root/maint/gnulib/lib/unigbrk/u8-grapheme-prev.c

/* */

DEFINITIONS

1. u8_grapheme_prev

   1 /* Previous grapheme cluster function.
   2    Copyright (C) 2010-2021 Free Software Foundation, Inc.
   3    Written by Ben Pfaff <blp@cs.stanford.edu>, 2010.
   4 
   5    This file is free software.
   6    It is dual-licensed under "the GNU LGPLv3+ or the GNU GPLv2+".
   7    You can redistribute it and/or modify it under either
   8      - the terms of the GNU Lesser General Public License as published
   9        by the Free Software Foundation; either version 3, or (at your
  10        option) any later version, or
  11      - the terms of the GNU General Public License as published by the
  12        Free Software Foundation; either version 2, or (at your option)
  13        any later version, or
  14      - the same dual license "the GNU LGPLv3+ or the GNU GPLv2+".
  15 
  16    This file is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19    Lesser General Public License and the GNU General Public License
  20    for more details.
  21 
  22    You should have received a copy of the GNU Lesser General Public
  23    License and of the GNU General Public License along with this
  24    program.  If not, see <https://www.gnu.org/licenses/>.  */
  25 
  26 #include <config.h>
  27 
  28 /* Specification.  */
  29 #include "unigbrk.h"
  30 
  31 #include "unistr.h"
  32 
  33 const uint8_t *
  34 u8_grapheme_prev (const uint8_t *s, const uint8_t *start)
     /*  */
  35 {
  36   ucs4_t next;
  37 
  38   if (s == start)
  39     return NULL;
  40 
  41   s = u8_prev (&next, s, start);
  42   while (s != start)
  43     {
  44       const uint8_t *prev_s;
  45       ucs4_t prev;
  46 
  47       prev_s = u8_prev (&prev, s, start);
  48       if (prev_s == NULL)
  49         {
  50           /* Ill-formed UTF-8 encoding. */
  51           return start;
  52         }
  53 
  54       if (uc_is_grapheme_break (prev, next))
  55         break;
  56 
  57       s = prev_s;
  58       next = prev;
  59     }
  60 
  61   return s;
  62 }

/* */