+2008-05-14 Ulrich Drepper <drepper@redhat.com>
+
+ * string/Makefile (distribute): Add str-two-way.h.
+
+2008-03-29 Eric Blake <ebb9@byu.net>
+
+ Rewrite string searches to O(n) rather than O(n^2).
+ * string/str-two-way.h: New file. For linear fixed-allocation
+ string searching.
+ * string/memmem.c: New implementation.
+ * string/strstr.c: New implementation.
+ * string/strcasestr.c: New implementation.
+
2008-04-11 Paolo Bonzini <bonzini@gnu.org>
* posix/regcomp.c (optimize_utf8): Add a note on why we test
(match_prefix): Don't treat IPv4 loopback address special when
converting to v4 mapped addressed.
- * sysdeps/posix/getaddrinfo.c (getaddrinfo): Add _res_hconf_init
+ * sysdeps/posix/getaddrinfo.c (getaddrinfo): Call _res_hconf_init
if necessary.
* posix/tst-rfc3484.c: Add dummy definition of _res_hconf_init.
* posix/tst-rfc3484-2.c: Likewise.
* getaddrinfo now handles DCCP and UDPlite.
Implemented by Ulrich Drepper.
+
+* New fixed-size conversion macros: htobe16, htole16, be16toh, le16toh,
+ htobe32, htole32, be32toh, le32toh, htobe64, htole64, be64toh, le64toh.
+ Implemented by Ulrich Drepper.
+
+* New implementation of memmem, strstr, and strcasestr which is O(n).
+ Implemented by Eric Blake.
\f
Version 2.8
case BUF_LAST:
break;
default:
- /* Word anchors etc. cannot be handled. */
+ /* Word anchors etc. cannot be handled. It's okay to test
+ opr.ctx_type since constraints (for all DFA nodes) are
+ created by ORing one or more opr.ctx_type values. */
return;
}
break;
node->node_idx = re_dfa_add_node (dfa, node->token);
if (BE (node->node_idx == -1, 0))
return REG_ESPACE;
+ if (node->token.type == ANCHOR)
+ dfa->nodes[node->node_idx].constraint = node->token.opr.ctx_type;
}
return REG_NOERROR;
}
destination. */
org_dest = dfa->edests[org_node].elems[0];
re_node_set_empty (dfa->edests + clone_node);
- if (dfa->nodes[org_node].type == ANCHOR)
+ /* If the node is root_node itself, it means the epsilon clsoure
+ has a loop. Then tie it to the destination of the root_node. */
+ if (org_node == root_node && clone_node != org_node)
{
- /* In case of the node has another constraint, append it. */
- if (org_node == root_node && clone_node != org_node)
- {
- /* ...but if the node is root_node itself, it means the
- epsilon closure have a loop, then tie it to the
- destination of the root_node. */
- ret = re_node_set_insert (dfa->edests + clone_node,
- org_dest);
- if (BE (ret < 0, 0))
- return REG_ESPACE;
- break;
- }
- constraint |= dfa->nodes[org_node].opr.ctx_type;
+ ret = re_node_set_insert (dfa->edests + clone_node, org_dest);
+ if (BE (ret < 0, 0))
+ return REG_ESPACE;
+ break;
}
+ /* In case of the node has another constraint, add it. */
+ constraint |= dfa->nodes[org_node].constraint;
clone_dest = duplicate_node (dfa, org_dest, constraint);
if (BE (clone_dest == -1, 0))
return REG_ESPACE;
clone_dest = search_duplicated_node (dfa, org_dest, constraint);
if (clone_dest == -1)
{
- /* There are no such a duplicated node, create a new one. */
+ /* There is no such duplicated node, create a new one. */
reg_errcode_t err;
clone_dest = duplicate_node (dfa, org_dest, constraint);
if (BE (clone_dest == -1, 0))
}
else
{
- /* There are a duplicated node which satisfy the constraint,
+ /* There is a duplicated node which satisfies the constraint,
use it to avoid infinite loop. */
ret = re_node_set_insert (dfa->edests + clone_node, clone_dest);
if (BE (ret < 0, 0))
if (BE (dup_idx != -1, 1))
{
dfa->nodes[dup_idx].constraint = constraint;
- if (dfa->nodes[org_idx].type == ANCHOR)
- dfa->nodes[dup_idx].constraint |= dfa->nodes[org_idx].opr.ctx_type;
+ dfa->nodes[dup_idx].constraint |= dfa->nodes[org_idx].constraint;
dfa->nodes[dup_idx].duplicated = 1;
/* Store the index of the original node. */
calc_eclosure_iter (re_node_set *new_set, re_dfa_t *dfa, int node, int root)
{
reg_errcode_t err;
- unsigned int constraint;
int i, incomplete;
re_node_set eclosure;
incomplete = 0;
We reference this value to avoid infinite loop. */
dfa->eclosures[node].nelem = -1;
- constraint = ((dfa->nodes[node].type == ANCHOR)
- ? dfa->nodes[node].opr.ctx_type : 0);
- /* If the current node has constraints, duplicate all nodes.
