/* Searching in a string.
- Copyright (C) 2005-2007 Free Software Foundation, Inc.
+ Copyright (C) 2005-2014 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 UNIT unsigned char
+#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)
+ const char **resultp)
{
size_t m = mbslen (needle);
mbchar_t *needle_mbchars;
size_t *table;
/* Allocate room for needle_mbchars and the table. */
- char *memory = (char *) malloc (m * (sizeof (mbchar_t) + sizeof (size_t)));
+ void *memory = nmalloca (m, sizeof (mbchar_t) + sizeof (size_t));
+ void *table_memory;
if (memory == NULL)
return false;
- needle_mbchars = (mbchar_t *) memory;
- table = (size_t *) (memory + m * sizeof (mbchar_t));
+ needle_mbchars = memory;
+ table = table_memory = needle_mbchars + m;
/* Fill needle_mbchars. */
{
/* 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++)
{
- mbchar_t *b = &needle_mbchars[i - 1];
-
- for (;;)
- {
- if (mb_equal (*b, needle_mbchars[j]))
- {
- table[i] = i - ++j;
- break;
- }
- if (j == 0)
- {
- table[i] = i;
- break;
- }
- j = j - table[j];
- }
+ /* 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]. */
}
}
/* Invariant: phaystack = rhaystack + j. */
while (mbui_avail (phaystack))
if (mb_equal (needle_mbchars[j], mbui_cur (phaystack)))
- {
- j++;
- mbui_advance (phaystack);
- if (j == m)
- {
- /* The entire needle has been found. */
- *resultp = mbui_cur_ptr (rhaystack);
- break;
- }
- }
+ {
+ j++;
+ mbui_advance (phaystack);
+ if (j == m)
+ {
+ /* The entire needle has been found. */
+ *resultp = mbui_cur_ptr (rhaystack);
+ break;
+ }
+ }
else if (j > 0)
- {
- /* Found a match of needle[0..j-1], mismatch at needle[j]. */
- size_t count = table[j];
- j -= count;
- for (; count > 0; count--)
- {
- if (!mbui_avail (rhaystack))
- abort ();
- mbui_advance (rhaystack);
- }
- }
+ {
+ /* Found a match of needle[0..j-1], mismatch at needle[j]. */
+ size_t count = table[j];
+ j -= count;
+ for (; count > 0; count--)
+ {
+ if (!mbui_avail (rhaystack))
+ abort ();
+ mbui_advance (rhaystack);
+ }
+ }
else
- {
- /* Found a mismatch at needle[0] already. */
- if (!mbui_avail (rhaystack))
- abort ();
- mbui_advance (rhaystack);
- mbui_advance (phaystack);
- }
+ {
+ /* Found a mismatch at needle[0] already. */
+ if (!mbui_avail (rhaystack))
+ abort ();
+ mbui_advance (rhaystack);
+ mbui_advance (phaystack);
+ }
}
- 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;
mbui_init (iter_needle, needle);
if (mbui_avail (iter_needle))
- {
- /* Minimizing the worst-case complexity:
- Let n = mbslen(haystack), m = mbslen(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 */
- mbui_iterator_t iter_needle_last_ccount; /* = needle + last_ccount */
-
- mbui_iterator_t iter_haystack;
-
- mbui_init (iter_needle_last_ccount, needle);
- mbui_init (iter_haystack, haystack);
- for (;; mbui_advance (iter_haystack))
- {
- if (!mbui_avail (iter_haystack))
- /* 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)
- {
- /* See if needle + comparison_count now reaches the end of
- needle. */
- size_t count = comparison_count - last_ccount;
- for (;
- count > 0 && mbui_avail (iter_needle_last_ccount);
- count--)
- mbui_advance (iter_needle_last_ccount);
- last_ccount = comparison_count;
- if (!mbui_avail (iter_needle_last_ccount))
- {
- /* Try the Knuth-Morris-Pratt algorithm. */
- const char *result;
- bool success =
- knuth_morris_pratt_multibyte (haystack, needle,
- &result);
- if (success)
- return (char *) result;
- try_kmp = false;
- }
- }
-
- outer_loop_count++;
- comparison_count++;
- 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;
