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/* Determine the number of screen columns needed for a character.
Copyright (C) 2006-2007, 2010-2021 Free Software Foundation, Inc.
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 2.1 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/>. */
#include <config.h>
/* Specification. */
#include <wchar.h>
/* Get iswprint. */
#include <wctype.h>
#include "localcharset.h"
#include "streq.h"
#include "uniwidth.h"
/* Returns 1 if the current locale is an UTF-8 locale, 0 otherwise. */
static inline int
is_locale_utf8 (void)
{
const char *encoding = locale_charset ();
return STREQ_OPT (encoding, "UTF-8", 'U', 'T', 'F', '-', '8', 0, 0, 0, 0);
}
#if GNULIB_WCHAR_SINGLE_LOCALE
/* When we know that the locale does not change, provide a speedup by
caching the value of is_locale_utf8. */
static int cached_is_locale_utf8 = -1;
static inline int
is_locale_utf8_cached (void)
{
if (cached_is_locale_utf8 < 0)
cached_is_locale_utf8 = is_locale_utf8 ();
return cached_is_locale_utf8;
}
#else
/* By default, don't make assumptions, hence no caching. */
# define is_locale_utf8_cached is_locale_utf8
#endif
int
wcwidth (wchar_t wc)
#undef wcwidth
{
/* In UTF-8 locales, use a Unicode aware width function. */
if (is_locale_utf8_cached ())
{
/* We assume that in a UTF-8 locale, a wide character is the same as a
Unicode character. */
return uc_width (wc, "UTF-8");
}
else
{
/* Otherwise, fall back to the system's wcwidth function. */
#if HAVE_WCWIDTH
return wcwidth (wc);
#else
return wc == 0 ? 0 : iswprint (wc) ? 1 : -1;
#endif
}
}
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