- Since they must inherit the constraints. */
- if (constraint
+ /* If the current node has constraints, duplicate all nodes
+ since they must inherit the constraints. */
+ if (dfa->nodes[node].constraint
&& dfa->edests[node].nelem
&& !dfa->nodes[dfa->edests[node].elems[0]].duplicated)
{
- err = duplicate_node_closure (dfa, node, node, node, constraint);
+ err = duplicate_node_closure (dfa, node, node, node,
+ dfa->nodes[node].constraint);
if (BE (err != REG_NOERROR, 0))
return err;
}
for (i = 0 ; i < nodes->nelem ; i++)
{
- unsigned int constraint = 0;
re_token_t *node = dfa->nodes + nodes->elems[i];
re_token_type_t type = node->type;
- if (node->constraint)
- constraint = node->constraint;
+ unsigned int constraint = node->constraint;
if (type == CHARACTER && !constraint)
continue;
newstate->halt = 1;
else if (type == OP_BACK_REF)
newstate->has_backref = 1;
- else if (type == ANCHOR)
- constraint = node->opr.ctx_type;
if (constraint)
{
tst-strtok tst-strxfrm bug-strcoll1 tst-strfry \
bug-strtok1 $(addprefix test-,$(strop-tests)) \
bug-envz1 tst-strxfrm2 tst-endian
-distribute := memcopy.h pagecopy.h tst-svc.expect test-string.h
+distribute := memcopy.h pagecopy.h tst-svc.expect test-string.h \
+ str-two-way.h
include ../Rules
-/* Copyright (C) 1991,92,93,94,96,97,98,2000,2004 Free Software Foundation, Inc.
+/* Copyright (C) 1991,92,93,94,96,97,98,2000,2004,2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
-#include <stddef.h>
+/* This particular implementation was written by Eric Blake, 2008. */
+
+#ifndef _LIBC
+# include <config.h>
+#endif
+
+/* Specification of memmem. */
#include <string.h>
#ifndef _LIBC
# define __builtin_expect(expr, val) (expr)
#endif
+#define RETURN_TYPE void *
+#define AVAILABLE(h, h_l, j, n_l) ((j) <= (h_l) - (n_l))
+#include "str-two-way.h"
+
#undef memmem
-/* Return the first occurrence of NEEDLE in HAYSTACK. */
+/* Return the first occurrence of NEEDLE in HAYSTACK. Return HAYSTACK
+ if NEEDLE_LEN is 0, otherwise NULL if NEEDLE is not found in
+ HAYSTACK. */
void *
-memmem (haystack, haystack_len, needle, needle_len)
- const void *haystack;
- size_t haystack_len;
- const void *needle;
- size_t needle_len;
+memmem (const void *haystack_start, size_t haystack_len,
+ const void *needle_start, size_t needle_len)
{
- const char *begin;
- const char *const last_possible
- = (const char *) haystack + haystack_len - needle_len;
+ /* Abstract memory is considered to be an array of 'unsigned char' values,
+ not an array of 'char' values. See ISO C 99 section 6.2.6.1. */
+ const unsigned char *haystack = (const unsigned char *) haystack_start;
+ const unsigned char *needle = (const unsigned char *) needle_start;
if (needle_len == 0)
/* The first occurrence of the empty string is deemed to occur at
if (__builtin_expect (haystack_len < needle_len, 0))
return NULL;
- for (begin = (const char *) haystack; begin <= last_possible; ++begin)
- if (begin[0] == ((const char *) needle)[0] &&
- !memcmp ((const void *) &begin[1],
- (const void *) ((const char *) needle + 1),
- needle_len - 1))
- return (void *) begin;
-
- return NULL;
+ /* Use optimizations in memchr when possible, to reduce the search
+ size of haystack using a linear algorithm with a smaller
+ coefficient. However, avoid memchr for long needles, since we
+ can often achieve sublinear performance. */
+ if (needle_len < LONG_NEEDLE_THRESHOLD)
+ {
+ haystack = memchr (haystack, *needle, haystack_len);
+ if (!haystack || __builtin_expect (needle_len == 1, 0))
+ return (void *) haystack;
+ haystack_len -= haystack - (const unsigned char *) haystack_start;
+ if (haystack_len < needle_len)
+ return NULL;
+ return two_way_short_needle (haystack, haystack_len, needle, needle_len);
+ }
+ else
+ return two_way_long_needle (haystack, haystack_len, needle, needle_len);
}
+
+#undef LONG_NEEDLE_THRESHOLD
--- /dev/null
+/* Byte-wise substring search, using the Two-Way algorithm.
