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annotate lib/unilbrk/u16-width-linebreaks.c @ 40057:b06060465f09

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maint: Run 'make update-copyright'
author Paul Eggert <eggert@cs.ucla.edu>
date Tue, 01 Jan 2019 00:25:11 +0100
parents 10eb9086bea0
children
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1 /* Line breaking of UTF-16 strings.
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2 Copyright (C) 2001-2003, 2006-2019 Free Software Foundation, Inc.
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3 Written by Bruno Haible <bruno@clisp.org>, 2001.
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4
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5 This program is free software: you can redistribute it and/or modify it
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6 under the terms of the GNU Lesser General Public License as published
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7 by the Free Software Foundation; either version 3 of the License, or
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8 (at your option) any later version.
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9
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10 This program is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Lesser General Public License for more details.
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14
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15 You should have received a copy of the GNU Lesser General Public License
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16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
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17
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18 #include <config.h>
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19
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20 /* Specification. */
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21 #include "unilbrk.h"
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22
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23 #include "unistr.h"
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24 #include "uniwidth.h"
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25
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26 int
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27 u16_width_linebreaks (const uint16_t *s, size_t n,
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28 int width, int start_column, int at_end_columns,
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29 const char *o, const char *encoding,
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30 char *p)
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31 {
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32 const uint16_t *s_end;
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33 char *last_p;
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34 int last_column;
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35 int piece_width;
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36
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37 u16_possible_linebreaks (s, n, encoding, p);
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38
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39 s_end = s + n;
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40 last_p = NULL;
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41 last_column = start_column;
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42 piece_width = 0;
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43 while (s < s_end)
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44 {
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45 ucs4_t uc;
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46 int count = u16_mbtouc_unsafe (&uc, s, s_end - s);
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47
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48 /* Respect the override. */
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49 if (o != NULL && *o != UC_BREAK_UNDEFINED)
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50 *p = *o;
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51
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52 if (*p == UC_BREAK_POSSIBLE || *p == UC_BREAK_MANDATORY)
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53 {
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54 /* An atomic piece of text ends here. */
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55 if (last_p != NULL && last_column + piece_width > width)
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56 {
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57 /* Insert a line break. */
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58 *last_p = UC_BREAK_POSSIBLE;
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59 last_column = 0;
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60 }
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61 }
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62
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63 if (*p == UC_BREAK_MANDATORY)
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64 {
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65 /* uc is a line break character. */
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66 /* Start a new piece at column 0. */
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67 last_p = NULL;
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68 last_column = 0;
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69 piece_width = 0;
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70 }
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71 else
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72 {
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73 /* uc is not a line break character. */
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74 int w;
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75
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76 if (*p == UC_BREAK_POSSIBLE)
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77 {
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78 /* Start a new piece. */
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79 last_p = p;
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80 last_column += piece_width;
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81 piece_width = 0;
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82 /* No line break for the moment, may be turned into
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83 UC_BREAK_POSSIBLE later, via last_p. */
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84 }
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85
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86 *p = UC_BREAK_PROHIBITED;
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87
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88 w = uc_width (uc, encoding);
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89 if (w >= 0) /* ignore control characters in the string */
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90 piece_width += w;
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91 }
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92
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93 s += count;
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94 p += count;
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95 if (o != NULL)
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96 o += count;
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97 }
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98
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99 /* The last atomic piece of text ends here. */
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100 if (last_p != NULL && last_column + piece_width + at_end_columns > width)
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101 {
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102 /* Insert a line break. */
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103 *last_p = UC_BREAK_POSSIBLE;
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104 last_column = 0;
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105 }
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106
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107 return last_column + piece_width;
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108 }