/* Searching in a string.
- Copyright (C) 2005-2007 Free Software Foundation, Inc.
+ Copyright (C) 2005-2008 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2005.
- This program is free software; you can redistribute it and/or modify
+ 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.
+ the Free Software Foundation; either version 3 of the License, 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
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. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#include <stdbool.h>
#include <stddef.h> /* for NULL, in case a nonstandard string.h lacks it */
-#if HAVE_MBRTOWC
-# include "mbuiter.h"
-#endif
+#include "malloca.h"
+#include "mbuiter.h"
+
+/* Knuth-Morris-Pratt algorithm. */
+#define CANON_ELEMENT(c) c
+#include "str-kmp.h"
/* Knuth-Morris-Pratt algorithm.
See http://en.wikipedia.org/wiki/Knuth-Morris-Pratt_algorithm
- Return a boolean indicating success. */
-
-static bool
-knuth_morris_pratt_unibyte (const char *haystack, const char *needle,
- const char **resultp)
-{
- size_t m = strlen (needle);
-
- /* Allocate the table. */
- size_t *table = (size_t *) malloc (m * sizeof (size_t));
- if (table == NULL)
- return false;
- /* Fill the table.
- For 0 < i < m:
- 0 < table[i] <= i is defined such that
- rhaystack[0..i-1] == needle[0..i-1] and rhaystack[i] != needle[i]
- implies
- forall 0 <= x < table[i]: rhaystack[x..x+m-1] != needle[0..m-1],
- and table[i] is as large as possible with this property.
- table[0] remains uninitialized. */
- {
- size_t i, j;
-
- table[1] = 1;
- j = 0;
- for (i = 2; i < m; i++)
- {
- unsigned char b = (unsigned char) needle[i - 1];
-
- for (;;)
- {
- if (b == (unsigned char) needle[j])
- {
- table[i] = i - ++j;
- break;
- }
- if (j == 0)
- {
- table[i] = i;
- break;
- }
- j = j - table[j];
- }
- }
- }
-
- /* Search, using the table to accelerate the processing. */
- {
- size_t j;
- const char *rhaystack;
- const char *phaystack;
-
- *resultp = NULL;
- j = 0;
- rhaystack = haystack;
- phaystack = haystack;
- /* Invariant: phaystack = rhaystack + j. */
- while (*phaystack != '\0')
- if ((unsigned char) needle[j] == (unsigned char) *phaystack)
- {
- j++;
- phaystack++;
- if (j == m)
- {
- /* The entire needle has been found. */
- *resultp = rhaystack;
- break;
- }
- }
- else if (j > 0)
- {
- /* Found a match of needle[0..j-1], mismatch at needle[j]. */
- rhaystack += table[j];
- j -= table[j];
- }
- else
- {
- /* Found a mismatch at needle[0] already. */
- rhaystack++;
- phaystack++;
- }
- }
-
- free (table);
- return true;
-}
-
-#if HAVE_MBRTOWC
+ Return a boolean indicating success:
+ Return true and set *RESULTP if the search was completed.
+ Return false if it was aborted because not enough memory was available. */
static bool
knuth_morris_pratt_multibyte (const char *haystack, const char *needle,
const char **resultp)
size_t *table;
/* Allocate room for needle_mbchars and the table. */
- char *memory = (char *) malloc (m * (sizeof (mbchar_t) + sizeof (size_t)));
+ char *memory = (char *) nmalloca (m, sizeof (mbchar_t) + sizeof (size_t));
if (memory == NULL)
return false;
needle_mbchars = (mbchar_t *) memory;
/* Fill the table.
For 0 < i < m:
0 < table[i] <= i is defined such that
- rhaystack[0..i-1] == needle[0..i-1] and rhaystack[i] != needle[i]
- implies
- forall 0 <= x < table[i]: rhaystack[x..x+m-1] != needle[0..m-1],
+ forall 0 < x < table[i]: needle[x..i-1] != needle[0..i-1-x],
and table[i] is as large as possible with this property.
+ This implies:
+ 1) For 0 < i < m:
+ If table[i] < i,
+ needle[table[i]..i-1] = needle[0..i-1-table[i]].
+ 2) For 0 < i < m:
+ rhaystack[0..i-1] == needle[0..i-1]
+ and exists h, i <= h < m: rhaystack[h] != needle[h]
+ implies
+ forall 0 <= x < table[i]: rhaystack[x..x+m-1] != needle[0..m-1].
table[0] remains uninitialized. */
{
size_t i, j;
+ /* i = 1: Nothing to verify for x = 0. */
table[1] = 1;
j = 0;
+
for (i = 2; i < m; i++)
{
+ /* Here: j = i-1 - table[i-1].
+ The inequality needle[x..i-1] != needle[0..i-1-x] is known to hold
+ for x < table[i-1], by induction.
+ Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1]. */
mbchar_t *b = &needle_mbchars[i - 1];
for (;;)
{
+ /* Invariants: The inequality needle[x..i-1] != needle[0..i-1-x]
+ is known to hold for x < i-1-j.
+ Furthermore, if j>0: needle[i-1-j..i-2] = needle[0..j-1]. */
if (mb_equal (*b, needle_mbchars[j]))
{
+ /* Set table[i] := i-1-j. */
table[i] = i - ++j;
break;
}
+ /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
+ for x = i-1-j, because
+ needle[i-1] != needle[j] = needle[i-1-x]. */
if (j == 0)
{
+ /* The inequality holds for all possible x. */
table[i] = i;
break;
}
+ /* The inequality needle[x..i-1] != needle[0..i-1-x] also holds
+ for i-1-j < x < i-1-j+table[j], because for these x:
+ needle[x..i-2]
+ = needle[x-(i-1-j)..j-1]
+ != needle[0..j-1-(x-(i-1-j))] (by definition of table[j])
+ = needle[0..i-2-x],
+ hence needle[x..i-1] != needle[0..i-1-x].
+ Furthermore
+ needle[i-1-j+table[j]..i-2]
+ = needle[table[j]..j-1]
+ = needle[0..j-1-table[j]] (by definition of table[j]). */
j = j - table[j];
}
+ /* Here: j = i - table[i]. */
}
}
}
}
- free (memory);
+ freea (memory);
return true;
}
-#endif
/* Find the first occurrence of the character string NEEDLE in the character
string HAYSTACK. Return NULL if NEEDLE is not found in HAYSTACK. */
- 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;
return (char *) haystack;
}
else
-#endif
{
if (*needle != '\0')
{
projects / gnulib.git / blobdiff