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

 /*
  * Copyright © 2015  Mozilla Foundation.
  * Copyright © 2015  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.
  *
  * Mozilla Author(s): Jonathan Kew
  * Google Author(s): Behdad Esfahbod
  */

 #include "hb.hh"

 #ifndef HB_NO_OT_SHAPE

 #include "hb-ot-shape-complex-use-machine.hh"
 #include "hb-ot-shape-complex-use-table.hh"
 #include "hb-ot-shape-complex-arabic.hh"
 #include "hb-ot-shape-complex-arabic-joining-list.hh"
 #include "hb-ot-shape-complex-vowel-constraints.hh"


 /*
  * Universal Shaping Engine.
  * https://docs.microsoft.com/en-us/typography/script-development/use
  */

 static const hb_tag_t
 use_basic_features[] =
 {
   /*
    * Basic features.
    * These features are applied all at once, before reordering, constrained
    * to the syllable.
    */
   HB_TAG('r','k','r','f'),
   HB_TAG('a','b','v','f'),
   HB_TAG('b','l','w','f'),
   HB_TAG('h','a','l','f'),
   HB_TAG('p','s','t','f'),
   HB_TAG('v','a','t','u'),
   HB_TAG('c','j','c','t'),
 };
 static const hb_tag_t
 use_topographical_features[] =
 {
   HB_TAG('i','s','o','l'),
   HB_TAG('i','n','i','t'),
   HB_TAG('m','e','d','i'),
   HB_TAG('f','i','n','a'),
 };
 /* Same order as use_topographical_features. */
 enum joining_form_t {
   JOINING_FORM_ISOL,
   JOINING_FORM_INIT,
   JOINING_FORM_MEDI,
   JOINING_FORM_FINA,
   _JOINING_FORM_NONE
 };
 static const hb_tag_t
 use_other_features[] =
 {
   /*
    * Other features.
    * These features are applied all at once, after reordering and
    * clearing syllables.
    */
   HB_TAG('a','b','v','s'),
   HB_TAG('b','l','w','s'),
   HB_TAG('h','a','l','n'),
   HB_TAG('p','r','e','s'),
   HB_TAG('p','s','t','s'),
 };

 static void
 setup_syllables_use (const hb_ot_shape_plan_t *plan,
 		     hb_font_t *font,
 		     hb_buffer_t *buffer);
 static void
 record_rphf_use (const hb_ot_shape_plan_t *plan,
 		 hb_font_t *font,
 		 hb_buffer_t *buffer);
 static void
 record_pref_use (const hb_ot_shape_plan_t *plan,
 		 hb_font_t *font,
 		 hb_buffer_t *buffer);
 static void
 reorder_use (const hb_ot_shape_plan_t *plan,
 	     hb_font_t *font,
 	     hb_buffer_t *buffer);

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

   /* Do this before any lookups have been applied. */
   map->add_gsub_pause (setup_syllables_use);

   /* "Default glyph pre-processing group" */
   map->enable_feature (HB_TAG('l','o','c','l'));
   map->enable_feature (HB_TAG('c','c','m','p'));
   map->enable_feature (HB_TAG('n','u','k','t'));
   map->enable_feature (HB_TAG('a','k','h','n'), F_MANUAL_ZWJ);

   /* "Reordering group" */
   map->add_gsub_pause (_hb_clear_substitution_flags);
   map->add_feature (HB_TAG('r','p','h','f'), F_MANUAL_ZWJ);
   map->add_gsub_pause (record_rphf_use);
   map->add_gsub_pause (_hb_clear_substitution_flags);
   map->enable_feature (HB_TAG('p','r','e','f'), F_MANUAL_ZWJ);
   map->add_gsub_pause (record_pref_use);

   /* "Orthographic unit shaping group" */
   for (unsigned int i = 0; i < ARRAY_LENGTH (use_basic_features); i++)
     map->enable_feature (use_basic_features[i], F_MANUAL_ZWJ);

   map->add_gsub_pause (reorder_use);
   map->add_gsub_pause (_hb_clear_syllables);

