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

 /*
  * Copyright © 2010,2012  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
  */

 #include "hb-ot-shape-complex-private.hh"
 #include "hb-ot-shape-private.hh"


 /* buffer var allocations */
 #define arabic_shaping_action() complex_var_u8_0() /* arabic shaping action */


 /*
  * Bits used in the joining tables
  */
 enum {
   JOINING_TYPE_U		= 0,
   JOINING_TYPE_R		= 1,
   JOINING_TYPE_D		= 2,
   JOINING_TYPE_C		= JOINING_TYPE_D,
   JOINING_GROUP_ALAPH		= 3,
   JOINING_GROUP_DALATH_RISH	= 4,
   NUM_STATE_MACHINE_COLS	= 5,

   /* We deliberately don't have a JOINING_TYPE_L since that's unused in Unicode. */

   JOINING_TYPE_T = 6,
   JOINING_TYPE_X = 7  /* means: use general-category to choose between U or T. */
 };

 /*
  * Joining types:
  */

 #include "hb-ot-shape-complex-arabic-table.hh"

 static unsigned int get_joining_type (hb_codepoint_t u, hb_unicode_general_category_t gen_cat)
 {
   if (likely (hb_in_range<hb_codepoint_t> (u, JOINING_TABLE_FIRST, JOINING_TABLE_LAST))) {
     unsigned int j_type = joining_table[u - JOINING_TABLE_FIRST];
     if (likely (j_type != JOINING_TYPE_X))
       return j_type;
   }

   /* Mongolian joining data is not in ArabicJoining.txt yet */
   if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x1800, 0x18AF)))
   {
     /* All letters, SIBE SYLLABLE BOUNDARY MARKER, and NIRUGU are D */
     if (gen_cat == HB_UNICODE_GENERAL_CATEGORY_OTHER_LETTER || u == 0x1807 || u == 0x180A)
       return JOINING_TYPE_D;
   }

   if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x200C, 0x200D))) {
     return u == 0x200C ? JOINING_TYPE_U : JOINING_TYPE_C;
   }

   return (FLAG(gen_cat) & (FLAG(HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) | FLAG(HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) | FLAG(HB_UNICODE_GENERAL_CATEGORY_FORMAT))) ?
 	 JOINING_TYPE_T : JOINING_TYPE_U;
 }

 static hb_codepoint_t get_arabic_shape (hb_codepoint_t u, unsigned int shape)
 {
   if (likely (hb_in_range<hb_codepoint_t> (u, SHAPING_TABLE_FIRST, SHAPING_TABLE_LAST)) && shape < 4)
     return shaping_table[u - SHAPING_TABLE_FIRST][shape];
   return u;
 }

 static uint16_t get_ligature (hb_codepoint_t first, hb_codepoint_t second)
 {
   if (unlikely (!second)) return 0;
   for (unsigned i = 0; i < ARRAY_LENGTH (ligature_table); i++)
     if (ligature_table[i].first == first)
       for (unsigned j = 0; j < ARRAY_LENGTH (ligature_table[i].ligatures); j++)
 	if (ligature_table[i].ligatures[j].second == second)
 	  return ligature_table[i].ligatures[j].ligature;
   return 0;
 }

 static const hb_tag_t arabic_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'),
   /* Syriac */
   HB_TAG('m','e','d','2'),
   HB_TAG('f','i','n','2'),
   HB_TAG('f','i','n','3'),
   HB_TAG_NONE
 };


 /* Same order as the feature array */
 enum {
   INIT,
   MEDI,
   FINA,
   ISOL,

   /* Syriac */
   MED2,
   FIN2,
   FIN3,

   NONE,

   ARABIC_NUM_FEATURES = NONE
 };

 static const struct arabic_state_table_entry {
 	uint8_t prev_action;
 	uint8_t curr_action;
 	uint16_t next_state;
 } arabic_state_table[][NUM_STATE_MACHINE_COLS] =
 {
   /*   jt_U,          jt_R,          jt_D,          jg_ALAPH,      jg_DALATH_RISH */