+ Copyright (C) 2008 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Written by Eric Blake <ebb9@byu.net>, 2008.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+/* Before including this file, you need to include <string.h> (and
+ <config.h> before that, if not part of libc), and define:
+ RESULT_TYPE A macro that expands to the return type.
+ AVAILABLE(h, h_l, j, n_l)
+ A macro that returns nonzero if there are
+ at least N_L bytes left starting at H[J].
+ H is 'unsigned char *', H_L, J, and N_L
+ are 'size_t'; H_L is an lvalue. For
+ NUL-terminated searches, H_L can be
+ modified each iteration to avoid having
+ to compute the end of H up front.
+
+ For case-insensitivity, you may optionally define:
+ CMP_FUNC(p1, p2, l) A macro that returns 0 iff the first L
+ characters of P1 and P2 are equal.
+ CANON_ELEMENT(c) A macro that canonicalizes an element right after
+ it has been fetched from one of the two strings.
+ The argument is an 'unsigned char'; the result
+ must be an 'unsigned char' as well.
+
+ This file undefines the macros documented above, and defines
+ LONG_NEEDLE_THRESHOLD.
+*/
+
+#include <limits.h>
+#include <stdint.h>
+
+/* We use the Two-Way string matching algorithm, which guarantees
+ linear complexity with constant space. Additionally, for long
+ needles, we also use a bad character shift table similar to the
+ Boyer-Moore algorithm to achieve improved (potentially sub-linear)
+ performance.
+
+ See http://www-igm.univ-mlv.fr/~lecroq/string/node26.html#SECTION00260
+ and http://en.wikipedia.org/wiki/Boyer-Moore_string_search_algorithm
+*/
+
+/* Point at which computing a bad-byte shift table is likely to be
+ worthwhile. Small needles should not compute a table, since it
+ adds (1 << CHAR_BIT) + NEEDLE_LEN computations of preparation for a
+ speedup no greater than a factor of NEEDLE_LEN. The larger the
+ needle, the better the potential performance gain. On the other
+ hand, on non-POSIX systems with CHAR_BIT larger than eight, the
+ memory required for the table is prohibitive. */
+#if CHAR_BIT < 10
+# define LONG_NEEDLE_THRESHOLD 32U
+#else
+# define LONG_NEEDLE_THRESHOLD SIZE_MAX
+#endif
+
+#ifndef MAX
+# define MAX(a, b) ((a < b) ? (b) : (a))
+#endif
+
+#ifndef CANON_ELEMENT
+# define CANON_ELEMENT(c) c
+#endif
+#ifndef CMP_FUNC
+# define CMP_FUNC memcmp
+#endif
+
+/* Perform a critical factorization of NEEDLE, of length NEEDLE_LEN.
+ Return the index of the first byte in the right half, and set
+ *PERIOD to the global period of the right half.
+
+ The global period of a string is the smallest index (possibly its
+ length) at which all remaining bytes in the string are repetitions
+ of the prefix (the last repetition may be a subset of the prefix).
+
+ When NEEDLE is factored into two halves, a local period is the
+ length of the smallest word that shares a suffix with the left half
+ and shares a prefix with the right half. All factorizations of a
+ non-empty NEEDLE have a local period of at least 1 and no greater
+ than NEEDLE_LEN.
+
+ A critical factorization has the property that the local period
+ equals the global period. All strings have at least one critical
+ factorization with the left half smaller than the global period.
