[Cvs-cvs] Changes to ccvs/lib/strstr.c

[Derek Robert Price]

Index: ccvs/lib/strstr.c
diff -u ccvs/lib/strstr.c:1.3 ccvs/lib/strstr.c:1.4
--- ccvs/lib/strstr.c:1.3       Mon May 23 17:44:32 2005
+++ ccvs/lib/strstr.c   Sun Sep  4 05:58:56 2005
@@ -1,119 +1,128 @@
-/* Copyright (C) 1994, 1999, 2002-2003 Free Software Foundation, Inc.
-This file is part of the GNU C Library.
-
-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. 
 */
-
-/*
- * 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, address@hidden     */
+/* Searching in a string.
+   Copyright (C) 2005 Free Software Foundation, Inc.
+   Written by Bruno Haible <address@hidden>, 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 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.  */
 
 #if HAVE_CONFIG_H
 # include <config.h>
 #endif
 
-#include <string.h>
+/* Specification.  */
+#include "strstr.h"
 
-typedef unsigned chartype;
+#include <stddef.h>  /* for NULL */
 
-#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 *) mbui_cur_ptr (iter_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;
 }