   /* State 0: prev was U, not willing to join. */
   { {NONE,NONE,0}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,6}, },

   /* State 1: prev was R or ISOL/ALAPH, not willing to join. */
   { {NONE,NONE,0}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN2,5}, {NONE,ISOL,6}, },

   /* State 2: prev was D/ISOL, willing to join. */
   { {NONE,NONE,0}, {INIT,FINA,1}, {INIT,FINA,3}, {INIT,FINA,4}, {INIT,FINA,6}, },

   /* State 3: prev was D/FINA, willing to join. */
   { {NONE,NONE,0}, {MEDI,FINA,1}, {MEDI,FINA,3}, {MEDI,FINA,4}, {MEDI,FINA,6}, },

   /* State 4: prev was FINA ALAPH, not willing to join. */
   { {NONE,NONE,0}, {MED2,ISOL,1}, {MED2,ISOL,2}, {MED2,FIN2,5}, {MED2,ISOL,6}, },

   /* State 5: prev was FIN2/FIN3 ALAPH, not willing to join. */
   { {NONE,NONE,0}, {ISOL,ISOL,1}, {ISOL,ISOL,2}, {ISOL,FIN2,5}, {ISOL,ISOL,6}, },

   /* State 6: prev was DALATH/RISH, not willing to join. */
   { {NONE,NONE,0}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN3,5}, {NONE,ISOL,6}, }
 };


 static void
 collect_features_arabic (hb_ot_shape_planner_t *plan)
 {
   hb_ot_map_builder_t *map = &plan->map;

   /* For Language forms (in ArabicOT speak), we do the iso/fina/medi/init together,
    * then rlig and calt each in their own stage.  This makes IranNastaliq's ALLAH
    * ligature work correctly. It's unfortunate though...
    *
    * This also makes Arial Bold in Windows7 work.  See:
    * https://bugzilla.mozilla.org/show_bug.cgi?id=644184
    *
    * TODO: Add test cases for these two.
    */

   map->add_bool_feature (HB_TAG('c','c','m','p'));
   map->add_bool_feature (HB_TAG('l','o','c','l'));

   map->add_gsub_pause (NULL);

   for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++)
     map->add_bool_feature (arabic_features[i], false);

   map->add_gsub_pause (NULL);

   map->add_bool_feature (HB_TAG('r','l','i','g'));
   map->add_gsub_pause (NULL);

   map->add_bool_feature (HB_TAG('c','a','l','t'));
   map->add_gsub_pause (NULL);

   /* ArabicOT spec enables 'cswh' for Arabic where as for basic shaper it's disabled by default. */
   map->add_bool_feature (HB_TAG('c','s','w','h'));
 }

 struct arabic_shape_plan_t
 {
   ASSERT_POD ();

   bool do_fallback;
   /* The "+ 1" in the next array is to accommodate for the "NONE" command,
    * which is not an OpenType feature, but this simplifies the code by not
    * having to do a "if (... < NONE) ..." and just rely on the fact that
    * mask_array[NONE] == 0. */
   hb_mask_t mask_array[ARABIC_NUM_FEATURES + 1];
 };

 static void *
 data_create_arabic (const hb_ot_shape_plan_t *plan)
 {
   arabic_shape_plan_t *arabic_plan = (arabic_shape_plan_t *) calloc (1, sizeof (arabic_shape_plan_t));
   if (unlikely (!arabic_plan))
     return NULL;

   hb_mask_t total_masks = 0;
   for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++) {
     arabic_plan->mask_array[i] = plan->map.get_1_mask (arabic_features[i]);
     total_masks |= arabic_plan->mask_array[i];
   }