+
+ Given an ordered alphabet, a critical factorization can be computed
+ in linear time, with 2 * NEEDLE_LEN comparisons, by computing the
+ larger of two ordered maximal suffixes. The ordered maximal
+ suffixes are determined by lexicographic comparison of
+ periodicity. */
+static size_t
+critical_factorization (const unsigned char *needle, size_t needle_len,
+ size_t *period)
+{
+ /* Index of last byte of left half, or SIZE_MAX. */
+ size_t max_suffix, max_suffix_rev;
+ size_t j; /* Index into NEEDLE for current candidate suffix. */
+ size_t k; /* Offset into current period. */
+ size_t p; /* Intermediate period. */
+ unsigned char a, b; /* Current comparison bytes. */
+
+ /* Invariants:
+ 0 <= j < NEEDLE_LEN - 1
+ -1 <= max_suffix{,_rev} < j (treating SIZE_MAX as if it were signed)
+ min(max_suffix, max_suffix_rev) < global period of NEEDLE
+ 1 <= p <= global period of NEEDLE
+ p == global period of the substring NEEDLE[max_suffix{,_rev}+1...j]
+ 1 <= k <= p
+ */
+
+ /* Perform lexicographic search. */
+ max_suffix = SIZE_MAX;
+ j = 0;
+ k = p = 1;
+ while (j + k < needle_len)
+ {
+ a = CANON_ELEMENT (needle[j + k]);
+ b = CANON_ELEMENT (needle[max_suffix + k]);
+ if (a < b)
+ {
+ /* Suffix is smaller, period is entire prefix so far. */
+ j += k;
+ k = 1;
+ p = j - max_suffix;
+ }
+ else if (a == b)
+ {
+ /* Advance through repetition of the current period. */
+ if (k != p)
+ ++k;
+ else
+ {
+ j += p;
+ k = 1;
+ }
+ }
+ else /* b < a */
+ {
+ /* Suffix is larger, start over from current location. */
+ max_suffix = j++;
+ k = p = 1;
+ }
+ }
+ *period = p;
+
+ /* Perform reverse lexicographic search. */
+ max_suffix_rev = SIZE_MAX;
+ j = 0;
+ k = p = 1;
+ while (j + k < needle_len)
+ {
+ a = CANON_ELEMENT (needle[j + k]);
+ b = CANON_ELEMENT (needle[max_suffix_rev + k]);
+ if (b < a)
+ {
+ /* Suffix is smaller, period is entire prefix so far. */
+ j += k;
+ k = 1;
+ p = j - max_suffix_rev;
+ }
+ else if (a == b)
+ {
+ /* Advance through repetition of the current period. */
+ if (k != p)
+ ++k;
+ else
+ {
+ j += p;
+ k = 1;
+ }
+ }
+ else /* a < b */
+ {
+ /* Suffix is larger, start over from current location. */
+ max_suffix_rev = j++;
+ k = p = 1;
+ }
+ }
+
+ /* Choose the longer suffix. Return the first byte of the right
+ half, rather than the last byte of the left half. */
+ if (max_suffix_rev + 1 < max_suffix + 1)
+ return max_suffix + 1;
+ *period = p;
+ return max_suffix_rev + 1;
+}
+
+/* Return the first location of non-empty NEEDLE within HAYSTACK, or
+ NULL. HAYSTACK_LEN is the minimum known length of HAYSTACK. This
+ method is optimized for NEEDLE_LEN < LONG_NEEDLE_THRESHOLD.
+ Performance is guaranteed to be linear, with an initialization cost
+ of 2 * NEEDLE_LEN comparisons.
+
+ If AVAILABLE does not modify HAYSTACK_LEN (as in memmem), then at
+ most 2 * HAYSTACK_LEN - NEEDLE_LEN comparisons occur in searching.
