src/hb-ot-shape-complex-arabic-fallback.hh - third_party/harfbuzz - Git at Google

 /*
  * Copyright © 2012  Google, Inc.
  *
  *  This is part of HarfBuzz, a text shaping library.
  *
  * Permission is hereby granted, without written agreement and without
  * license or royalty fees, to use, copy, modify, and distribute this
  * software and its documentation for any purpose, provided that the
  * above copyright notice and the following two paragraphs appear in
  * all copies of this software.
  *
  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  * DAMAGE.
  *
  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  *
  * Google Author(s): Behdad Esfahbod
  */

 #ifndef HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH
 #define HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH

 #include "hb-private.hh"

 #include "hb-ot-shape-private.hh"
 #include "hb-ot-layout-gsub-table.hh"


 /* Features ordered the same as the entries in shaping_table rows,
  * followed by rlig.  Don't change. */
 static const hb_tag_t arabic_fallback_features[] =
 {
   HB_TAG('i','n','i','t'),
   HB_TAG('m','e','d','i'),
   HB_TAG('f','i','n','a'),
   HB_TAG('i','s','o','l'),
   HB_TAG('r','l','i','g'),
 };

 static OT::SubstLookup *
 arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED,
 					  hb_font_t *font,
 					  unsigned int feature_index)
 {
   OT::GlyphID glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
   OT::GlyphID substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
   unsigned int num_glyphs = 0;

   /* Populate arrays */
   for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++)
   {
     hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index];
     hb_codepoint_t u_glyph, s_glyph;

     if (!s ||
 	!hb_font_get_glyph (font, u, 0, &u_glyph) ||
 	!hb_font_get_glyph (font, s, 0, &s_glyph) ||
 	u_glyph == s_glyph ||
 	u_glyph > 0xFFFFu || s_glyph > 0xFFFFu)
       continue;

     glyphs[num_glyphs].set (u_glyph);
     substitutes[num_glyphs].set (s_glyph);

     num_glyphs++;
   }

   if (!num_glyphs)
     return NULL;

   /* Bubble-sort!
    * May not be good-enough for presidential candidate interviews, but good-enough for us... */
   hb_bubble_sort (&glyphs[0], num_glyphs, OT::GlyphID::cmp, &substitutes[0]);

   OT::Supplier<OT::GlyphID> glyphs_supplier      (glyphs, num_glyphs);
   OT::Supplier<OT::GlyphID> substitutes_supplier (substitutes, num_glyphs);

   /* Each glyph takes four bytes max, and there's some overhead. */
   char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
   OT::hb_serialize_context_t c (buf, sizeof (buf));
   OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
   bool ret = lookup->serialize_single (&c,
 				       OT::LookupFlag::IgnoreMarks,
 				       glyphs_supplier,
 				       substitutes_supplier,
 				       num_glyphs);
   c.end_serialize ();
   /* TODO sanitize the results? */

   return ret ? c.copy<OT::SubstLookup> () : NULL;
 }

 static OT::SubstLookup *
 arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
 					    hb_font_t *font)
 {
   OT::GlyphID first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
   unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
   unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
   unsigned int num_first_glyphs = 0;

   /* We know that all our ligatures are 2-component */
   OT::GlyphID ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
   unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
   OT::GlyphID component_list[ARRAY_LENGTH_CONST (ligature_list) * 1/* One extra component per ligature */];
   unsigned int num_ligatures = 0;

   /* Populate arrays */

   /* Sort out the first-glyphs */
   for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
   {
     hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
     hb_codepoint_t first_glyph;
     if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
       continue;
     first_glyphs[num_first_glyphs].set (first_glyph);
     ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
     first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
     num_first_glyphs++;
   }
   hb_bubble_sort (&first_glyphs[0], num_first_glyphs, OT::GlyphID::cmp, &first_glyphs_indirection[0]);

