74 lines
2.1 KiB
C
74 lines
2.1 KiB
C
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/* Determine the number of screen columns needed for a character.
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Copyright (C) 2006-2007, 2010-2023 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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#include <config.h>
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/* Specification. */
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#include <wchar.h>
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/* Get iswprint. */
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#include <wctype.h>
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#include "localcharset.h"
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#include "streq.h"
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#include "uniwidth.h"
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/* Returns 1 if the current locale is an UTF-8 locale, 0 otherwise. */
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static inline int
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is_locale_utf8 (void)
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{
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const char *encoding = locale_charset ();
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return STREQ_OPT (encoding, "UTF-8", 'U', 'T', 'F', '-', '8', 0, 0, 0, 0);
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}
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#if GNULIB_WCHAR_SINGLE_LOCALE
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/* When we know that the locale does not change, provide a speedup by
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caching the value of is_locale_utf8. */
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static int cached_is_locale_utf8 = -1;
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static inline int
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is_locale_utf8_cached (void)
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{
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if (cached_is_locale_utf8 < 0)
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cached_is_locale_utf8 = is_locale_utf8 ();
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return cached_is_locale_utf8;
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}
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#else
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/* By default, don't make assumptions, hence no caching. */
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# define is_locale_utf8_cached is_locale_utf8
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#endif
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int
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wcwidth (wchar_t wc)
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#undef wcwidth
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{
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/* In UTF-8 locales, use a Unicode aware width function. */
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if (is_locale_utf8_cached ())
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{
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/* We assume that in a UTF-8 locale, a wide character is the same as a
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Unicode character. */
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return uc_width (wc, "UTF-8");
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}
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else
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{
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/* Otherwise, fall back to the system's wcwidth function. */
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#if HAVE_WCWIDTH
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return wcwidth (wc);
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#else
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return wc == 0 ? 0 : iswprint (wc) ? 1 : -1;
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#endif
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}
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}
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