57 lines
2.2 KiB
C
Executable File
57 lines
2.2 KiB
C
Executable File
/* Locate a substring in a wide string.
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Copyright (C) 1999, 2011-2024 Free Software Foundation, Inc.
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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 Eric Blake, 2008. */
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#define AVAILABLE(h, h_l, j, n_l) \
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(!MEMCHR0 ((h) + (h_l), (j) + (n_l) - (h_l)) \
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&& ((h_l) = (j) + (n_l)))
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#include "wcs-two-way.h"
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RETURN_TYPE
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FUNC (const UNIT *haystack_start, const UNIT *needle_start)
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{
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const UNIT *haystack = haystack_start;
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const UNIT *needle = needle_start;
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size_t needle_len; /* Length of NEEDLE. */
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size_t haystack_len; /* Known minimum length of HAYSTACK. */
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bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */
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/* Determine length of NEEDLE, and in the process, make sure
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HAYSTACK is at least as long (no point processing all of a long
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NEEDLE if HAYSTACK is too short). */
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while (*haystack && *needle)
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ok &= *haystack++ == *needle++;
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if (*needle)
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return NULL;
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if (ok)
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return (RETURN_TYPE) haystack_start;
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/* Reduce the size of haystack using STRCHR, since it has a smaller
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linear coefficient than the Two-Way algorithm. */
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needle_len = needle - needle_start;
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haystack = STRCHR (haystack_start + 1, *needle_start);
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if (!haystack || __builtin_expect (needle_len == 1, 0))
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return (RETURN_TYPE) haystack;
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needle -= needle_len;
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haystack_len = (haystack > haystack_start + needle_len ? 1
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: needle_len + haystack_start - haystack);
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/* Perform the search. */
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return two_way_short_needle (haystack, haystack_len,
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needle, needle_len);
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}
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