   /* Pitfalls:
    * - This path fires if user force-set init/medi/fina/isol off,
    * - If font does not declare script 'arab', well, what to do?
    *   Most probably it's safe to assume that init/medi/fina/isol
    *   still mean Arabic shaping, although they do not have to.
    */
   arabic_plan->do_fallback = 0 == total_masks;

   return arabic_plan;
 }

 static void
 data_destroy_arabic (void *data)
 {
   free (data);
 }

 static void
 arabic_fallback_shape (hb_font_t *font, hb_buffer_t *buffer)
 {
   /* Only Arabic has presentation forms encoded in Unicode. */
   if (buffer->props.script != HB_SCRIPT_ARABIC)
     return;

   unsigned int count = buffer->len;
   hb_codepoint_t glyph;

   /* Shape to presentation forms */
   for (unsigned int i = 0; i < count; i++) {
     hb_codepoint_t u = buffer->info[i].codepoint;
     hb_codepoint_t shaped = get_arabic_shape (u, buffer->info[i].arabic_shaping_action());
     if (shaped != u && font->get_glyph (shaped, 0, &glyph))
       buffer->info[i].codepoint = shaped;
   }

   /* Mandatory ligatures */
   buffer->clear_output ();
   for (buffer->idx = 0; buffer->idx + 1 < count;) {
     hb_codepoint_t ligature = get_ligature (buffer->cur().codepoint,
 					    buffer->cur(+1).codepoint);
     if (likely (!ligature) || !(font->get_glyph (ligature, 0, &glyph))) {
       buffer->next_glyph ();
       continue;
     }

     buffer->replace_glyphs (2, 1, &ligature);

     /* Technically speaking we can skip marks and stuff, like the GSUB path does.
      * But who cares, we're in fallback! */
   }
   for (; buffer->idx < count;)
       buffer->next_glyph ();
   buffer->swap_buffers ();
 }

 static void
 arabic_joining (hb_buffer_t *buffer)
 {
   unsigned int count = buffer->len;
   unsigned int prev = 0, state = 0;

   HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);

   for (unsigned int i = 0; i < count; i++)
   {
     unsigned int this_type = get_joining_type (buffer->info[i].codepoint, _hb_glyph_info_get_general_category (&buffer->info[i]));

     if (unlikely (this_type == JOINING_TYPE_T)) {
       buffer->info[i].arabic_shaping_action() = NONE;
       continue;
     }

     const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];

     if (entry->prev_action != NONE)
       buffer->info[prev].arabic_shaping_action() = entry->prev_action;

     buffer->info[i].arabic_shaping_action() = entry->curr_action;

     prev = i;
     state = entry->next_state;
   }

   HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
 }

 static void
 preprocess_text_arabic (const hb_ot_shape_plan_t *plan,
 			hb_buffer_t              *buffer,
 			hb_font_t                *font)
 {
   const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;

   if (unlikely (arabic_plan->do_fallback))
   {
     arabic_joining (buffer);
     arabic_fallback_shape (font, buffer);
   }
 }

 static void
 setup_masks_arabic (const hb_ot_shape_plan_t *plan,
 		    hb_buffer_t              *buffer,
 		    hb_font_t                *font)
 {
   const arabic_shape_plan_t *arabic_plan = (const arabic_shape_plan_t *) plan->data;

   if (likely (!arabic_plan->do_fallback))
   {
     arabic_joining (buffer);
     unsigned int count = buffer->len;
     for (unsigned int i = 0; i < count; i++)
       buffer->info[i].mask |= arabic_plan->mask_array[buffer->info[i].arabic_shaping_action()];
   }
 }

 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
 {
   "arabic",
   collect_features_arabic,
   NULL, /* override_features */
   data_create_arabic,
   data_destroy_arabic,
   preprocess_text_arabic,
   NULL, /* normalization_preference */
   setup_masks_arabic,
   true, /* zero_width_attached_marks */
 };
	/*
	* Copyright © 2010,2012 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
	*/

	#include "hb-ot-shape-complex-private.hh"
	#include "hb-ot-shape-private.hh"



	/* buffer var allocations */
	#define arabic_shaping_action() complex_var_u8_0() /* arabic shaping action */


