Home | History | Annotate | Download | only in src 
      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 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 
     38 #if HB_USE_ATEXIT
     39 static void free_static_shapers ();
     40 #endif
     41 
     42 static struct hb_shapers_lazy_loader_t : hb_lazy_loader_t<const hb_shaper_entry_t,
     43 							  hb_shapers_lazy_loader_t>
     44 {
     45   static hb_shaper_entry_t *create ()
     46   {
     47     char *env = getenv ("HB_SHAPER_LIST");
     48     if (!env || !*env)
     49       return nullptr;
     50 
     51     hb_shaper_entry_t *shapers = (hb_shaper_entry_t *) calloc (1, sizeof (all_shapers));
     52     if (unlikely (!shapers))
     53       return nullptr;
     54 
     55     memcpy (shapers, all_shapers, sizeof (all_shapers));
     56 
     57      /* Reorder shaper list to prefer requested shapers. */
     58     unsigned int i = 0;
     59     char *end, *p = env;
     60     for (;;)
     61     {
     62       end = strchr (p, ',');
     63       if (!end)
     64 	end = p + strlen (p);
     65 
     66       for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)
     67 	if (end - p == (int) strlen (shapers[j].name) &&
     68 	    0 == strncmp (shapers[j].name, p, end - p))
     69 	{
     70 	  /* Reorder this shaper to position i */
     71 	 struct hb_shaper_entry_t t = shapers[j];
     72 	 memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
     73 	 shapers[i] = t;
     74 	 i++;
     75 	}
     76 
     77       if (!*end)
     78 	break;
     79       else
     80 	p = end + 1;
     81     }
     82 
     83 #if HB_USE_ATEXIT
     84     atexit (free_static_shapers);
     85 #endif
     86 
     87     return shapers;
     88   }
     89   static void destroy (const hb_shaper_entry_t *p) { free ((void *) p); }
     90   static const hb_shaper_entry_t *get_null ()      { return all_shapers; }
     91 } static_shapers;
     92 
     93 #if HB_USE_ATEXIT
     94 static
     95 void free_static_shapers ()
     96 {
     97   static_shapers.free_instance ();
     98 }
     99 #endif
    100 
    101 const hb_shaper_entry_t *
    102 _hb_shapers_get ()
    103 {
    104   return static_shapers.get_unconst ();
    105 }
    106