third_party/harfbuzz-ng/src/hb-utf-private.hh

   1 /*
   2  * Copyright © 2011,2012,2014  Google, Inc.
   3  *
   4  *  This is part of HarfBuzz, a text shaping library.
   5  *
   6  * Permission is hereby granted, without written agreement and without
   7  * license or royalty fees, to use, copy, modify, and distribute this
   8  * software and its documentation for any purpose, provided that the
   9  * above copyright notice and the following two paragraphs appear in
  10  * all copies of this software.
  11  *
  12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  16  * DAMAGE.
  17  *
  18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  23  *
  24  * Google Author(s): Behdad Esfahbod
  25  */
  26
  27 #ifndef HB_UTF_PRIVATE_HH
  28 #define HB_UTF_PRIVATE_HH
  29
  30 #include "hb-private.hh"
  31
  32
  33 struct hb_utf8_t
  34 {
  35   typedef uint8_t codepoint_t;
  36
  37   static inline const uint8_t *
  38   next (const uint8_t *text,
  39         const uint8_t *end,
  40         hb_codepoint_t *unicode,
  41         hb_codepoint_t replacement)
  42   {
  43     /* Written to only accept well-formed sequences.
  44      * Based on ideas from ICU's U8_NEXT.
  45      * Generates one "replacement" for each ill-formed byte. */
  46
  47     hb_codepoint_t c = *text++;
  48
  49     if (c > 0x7Fu)
  50     {
  51       if (hb_in_range (c, 0xC2u, 0xDFu)) /* Two-byte */
  52       {
  53         unsigned int t1;
  54         if (likely (text < end &&
  55                     (t1 = text[0] - 0x80u) <= 0x3Fu))
  56         {
  57           c = ((c&0x1Fu)<<6) | t1;
  58           text++;
  59         }
  60         else
  61           goto error;
  62       }
  63       else if (hb_in_range (c, 0xE0u, 0xEFu)) /* Three-byte */
  64       {
  65         unsigned int t1, t2;
  66         if (likely (1 < end - text &&
  67                     (t1 = text[0] - 0x80u) <= 0x3Fu &&
  68                     (t2 = text[1] - 0x80u) <= 0x3Fu))
  69         {
  70           c = ((c&0xFu)<<12) | (t1<<6) | t2;
  71           if (unlikely (c < 0x0800u || hb_in_range (c, 0xD800u, 0xDFFFu)))
  72             goto error;
  73           text += 2;
  74         }
  75         else
  76           goto error;
  77       }
  78       else if (hb_in_range (c, 0xF0u, 0xF4u)) /* Four-byte */
  79       {
  80         unsigned int t1, t2, t3;
  81         if (likely (2 < end - text &&
  82                     (t1 = text[0] - 0x80u) <= 0x3Fu &&
  83                     (t2 = text[1] - 0x80u) <= 0x3Fu &&
  84                     (t3 = text[2] - 0x80u) <= 0x3Fu))
  85         {
  86           c = ((c&0x7u)<<18) | (t1<<12) | (t2<<6) | t3;
  87           if (unlikely (!hb_in_range (c, 0x10000u, 0x10FFFFu)))
  88             goto error;
  89           text += 3;
  90         }
  91         else
  92           goto error;
  93       }
  94       else
  95         goto error;
  96     }
  97
  98     *unicode = c;
  99     return text;
 100
 101   error:
 102     *unicode = replacement;
 103     return text;
 104   }
 105
 106   static inline const uint8_t *
 107   prev (const uint8_t *text,
 108         const uint8_t *start,
 109         hb_codepoint_t *unicode,
 110         hb_codepoint_t replacement)
 111   {
 112     const uint8_t *end = text--;
 113     while (start < text && (*text & 0xc0) == 0x80 && end - text < 4)
 114       text--;
 115
 116     if (likely (next (text, end, unicode, replacement) == end))
 117       return text;
 118
 119     *unicode = replacement;
 120     return end - 1;
 121   }
 122
 123   static inline unsigned int
 124   strlen (const uint8_t *text)
 125   {
 126     return ::strlen ((const char *) text);
 127   }
 128 };
 129
 130
 131 struct hb_utf16_t
 132 {
