1/* Line breaking of UTF-16 strings.
2   Copyright (C) 2001-2003, 2006-2010 Free Software Foundation, Inc.
3   Written by Bruno Haible <bruno@clisp.org>, 2001.
4
5   This program is free software: you can redistribute it and/or modify it
6   under the terms of the GNU Lesser General Public License as published
7   by the Free Software Foundation; either version 3 of the License, or
8   (at your option) any later version.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
13   Lesser General Public License for more details.
14
15   You should have received a copy of the GNU Lesser General Public License
16   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
17
18#include <config.h>
19
20/* Specification.  */
21#include "unilbrk.h"
22
23#include <stdlib.h>
24#include <string.h>
25
26#include "unilbrk/lbrktables.h"
27#include "uniwidth/cjk.h"
28#include "unistr.h"
29
30void
31u16_possible_linebreaks (const uint16_t *s, size_t n, const char *encoding, char *p)
32{
33  int LBP_AI_REPLACEMENT = (is_cjk_encoding (encoding) ? LBP_ID : LBP_AL);
34  const uint16_t *s_end = s + n;
35  int last_prop = LBP_BK; /* line break property of last non-space character */
36  char *seen_space = NULL; /* Was a space seen after the last non-space character? */
37  char *seen_space2 = NULL; /* At least two spaces after the last non-space? */
38
39  /* Don't break inside multibyte characters.  */
40  memset (p, UC_BREAK_PROHIBITED, n);
41
42  while (s < s_end)
43    {
44      ucs4_t uc;
45      int count = u16_mbtouc_unsafe (&uc, s, s_end - s);
46      int prop = unilbrkprop_lookup (uc);
47
48      if (prop == LBP_BK)
49        {
50          /* Mandatory break.  */
51          *p = UC_BREAK_MANDATORY;
52          last_prop = LBP_BK;
53          seen_space = NULL;
54          seen_space2 = NULL;
55        }
56      else
57        {
58          char *q;
59
60          /* Resolve property values whose behaviour is not fixed.  */
61          switch (prop)
62            {
63            case LBP_AI:
64              /* Resolve ambiguous.  */
65              prop = LBP_AI_REPLACEMENT;
66              break;
67            case LBP_CB:
68              /* This is arbitrary.  */
69              prop = LBP_ID;
70              break;
71            case LBP_SA:
72              /* We don't handle complex scripts yet.
73                 Treat LBP_SA like LBP_XX.  */
74            case LBP_XX:
75              /* This is arbitrary.  */
76              prop = LBP_AL;
77              break;
78            }
79
80          /* Deal with spaces and combining characters.  */
81          q = p;
82          if (prop == LBP_SP)
83            {
84              /* Don't break just before a space.  */
85              *p = UC_BREAK_PROHIBITED;
86              seen_space2 = seen_space;
87              seen_space = p;
88            }
89          else if (prop == LBP_ZW)
90            {
91              /* Don't break just before a zero-width space.  */
92              *p = UC_BREAK_PROHIBITED;
93              last_prop = LBP_ZW;
94              seen_space = NULL;
95              seen_space2 = NULL;
96            }
97          else if (prop == LBP_CM)
98            {
99              /* Don't break just before a combining character, except immediately after a
100                 zero-width space.  */
101              if (last_prop == LBP_ZW)
102                {
103                  /* Break after zero-width space.  */
104                  *p = UC_BREAK_POSSIBLE;
105                  /* A combining character turns a preceding space into LBP_ID.  */
106                  last_prop = LBP_ID;
107                }
108              else
109                {
110                  *p = UC_BREAK_PROHIBITED;
111                  /* A combining character turns a preceding space into LBP_ID.  */
112                  if (seen_space != NULL)
113                    {
114                      q = seen_space;
115                      seen_space = seen_space2;
116                      prop = LBP_ID;
117                      goto lookup_via_table;
118                    }
119                }
120            }
121          else
122            {
123             lookup_via_table:
124              /* prop must be usable as an index for table 7.3 of UTR #14.  */
125              if (!(prop >= 0 && prop < sizeof (unilbrk_table) / sizeof (unilbrk_table[0])))
126                abort ();
127
128              if (last_prop == LBP_BK)
129                {
130                  /* Don't break at the beginning of a line.  */
131                  *q = UC_BREAK_PROHIBITED;
132                }
133              else if (last_prop == LBP_ZW)
134                {
135                  /* Break after zero-width space.  */
136                  *q = UC_BREAK_POSSIBLE;
137                }
138              else
139                {
140                  switch (unilbrk_table [last_prop] [prop])
141                    {
142                    case D:
143                      *q = UC_BREAK_POSSIBLE;
144                      break;
145                    case I:
146                      *q = (seen_space != NULL ? UC_BREAK_POSSIBLE : UC_BREAK_PROHIBITED);
147                      break;
148                    case P:
149                      *q = UC_BREAK_PROHIBITED;
150                      break;
151                    default:
152                      abort ();
153                    }
154                }
155              last_prop = prop;
156              seen_space = NULL;
157              seen_space2 = NULL;
158            }
159        }
160
161      s += count;
162      p += count;
163    }
164}
165