+ If AVAILABLE modifies HAYSTACK_LEN (as in strstr), then at most 3 *
+ HAYSTACK_LEN - NEEDLE_LEN comparisons occur in searching. */
+static RETURN_TYPE
+two_way_short_needle (const unsigned char *haystack, size_t haystack_len,
+ const unsigned char *needle, size_t needle_len)
+{
+ size_t i; /* Index into current byte of NEEDLE. */
+ size_t j; /* Index into current window of HAYSTACK. */
+ size_t period; /* The period of the right half of needle. */
+ size_t suffix; /* The index of the right half of needle. */
+
+ /* Factor the needle into two halves, such that the left half is
+ smaller than the global period, and the right half is
+ periodic (with a period as large as NEEDLE_LEN - suffix). */
+ suffix = critical_factorization (needle, needle_len, &period);
+
+ /* Perform the search. Each iteration compares the right half
+ first. */
+ if (CMP_FUNC (needle, needle + period, suffix) == 0)
+ {
+ /* Entire needle is periodic; a mismatch can only advance by the
+ period, so use memory to avoid rescanning known occurrences
+ of the period. */
+ size_t memory = 0;
+ j = 0;
+ while (AVAILABLE (haystack, haystack_len, j, needle_len))
+ {
+ /* Scan for matches in right half. */
+ i = MAX (suffix, memory);
+ while (i < needle_len && (CANON_ELEMENT (needle[i])
+ == CANON_ELEMENT (haystack[i + j])))
+ ++i;
+ if (needle_len <= i)
+ {
+ /* Scan for matches in left half. */
+ i = suffix - 1;
+ while (memory < i + 1 && (CANON_ELEMENT (needle[i])
+ == CANON_ELEMENT (haystack[i + j])))
+ --i;
+ if (i + 1 < memory + 1)
+ return (RETURN_TYPE) (haystack + j);
+ /* No match, so remember how many repetitions of period
+ on the right half were scanned. */
+ j += period;
+ memory = needle_len - period;
+ }
+ else
+ {
+ j += i - suffix + 1;
+ memory = 0;
+ }
+ }
+ }
+ else
+ {
+ /* The two halves of needle are distinct; no extra memory is
+ required, and any mismatch results in a maximal shift. */
+ period = MAX (suffix, needle_len - suffix) + 1;
+ j = 0;
+ while (AVAILABLE (haystack, haystack_len, j, needle_len))
+ {
+ /* Scan for matches in right half. */
+ i = suffix;
+ while (i < needle_len && (CANON_ELEMENT (needle[i])
+ == CANON_ELEMENT (haystack[i + j])))
+ ++i;
+ if (needle_len <= i)
+ {
+ /* Scan for matches in left half. */
+ i = suffix - 1;
+ while (i != SIZE_MAX && (CANON_ELEMENT (needle[i])
+ == CANON_ELEMENT (haystack[i + j])))
+ --i;
+ if (i == SIZE_MAX)
+ return (RETURN_TYPE) (haystack + j);
+ j += period;
+ }
+ else
+ j += i - suffix + 1;
+ }
+ }
+ return NULL;
+}
+
+/* Return the first location of non-empty NEEDLE within HAYSTACK, or
+ NULL. HAYSTACK_LEN is the minimum known length of HAYSTACK. This
+ method is optimized for LONG_NEEDLE_THRESHOLD <= NEEDLE_LEN.
+ Performance is guaranteed to be linear, with an initialization cost
+ of 3 * NEEDLE_LEN + (1 << CHAR_BIT) operations.
+
+ If AVAILABLE does not modify HAYSTACK_LEN (as in memmem), then at
+ most 2 * HAYSTACK_LEN - NEEDLE_LEN comparisons occur in searching,
+ and sublinear performance O(HAYSTACK_LEN / NEEDLE_LEN) is possible.
+ If AVAILABLE modifies HAYSTACK_LEN (as in strstr), then at most 3 *
+ HAYSTACK_LEN - NEEDLE_LEN comparisons occur in searching, and
+ sublinear performance is not possible. */
+static RETURN_TYPE
+two_way_long_needle (const unsigned char *haystack, size_t haystack_len,
+ const unsigned char *needle, size_t needle_len)
+{
+ size_t i; /* Index into current byte of NEEDLE. */
+ size_t j; /* Index into current window of HAYSTACK. */
+ size_t period; /* The period of the right half of needle. */
+ size_t suffix; /* The index of the right half of needle. */
+ size_t shift_table[1U << CHAR_BIT]; /* See below. */
+
+ /* Factor the needle into two halves, such that the left half is
+ smaller than the global period, and the right half is
+ periodic (with a period as large as NEEDLE_LEN - suffix). */
+ suffix = critical_factorization (needle, needle_len, &period);
+
+ /* Populate shift_table. For each possible byte value c,
+ shift_table[c] is the distance from the last occurrence of c to
+ the end of NEEDLE, or NEEDLE_LEN if c is absent from the NEEDLE.