	/*
	* Bits used in the joining tables
	*/
	enum {
	JOINING_TYPE_U = 0,
	JOINING_TYPE_R = 1,
	JOINING_TYPE_D = 2,
	JOINING_TYPE_C = JOINING_TYPE_D,
	JOINING_GROUP_ALAPH = 3,
	JOINING_GROUP_DALATH_RISH = 4,
	NUM_STATE_MACHINE_COLS = 5,

	/* We deliberately don't have a JOINING_TYPE_L since that's unused in Unicode. */

	JOINING_TYPE_T = 6,
	JOINING_TYPE_X = 7 /* means: use general-category to choose between U or T. */
	};

	/*
	* Joining types:
	*/

	#include "hb-ot-shape-complex-arabic-table.hh"

	static unsigned int get_joining_type (hb_codepoint_t u, hb_unicode_general_category_t gen_cat)
	{
	if (likely (hb_in_range<hb_codepoint_t> (u, JOINING_TABLE_FIRST, JOINING_TABLE_LAST))) {
	unsigned int j_type = joining_table[u - JOINING_TABLE_FIRST];
	if (likely (j_type != JOINING_TYPE_X))
	return j_type;
	}

	/* Mongolian joining data is not in ArabicJoining.txt yet */
	if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x1800, 0x18AF)))
	{
	/* All letters, SIBE SYLLABLE BOUNDARY MARKER, and NIRUGU are D */
	if (gen_cat == HB_UNICODE_GENERAL_CATEGORY_OTHER_LETTER \|\| u == 0x1807 \|\| u == 0x180A)
	return JOINING_TYPE_D;
	}

	if (unlikely (hb_in_range<hb_codepoint_t> (u, 0x200C, 0x200D))) {
	return u == 0x200C ? JOINING_TYPE_U : JOINING_TYPE_C;
	}

	return (FLAG(gen_cat) & (FLAG(HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK) \| FLAG(HB_UNICODE_GENERAL_CATEGORY_ENCLOSING_MARK) \| FLAG(HB_UNICODE_GENERAL_CATEGORY_FORMAT))) ?
	JOINING_TYPE_T : JOINING_TYPE_U;
	}

	static hb_codepoint_t get_arabic_shape (hb_codepoint_t u, unsigned int shape)
	{
	if (likely (hb_in_range<hb_codepoint_t> (u, SHAPING_TABLE_FIRST, SHAPING_TABLE_LAST)) && shape < 4)
	return shaping_table[u - SHAPING_TABLE_FIRST][shape];
	return u;
	}

	static uint16_t get_ligature (hb_codepoint_t first, hb_codepoint_t second)
	{
	if (unlikely (!second)) return 0;
	for (unsigned i = 0; i < ARRAY_LENGTH (ligature_table); i++)
	if (ligature_table[i].first == first)
	for (unsigned j = 0; j < ARRAY_LENGTH (ligature_table[i].ligatures); j++)
	if (ligature_table[i].ligatures[j].second == second)
	return ligature_table[i].ligatures[j].ligature;
	return 0;
	}

	static const hb_tag_t arabic_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'),
	/* Syriac */
	HB_TAG('m','e','d','2'),
	HB_TAG('f','i','n','2'),
	HB_TAG('f','i','n','3'),
	HB_TAG_NONE
	};


	/* Same order as the feature array */
	enum {
	INIT,
	MEDI,
	FINA,
	ISOL,

	/* Syriac */
	MED2,
	FIN2,
	FIN3,

	NONE,

	ARABIC_NUM_FEATURES = NONE
	};

	static const struct arabic_state_table_entry {
	uint8_t prev_action;
	uint8_t curr_action;
	uint16_t next_state;
	} arabic_state_table[][NUM_STATE_MACHINE_COLS] =
	{
	/* jt_U, jt_R, jt_D, jg_ALAPH, jg_DALATH_RISH */

	/* State 0: prev was U, not willing to join. */
	{ {NONE,NONE,0}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,ISOL,1}, {NONE,ISOL,6}, },

