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Diffstat (limited to 'lib/c-strcasestr.c')
| -rw-r--r-- | lib/c-strcasestr.c | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/lib/c-strcasestr.c b/lib/c-strcasestr.c new file mode 100644 index 0000000..cffece8 --- /dev/null +++ b/lib/c-strcasestr.c @@ -0,0 +1,77 @@ +/* c-strcasestr.c -- case insensitive substring search in C locale + Copyright (C) 2005-2015 Free Software Foundation, Inc. + Written by Bruno Haible <bruno@clisp.org>, 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 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 + 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, see <http://www.gnu.org/licenses/>. */ + +#include <config.h> + +/* Specification. */ +#include "c-strcasestr.h" + +#include <stdbool.h> +#include <string.h> + +#include "c-ctype.h" +#include "c-strcase.h" + +/* 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 +#define CMP_FUNC(p1, p2, l) \ + c_strncasecmp ((const char *) (p1), (const char *) (p2), l) +#include "str-two-way.h" + +/* Find the first occurrence of NEEDLE in HAYSTACK, using case-insensitive + comparison from the C locale, regardless of the current locale. */ +char * +c_strcasestr (const char *haystack_start, const char *needle_start) +{ + 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) + ok &= (c_tolower ((unsigned char) *haystack++) + == c_tolower ((unsigned char) *needle++)); + 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 |