   /* "Topographical features" */
   for (unsigned int i = 0; i < ARRAY_LENGTH (use_topographical_features); i++)
     map->add_feature (use_topographical_features[i]);
   map->add_gsub_pause (nullptr);

   /* "Standard typographic presentation" */
   for (unsigned int i = 0; i < ARRAY_LENGTH (use_other_features); i++)
     map->enable_feature (use_other_features[i], F_MANUAL_ZWJ);
 }

 struct use_shape_plan_t
 {
   hb_mask_t rphf_mask;

   arabic_shape_plan_t *arabic_plan;
 };

 static void *
 data_create_use (const hb_ot_shape_plan_t *plan)
 {
   use_shape_plan_t *use_plan = (use_shape_plan_t *) hb_calloc (1, sizeof (use_shape_plan_t));
   if (unlikely (!use_plan))
     return nullptr;

   use_plan->rphf_mask = plan->map.get_1_mask (HB_TAG('r','p','h','f'));

   if (has_arabic_joining (plan->props.script))
   {
     use_plan->arabic_plan = (arabic_shape_plan_t *) data_create_arabic (plan);
     if (unlikely (!use_plan->arabic_plan))
     {
       hb_free (use_plan);
       return nullptr;
     }
   }

   return use_plan;
 }

 static void
 data_destroy_use (void *data)
 {
   use_shape_plan_t *use_plan = (use_shape_plan_t *) data;

   if (use_plan->arabic_plan)
     data_destroy_arabic (use_plan->arabic_plan);

   hb_free (data);
 }

 static void
 setup_masks_use (const hb_ot_shape_plan_t *plan,
 		 hb_buffer_t              *buffer,
 		 hb_font_t                *font HB_UNUSED)
 {
   const use_shape_plan_t *use_plan = (const use_shape_plan_t *) plan->data;

   /* Do this before allocating use_category(). */
   if (use_plan->arabic_plan)
   {
     setup_masks_arabic_plan (use_plan->arabic_plan, buffer, plan->props.script);
   }

   HB_BUFFER_ALLOCATE_VAR (buffer, use_category);

   /* We cannot setup masks here.  We save information about characters
    * and setup masks later on in a pause-callback. */

   unsigned int count = buffer->len;
   hb_glyph_info_t *info = buffer->info;
   for (unsigned int i = 0; i < count; i++)
     info[i].use_category() = hb_use_get_category (info[i].codepoint);
 }

 static void
 setup_rphf_mask (const hb_ot_shape_plan_t *plan,
 		 hb_buffer_t *buffer)
 {
   const use_shape_plan_t *use_plan = (const use_shape_plan_t *) plan->data;

   hb_mask_t mask = use_plan->rphf_mask;
   if (!mask) return;

   hb_glyph_info_t *info = buffer->info;

   foreach_syllable (buffer, start, end)
   {
     unsigned int limit = info[start].use_category() == USE(R) ? 1 : hb_min (3u, end - start);
     for (unsigned int i = start; i < start + limit; i++)
       info[i].mask |= mask;
   }
 }

 static void
 setup_topographical_masks (const hb_ot_shape_plan_t *plan,
 			   hb_buffer_t *buffer)
 {
   const use_shape_plan_t *use_plan = (const use_shape_plan_t *) plan->data;
   if (use_plan->arabic_plan)
     return;

   static_assert ((JOINING_FORM_INIT < 4 && JOINING_FORM_ISOL < 4 && JOINING_FORM_MEDI < 4 && JOINING_FORM_FINA < 4), "");
   hb_mask_t masks[4], all_masks = 0;
   for (unsigned int i = 0; i < 4; i++)
   {
     masks[i] = plan->map.get_1_mask (use_topographical_features[i]);
     if (masks[i] == plan->map.get_global_mask ())
       masks[i] = 0;
     all_masks |= masks[i];
   }
   if (!all_masks)
     return;
   hb_mask_t other_masks = ~all_masks;