   /* Now that the first-glyphs are sorted, walk again, populate ligatures. */
   for (unsigned int i = 0; i < num_first_glyphs; i++)
   {
     unsigned int first_glyph_idx = first_glyphs_indirection[i];

     for (unsigned int second_glyph_idx = 0; second_glyph_idx < ARRAY_LENGTH (ligature_table[0].ligatures); second_glyph_idx++)
     {
       hb_codepoint_t second_u   = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].second;
       hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].ligature;
       hb_codepoint_t second_glyph, ligature_glyph;
       if (!second_u ||
 	  !hb_font_get_glyph (font, second_u,   0, &second_glyph) ||
 	  !hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))
 	continue;

       ligature_per_first_glyph_count_list[i]++;

       ligature_list[num_ligatures].set (ligature_glyph);
       component_count_list[num_ligatures] = 2;
       component_list[num_ligatures].set (second_glyph);
       num_ligatures++;
     }
   }

   if (!num_ligatures)
     return NULL;

   OT::Supplier<OT::GlyphID>   first_glyphs_supplier                      (first_glyphs, num_first_glyphs);
   OT::Supplier<unsigned int > ligature_per_first_glyph_count_supplier    (ligature_per_first_glyph_count_list, num_first_glyphs);
   OT::Supplier<OT::GlyphID>   ligatures_supplier                         (ligature_list, num_ligatures);
   OT::Supplier<unsigned int > component_count_supplier                   (component_count_list, num_ligatures);
   OT::Supplier<OT::GlyphID>   component_supplier                         (component_list, num_ligatures);

   /* 16 bytes per ligature ought to be enough... */
   char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
   OT::hb_serialize_context_t c (buf, sizeof (buf));
   OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
   bool ret = lookup->serialize_ligature (&c,
 					 OT::LookupFlag::IgnoreMarks,
 					 first_glyphs_supplier,
 					 ligature_per_first_glyph_count_supplier,
 					 num_first_glyphs,
 					 ligatures_supplier,
 					 component_count_supplier,
 					 component_supplier);

   c.end_serialize ();
   /* TODO sanitize the results? */

   return ret ? c.copy<OT::SubstLookup> () : NULL;
 }

 static OT::SubstLookup *
 arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
 				   hb_font_t *font,
 				   unsigned int feature_index)
 {
   if (feature_index < 4)
     return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
   else
     return arabic_fallback_synthesize_lookup_ligature (plan, font);
 }

 #define ARABIC_FALLBACK_MAX_LOOKUPS 5

 struct arabic_fallback_plan_t
 {
   ASSERT_POD ();

   unsigned int num_lookups;
   bool free_lookups;

   hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];
   OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];
   hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
 };

 static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};

 #if (defined(_WIN32) || defined(__CYGWIN__)) && !defined(HB_NO_WIN1256)
 #define HB_WITH_WIN1256
 #endif

 #ifdef HB_WITH_WIN1256
 #include "hb-ot-shape-complex-arabic-win1256.hh"
 #endif

 struct ManifestLookup {
   OT::Tag tag;
   OT::OffsetTo<OT::SubstLookup> lookupOffset;
 };
 typedef OT::ArrayOf<ManifestLookup> Manifest;

 static bool
 arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan,
 				   const hb_ot_shape_plan_t *plan,
 				   hb_font_t *font)
 {
 #ifdef HB_WITH_WIN1256
   /* Does this font look like it's Windows-1256-encoded? */
   hb_codepoint_t g;
   if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ &&
 	hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ &&
 	hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ &&
 	hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ &&
 	hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */))
     return false;

   const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest);
   ASSERT_STATIC (sizeof (arabic_win1256_gsub_lookups.manifestData) / sizeof (ManifestLookup)
 		 <= ARABIC_FALLBACK_MAX_LOOKUPS);
   /* TODO sanitize the table? */

   unsigned j = 0;
   unsigned int count = manifest.len;
   for (unsigned int i = 0; i < count; i++)
   {
     fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag);
     if (fallback_plan->mask_array[j])
     {
       fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset));
       if (fallback_plan->lookup_array[j])
       {
 	fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
 	j++;
       }
     }
   }

   fallback_plan->num_lookups = j;
   fallback_plan->free_lookups = false;