- comparison_count++;
- if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle)))
- /* Nothing in this round. */
- break;
- }
- }
- }
- }
+ {
+ /* Minimizing the worst-case complexity:
+ Let n = mbslen(haystack), m = mbslen(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 */
+ mbui_iterator_t iter_needle_last_ccount; /* = needle + last_ccount */
+
+ mbui_iterator_t iter_haystack;
+
+ mbui_init (iter_needle_last_ccount, needle);
+ mbui_init (iter_haystack, haystack);
+ for (;; mbui_advance (iter_haystack))
+ {
+ if (!mbui_avail (iter_haystack))
+ /* 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)
+ {
+ /* See if needle + comparison_count now reaches the end of
+ needle. */
+ size_t count = comparison_count - last_ccount;
+ for (;
+ count > 0 && mbui_avail (iter_needle_last_ccount);
+ count--)
+ mbui_advance (iter_needle_last_ccount);
+ last_ccount = comparison_count;
+ if (!mbui_avail (iter_needle_last_ccount))
+ {
+ /* Try the Knuth-Morris-Pratt algorithm. */
+ const char *result;
+ bool success =
+ knuth_morris_pratt_multibyte (haystack, needle,
+ &result);
+ if (success)
+ return (char *) result;
+ try_kmp = false;
+ }
+ }
+
+ outer_loop_count++;
+ comparison_count++;
+ 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;
+ comparison_count++;
+ if (!mb_equal (mbui_cur (rhaystack), mbui_cur (rneedle)))
+ /* Nothing in this round. */
+ break;
+ }
+ }
+ }
+ }
else
- return (char *) haystack;
+ return (char *) haystack;
}
else
-#endif
{
if (*needle != '\0')
- {
- /* Minimizing the worst-case complexity:
- Let n = strlen(haystack), m = 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 char *needle_last_ccount = needle; /* = needle + last_ccount */
-
- /* Speed up the following searches of needle by caching its first
- character. */
- char b = *needle++;
-
- for (;; haystack++)
- {
- 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)
- {
- /* See if needle + comparison_count now reaches the end of
- needle. */
- if (needle_last_ccount != NULL)
- {
- needle_last_ccount +=
- 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 char *result;
- bool success =
- knuth_morris_pratt_unibyte (haystack, needle - 1,
- &result);
- if (success)
- return (char *) result;
- try_kmp = false;
- }
- }
-
- outer_loop_count++;
- comparison_count++;
- 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;
- comparison_count++;
- if (*rhaystack != *rneedle)
- /* Nothing in this round. */
- break;
- }
- }
- }
- }
+ {
+ /* Minimizing the worst-case complexity:
+ Let n = strlen(haystack), m = 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 char *needle_last_ccount = needle; /* = needle + last_ccount */
+
+ /* Speed up the following searches of needle by caching its first
+ character. */
+ char b = *needle++;
+
+ for (;; haystack++)
+ {
+ 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)
+ {
+ /* See if needle + comparison_count now reaches the end of
+ needle. */
+ if (needle_last_ccount != NULL)
+ {
+ needle_last_ccount +=
+ 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 unsigned char *result;
+ bool success =
+ knuth_morris_pratt ((const unsigned char *) haystack,
+ (const unsigned char *) (needle - 1),
+ strlen (needle - 1),
+ &result);
+ if (success)
+ return (char *) result;
+ try_kmp = false;
+ }
+ }
+
+ outer_loop_count++;
+ comparison_count++;
+ 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;
+ comparison_count++;
+ if (*rhaystack != *rneedle)
+ /* Nothing in this round. */
+ break;
+ }
+ }
+ }
+ }
else
- return (char *) haystack;
+ return (char *) haystack;
}
}
projects / gnulib.git / blobdiff