   unsigned int last_start = 0;
   joining_form_t last_form = _JOINING_FORM_NONE;
   hb_glyph_info_t *info = buffer->info;
   foreach_syllable (buffer, start, end)
   {
     use_syllable_type_t syllable_type = (use_syllable_type_t) (info[start].syllable() & 0x0F);
     switch (syllable_type)
     {
       case use_symbol_cluster:
       case use_hieroglyph_cluster:
       case use_non_cluster:
 	/* These don't join.  Nothing to do. */
 	last_form = _JOINING_FORM_NONE;
 	break;

       case use_virama_terminated_cluster:
       case use_sakot_terminated_cluster:
       case use_standard_cluster:
       case use_number_joiner_terminated_cluster:
       case use_numeral_cluster:
       case use_broken_cluster:

 	bool join = last_form == JOINING_FORM_FINA || last_form == JOINING_FORM_ISOL;

 	if (join)
 	{
 	  /* Fixup previous syllable's form. */
 	  last_form = last_form == JOINING_FORM_FINA ? JOINING_FORM_MEDI : JOINING_FORM_INIT;
 	  for (unsigned int i = last_start; i < start; i++)
 	    info[i].mask = (info[i].mask & other_masks) | masks[last_form];
 	}

 	/* Form for this syllable. */
 	last_form = join ? JOINING_FORM_FINA : JOINING_FORM_ISOL;
 	for (unsigned int i = start; i < end; i++)
 	  info[i].mask = (info[i].mask & other_masks) | masks[last_form];

 	break;
     }

     last_start = start;
   }
 }

 static void
 setup_syllables_use (const hb_ot_shape_plan_t *plan,
 		     hb_font_t *font HB_UNUSED,
 		     hb_buffer_t *buffer)
 {
   find_syllables_use (buffer);
   foreach_syllable (buffer, start, end)
     buffer->unsafe_to_break (start, end);
   setup_rphf_mask (plan, buffer);
   setup_topographical_masks (plan, buffer);
 }

 static void
 record_rphf_use (const hb_ot_shape_plan_t *plan,
 		 hb_font_t *font HB_UNUSED,
 		 hb_buffer_t *buffer)
 {
   const use_shape_plan_t *use_plan = (const use_shape_plan_t *) plan->data;

   hb_mask_t mask = use_plan->rphf_mask;
   if (!mask) return;
   hb_glyph_info_t *info = buffer->info;

   foreach_syllable (buffer, start, end)
   {
     /* Mark a substituted repha as USE(R). */
     for (unsigned int i = start; i < end && (info[i].mask & mask); i++)
       if (_hb_glyph_info_substituted (&info[i]))
       {
 	info[i].use_category() = USE(R);
 	break;
       }
   }
 }

 static void
 record_pref_use (const hb_ot_shape_plan_t *plan HB_UNUSED,
 		 hb_font_t *font HB_UNUSED,
 		 hb_buffer_t *buffer)
 {
   hb_glyph_info_t *info = buffer->info;

   foreach_syllable (buffer, start, end)
   {
     /* Mark a substituted pref as VPre, as they behave the same way. */
     for (unsigned int i = start; i < end; i++)
       if (_hb_glyph_info_substituted (&info[i]))
       {
 	info[i].use_category() = USE(VPre);
 	break;
       }
   }
 }

 static inline bool
 is_halant_use (const hb_glyph_info_t &info)
 {
   return (info.use_category() == USE(H) || info.use_category() == USE(HVM)) &&
 	 !_hb_glyph_info_ligated (&info);
 }

 static void
 reorder_syllable_use (hb_buffer_t *buffer, unsigned int start, unsigned int end)
 {
   use_syllable_type_t syllable_type = (use_syllable_type_t) (buffer->info[start].syllable() & 0x0F);
   /* Only a few syllable types need reordering. */
   if (unlikely (!(FLAG_UNSAFE (syllable_type) &
 		  (FLAG (use_virama_terminated_cluster) |
 		   FLAG (use_sakot_terminated_cluster) |
 		   FLAG (use_standard_cluster) |
 		   FLAG (use_broken_cluster) |
 		   0))))
     return;

   hb_glyph_info_t *info = buffer->info;