   return j > 0;
 #else
   return false;
 #endif
 }

 static bool
 arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan,
 				   const hb_ot_shape_plan_t *plan,
 				   hb_font_t *font)
 {
   ASSERT_STATIC (ARRAY_LENGTH_CONST(arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS);
   unsigned int j = 0;
   for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)
   {
     fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]);
     if (fallback_plan->mask_array[j])
     {
       fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i);
       if (fallback_plan->lookup_array[j])
       {
 	fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
 	j++;
       }
     }
   }

   fallback_plan->num_lookups = j;
   fallback_plan->free_lookups = true;

   return j > 0;
 }

 static arabic_fallback_plan_t *
 arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
 			     hb_font_t *font)
 {
   arabic_fallback_plan_t *fallback_plan = (arabic_fallback_plan_t *) calloc (1, sizeof (arabic_fallback_plan_t));
   if (unlikely (!fallback_plan))
     return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);

   fallback_plan->num_lookups = 0;
   fallback_plan->free_lookups = false;

   /* Try synthesizing GSUB table using Unicode Arabic Presentation Forms,
    * in case the font has cmap entries for the presentation-forms characters. */
   if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font))
     return fallback_plan;

   /* See if this looks like a Windows-1256-encoded font.  If it does, use a
    * hand-coded GSUB table. */
   if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font))
     return fallback_plan;

   free (fallback_plan);
   return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
 }

 static void
 arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
 {
   if (!fallback_plan || fallback_plan == &arabic_fallback_plan_nil)
     return;

   for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
     if (fallback_plan->lookup_array[i])
     {
       fallback_plan->accel_array[i].fini ();
       if (fallback_plan->free_lookups)
 	free (fallback_plan->lookup_array[i]);
     }

   free (fallback_plan);
 }

 static void
 arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
 			    hb_font_t *font,
 			    hb_buffer_t *buffer)
 {
   OT::hb_apply_context_t c (0, font, buffer);
   for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
     if (fallback_plan->lookup_array[i]) {
       c.set_lookup_mask (fallback_plan->mask_array[i]);
       hb_ot_layout_substitute_lookup (&c,
 				      *fallback_plan->lookup_array[i],
 				      fallback_plan->accel_array[i]);
     }
 }


 #endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */
	/*
	* Copyright © 2012 Google, Inc.
	*
	* This is part of HarfBuzz, a text shaping library.
	*
	* Permission is hereby granted, without written agreement and without
	* license or royalty fees, to use, copy, modify, and distribute this
	* software and its documentation for any purpose, provided that the
	* above copyright notice and the following two paragraphs appear in
	* all copies of this software.
	*
	* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
	* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
	* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
	* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
	* DAMAGE.
	*
	* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
	* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
	* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
	* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
	* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
	*
	* Google Author(s): Behdad Esfahbod
	*/

	#ifndef HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH
	#define HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH

	#include "hb-private.hh"

	#include "hb-ot-shape-private.hh"
	#include "hb-ot-layout-gsub-table.hh"


	/* Features ordered the same as the entries in shaping_table rows,
	* followed by rlig. Don't change. */
	static const hb_tag_t arabic_fallback_features[] =
	{
	HB_TAG('i','n','i','t'),
	HB_TAG('m','e','d','i'),
	HB_TAG('f','i','n','a'),
	HB_TAG('i','s','o','l'),
	HB_TAG('r','l','i','g'),
	};

	static OT::SubstLookup *
	arabic_fallback_synthesize_lookup_single (const hb_ot_shape_plan_t *plan HB_UNUSED,
	hb_font_t *font,
	unsigned int feature_index)
	{
	OT::GlyphID glyphs[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
	OT::GlyphID substitutes[SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1];
	unsigned int num_glyphs = 0;

	/* Populate arrays */
	for (hb_codepoint_t u = SHAPING_TABLE_FIRST; u < SHAPING_TABLE_LAST + 1; u++)
	{
	hb_codepoint_t s = shaping_table[u - SHAPING_TABLE_FIRST][feature_index];
	hb_codepoint_t u_glyph, s_glyph;

	if (!s \|\|
	!hb_font_get_glyph (font, u, 0, &u_glyph) \|\|
	!hb_font_get_glyph (font, s, 0, &s_glyph) \|\|
	u_glyph == s_glyph \|\|
	u_glyph > 0xFFFFu \|\| s_glyph > 0xFFFFu)
	continue;

	glyphs[num_glyphs].set (u_glyph);
	substitutes[num_glyphs].set (s_glyph);

	num_glyphs++;
	}

	if (!num_glyphs)
	return NULL;

