michael@0: /*
michael@0:  * Copyright © 2012  Google, Inc.
michael@0:  *
michael@0:  *  This is part of HarfBuzz, a text shaping library.
michael@0:  *
michael@0:  * Permission is hereby granted, without written agreement and without
michael@0:  * license or royalty fees, to use, copy, modify, and distribute this
michael@0:  * software and its documentation for any purpose, provided that the
michael@0:  * above copyright notice and the following two paragraphs appear in
michael@0:  * all copies of this software.
michael@0:  *
michael@0:  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
michael@0:  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
michael@0:  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
michael@0:  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
michael@0:  * DAMAGE.
michael@0:  *
michael@0:  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
michael@0:  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
michael@0:  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
michael@0:  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
michael@0:  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
michael@0:  *
michael@0:  * Google Author(s): Behdad Esfahbod
michael@0:  */
michael@0: 
michael@0: #include "hb-private.hh"
michael@0: #include "hb-shaper-private.hh"
michael@0: #include "hb-atomic-private.hh"
michael@0: 
michael@0: 
michael@0: static const hb_shaper_pair_t all_shapers[] = {
michael@0: #define HB_SHAPER_IMPLEMENT(name) {#name, _hb_##name##_shape},
michael@0: #include "hb-shaper-list.hh"
michael@0: #undef HB_SHAPER_IMPLEMENT
michael@0: };
michael@0: 
michael@0: 
michael@0: /* Thread-safe, lock-free, shapers */
michael@0: 
michael@0: static const hb_shaper_pair_t *static_shapers;
michael@0: 
michael@0: static inline
michael@0: void free_static_shapers (void)
michael@0: {
michael@0:   if (unlikely (static_shapers != all_shapers))
michael@0:     free ((void *) static_shapers);
michael@0: }
michael@0: 
michael@0: const hb_shaper_pair_t *
michael@0: _hb_shapers_get (void)
michael@0: {
michael@0: retry:
michael@0:   hb_shaper_pair_t *shapers = (hb_shaper_pair_t *) hb_atomic_ptr_get (&static_shapers);
michael@0: 
michael@0:   if (unlikely (!shapers))
michael@0:   {
michael@0:     char *env = getenv ("HB_SHAPER_LIST");
michael@0:     if (!env || !*env) {
michael@0:       (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);
michael@0:       return (const hb_shaper_pair_t *) all_shapers;
michael@0:     }
michael@0: 
michael@0:     /* Not found; allocate one. */
michael@0:     shapers = (hb_shaper_pair_t *) malloc (sizeof (all_shapers));
michael@0:     if (unlikely (!shapers)) {
michael@0:       (void) hb_atomic_ptr_cmpexch (&static_shapers, NULL, &all_shapers[0]);
michael@0:       return (const hb_shaper_pair_t *) all_shapers;
michael@0:     }
michael@0: 
michael@0:     memcpy (shapers, all_shapers, sizeof (all_shapers));
michael@0: 
michael@0:      /* Reorder shaper list to prefer requested shapers. */
michael@0:     unsigned int i = 0;
michael@0:     char *end, *p = env;
michael@0:     for (;;) {
michael@0:       end = strchr (p, ',');
michael@0:       if (!end)
michael@0: 	end = p + strlen (p);
michael@0: 
michael@0:       for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)
michael@0: 	if (end - p == (int) strlen (shapers[j].name) &&
michael@0: 	    0 == strncmp (shapers[j].name, p, end - p))
michael@0: 	{
michael@0: 	  /* Reorder this shaper to position i */
michael@0: 	 struct hb_shaper_pair_t t = shapers[j];
michael@0: 	 memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
michael@0: 	 shapers[i] = t;
michael@0: 	 i++;
michael@0: 	}
michael@0: 
michael@0:       if (!*end)
michael@0: 	break;
michael@0:       else
michael@0: 	p = end + 1;
michael@0:     }
michael@0: 
michael@0:     if (!hb_atomic_ptr_cmpexch (&static_shapers, NULL, shapers)) {
michael@0:       free (shapers);
michael@0:       goto retry;
michael@0:     }
michael@0: 
michael@0: #ifdef HAVE_ATEXIT
michael@0:     atexit (free_static_shapers); /* First person registers atexit() callback. */
michael@0: #endif
michael@0:   }
michael@0: 
michael@0:   return shapers;
michael@0: }