 #define POST_BASE_FLAGS64 (FLAG64 (USE(FAbv)) | \
 			   FLAG64 (USE(FBlw)) | \
 			   FLAG64 (USE(FPst)) | \
 			   FLAG64 (USE(MAbv)) | \
 			   FLAG64 (USE(MBlw)) | \
 			   FLAG64 (USE(MPst)) | \
 			   FLAG64 (USE(MPre)) | \
 			   FLAG64 (USE(VAbv)) | \
 			   FLAG64 (USE(VBlw)) | \
 			   FLAG64 (USE(VPst)) | \
 			   FLAG64 (USE(VPre)) | \
 			   FLAG64 (USE(VMAbv)) | \
 			   FLAG64 (USE(VMBlw)) | \
 			   FLAG64 (USE(VMPst)) | \
 			   FLAG64 (USE(VMPre)))

   /* Move things forward. */
   if (info[start].use_category() == USE(R) && end - start > 1)
   {
     /* Got a repha.  Reorder it towards the end, but before the first post-base
      * glyph. */
     for (unsigned int i = start + 1; i < end; i++)
     {
       bool is_post_base_glyph = (FLAG64_UNSAFE (info[i].use_category()) & POST_BASE_FLAGS64) ||
 				is_halant_use (info[i]);
       if (is_post_base_glyph || i == end - 1)
       {
 	/* If we hit a post-base glyph, move before it; otherwise move to the
 	 * end. Shift things in between backward. */

 	if (is_post_base_glyph)
 	  i--;

 	buffer->merge_clusters (start, i + 1);
 	hb_glyph_info_t t = info[start];
 	memmove (&info[start], &info[start + 1], (i - start) * sizeof (info[0]));
 	info[i] = t;

 	break;
       }
     }
   }

   /* Move things back. */
   unsigned int j = start;
   for (unsigned int i = start; i < end; i++)
   {
     uint32_t flag = FLAG_UNSAFE (info[i].use_category());
     if (is_halant_use (info[i]))
     {
       /* If we hit a halant, move after it; otherwise move to the beginning, and
        * shift things in between forward. */
       j = i + 1;
     }
     else if (((flag) & (FLAG (USE(VPre)) | FLAG (USE(VMPre)))) &&
 	     /* Only move the first component of a MultipleSubst. */
 	     0 == _hb_glyph_info_get_lig_comp (&info[i]) &&
 	     j < i)
     {
       buffer->merge_clusters (j, i + 1);
       hb_glyph_info_t t = info[i];
       memmove (&info[j + 1], &info[j], (i - j) * sizeof (info[0]));
       info[j] = t;
     }
   }
 }

 static void
 reorder_use (const hb_ot_shape_plan_t *plan,
 	     hb_font_t *font,
 	     hb_buffer_t *buffer)
 {
   if (buffer->message (font, "start reordering USE"))
   {
     hb_syllabic_insert_dotted_circles (font, buffer,
 				       use_broken_cluster,
 				       USE(B),
 				       USE(R));

     foreach_syllable (buffer, start, end)
       reorder_syllable_use (buffer, start, end);

     (void) buffer->message (font, "end reordering USE");
   }

   HB_BUFFER_DEALLOCATE_VAR (buffer, use_category);
 }


 static void
 preprocess_text_use (const hb_ot_shape_plan_t *plan,
 		     hb_buffer_t              *buffer,
 		     hb_font_t                *font)
 {
   _hb_preprocess_text_vowel_constraints (plan, buffer, font);
 }

 static bool
 compose_use (const hb_ot_shape_normalize_context_t *c,
 	     hb_codepoint_t  a,
 	     hb_codepoint_t  b,
 	     hb_codepoint_t *ab)
 {
   /* Avoid recomposing split matras. */
   if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
     return false;

   return (bool)c->unicode->compose (a, b, ab);
 }


 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_use =
 {
   collect_features_use,
   nullptr, /* override_features */
   data_create_use,
   data_destroy_use,
   preprocess_text_use,
   nullptr, /* postprocess_glyphs */
   HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
   nullptr, /* decompose */
   compose_use,
   setup_masks_use,
   HB_TAG_NONE, /* gpos_tag */
   nullptr, /* reorder_marks */
   HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_EARLY,
   false, /* fallback_position */
 };