+ shift_table[NEEDLE[NEEDLE_LEN - 1]] contains the only 0. */
+ for (i = 0; i < 1U << CHAR_BIT; i++)
+ shift_table[i] = needle_len;
+ for (i = 0; i < needle_len; i++)
+ shift_table[CANON_ELEMENT (needle[i])] = needle_len - i - 1;
+
+ /* Perform the search. Each iteration compares the right half
+ first. */
+ if (CMP_FUNC (needle, needle + period, suffix) == 0)
+ {
+ /* Entire needle is periodic; a mismatch can only advance by the
+ period, so use memory to avoid rescanning known occurrences
+ of the period. */
+ size_t memory = 0;
+ size_t shift;
+ j = 0;
+ while (AVAILABLE (haystack, haystack_len, j, needle_len))
+ {
+ /* Check the last byte first; if it does not match, then
+ shift to the next possible match location. */
+ shift = shift_table[CANON_ELEMENT (haystack[j + needle_len - 1])];
+ if (0 < shift)
+ {
+ if (memory && shift < period)
+ {
+ /* Since needle is periodic, but the last period has
+ a byte out of place, there can be no match until
+ after the mismatch. */
+ shift = needle_len - period;
+ memory = 0;
+ }
+ j += shift;
+ continue;
+ }
+ /* Scan for matches in right half. The last byte has
+ already been matched, by virtue of the shift table. */
+ i = MAX (suffix, memory);
+ while (i < needle_len - 1 && (CANON_ELEMENT (needle[i])
+ == CANON_ELEMENT (haystack[i + j])))
+ ++i;
+ if (needle_len - 1 <= i)
+ {
+ /* Scan for matches in left half. */
+ i = suffix - 1;
+ while (memory < i + 1 && (CANON_ELEMENT (needle[i])
+ == CANON_ELEMENT (haystack[i + j])))
+ --i;
+ if (i + 1 < memory + 1)
+ return (RETURN_TYPE) (haystack + j);
+ /* No match, so remember how many repetitions of period
+ on the right half were scanned. */
+ j += period;
+ memory = needle_len - period;
+ }
+ else
+ {
+ j += i - suffix + 1;
+ memory = 0;
+ }
+ }
+ }
+ else
+ {
+ /* The two halves of needle are distinct; no extra memory is
+ required, and any mismatch results in a maximal shift. */
+ size_t shift;
+ period = MAX (suffix, needle_len - suffix) + 1;
+ j = 0;
+ while (AVAILABLE (haystack, haystack_len, j, needle_len))
+ {
+ /* Check the last byte first; if it does not match, then
+ shift to the next possible match location. */
+ shift = shift_table[CANON_ELEMENT (haystack[j + needle_len - 1])];
+ if (0 < shift)
+ {
+ j += shift;
+ continue;
+ }
+ /* Scan for matches in right half. The last byte has
+ already been matched, by virtue of the shift table. */
+ i = suffix;
+ while (i < needle_len - 1 && (CANON_ELEMENT (needle[i])
+ == CANON_ELEMENT (haystack[i + j])))
+ ++i;
+ if (needle_len - 1 <= i)
+ {
+ /* Scan for matches in left half. */
+ i = suffix - 1;
+ while (i != SIZE_MAX && (CANON_ELEMENT (needle[i])
+ == CANON_ELEMENT (haystack[i + j])))
+ --i;
+ if (i == SIZE_MAX)
+ return (RETURN_TYPE) (haystack + j);
+ j += period;
+ }
+ else
+ j += i - suffix + 1;
+ }
+ }
+ return NULL;
+}
+
+#undef AVAILABLE
+#undef CANON_ELEMENT
+#undef CMP_FUNC
+#undef MAX
+#undef RETURN_TYPE
/* Return the offset of one string within another.
- Copyright (C) 1994, 1996-2000, 2004 Free Software Foundation, Inc.
