gfx/harfbuzz/src/hb-shaper.cc

   1 /*
   2  * Copyright © 2012  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 #include "hb.hh"
  28 #include "hb-shaper.hh"
  29 #include "hb-machinery.hh"
  30
  31
  32 static const hb_shaper_entry_t _hb_all_shapers[] = {
  33 #define HB_SHAPER_IMPLEMENT(name) {#name, _hb_##name##_shape},
  34 #include "hb-shaper-list.hh"
  35 #undef HB_SHAPER_IMPLEMENT
  36 };
  37 #ifndef HB_NO_SHAPER
  38 static_assert (0 != ARRAY_LENGTH_CONST (_hb_all_shapers), "No shaper enabled.");
  39 #endif
  40
  41 static inline void free_static_shapers ();
  42
  43 static struct hb_shapers_lazy_loader_t : hb_lazy_loader_t<hb_shaper_entry_t,
  44                                                           hb_shapers_lazy_loader_t>
  45 {
  46   static hb_shaper_entry_t *create ()
  47   {
  48     char *env = getenv ("HB_SHAPER_LIST");
  49     if (!env || !*env)
  50       return nullptr;
  51
  52     hb_shaper_entry_t *shapers = (hb_shaper_entry_t *) hb_calloc (1, sizeof (_hb_all_shapers));
  53     if (unlikely (!shapers))
  54       return nullptr;
  55
  56     hb_memcpy (shapers, _hb_all_shapers, sizeof (_hb_all_shapers));
  57
  58      /* Reorder shaper list to prefer requested shapers. */
  59     unsigned int i = 0;
  60     char *end, *p = env;
  61     for (;;)
  62     {
  63       end = strchr (p, ',');
  64       if (!end)
  65         end = p + strlen (p);
  66
  67       for (unsigned int j = i; j < ARRAY_LENGTH_CONST (_hb_all_shapers); j++)
  68         if (end - p == (int) strlen (shapers[j].name) &&
  69             0 == strncmp (shapers[j].name, p, end - p))
  70         {
  71           /* Reorder this shaper to position i */
  72          struct hb_shaper_entry_t t = shapers[j];
  73          memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
  74          shapers[i] = t;
  75          i++;
  76         }
  77
  78       if (!*end)
  79         break;
  80       else
  81         p = end + 1;
  82     }
  83
  84     hb_atexit (free_static_shapers);
  85
  86     return shapers;
  87   }
  88   static void destroy (hb_shaper_entry_t *p) { hb_free (p); }
  89   static const hb_shaper_entry_t *get_null ()      { return _hb_all_shapers; }
  90 } static_shapers;
  91
  92 static inline
  93 void free_static_shapers ()
  94 {
  95   static_shapers.free_instance ();
  96 }
  97
  98 const hb_shaper_entry_t *
  99 _hb_shapers_get ()
 100 {
 101   return static_shapers.get_unconst ();
 102 }