
+}