/* Determine the number of screen columns needed for a character.

   Copyright (C) 2006-2007, 2010-2018 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU 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

/* 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_width1 (wc);

    }

  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

    }

}