	/* Bubble-sort!
	* May not be good-enough for presidential candidate interviews, but good-enough for us... */
	hb_bubble_sort (&glyphs[0], num_glyphs, OT::GlyphID::cmp, &substitutes[0]);

	OT::Supplier<OT::GlyphID> glyphs_supplier (glyphs, num_glyphs);
	OT::Supplier<OT::GlyphID> substitutes_supplier (substitutes, num_glyphs);

	/* Each glyph takes four bytes max, and there's some overhead. */
	char buf[(SHAPING_TABLE_LAST - SHAPING_TABLE_FIRST + 1) * 4 + 128];
	OT::hb_serialize_context_t c (buf, sizeof (buf));
	OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
	bool ret = lookup->serialize_single (&c,
	OT::LookupFlag::IgnoreMarks,
	glyphs_supplier,
	substitutes_supplier,
	num_glyphs);
	c.end_serialize ();
	/* TODO sanitize the results? */

	return ret ? c.copy<OT::SubstLookup> () : NULL;
	}

	static OT::SubstLookup *
	arabic_fallback_synthesize_lookup_ligature (const hb_ot_shape_plan_t *plan HB_UNUSED,
	hb_font_t *font)
	{
	OT::GlyphID first_glyphs[ARRAY_LENGTH_CONST (ligature_table)];
	unsigned int first_glyphs_indirection[ARRAY_LENGTH_CONST (ligature_table)];
	unsigned int ligature_per_first_glyph_count_list[ARRAY_LENGTH_CONST (first_glyphs)];
	unsigned int num_first_glyphs = 0;

	/* We know that all our ligatures are 2-component */
	OT::GlyphID ligature_list[ARRAY_LENGTH_CONST (first_glyphs) * ARRAY_LENGTH_CONST(ligature_table[0].ligatures)];
	unsigned int component_count_list[ARRAY_LENGTH_CONST (ligature_list)];
	OT::GlyphID component_list[ARRAY_LENGTH_CONST (ligature_list) * 1/* One extra component per ligature */];
	unsigned int num_ligatures = 0;

	/* Populate arrays */

	/* Sort out the first-glyphs */
	for (unsigned int first_glyph_idx = 0; first_glyph_idx < ARRAY_LENGTH (first_glyphs); first_glyph_idx++)
	{
	hb_codepoint_t first_u = ligature_table[first_glyph_idx].first;
	hb_codepoint_t first_glyph;
	if (!hb_font_get_glyph (font, first_u, 0, &first_glyph))
	continue;
	first_glyphs[num_first_glyphs].set (first_glyph);
	ligature_per_first_glyph_count_list[num_first_glyphs] = 0;
	first_glyphs_indirection[num_first_glyphs] = first_glyph_idx;
	num_first_glyphs++;
	}
	hb_bubble_sort (&first_glyphs[0], num_first_glyphs, OT::GlyphID::cmp, &first_glyphs_indirection[0]);

	/* Now that the first-glyphs are sorted, walk again, populate ligatures. */
	for (unsigned int i = 0; i < num_first_glyphs; i++)
	{
	unsigned int first_glyph_idx = first_glyphs_indirection[i];

	for (unsigned int second_glyph_idx = 0; second_glyph_idx < ARRAY_LENGTH (ligature_table[0].ligatures); second_glyph_idx++)
	{
	hb_codepoint_t second_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].second;
	hb_codepoint_t ligature_u = ligature_table[first_glyph_idx].ligatures[second_glyph_idx].ligature;
	hb_codepoint_t second_glyph, ligature_glyph;
	if (!second_u \|\|
	!hb_font_get_glyph (font, second_u, 0, &second_glyph) \|\|
	!hb_font_get_glyph (font, ligature_u, 0, &ligature_glyph))
	continue;

	ligature_per_first_glyph_count_list[i]++;

	ligature_list[num_ligatures].set (ligature_glyph);
	component_count_list[num_ligatures] = 2;
	component_list[num_ligatures].set (second_glyph);
	num_ligatures++;
	}
	}

	if (!num_ligatures)
	return NULL;