 133   typedef uint16_t codepoint_t;
 134
 135   static inline const uint16_t *
 136   next (const uint16_t *text,
 137         const uint16_t *end,
 138         hb_codepoint_t *unicode,
 139         hb_codepoint_t replacement)
 140   {
 141     hb_codepoint_t c = *text++;
 142
 143     if (likely (!hb_in_range (c, 0xD800u, 0xDFFFu)))
 144     {
 145       *unicode = c;
 146       return text;
 147     }
 148
 149     if (likely (hb_in_range (c, 0xD800u, 0xDBFFu)))
 150     {
 151       /* High-surrogate in c */
 152       hb_codepoint_t l;
 153       if (text < end && ((l = *text), likely (hb_in_range (l, 0xDC00u, 0xDFFFu))))
 154       {
 155         /* Low-surrogate in l */
 156         *unicode = (c << 10) + l - ((0xD800u << 10) - 0x10000u + 0xDC00u);
 157          text++;
 158          return text;
 159       }
 160     }
 161
 162     /* Lonely / out-of-order surrogate. */
 163     *unicode = replacement;
 164     return text;
 165   }
 166
 167   static inline const uint16_t *
 168   prev (const uint16_t *text,
 169         const uint16_t *start,
 170         hb_codepoint_t *unicode,
 171         hb_codepoint_t replacement)
 172   {
 173     const uint16_t *end = text--;
 174     hb_codepoint_t c = *text;
 175
 176     if (likely (!hb_in_range (c, 0xD800u, 0xDFFFu)))
 177     {
 178       *unicode = c;
 179       return text;
 180     }
 181
 182     if (likely (start < text && hb_in_range (c, 0xDC00u, 0xDFFFu)))
 183       text--;
 184
 185     if (likely (next (text, end, unicode, replacement) == end))
 186       return text;
 187
 188     *unicode = replacement;
 189     return end - 1;
 190   }
 191
 192
 193   static inline unsigned int
 194   strlen (const uint16_t *text)
 195   {
 196     unsigned int l = 0;
 197     while (*text++) l++;
 198     return l;
 199   }
 200 };
 201
 202
 203 template <bool validate=true>
 204 struct hb_utf32_t
 205 {
 206   typedef uint32_t codepoint_t;
 207
 208   static inline const uint32_t *
 209   next (const uint32_t *text,
 210         const uint32_t *end HB_UNUSED,
 211         hb_codepoint_t *unicode,
 212         hb_codepoint_t replacement)
 213   {
 214     hb_codepoint_t c = *text++;
 215     if (validate && unlikely (c > 0x10FFFFu || hb_in_range (c, 0xD800u, 0xDFFFu)))
 216       goto error;
 217     *unicode = c;
 218     return text;
 219
 220   error:
 221     *unicode = replacement;
 222     return text;
 223   }
 224
 225   static inline const uint32_t *
 226   prev (const uint32_t *text,
 227         const uint32_t *start HB_UNUSED,
 228         hb_codepoint_t *unicode,
 229         hb_codepoint_t replacement)
 230   {
 231     next (text - 1, text, unicode, replacement);
 232     return text - 1;
 233   }
 234
 235   static inline unsigned int
 236   strlen (const uint32_t *text)
 237   {
 238     unsigned int l = 0;
 239     while (*text++) l++;
 240     return l;
 241   }
 242 };
 243
 244
 245 struct hb_latin1_t
 246 {
 247   typedef uint8_t codepoint_t;
 248
 249   static inline const uint8_t *
 250   next (const uint8_t *text,
 251         const uint8_t *end HB_UNUSED,
 252         hb_codepoint_t *unicode,
 253         hb_codepoint_t replacement HB_UNUSED)
 254   {
 255     *unicode = *text++;
 256     return text;
 257   }
 258
 259   static inline const uint8_t *
 260   prev (const uint8_t *text,
 261         const uint8_t *start HB_UNUSED,
 262         hb_codepoint_t *unicode,
 263         hb_codepoint_t replacement)
 264   {
 265     *unicode = *--text;
 266     return text;
 267   }
 268
 269   static inline unsigned int
 270   strlen (const uint8_t *text)
 271   {
 272     unsigned int l = 0;
 273     while (*text++) l++;
 274     return l;
 275   }
 276 };
 277
 278 #endif /* HB_UTF_PRIVATE_HH */