 #endif
	/*
	* Copyright © 2015 Mozilla Foundation.
	* Copyright © 2015 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.
	*
	* Mozilla Author(s): Jonathan Kew
	* Google Author(s): Behdad Esfahbod
	*/

	#include "hb.hh"

	#ifndef HB_NO_OT_SHAPE

	#include "hb-ot-shape-complex-use-machine.hh"
	#include "hb-ot-shape-complex-use-table.hh"
	#include "hb-ot-shape-complex-arabic.hh"
	#include "hb-ot-shape-complex-arabic-joining-list.hh"
	#include "hb-ot-shape-complex-vowel-constraints.hh"


	/*
	* Universal Shaping Engine.
	* https://docs.microsoft.com/en-us/typography/script-development/use
	*/

	static const hb_tag_t
	use_basic_features[] =
	{
	/*
	* Basic features.
	* These features are applied all at once, before reordering, constrained
	* to the syllable.
	*/
	HB_TAG('r','k','r','f'),
	HB_TAG('a','b','v','f'),
	HB_TAG('b','l','w','f'),
	HB_TAG('h','a','l','f'),
	HB_TAG('p','s','t','f'),
	HB_TAG('v','a','t','u'),
	HB_TAG('c','j','c','t'),
	};
	static const hb_tag_t
	use_topographical_features[] =
	{
	HB_TAG('i','s','o','l'),
	HB_TAG('i','n','i','t'),
	HB_TAG('m','e','d','i'),
	HB_TAG('f','i','n','a'),
	};
	/* Same order as use_topographical_features. */
	enum joining_form_t {
	JOINING_FORM_ISOL,
	JOINING_FORM_INIT,
	JOINING_FORM_MEDI,
	JOINING_FORM_FINA,
	_JOINING_FORM_NONE
	};
	static const hb_tag_t
	use_other_features[] =
	{
	/*
	* Other features.
	* These features are applied all at once, after reordering and
	* clearing syllables.
	*/
	HB_TAG('a','b','v','s'),
	HB_TAG('b','l','w','s'),
	HB_TAG('h','a','l','n'),
	HB_TAG('p','r','e','s'),
	HB_TAG('p','s','t','s'),
	};

	static void
	setup_syllables_use (const hb_ot_shape_plan_t *plan,
	hb_font_t *font,
	hb_buffer_t *buffer);
	static void
	record_rphf_use (const hb_ot_shape_plan_t *plan,
	hb_font_t *font,
	hb_buffer_t *buffer);
	static void
	record_pref_use (const hb_ot_shape_plan_t *plan,
	hb_font_t *font,
	hb_buffer_t *buffer);
	static void
	reorder_use (const hb_ot_shape_plan_t *plan,
	hb_font_t *font,
	hb_buffer_t *buffer);

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

	/* Do this before any lookups have been applied. */
	map->add_gsub_pause (setup_syllables_use);

	/* "Default glyph pre-processing group" */
	map->enable_feature (HB_TAG('l','o','c','l'));
	map->enable_feature (HB_TAG('c','c','m','p'));
	map->enable_feature (HB_TAG('n','u','k','t'));
	map->enable_feature (HB_TAG('a','k','h','n'), F_MANUAL_ZWJ);

	/* "Reordering group" */
	map->add_gsub_pause (_hb_clear_substitution_flags);
	map->add_feature (HB_TAG('r','p','h','f'), F_MANUAL_ZWJ);
	map->add_gsub_pause (record_rphf_use);
	map->add_gsub_pause (_hb_clear_substitution_flags);
	map->enable_feature (HB_TAG('p','r','e','f'), F_MANUAL_ZWJ);
	map->add_gsub_pause (record_pref_use);

	/* "Orthographic unit shaping group" */
	for (unsigned int i = 0; i < ARRAY_LENGTH (use_basic_features); i++)
	map->enable_feature (use_basic_features[i], F_MANUAL_ZWJ);

	map->add_gsub_pause (reorder_use);
	map->add_gsub_pause (_hb_clear_syllables);

