maint/gnulib/lib/unilbrk/u16-possible-linebreaks.c

/* */
This source file includes following definitions.
u16_possible_linebreaks
   1 /* Line breaking of UTF-16 strings.
   2    Copyright (C) 2001-2003, 2006-2021 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2001.
   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 "unilbrk.h"
  30 
  31 #include <stdlib.h>
  32 #include <string.h>
  33 
  34 #include "unilbrk/lbrktables.h"
  35 #include "uniwidth/cjk.h"
  36 #include "unistr.h"
  37 
  38 void
  39 u16_possible_linebreaks (const uint16_t *s, size_t n, const char *encoding, char *p)
     /*  */
  40 {
  41   if (n > 0)
  42     {
  43       int LBP_AI_REPLACEMENT = (is_cjk_encoding (encoding) ? LBP_ID : LBP_AL);
  44       const uint16_t *s_end = s + n;
  45       int last_prop = LBP_BK; /* line break property of last non-space character */
  46       char *seen_space = NULL; /* Was a space seen after the last non-space character? */
  47       char *seen_space2 = NULL; /* At least two spaces after the last non-space? */
  48 
  49       /* Don't break inside multibyte characters.  */
  50       memset (p, UC_BREAK_PROHIBITED, n);
  51 
  52       do
  53         {
  54           ucs4_t uc;
  55           int count = u16_mbtouc_unsafe (&uc, s, s_end - s);
  56           int prop = unilbrkprop_lookup (uc);
  57 
  58           if (prop == LBP_BK)
  59             {
  60               /* Mandatory break.  */
  61               *p = UC_BREAK_MANDATORY;
  62               last_prop = LBP_BK;
  63               seen_space = NULL;
  64               seen_space2 = NULL;
  65             }
  66           else
  67             {
  68               char *q;
  69 
  70               /* Resolve property values whose behaviour is not fixed.  */
  71               switch (prop)
  72                 {
  73                 case LBP_AI:
  74                   /* Resolve ambiguous.  */
  75                   prop = LBP_AI_REPLACEMENT;
  76                   break;
  77                 case LBP_CB:
  78                   /* This is arbitrary.  */
  79                   prop = LBP_ID;
  80                   break;
  81                 case LBP_SA:
  82                   /* We don't handle complex scripts yet.
  83                      Treat LBP_SA like LBP_XX.  */
  84                 case LBP_XX:
  85                   /* This is arbitrary.  */
  86                   prop = LBP_AL;
  87                   break;
  88                 }
  89 
  90               /* Deal with spaces and combining characters.  */
  91               q = p;
  92               if (prop == LBP_SP)
  93                 {
  94                   /* Don't break just before a space.  */
  95                   *p = UC_BREAK_PROHIBITED;
  96                   seen_space2 = seen_space;
  97                   seen_space = p;
  98                 }
  99               else if (prop == LBP_ZW)
 100                 {
 101                   /* Don't break just before a zero-width space.  */
 102                   *p = UC_BREAK_PROHIBITED;
 103                   last_prop = LBP_ZW;
 104                   seen_space = NULL;
 105                   seen_space2 = NULL;
 106                 }
 107               else if (prop == LBP_CM)
 108                 {
 109                   /* Don't break just before a combining character, except immediately
 110                      after a zero-width space.  */
 111                   if (last_prop == LBP_ZW)
 112                     {
 113                       /* Break after zero-width space.  */
 114                       *p = UC_BREAK_POSSIBLE;
 115                       /* A combining character turns a preceding space into LBP_ID.  */
 116                       last_prop = LBP_ID;
 117                     }
 118                   else
 119                     {
 120                       *p = UC_BREAK_PROHIBITED;
 121                       /* A combining character turns a preceding space into LBP_ID.  */
 122                       if (seen_space != NULL)
 123                         {
 124                           q = seen_space;
 125                           seen_space = seen_space2;
 126                           prop = LBP_ID;
 127                           goto lookup_via_table;
 128                         }
 129                     }
 130                 }
 131               else
 132                 {
 133                  lookup_via_table:
 134                   /* prop must be usable as an index for table 7.3 of UTR #14.  */
 135                   if (!(prop >= 0 && prop < sizeof (unilbrk_table) / sizeof (unilbrk_table[0])))
 136                     abort ();
 137 
 138                   if (last_prop == LBP_BK)
 139                     {
 140                       /* Don't break at the beginning of a line.  */
 141                       *q = UC_BREAK_PROHIBITED;
 142                     }
 143                   else if (last_prop == LBP_ZW)
 144                     {
 145                       /* Break after zero-width space.  */
 146                       *q = UC_BREAK_POSSIBLE;
 147                     }
 148                   else
 149                     {
 150                       switch (unilbrk_table [last_prop] [prop])
 151                         {
 152                         case D:
 153                           *q = UC_BREAK_POSSIBLE;
 154                           break;
 155                         case I:
 156                           *q = (seen_space != NULL ? UC_BREAK_POSSIBLE : UC_BREAK_PROHIBITED);
 157                           break;
 158                         case P:
 159                           *q = UC_BREAK_PROHIBITED;
 160                           break;
 161                         default:
 162                           abort ();
 163                         }
 164                     }
 165                   last_prop = prop;
 166                   seen_space = NULL;
 167                   seen_space2 = NULL;
 168                 }
 169             }
 170 
 171           s += count;
 172           p += count;
 173         }
 174       while (s < s_end);
 175     }
 176 }
/* */
root/maint/gnulib/lib/unilbrk/u16-possible-linebreaks.c

DEFINITIONS
