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Collin Funk
76 lines
2.0 KiB
C
76 lines
2.0 KiB
C
/* Locate a substring in a wide string.
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Copyright (C) 2011-2026 Free Software Foundation, Inc.
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Written by Bruno Haible <bruno@clisp.org>, 2011.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Bruno Haible, 1999. */
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#include <config.h>
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/* Specification. */
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#include <wchar.h>
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#if NEED_LINEAR_WCSSTR
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/* Use Two-Way algorithm, worst-case O(n+m). */
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# define FUNC wcsstr
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# define UNIT wchar_t
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# define RETURN_TYPE wchar_t *
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# define MEMCHR0(s, n) wmemchr (s, 0, n)
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# define STRCHR wcschr
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# include "wcsstr-impl.h"
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#else
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/* Use simple implementation, worst-case O(nm). */
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wchar_t *
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wcsstr (const wchar_t *haystack, const wchar_t *needle)
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{
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wchar_t n = needle[0];
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/* Is needle empty? */
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if (n == (wchar_t)'\0')
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return (wchar_t *) haystack;
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/* Is needle nearly empty? */
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if (needle[1] == (wchar_t)'\0')
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return wcschr (haystack, n);
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/* Search for needle's first character. */
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for (; *haystack != (wchar_t)'\0'; haystack++)
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{
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if (*haystack == n)
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{
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/* Compare with needle's remaining characters. */
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const wchar_t *hptr = haystack + 1;
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const wchar_t *nptr = needle + 1;
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for (;;)
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{
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if (*hptr != *nptr)
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break;
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hptr++; nptr++;
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if (*nptr == (wchar_t)'\0')
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return (wchar_t *) haystack;
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}
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}
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}
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return NULL;
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}
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#endif
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