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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 #ifndef HB_NO_SHAPER
38 static_assert (0 != ARRAY_LENGTH_CONST (all_shapers), "No shaper enabled.");
39 #endif
40 
41 #if HB_USE_ATEXIT
42 static void free_static_shapers ();
43 #endif
44 
45 static struct hb_shapers_lazy_loader_t : hb_lazy_loader_t<const hb_shaper_entry_t,
46 							  hb_shapers_lazy_loader_t>
47 {
createhb_shapers_lazy_loader_t48   static hb_shaper_entry_t *create ()
49   {
50     char *env = getenv ("HB_SHAPER_LIST");
51     if (!env || !*env)
52       return nullptr;
53 
54     hb_shaper_entry_t *shapers = (hb_shaper_entry_t *) calloc (1, sizeof (all_shapers));
55     if (unlikely (!shapers))
56       return nullptr;
57 
58     memcpy (shapers, all_shapers, sizeof (all_shapers));
59 
60      /* Reorder shaper list to prefer requested shapers. */
61     unsigned int i = 0;
62     char *end, *p = env;
63     for (;;)
64     {
65       end = strchr (p, ',');
66       if (!end)
67 	end = p + strlen (p);
68 
69       for (unsigned int j = i; j < ARRAY_LENGTH (all_shapers); j++)
70 	if (end - p == (int) strlen (shapers[j].name) &&
71 	    0 == strncmp (shapers[j].name, p, end - p))
72 	{
73 	  /* Reorder this shaper to position i */
74 	 struct hb_shaper_entry_t t = shapers[j];
75 	 memmove (&shapers[i + 1], &shapers[i], sizeof (shapers[i]) * (j - i));
76 	 shapers[i] = t;
77 	 i++;
78 	}
79 
80       if (!*end)
81 	break;
82       else
83 	p = end + 1;
84     }
85 
86 #if HB_USE_ATEXIT
87     atexit (free_static_shapers);
88 #endif
89 
90     return shapers;
91   }
destroyhb_shapers_lazy_loader_t92   static void destroy (const hb_shaper_entry_t *p) { free ((void *) p); }
get_nullhb_shapers_lazy_loader_t93   static const hb_shaper_entry_t *get_null ()      { return all_shapers; }
94 } static_shapers;
95 
96 #if HB_USE_ATEXIT
97 static
free_static_shapers()98 void free_static_shapers ()
99 {
100   static_shapers.free_instance ();
101 }
102 #endif
103 
104 const hb_shaper_entry_t *
_hb_shapers_get()105 _hb_shapers_get ()
106 {
107   return static_shapers.get_unconst ();
108 }
109