	/* State 1: prev was R or ISOL/ALAPH, not willing to join. */
	{ {NONE,NONE,0}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN2,5}, {NONE,ISOL,6}, },

	/* State 2: prev was D/ISOL, willing to join. */
	{ {NONE,NONE,0}, {INIT,FINA,1}, {INIT,FINA,3}, {INIT,FINA,4}, {INIT,FINA,6}, },

	/* State 3: prev was D/FINA, willing to join. */
	{ {NONE,NONE,0}, {MEDI,FINA,1}, {MEDI,FINA,3}, {MEDI,FINA,4}, {MEDI,FINA,6}, },

	/* State 4: prev was FINA ALAPH, not willing to join. */
	{ {NONE,NONE,0}, {MED2,ISOL,1}, {MED2,ISOL,2}, {MED2,FIN2,5}, {MED2,ISOL,6}, },

	/* State 5: prev was FIN2/FIN3 ALAPH, not willing to join. */
	{ {NONE,NONE,0}, {ISOL,ISOL,1}, {ISOL,ISOL,2}, {ISOL,FIN2,5}, {ISOL,ISOL,6}, },

	/* State 6: prev was DALATH/RISH, not willing to join. */
	{ {NONE,NONE,0}, {NONE,ISOL,1}, {NONE,ISOL,2}, {NONE,FIN3,5}, {NONE,ISOL,6}, }
	};



	static void
	collect_features_arabic (hb_ot_shape_planner_t *plan)
	{
	hb_ot_map_builder_t *map = &plan->map;

	/* For Language forms (in ArabicOT speak), we do the iso/fina/medi/init together,
	* then rlig and calt each in their own stage. This makes IranNastaliq's ALLAH
	* ligature work correctly. It's unfortunate though...
	*
	* This also makes Arial Bold in Windows7 work. See:
	* https://bugzilla.mozilla.org/show_bug.cgi?id=644184
	*
	* TODO: Add test cases for these two.
	*/

	map->add_bool_feature (HB_TAG('c','c','m','p'));
	map->add_bool_feature (HB_TAG('l','o','c','l'));

	map->add_gsub_pause (NULL);

	for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++)
	map->add_bool_feature (arabic_features[i], false);

	map->add_gsub_pause (NULL);

	map->add_bool_feature (HB_TAG('r','l','i','g'));
	map->add_gsub_pause (NULL);

	map->add_bool_feature (HB_TAG('c','a','l','t'));
	map->add_gsub_pause (NULL);

	/* ArabicOT spec enables 'cswh' for Arabic where as for basic shaper it's disabled by default. */
	map->add_bool_feature (HB_TAG('c','s','w','h'));
	}

	struct arabic_shape_plan_t
	{
	ASSERT_POD ();

	bool do_fallback;
	/* The "+ 1" in the next array is to accommodate for the "NONE" command,
	* which is not an OpenType feature, but this simplifies the code by not
	* having to do a "if (... < NONE) ..." and just rely on the fact that
	* mask_array[NONE] == 0. */
	hb_mask_t mask_array[ARABIC_NUM_FEATURES + 1];
	};

	static void *
	data_create_arabic (const hb_ot_shape_plan_t *plan)
	{
	arabic_shape_plan_t arabic_plan = (arabic_shape_plan_t ) calloc (1, sizeof (arabic_shape_plan_t));
	if (unlikely (!arabic_plan))
	return NULL;

	hb_mask_t total_masks = 0;
	for (unsigned int i = 0; i < ARABIC_NUM_FEATURES; i++) {
	arabic_plan->mask_array[i] = plan->map.get_1_mask (arabic_features[i]);
	total_masks \|= arabic_plan->mask_array[i];
	}