	/* "Topographical features" */
	for (unsigned int i = 0; i < ARRAY_LENGTH (use_topographical_features); i++)
	map->add_feature (use_topographical_features[i]);
	map->add_gsub_pause (nullptr);

	/* "Standard typographic presentation" */
	for (unsigned int i = 0; i < ARRAY_LENGTH (use_other_features); i++)
	map->enable_feature (use_other_features[i], F_MANUAL_ZWJ);
	}

	struct use_shape_plan_t
	{
	hb_mask_t rphf_mask;

	arabic_shape_plan_t *arabic_plan;
	};

	static void *
	data_create_use (const hb_ot_shape_plan_t *plan)
	{
	use_shape_plan_t use_plan = (use_shape_plan_t ) hb_calloc (1, sizeof (use_shape_plan_t));
	if (unlikely (!use_plan))
	return nullptr;

	use_plan->rphf_mask = plan->map.get_1_mask (HB_TAG('r','p','h','f'));

	if (has_arabic_joining (plan->props.script))
	{
	use_plan->arabic_plan = (arabic_shape_plan_t *) data_create_arabic (plan);
	if (unlikely (!use_plan->arabic_plan))
	{
	hb_free (use_plan);
	return nullptr;
	}
	}

	return use_plan;
	}

	static void
	data_destroy_use (void *data)
	{
	use_shape_plan_t use_plan = (use_shape_plan_t ) data;

	if (use_plan->arabic_plan)
	data_destroy_arabic (use_plan->arabic_plan);

	hb_free (data);
	}

	static void
	setup_masks_use (const hb_ot_shape_plan_t *plan,
	hb_buffer_t *buffer,
	hb_font_t *font HB_UNUSED)
	{
	const use_shape_plan_t use_plan = (const use_shape_plan_t ) plan->data;

	/* Do this before allocating use_category(). */
	if (use_plan->arabic_plan)
	{
	setup_masks_arabic_plan (use_plan->arabic_plan, buffer, plan->props.script);
	}

	HB_BUFFER_ALLOCATE_VAR (buffer, use_category);

	/* We cannot setup masks here. We save information about characters
	* and setup masks later on in a pause-callback. */

	unsigned int count = buffer->len;
	hb_glyph_info_t *info = buffer->info;
	for (unsigned int i = 0; i < count; i++)
	info[i].use_category() = hb_use_get_category (info[i].codepoint);
	}

	static void
	setup_rphf_mask (const hb_ot_shape_plan_t *plan,
	hb_buffer_t *buffer)
	{
	const use_shape_plan_t use_plan = (const use_shape_plan_t ) plan->data;

	hb_mask_t mask = use_plan->rphf_mask;
	if (!mask) return;

	hb_glyph_info_t *info = buffer->info;

	foreach_syllable (buffer, start, end)
	{
	unsigned int limit = info[start].use_category() == USE(R) ? 1 : hb_min (3u, end - start);
	for (unsigned int i = start; i < start + limit; i++)
	info[i].mask \|= mask;
	}
	}

	static void
	setup_topographical_masks (const hb_ot_shape_plan_t *plan,
	hb_buffer_t *buffer)
	{
	const use_shape_plan_t use_plan = (const use_shape_plan_t ) plan->data;
	if (use_plan->arabic_plan)
	return;

	static_assert ((JOINING_FORM_INIT < 4 && JOINING_FORM_ISOL < 4 && JOINING_FORM_MEDI < 4 && JOINING_FORM_FINA < 4), "");
	hb_mask_t masks[4], all_masks = 0;
	for (unsigned int i = 0; i < 4; i++)
	{
	masks[i] = plan->map.get_1_mask (use_topographical_features[i]);
	if (masks[i] == plan->map.get_global_mask ())
	masks[i] = 0;
	all_masks \|= masks[i];
	}
	if (!all_masks)
	return;
	hb_mask_t other_masks = ~all_masks;