	OT::Supplier<OT::GlyphID> first_glyphs_supplier (first_glyphs, num_first_glyphs);
	OT::Supplier<unsigned int > ligature_per_first_glyph_count_supplier (ligature_per_first_glyph_count_list, num_first_glyphs);
	OT::Supplier<OT::GlyphID> ligatures_supplier (ligature_list, num_ligatures);
	OT::Supplier<unsigned int > component_count_supplier (component_count_list, num_ligatures);
	OT::Supplier<OT::GlyphID> component_supplier (component_list, num_ligatures);

	/* 16 bytes per ligature ought to be enough... */
	char buf[ARRAY_LENGTH_CONST (ligature_list) * 16 + 128];
	OT::hb_serialize_context_t c (buf, sizeof (buf));
	OT::SubstLookup *lookup = c.start_serialize<OT::SubstLookup> ();
	bool ret = lookup->serialize_ligature (&c,
	OT::LookupFlag::IgnoreMarks,
	first_glyphs_supplier,
	ligature_per_first_glyph_count_supplier,
	num_first_glyphs,
	ligatures_supplier,
	component_count_supplier,
	component_supplier);

	c.end_serialize ();
	/* TODO sanitize the results? */

	return ret ? c.copy<OT::SubstLookup> () : NULL;
	}

	static OT::SubstLookup *
	arabic_fallback_synthesize_lookup (const hb_ot_shape_plan_t *plan,
	hb_font_t *font,
	unsigned int feature_index)
	{
	if (feature_index < 4)
	return arabic_fallback_synthesize_lookup_single (plan, font, feature_index);
	else
	return arabic_fallback_synthesize_lookup_ligature (plan, font);
	}

	#define ARABIC_FALLBACK_MAX_LOOKUPS 5

	struct arabic_fallback_plan_t
	{
	ASSERT_POD ();

	unsigned int num_lookups;
	bool free_lookups;

	hb_mask_t mask_array[ARABIC_FALLBACK_MAX_LOOKUPS];
	OT::SubstLookup *lookup_array[ARABIC_FALLBACK_MAX_LOOKUPS];
	hb_ot_layout_lookup_accelerator_t accel_array[ARABIC_FALLBACK_MAX_LOOKUPS];
	};

	static const arabic_fallback_plan_t arabic_fallback_plan_nil = {};

	#if (defined(_WIN32) \|\| defined(__CYGWIN__)) && !defined(HB_NO_WIN1256)
	#define HB_WITH_WIN1256
	#endif

	#ifdef HB_WITH_WIN1256
	#include "hb-ot-shape-complex-arabic-win1256.hh"
	#endif

	struct ManifestLookup {
	OT::Tag tag;
	OT::OffsetTo<OT::SubstLookup> lookupOffset;
	};
	typedef OT::ArrayOf<ManifestLookup> Manifest;

	static bool
	arabic_fallback_plan_init_win1256 (arabic_fallback_plan_t *fallback_plan,
	const hb_ot_shape_plan_t *plan,
	hb_font_t *font)
	{
	#ifdef HB_WITH_WIN1256
	/* Does this font look like it's Windows-1256-encoded? */
	hb_codepoint_t g;
	if (!(hb_font_get_glyph (font, 0x0627u, 0, &g) && g == 199 /* ALEF */ &&
	hb_font_get_glyph (font, 0x0644u, 0, &g) && g == 225 /* LAM */ &&
	hb_font_get_glyph (font, 0x0649u, 0, &g) && g == 236 /* ALEF MAKSURA */ &&
	hb_font_get_glyph (font, 0x064Au, 0, &g) && g == 237 /* YEH */ &&
	hb_font_get_glyph (font, 0x0652u, 0, &g) && g == 250 /* SUKUN */))
	return false;

