Imported Upstream version 0.9.6+really0.9.3upstream/0.9.6+really0.9.3

1 files changed, 17 insertions, 99 deletions

diff --git a/lib/unistr/u-strstr.h b/lib/unistr/u-strstr.h
index 459215ec..df32be8b 100644
--- a/lib/unistr/u-strstr.h
+++ b/lib/unistr/u-strstr.h
@@ -1,6 +1,6 @@
 /* Substring test for UTF-8/UTF-16/UTF-32 strings.
-   Copyright (C) 1999, 2002, 2006, 2010-2015 Free Software Foundation, Inc.
-   Written by Bruno Haible <bruno@clisp.org>, 2002, 2005.
+   Copyright (C) 1999, 2002, 2006, 2009-2010 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2002.
 
    This program is free software: you can redistribute it and/or modify it
    under the terms of the GNU Lesser General Public License as published
@@ -24,108 +24,26 @@ FUNC (const UNIT *haystack, const UNIT *needle)
   if (first == 0)
     return (UNIT *) haystack;
 
-  /* Is needle nearly empty (only one unit)?  */
+  /* Is needle nearly empty?  */
   if (needle[1] == 0)
     return U_STRCHR (haystack, first);
 
-#ifdef U_STRMBTOUC
-  /* Is needle nearly empty (only one character)?  */
-  {
-    ucs4_t first_uc;
-    int count = U_STRMBTOUC (&first_uc, needle);
-    if (count > 0 && needle[count] == 0)
-      return U_STRCHR (haystack, first_uc);
-  }
-#endif
-
-#if UNIT_IS_UINT8_T
-  return (uint8_t *) strstr ((const char *) haystack, (const char *) needle);
-#else
-  {
-    /* Minimizing the worst-case complexity:
-       Let n = U_STRLEN(haystack), m = U_STRLEN(needle).
-       The naïve algorithm is O(n*m) worst-case.
-       The Knuth-Morris-Pratt algorithm is O(n) worst-case but it needs a
-       memory allocation.
-       To achieve linear complexity and yet amortize the cost of the
-       memory allocation, we activate the Knuth-Morris-Pratt algorithm
-       only once the naïve algorithm has already run for some time; more
-       precisely, when
-         - the outer loop count is >= 10,
-         - the average number of comparisons per outer loop is >= 5,
-         - the total number of comparisons is >= m.
-       But we try it only once.  If the memory allocation attempt failed,
-       we don't retry it.  */
-    bool try_kmp = true;
-    size_t outer_loop_count = 0;
-    size_t comparison_count = 0;
-    size_t last_ccount = 0;                  /* last comparison count */
-    const UNIT *needle_last_ccount = needle; /* = needle + last_ccount */
-
-    /* Speed up the following searches of needle by caching its first
-       character.  */
-    UNIT b = *needle++;
-
-    for (;; haystack++)
+  /* Search for needle's first unit.  */
+  for (; *haystack != 0; haystack++)
+    if (*haystack == first)
       {
-        if (*haystack == 0)
-          /* No match.  */
-          return NULL;
-
-        /* See whether it's advisable to use an asymptotically faster
-           algorithm.  */
-        if (try_kmp
-            && outer_loop_count >= 10
-            && comparison_count >= 5 * outer_loop_count)
+        /* Compare with needle's remaining units.  */
+        const UNIT *hptr = haystack + 1;
+        const UNIT *nptr = needle + 1;
+        for (;;)
           {
-            /* See if needle + comparison_count now reaches the end of
-               needle.  */
-            if (needle_last_ccount != NULL)
-              {
-                needle_last_ccount +=
-                  U_STRNLEN (needle_last_ccount,
-                             comparison_count - last_ccount);
-                if (*needle_last_ccount == 0)
-                  needle_last_ccount = NULL;
-                last_ccount = comparison_count;
-              }
-            if (needle_last_ccount == NULL)
-              {
-                /* Try the Knuth-Morris-Pratt algorithm.  */
-                const UNIT *result;
-                bool success =
-                  knuth_morris_pratt (haystack,
-                                      needle - 1, U_STRLEN (needle - 1),
-                                      &result);
-                if (success)
-                  return (UNIT *) result;
-                try_kmp = false;
-              }
-          }
-
-        outer_loop_count++;
-        comparison_count++;
-        if (*haystack == b)
-          /* The first character matches.  */
-          {
-            const UNIT *rhaystack = haystack + 1;
-            const UNIT *rneedle = needle;
-
-            for (;; rhaystack++, rneedle++)
-              {
-                if (*rneedle == 0)
-                  /* Found a match.  */
-                  return (UNIT *) haystack;
-                if (*rhaystack == 0)
-                  /* No match.  */
-                  return NULL;
-                comparison_count++;
-                if (*rhaystack != *rneedle)
-                  /* Nothing in this round.  */
-                  break;
-              }
+            if (*hptr != *nptr)
+              break;
+            hptr++; nptr++;
+            if (*nptr == 0)
+              return (UNIT *) haystack;
           }
       }
-  }
-#endif
+
+  return NULL;
 }