+ Copyright (C) 1994, 1996-2000, 2004, 2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
# include <config.h>
#endif
+/* Specification. */
+#include <string.h>
+
#include <ctype.h>
+#include <stdbool.h>
+#include <strings.h>
-#if defined _LIBC || defined HAVE_STRING_H
-# include <string.h>
-#endif
+#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))
-#ifdef _LIBC
-# include <locale/localeinfo.h>
-# define TOLOWER(c) __tolower_l ((unsigned char) c, loc)
-#else
-# define TOLOWER(c) _tolower (c)
-#endif
-
-typedef unsigned chartype;
+/* Two-Way algorithm. */
+#define RETURN_TYPE char *
+#define AVAILABLE(h, h_l, j, n_l) \
+ (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \
+ && ((h_l) = (j) + (n_l)))
+#define CANON_ELEMENT(c) TOLOWER (c)
+#define CMP_FUNC(p1, p2, l) \
+ strncasecmp ((const char *) (p1), (const char *) (p2), l)
+#include "str-two-way.h"
#undef strcasestr
#undef __strcasestr
+/* Find the first occurrence of NEEDLE in HAYSTACK, using
+ case-insensitive comparison. This function gives unspecified
+ results in multibyte locales. */
char *
-__strcasestr (phaystack, pneedle)
- const char *phaystack;
- const char *pneedle;
+__strcasestr (const char *haystack_start, const char *needle_start)
{
- register const unsigned char *haystack, *needle;
- register chartype b, c;
-#ifdef _LIBC
- __locale_t loc = _NL_CURRENT_LOCALE;
-#endif
-
- haystack = (const unsigned char *) phaystack;
- needle = (const unsigned char *) pneedle;
-
- b = TOLOWER (*needle);
- if (b != '\0')
+ const char *haystack = haystack_start;
+ const char *needle = needle_start;
+ size_t needle_len; /* Length of NEEDLE. */
+ size_t haystack_len; /* Known minimum length of HAYSTACK. */
+ bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
+
+ /* Determine length of NEEDLE, and in the process, make sure
+ HAYSTACK is at least as long (no point processing all of a long
+ NEEDLE if HAYSTACK is too short). */
+ while (*haystack && *needle)
{
- haystack--; /* possible ANSI violation */
- do
- {
- c = *++haystack;
- if (c == '\0')
- goto ret0;
- }
- while (TOLOWER (c) != (int) b);
-
- c = TOLOWER (*++needle);
- if (c == '\0')
- goto foundneedle;
- ++needle;
- goto jin;
-
- for (;;)
- {
- register chartype a;
- register const unsigned char *rhaystack, *rneedle;
-
- do
- {
- a = *++haystack;
- if (a == '\0')
- goto ret0;
- if (TOLOWER (a) == (int) b)
- break;
- a = *++haystack;
- if (a == '\0')
- goto ret0;
-shloop:
- ;
- }
- while (TOLOWER (a) != (int) b);
-
-jin: a = *++haystack;
- if (a == '\0')
- goto ret0;
-
- if (TOLOWER (a) != (int) c)
- goto shloop;
-
- rhaystack = haystack-- + 1;
- rneedle = needle;
- a = TOLOWER (*rneedle);
-
- if (TOLOWER (*rhaystack) == (int) a)
- do
- {
- if (a == '\0')
- goto foundneedle;
- ++rhaystack;
- a = TOLOWER (*++needle);
- if (TOLOWER (*rhaystack) != (int) a)
- break;
- if (a == '\0')
- goto foundneedle;
- ++rhaystack;
- a = TOLOWER (*++needle);
- }
- while (TOLOWER (*rhaystack) == (int) a);
-
- needle = rneedle; /* took the register-poor approach */
-
- if (a == '\0')
- break;
- }
+ ok &= (TOLOWER ((unsigned char) *haystack)
+ == TOLOWER ((unsigned char) *needle));
+ haystack++;
+ needle++;
}
-foundneedle:
- return (char*) haystack;
-ret0:
- return 0;
+ if (*needle)
+ return NULL;
+ if (ok)
+ return (char *) haystack_start;
+ needle_len = needle - needle_start;
+ haystack = haystack_start + 1;
+ haystack_len = needle_len - 1;
+
+ /* Perform the search. Abstract memory is considered to be an array
+ of 'unsigned char' values, not an array of 'char' values. See
+ ISO C 99 section 6.2.6.1. */
+ if (needle_len < LONG_NEEDLE_THRESHOLD)
+ return two_way_short_needle ((const unsigned char *) haystack,
+ haystack_len,
+ (const unsigned char *) needle_start,
+ needle_len);
+ return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
+ (const unsigned char *) needle_start,
+ needle_len);
}
+#undef LONG_NEEDLE_THRESHOLD
+
weak_alias (__strcasestr, strcasestr)
/* Return the offset of one string within another.
- Copyright (C) 1994,1996,1997,2000,2001,2003 Free Software Foundation, Inc.