	/* Pitfalls:
	* - This path fires if user force-set init/medi/fina/isol off,
	* - If font does not declare script 'arab', well, what to do?
	* Most probably it's safe to assume that init/medi/fina/isol
	* still mean Arabic shaping, although they do not have to.
	*/
	arabic_plan->do_fallback = 0 == total_masks;

	return arabic_plan;
	}

	static void
	data_destroy_arabic (void *data)
	{
	free (data);
	}

	static void
	arabic_fallback_shape (hb_font_t font, hb_buffer_t buffer)
	{
	/* Only Arabic has presentation forms encoded in Unicode. */
	if (buffer->props.script != HB_SCRIPT_ARABIC)
	return;

	unsigned int count = buffer->len;
	hb_codepoint_t glyph;

	/* Shape to presentation forms */
	for (unsigned int i = 0; i < count; i++) {
	hb_codepoint_t u = buffer->info[i].codepoint;
	hb_codepoint_t shaped = get_arabic_shape (u, buffer->info[i].arabic_shaping_action());
	if (shaped != u && font->get_glyph (shaped, 0, &glyph))
	buffer->info[i].codepoint = shaped;
	}

	/* Mandatory ligatures */
	buffer->clear_output ();
	for (buffer->idx = 0; buffer->idx + 1 < count;) {
	hb_codepoint_t ligature = get_ligature (buffer->cur().codepoint,
	buffer->cur(+1).codepoint);
	if (likely (!ligature) \|\| !(font->get_glyph (ligature, 0, &glyph))) {
	buffer->next_glyph ();
	continue;
	}

	buffer->replace_glyphs (2, 1, &ligature);

	/* Technically speaking we can skip marks and stuff, like the GSUB path does.
	* But who cares, we're in fallback! */
	}
	for (; buffer->idx < count;)
	buffer->next_glyph ();
	buffer->swap_buffers ();
	}

	static void
	arabic_joining (hb_buffer_t *buffer)
	{
	unsigned int count = buffer->len;
	unsigned int prev = 0, state = 0;

	HB_BUFFER_ALLOCATE_VAR (buffer, arabic_shaping_action);

	for (unsigned int i = 0; i < count; i++)
	{
	unsigned int this_type = get_joining_type (buffer->info[i].codepoint, _hb_glyph_info_get_general_category (&buffer->info[i]));

	if (unlikely (this_type == JOINING_TYPE_T)) {
	buffer->info[i].arabic_shaping_action() = NONE;
	continue;
	}

	const arabic_state_table_entry *entry = &arabic_state_table[state][this_type];

	if (entry->prev_action != NONE)
	buffer->info[prev].arabic_shaping_action() = entry->prev_action;

	buffer->info[i].arabic_shaping_action() = entry->curr_action;

	prev = i;
	state = entry->next_state;
	}

	HB_BUFFER_DEALLOCATE_VAR (buffer, arabic_shaping_action);
	}

	static void
	preprocess_text_arabic (const hb_ot_shape_plan_t *plan,
	hb_buffer_t *buffer,
	hb_font_t *font)
	{
	const arabic_shape_plan_t arabic_plan = (const arabic_shape_plan_t ) plan->data;

	if (unlikely (arabic_plan->do_fallback))
	{
	arabic_joining (buffer);
	arabic_fallback_shape (font, buffer);
	}
	}

	static void
	setup_masks_arabic (const hb_ot_shape_plan_t *plan,
	hb_buffer_t *buffer,
	hb_font_t *font)
	{
	const arabic_shape_plan_t arabic_plan = (const arabic_shape_plan_t ) plan->data;

	if (likely (!arabic_plan->do_fallback))
	{
	arabic_joining (buffer);
	unsigned int count = buffer->len;
	for (unsigned int i = 0; i < count; i++)
	buffer->info[i].mask \|= arabic_plan->mask_array[buffer->info[i].arabic_shaping_action()];
	}
	}

	const hb_ot_complex_shaper_t _hb_ot_complex_shaper_arabic =
	{
	"arabic",
	collect_features_arabic,
	NULL, /* override_features */
	data_create_arabic,
	data_destroy_arabic,
	preprocess_text_arabic,
	NULL, /* normalization_preference */
	setup_masks_arabic,
	true, /* zero_width_attached_marks */
	};