	const Manifest &manifest = reinterpret_cast<const Manifest&> (arabic_win1256_gsub_lookups.manifest);
	ASSERT_STATIC (sizeof (arabic_win1256_gsub_lookups.manifestData) / sizeof (ManifestLookup)
	<= ARABIC_FALLBACK_MAX_LOOKUPS);
	/* TODO sanitize the table? */

	unsigned j = 0;
	unsigned int count = manifest.len;
	for (unsigned int i = 0; i < count; i++)
	{
	fallback_plan->mask_array[j] = plan->map.get_1_mask (manifest[i].tag);
	if (fallback_plan->mask_array[j])
	{
	fallback_plan->lookup_array[j] = const_cast<OT::SubstLookup*> (&(&manifest+manifest[i].lookupOffset));
	if (fallback_plan->lookup_array[j])
	{
	fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
	j++;
	}
	}
	}

	fallback_plan->num_lookups = j;
	fallback_plan->free_lookups = false;

	return j > 0;
	#else
	return false;
	#endif
	}

	static bool
	arabic_fallback_plan_init_unicode (arabic_fallback_plan_t *fallback_plan,
	const hb_ot_shape_plan_t *plan,
	hb_font_t *font)
	{
	ASSERT_STATIC (ARRAY_LENGTH_CONST(arabic_fallback_features) <= ARABIC_FALLBACK_MAX_LOOKUPS);
	unsigned int j = 0;
	for (unsigned int i = 0; i < ARRAY_LENGTH(arabic_fallback_features) ; i++)
	{
	fallback_plan->mask_array[j] = plan->map.get_1_mask (arabic_fallback_features[i]);
	if (fallback_plan->mask_array[j])
	{
	fallback_plan->lookup_array[j] = arabic_fallback_synthesize_lookup (plan, font, i);
	if (fallback_plan->lookup_array[j])
	{
	fallback_plan->accel_array[j].init (*fallback_plan->lookup_array[j]);
	j++;
	}
	}
	}

	fallback_plan->num_lookups = j;
	fallback_plan->free_lookups = true;

	return j > 0;
	}

	static arabic_fallback_plan_t *
	arabic_fallback_plan_create (const hb_ot_shape_plan_t *plan,
	hb_font_t *font)
	{
	arabic_fallback_plan_t fallback_plan = (arabic_fallback_plan_t ) calloc (1, sizeof (arabic_fallback_plan_t));
	if (unlikely (!fallback_plan))
	return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);

	fallback_plan->num_lookups = 0;
	fallback_plan->free_lookups = false;

	/* Try synthesizing GSUB table using Unicode Arabic Presentation Forms,
	* in case the font has cmap entries for the presentation-forms characters. */
	if (arabic_fallback_plan_init_unicode (fallback_plan, plan, font))
	return fallback_plan;

	/* See if this looks like a Windows-1256-encoded font. If it does, use a
	* hand-coded GSUB table. */
	if (arabic_fallback_plan_init_win1256 (fallback_plan, plan, font))
	return fallback_plan;

	free (fallback_plan);
	return const_cast<arabic_fallback_plan_t *> (&arabic_fallback_plan_nil);
	}

	static void
	arabic_fallback_plan_destroy (arabic_fallback_plan_t *fallback_plan)
	{
	if (!fallback_plan \|\| fallback_plan == &arabic_fallback_plan_nil)
	return;

	for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
	if (fallback_plan->lookup_array[i])
	{
	fallback_plan->accel_array[i].fini ();
	if (fallback_plan->free_lookups)
	free (fallback_plan->lookup_array[i]);
	}

	free (fallback_plan);
	}

	static void
	arabic_fallback_plan_shape (arabic_fallback_plan_t *fallback_plan,
	hb_font_t *font,
	hb_buffer_t *buffer)
	{
	OT::hb_apply_context_t c (0, font, buffer);
	for (unsigned int i = 0; i < fallback_plan->num_lookups; i++)
	if (fallback_plan->lookup_array[i]) {
	c.set_lookup_mask (fallback_plan->mask_array[i]);
	hb_ot_layout_substitute_lookup (&c,
	*fallback_plan->lookup_array[i],
	fallback_plan->accel_array[i]);
	}
	}


	#endif /* HB_OT_SHAPE_COMPLEX_ARABIC_FALLBACK_HH */