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/* Locate a substring in a wide string.
Copyright (C) 2011-2023 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2011.
This file 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 3 of the
License, or (at your option) any later version.
This file 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 this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible, 1999. */
#include <config.h>
/* Specification. */
#include <wchar.h>
#if NEED_LINEAR_WCSSTR
/* Use Two-Way algorithm, worst-case O(n+m). */
# define FUNC wcsstr
# define UNIT wchar_t
# define RETURN_TYPE wchar_t *
# define MEMCHR0(s, n) wmemchr (s, 0, n)
# define STRCHR wcschr
# include "wcsstr-impl.h"
#else
/* Use simple implementation, worst-case O(nm). */
wchar_t *
wcsstr (const wchar_t *haystack, const wchar_t *needle)
{
wchar_t n = needle[0];
/* Is needle empty? */
if (n == (wchar_t)'\0')
return (wchar_t *) haystack;
/* Is needle nearly empty? */
if (needle[1] == (wchar_t)'\0')
return wcschr (haystack, n);
/* Search for needle's first character. */
for (; *haystack != (wchar_t)'\0'; haystack++)
{
if (*haystack == n)
{
/* Compare with needle's remaining characters. */
const wchar_t *hptr = haystack + 1;
const wchar_t *nptr = needle + 1;
for (;;)
{
if (*hptr != *nptr)
break;
hptr++; nptr++;
if (*nptr == (wchar_t)'\0')
return (wchar_t *) haystack;
}
}
}
return NULL;
}
#endif
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