+ Copyright (C) 1994,1996,1997,2000,2001,2003,2008 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 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 */
+/* This particular implementation was written by Eric Blake, 2008. */
-#if HAVE_CONFIG_H
+#ifndef _LIBC
# include <config.h>
#endif
-#if defined _LIBC || defined HAVE_STRING_H
-# include <string.h>
+/* Specification of strstr. */
+#include <string.h>
+
+#include <stdbool.h>
+
+#ifndef _LIBC
+# define __builtin_expect(expr, val) (expr)
#endif
-typedef unsigned chartype;
+#define RETURN_TYPE char *
+#define AVAILABLE(h, h_l, j, n_l) \
+ (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \
+ && ((h_l) = (j) + (n_l)))
+#include "str-two-way.h"
#undef strstr
+/* Return the first occurrence of NEEDLE in HAYSTACK. Return HAYSTACK
+ if NEEDLE is empty, otherwise NULL if NEEDLE is not found in
+ HAYSTACK. */
char *
-strstr (phaystack, pneedle)
- const char *phaystack;
- const char *pneedle;
+strstr (const char *haystack_start, const char *needle_start)
{
- const unsigned char *haystack, *needle;
- chartype b;
- const unsigned char *rneedle;
-
- haystack = (const unsigned char *) phaystack;
+ const char *haystack = haystack_start;
+ const char *needle = needle_start;
+ size_t needle_len; /* Length of NEEDLE. */
+ size_t haystack_len; /* Known minimum length of HAYSTACK. */
+ bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
- if ((b = *(needle = (const unsigned char *) pneedle)))
- {
- chartype c;
- haystack--; /* possible ANSI violation */
+ /* Determine length of NEEDLE, and in the process, make sure
+ HAYSTACK is at least as long (no point processing all of a long
+ NEEDLE if HAYSTACK is too short). */
+ while (*haystack && *needle)
+ ok &= *haystack++ == *needle++;
+ if (*needle)
+ return NULL;
+ if (ok)
+ return (char *) haystack_start;
- {
- chartype a;
- do
- if (!(a = *++haystack))
- goto ret0;
- while (a != b);
- }
+ /* Reduce the size of haystack using strchr, since it has a smaller
+ linear coefficient than the Two-Way algorithm. */
+ needle_len = needle - needle_start;
+ haystack = strchr (haystack_start + 1, *needle_start);
+ if (!haystack || __builtin_expect (needle_len == 1, 0))
+ return (char *) haystack;
+ needle -= needle_len;
+ haystack_len = (haystack > haystack_start + needle_len ? 1
+ : needle_len + haystack_start - haystack);
- if (!(c = *++needle))
- goto foundneedle;
- ++needle;
- goto jin;
-
- for (;;)
- {
- {
- chartype a;
- if (0)
- jin:{
- if ((a = *++haystack) == c)
- goto crest;
- }
- else
- a = *++haystack;
- do
- {
- for (; a != b; a = *++haystack)
- {
- if (!a)
- goto ret0;
- if ((a = *++haystack) == b)
- break;
- if (!a)
- goto ret0;
- }
- }
- while ((a = *++haystack) != c);
- }
- crest:
- {
- chartype a;
- {
- const unsigned char *rhaystack;
- if (*(rhaystack = haystack-- + 1) == (a = *(rneedle = needle)))
- do
- {
- if (!a)
- goto foundneedle;
- if (*++rhaystack != (a = *++needle))
- break;
- if (!a)
- goto foundneedle;
- }
- while (*++rhaystack == (a = *++needle));
- needle = rneedle; /* took the register-poor aproach */
- }
- if (!a)
- break;
- }
- }
- }
-foundneedle:
- return (char *) haystack;
-ret0:
- return 0;
+ /* Perform the search. Abstract memory is considered to be an array
+ of 'unsigned char' values, not an array of 'char' values. See
+ ISO C 99 section 6.2.6.1. */
+ if (needle_len < LONG_NEEDLE_THRESHOLD)
+ return two_way_short_needle ((const unsigned char *) haystack,
+ haystack_len,
+ (const unsigned char *) needle, needle_len);
+ return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
+ (const unsigned char *) needle, needle_len);
}
libc_hidden_builtin_def (strstr)
+
+#undef LONG_NEEDLE_THRESHOLD
projects / platform / upstream / glibc.git / commitdiff