-/* Copyright (C) 1994, 1999, 2002-2003 Free Software Foundation, Inc.
-This file is part of the GNU C Library.
+/* Searching in a string.
+ Copyright (C) 2005 Free Software Foundation, Inc.
+ Written by Bruno Haible <bruno@clisp.org>, 2005.
-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 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.
+ 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. */
-
-/*
- * My personal strstr() implementation that beats most other algorithms.
- * Until someone tells me otherwise, I assume that this is the
- * fastest implementation of strstr() in C.
- * I deliberately chose not to comment it. You should have at least
- * as much fun trying to understand it, as I had to write it :-).
- *
- * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de */
+ 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. */
#if HAVE_CONFIG_H
# include <config.h>
#endif
-#include <string.h>
-
-typedef unsigned chartype;
+/* Specification. */
+#include "strstr.h"
-#undef strstr
+#if HAVE_MBRTOWC
+# include "mbuiter.h"
+#endif
+/* Find the first occurrence of NEEDLE in HAYSTACK. */
char *
-strstr (const char *phaystack, const char *pneedle)
+strstr (const char *haystack, const char *needle)
{
- register const unsigned char *haystack, *needle;
- register chartype b, c;
+ /* Be careful not to look at the entire extent of haystack or needle
+ until needed. This is useful because of these two cases:
+ - haystack may be very long, and a match of needle found early,
+ - needle may be very long, and not even a short initial segment of
+ needle may be found in haystack. */
+#if HAVE_MBRTOWC
+ if (MB_CUR_MAX > 1)
+ {
+ mbui_iterator_t iter_needle;
- haystack = (const unsigned char *) phaystack;
- needle = (const unsigned char *) pneedle;
+ mbui_init (iter_needle, needle);
+ if (mbui_avail (iter_needle))
+ {
+ mbui_iterator_t iter_haystack;
- b = *needle;
- if (b != '\0')
+ mbui_init (iter_haystack, haystack);
+ for (;; mbui_advance (iter_haystack))
+ {
+ if (!mbui_avail (iter_haystack))
+ /* No match. */
+ return NULL;
+
+ if (mb_equal (mbui_cur (iter_haystack), mbui_cur (iter_needle)))
+ /* The first character matches. */
+ {
+ mbui_iterator_t rhaystack;
+ mbui_iterator_t rneedle;
+
+ memcpy (&rhaystack, &iter_haystack, sizeof (mbui_iterator_t));
+ mbui_advance (rhaystack);
+
+ mbui_init (rneedle, needle);
+ if (!mbui_avail (rneedle))
+ abort ();
+ mbui_advance (rneedle);
+
+ for (;; mbui_advance (rhaystack), mbui_advance (rneedle))
+ {
+ if (!mbui_avail (rneedle))
+ /* Found a match. */
+ return (char *) haystack;
+ if (!mbui_avail (rhaystack))
+ /* No match. */
+ return NULL;
+ if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle)))
+ /* Nothing in this round. */
+ break;
+ }
+ }
+ }
+ }
+ else
+ return (char *) haystack;
+ }
+ else
+#endif
{
- haystack--; /* possible ANSI violation */
- do
+ if (*needle != '\0')
{
- c = *++haystack;
- if (c == '\0')
- goto ret0;
- }
- while (c != b);
+ /* Speed up the following searches of needle by caching its first
+ character. */
+ char b = *needle++;
- c = *++needle;
- if (c == '\0')
- goto foundneedle;
- ++needle;
- goto jin;
-
- for (;;)
- {
- register chartype a;
- register const unsigned char *rhaystack, *rneedle;
-
- do
+ for (;; haystack++)
{
- a = *++haystack;
- if (a == '\0')
- goto ret0;
- if (a == b)
- break;
- a = *++haystack;
- if (a == '\0')
- goto ret0;
-shloop:; }
- while (a != b);
-
-jin: a = *++haystack;
- if (a == '\0')
- goto ret0;
-
- if (a != c)
- goto shloop;
-
- rhaystack = haystack-- + 1;
- rneedle = needle;
- a = *rneedle;
-
- if (*rhaystack == a)
- do
- {
- if (a == '\0')
- goto foundneedle;
- ++rhaystack;
- a = *++needle;
- if (*rhaystack != a)
- break;
- if (a == '\0')
- goto foundneedle;
- ++rhaystack;
- a = *++needle;
- }
- while (*rhaystack == a);
-
- needle = rneedle; /* took the register-poor approach */
-
- if (a == '\0')
- break;
- }
+ if (*haystack == '\0')
+ /* No match. */
+ return NULL;
+ if (*haystack == b)
+ /* The first character matches. */
+ {
+ const char *rhaystack = haystack + 1;
+ const char *rneedle = needle;
+
+ for (;; rhaystack++, rneedle++)
+ {
+ if (*rneedle == '\0')
+ /* Found a match. */
+ return (char *) haystack;
+ if (*rhaystack == '\0')
+ /* No match. */
+ return NULL;
+ if (*rhaystack != *rneedle)
+ /* Nothing in this round. */
+ break;
+ }
+ }
+ }
+ }
+ else
+ return (char *) haystack;
}
-foundneedle:
- return (char*) haystack;
-ret0:
- return 0;
}
projects / pspp / commitdiff