	unsigned int last_start = 0;
	joining_form_t last_form = _JOINING_FORM_NONE;
	hb_glyph_info_t *info = buffer->info;
	foreach_syllable (buffer, start, end)
	{
	use_syllable_type_t syllable_type = (use_syllable_type_t) (info[start].syllable() & 0x0F);
	switch (syllable_type)
	{
	case use_symbol_cluster:
	case use_hieroglyph_cluster:
	case use_non_cluster:
	/* These don't join. Nothing to do. */
	last_form = _JOINING_FORM_NONE;
	break;

	case use_virama_terminated_cluster:
	case use_sakot_terminated_cluster:
	case use_standard_cluster:
	case use_number_joiner_terminated_cluster:
	case use_numeral_cluster:
	case use_broken_cluster:

	bool join = last_form == JOINING_FORM_FINA \|\| last_form == JOINING_FORM_ISOL;

	if (join)
	{
	/* Fixup previous syllable's form. */
	last_form = last_form == JOINING_FORM_FINA ? JOINING_FORM_MEDI : JOINING_FORM_INIT;
	for (unsigned int i = last_start; i < start; i++)
	info[i].mask = (info[i].mask & other_masks) \| masks[last_form];
	}

	/* Form for this syllable. */
	last_form = join ? JOINING_FORM_FINA : JOINING_FORM_ISOL;
	for (unsigned int i = start; i < end; i++)
	info[i].mask = (info[i].mask & other_masks) \| masks[last_form];

	break;
	}

	last_start = start;
	}
	}

	static void
	setup_syllables_use (const hb_ot_shape_plan_t *plan,
	hb_font_t *font HB_UNUSED,
	hb_buffer_t *buffer)
	{
	find_syllables_use (buffer);
	foreach_syllable (buffer, start, end)
	buffer->unsafe_to_break (start, end);
	setup_rphf_mask (plan, buffer);
	setup_topographical_masks (plan, buffer);
	}

	static void
	record_rphf_use (const hb_ot_shape_plan_t *plan,
	hb_font_t *font HB_UNUSED,
	hb_buffer_t *buffer)
	{
	const use_shape_plan_t use_plan = (const use_shape_plan_t ) plan->data;

	hb_mask_t mask = use_plan->rphf_mask;
	if (!mask) return;
	hb_glyph_info_t *info = buffer->info;

	foreach_syllable (buffer, start, end)
	{
	/* Mark a substituted repha as USE(R). */
	for (unsigned int i = start; i < end && (info[i].mask & mask); i++)
	if (_hb_glyph_info_substituted (&info[i]))
	{
	info[i].use_category() = USE(R);
	break;
	}
	}
	}

	static void
	record_pref_use (const hb_ot_shape_plan_t *plan HB_UNUSED,
	hb_font_t *font HB_UNUSED,
	hb_buffer_t *buffer)
	{
	hb_glyph_info_t *info = buffer->info;

	foreach_syllable (buffer, start, end)
	{
	/* Mark a substituted pref as VPre, as they behave the same way. */
	for (unsigned int i = start; i < end; i++)
	if (_hb_glyph_info_substituted (&info[i]))
	{
	info[i].use_category() = USE(VPre);
	break;
	}
	}
	}

	static inline bool
	is_halant_use (const hb_glyph_info_t &info)
	{
	return (info.use_category() == USE(H) \|\| info.use_category() == USE(HVM)) &&
	!_hb_glyph_info_ligated (&info);
	}

	static void
	reorder_syllable_use (hb_buffer_t *buffer, unsigned int start, unsigned int end)
	{
	use_syllable_type_t syllable_type = (use_syllable_type_t) (buffer->info[start].syllable() & 0x0F);
	/* Only a few syllable types need reordering. */
	if (unlikely (!(FLAG_UNSAFE (syllable_type) &
	(FLAG (use_virama_terminated_cluster) \|
	FLAG (use_sakot_terminated_cluster) \|
	FLAG (use_standard_cluster) \|
	FLAG (use_broken_cluster) \|
	0))))
	return;

	hb_glyph_info_t *info = buffer->info;

