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mbswidth.c

/* Determine the number of screen columns needed for a string.
   Copyright (C) 2000-2007 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 <http://www.gnu.org/licenses/>.  */

/* Written by Bruno Haible <haible@clisp.cons.org>.  */

#include <config.h>

/* Specification.  */
#include "mbswidth.h"

/* Get MB_CUR_MAX.  */
#include <stdlib.h>

#include <string.h>

/* Get isprint().  */
#include <ctype.h>

/* Get mbstate_t, mbrtowc(), mbsinit(), wcwidth().  */
#include <wchar.h>

/* Get iswcntrl().  */
#include <wctype.h>

#ifndef mbsinit
# if !HAVE_MBSINIT
#  define mbsinit(ps) 1
# endif
#endif

/* Returns the number of columns needed to represent the multibyte
   character string pointed to by STRING.  If a non-printable character
   occurs, and MBSW_REJECT_UNPRINTABLE is specified, -1 is returned.
   With flags = MBSW_REJECT_INVALID | MBSW_REJECT_UNPRINTABLE, this is
   the multibyte analogue of the wcswidth function.
   If STRING is not of length < INT_MAX / 2, integer overflow can occur.  */
int
mbswidth (const char *string, int flags)
{
  return mbsnwidth (string, strlen (string), flags);
}

/* Returns the number of columns needed to represent the multibyte
   character string pointed to by STRING of length NBYTES.  If a
   non-printable character occurs, and MBSW_REJECT_UNPRINTABLE is
   specified, -1 is returned.
   If NBYTES is not < INT_MAX / 2, integer overflow can occur.  */
int
mbsnwidth (const char *string, size_t nbytes, int flags)
{
  const char *p = string;
  const char *plimit = p + nbytes;
  int width;

  width = 0;
#if HAVE_MBRTOWC
  if (MB_CUR_MAX > 1)
    {
      while (p < plimit)
      switch (*p)
        {
          case ' ': case '!': case '"': case '#': case '%':
          case '&': case '\'': case '(': case ')': case '*':
          case '+': case ',': case '-': case '.': case '/':
          case '0': case '1': case '2': case '3': case '4':
          case '5': case '6': case '7': case '8': case '9':
          case ':': case ';': case '<': case '=': case '>':
          case '?':
          case 'A': case 'B': case 'C': case 'D': case 'E':
          case 'F': case 'G': case 'H': case 'I': case 'J':
          case 'K': case 'L': case 'M': case 'N': case 'O':
          case 'P': case 'Q': case 'R': case 'S': case 'T':
          case 'U': case 'V': case 'W': case 'X': case 'Y':
          case 'Z':
          case '[': case '\\': case ']': case '^': case '_':
          case 'a': case 'b': case 'c': case 'd': case 'e':
          case 'f': case 'g': case 'h': case 'i': case 'j':
          case 'k': case 'l': case 'm': case 'n': case 'o':
          case 'p': case 'q': case 'r': case 's': case 't':
          case 'u': case 'v': case 'w': case 'x': case 'y':
          case 'z': case '{': case '|': case '}': case '~':
            /* These characters are printable ASCII characters.  */
            p++;
            width++;
            break;
          default:
            /* If we have a multibyte sequence, scan it up to its end.  */
            {
            mbstate_t mbstate;
            memset (&mbstate, 0, sizeof mbstate);
            do
              {
                wchar_t wc;
                size_t bytes;
                int w;

                bytes = mbrtowc (&wc, p, plimit - p, &mbstate);

                if (bytes == (size_t) -1)
                  /* An invalid multibyte sequence was encountered.  */
                  {
                  if (!(flags & MBSW_REJECT_INVALID))
                    {
                      p++;
                      width++;
                      break;
                    }
                  else
                    return -1;
                  }

                if (bytes == (size_t) -2)
                  /* An incomplete multibyte character at the end.  */
                  {
                  if (!(flags & MBSW_REJECT_INVALID))
                    {
                      p = plimit;
                      width++;
                      break;
                    }
                  else
                    return -1;
                  }

                if (bytes == 0)
                  /* A null wide character was encountered.  */
                  bytes = 1;

                w = wcwidth (wc);
                if (w >= 0)
                  /* A printable multibyte character.  */
                  width += w;
                else
                  /* An unprintable multibyte character.  */
                  if (!(flags & MBSW_REJECT_UNPRINTABLE))
                  width += (iswcntrl (wc) ? 0 : 1);
                  else
                  return -1;

                p += bytes;
              }
            while (! mbsinit (&mbstate));
            }
            break;
        }
      return width;
    }
#endif

  while (p < plimit)
    {
      unsigned char c = (unsigned char) *p++;

      if (isprint (c))
      width++;
      else if (!(flags & MBSW_REJECT_UNPRINTABLE))
      width += (iscntrl (c) ? 0 : 1);
      else
      return -1;
    }
  return width;
}

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