	#define POST_BASE_FLAGS64 (FLAG64 (USE(FAbv)) \| \
	FLAG64 (USE(FBlw)) \| \
	FLAG64 (USE(FPst)) \| \
	FLAG64 (USE(MAbv)) \| \
	FLAG64 (USE(MBlw)) \| \
	FLAG64 (USE(MPst)) \| \
	FLAG64 (USE(MPre)) \| \
	FLAG64 (USE(VAbv)) \| \
	FLAG64 (USE(VBlw)) \| \
	FLAG64 (USE(VPst)) \| \
	FLAG64 (USE(VPre)) \| \
	FLAG64 (USE(VMAbv)) \| \
	FLAG64 (USE(VMBlw)) \| \
	FLAG64 (USE(VMPst)) \| \
	FLAG64 (USE(VMPre)))

	/* Move things forward. */
	if (info[start].use_category() == USE(R) && end - start > 1)
	{
	/* Got a repha. Reorder it towards the end, but before the first post-base
	* glyph. */
	for (unsigned int i = start + 1; i < end; i++)
	{
	bool is_post_base_glyph = (FLAG64_UNSAFE (info[i].use_category()) & POST_BASE_FLAGS64) \|\|
	is_halant_use (info[i]);
	if (is_post_base_glyph \|\| i == end - 1)
	{
	/* If we hit a post-base glyph, move before it; otherwise move to the
	* end. Shift things in between backward. */

	if (is_post_base_glyph)
	i--;

	buffer->merge_clusters (start, i + 1);
	hb_glyph_info_t t = info[start];
	memmove (&info[start], &info[start + 1], (i - start) * sizeof (info[0]));
	info[i] = t;

	break;
	}
	}
	}

	/* Move things back. */
	unsigned int j = start;
	for (unsigned int i = start; i < end; i++)
	{
	uint32_t flag = FLAG_UNSAFE (info[i].use_category());
	if (is_halant_use (info[i]))
	{
	/* If we hit a halant, move after it; otherwise move to the beginning, and
	* shift things in between forward. */
	j = i + 1;
	}
	else if (((flag) & (FLAG (USE(VPre)) \| FLAG (USE(VMPre)))) &&
	/* Only move the first component of a MultipleSubst. */
	0 == _hb_glyph_info_get_lig_comp (&info[i]) &&
	j < i)
	{
	buffer->merge_clusters (j, i + 1);
	hb_glyph_info_t t = info[i];
	memmove (&info[j + 1], &info[j], (i - j) * sizeof (info[0]));
	info[j] = t;
	}
	}
	}

	static void
	reorder_use (const hb_ot_shape_plan_t *plan,
	hb_font_t *font,
	hb_buffer_t *buffer)
	{
	if (buffer->message (font, "start reordering USE"))
	{
	hb_syllabic_insert_dotted_circles (font, buffer,
	use_broken_cluster,
	USE(B),
	USE(R));

	foreach_syllable (buffer, start, end)
	reorder_syllable_use (buffer, start, end);

	(void) buffer->message (font, "end reordering USE");
	}

	HB_BUFFER_DEALLOCATE_VAR (buffer, use_category);
	}


	static void
	preprocess_text_use (const hb_ot_shape_plan_t *plan,
	hb_buffer_t *buffer,
	hb_font_t *font)
	{
	_hb_preprocess_text_vowel_constraints (plan, buffer, font);
	}

	static bool
	compose_use (const hb_ot_shape_normalize_context_t *c,
	hb_codepoint_t a,
	hb_codepoint_t b,
	hb_codepoint_t *ab)
	{
	/* Avoid recomposing split matras. */
	if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a)))
	return false;

	return (bool)c->unicode->compose (a, b, ab);
	}


	const hb_ot_complex_shaper_t _hb_ot_complex_shaper_use =
	{
	collect_features_use,
	nullptr, /* override_features */
	data_create_use,
	data_destroy_use,
	preprocess_text_use,
	nullptr, /* postprocess_glyphs */
	HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT,
	nullptr, /* decompose */
	compose_use,
	setup_masks_use,
	HB_TAG_NONE, /* gpos_tag */
	nullptr, /* reorder_marks */
	HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_EARLY,
	false, /* fallback_position */
	};


	#endif