src/hb-ot-layout.cc - third_party/harfbuzz - Git at Google

 /*
  * Copyright © 1998-2004  David Turner and Werner Lemberg
  * Copyright © 2006  Behdad Esfahbod
  * Copyright © 2007,2008,2009  Red Hat, Inc.
  * 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.
  *
  * Red Hat Author(s): Behdad Esfahbod
  * Google Author(s): Behdad Esfahbod
  */

 #include "hb-ot-layout-private.hh"

 #include "hb-ot-layout-gdef-table.hh"
 #include "hb-ot-layout-gsub-table.hh"
 #include "hb-ot-layout-gpos-table.hh"
 #include "hb-ot-maxp-table.hh"


 #include <stdlib.h>
 #include <string.h>


 HB_SHAPER_DATA_ENSURE_DECLARE(ot, face)

 hb_ot_layout_t *
 _hb_ot_layout_create (hb_face_t *face)
 {
   hb_ot_layout_t *layout = (hb_ot_layout_t *) calloc (1, sizeof (hb_ot_layout_t));
   if (unlikely (!layout))
     return NULL;

   layout->gdef_blob = Sanitizer<GDEF>::sanitize (face->reference_table (HB_OT_TAG_GDEF));
   layout->gdef = Sanitizer<GDEF>::lock_instance (layout->gdef_blob);

   layout->gsub_blob = Sanitizer<GSUB>::sanitize (face->reference_table (HB_OT_TAG_GSUB));
   layout->gsub = Sanitizer<GSUB>::lock_instance (layout->gsub_blob);

   layout->gpos_blob = Sanitizer<GPOS>::sanitize (face->reference_table (HB_OT_TAG_GPOS));
   layout->gpos = Sanitizer<GPOS>::lock_instance (layout->gpos_blob);

   layout->gsub_lookup_count = layout->gsub->get_lookup_count ();
   layout->gpos_lookup_count = layout->gpos->get_lookup_count ();

   layout->gsub_digests = (hb_set_digest_t *) calloc (layout->gsub->get_lookup_count (), sizeof (hb_set_digest_t));
   layout->gpos_digests = (hb_set_digest_t *) calloc (layout->gpos->get_lookup_count (), sizeof (hb_set_digest_t));

   if (unlikely ((layout->gsub_lookup_count && !layout->gsub_digests) ||
 		(layout->gpos_lookup_count && !layout->gpos_digests)))
   {
     _hb_ot_layout_destroy (layout);
     return NULL;
   }

   for (unsigned int i = 0; i < layout->gsub_lookup_count; i++)
     layout->gsub->add_coverage (&layout->gsub_digests[i], i);
   for (unsigned int i = 0; i < layout->gpos_lookup_count; i++)
     layout->gpos->add_coverage (&layout->gpos_digests[i], i);

   return layout;
 }

 void
 _hb_ot_layout_destroy (hb_ot_layout_t *layout)
 {
   hb_blob_destroy (layout->gdef_blob);
   hb_blob_destroy (layout->gsub_blob);
   hb_blob_destroy (layout->gpos_blob);

   free (layout->gsub_digests);
   free (layout->gpos_digests);

   free (layout);
 }

 static inline const GDEF&
 _get_gdef (hb_face_t *face)
 {
   if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(GDEF);
   return *hb_ot_layout_from_face (face)->gdef;
 }
 static inline const GSUB&
 _get_gsub (hb_face_t *face)
 {
   if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(GSUB);
   return *hb_ot_layout_from_face (face)->gsub;
 }
 static inline const GPOS&
 _get_gpos (hb_face_t *face)
 {
   if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(GPOS);
   return *hb_ot_layout_from_face (face)->gpos;
 }


 /*
  * GDEF
  */

 hb_bool_t
 hb_ot_layout_has_glyph_classes (hb_face_t *face)
 {
   return _get_gdef (face).has_glyph_classes ();
 }


 unsigned int
 hb_ot_layout_get_attach_points (hb_face_t      *face,
 				hb_codepoint_t  glyph,
 				unsigned int    start_offset,
 				unsigned int   *point_count /* IN/OUT */,
 				unsigned int   *point_array /* OUT */)
 {
   return _get_gdef (face).get_attach_points (glyph, start_offset, point_count, point_array);
 }

 unsigned int
 hb_ot_layout_get_ligature_carets (hb_font_t      *font,
 				  hb_direction_t  direction,
 				  hb_codepoint_t  glyph,
 				  unsigned int    start_offset,
 				  unsigned int   *caret_count /* IN/OUT */,
 				  int            *caret_array /* OUT */)
 {
   return _get_gdef (font->face).get_lig_carets (font, direction, glyph, start_offset, caret_count, caret_array);
 }


 /*
  * GSUB/GPOS
  */

 static const GSUBGPOS&
 get_gsubgpos_table (hb_face_t *face,
 		    hb_tag_t   table_tag)
 {
   switch (table_tag) {
     case HB_OT_TAG_GSUB: return _get_gsub (face);
     case HB_OT_TAG_GPOS: return _get_gpos (face);
     default:             return Null(GSUBGPOS);
   }
 }


 unsigned int
 hb_ot_layout_table_get_script_tags (hb_face_t    *face,
 				    hb_tag_t      table_tag,
 				    unsigned int  start_offset,
 				    unsigned int *script_count /* IN/OUT */,
 				    hb_tag_t     *script_tags /* OUT */)
 {
   const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);

   return g.get_script_tags (start_offset, script_count, script_tags);
 }

 hb_bool_t
 hb_ot_layout_table_find_script (hb_face_t    *face,
 				hb_tag_t      table_tag,
 				hb_tag_t      script_tag,
 				unsigned int *script_index)
 {
   ASSERT_STATIC (Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
   const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);

   if (g.find_script_index (script_tag, script_index))
     return true;

   /* try finding 'DFLT' */
   if (g.find_script_index (HB_OT_TAG_DEFAULT_SCRIPT, script_index))
     return false;

   /* try with 'dflt'; MS site has had typos and many fonts use it now :(.
    * including many versions of DejaVu Sans Mono! */
   if (g.find_script_index (HB_OT_TAG_DEFAULT_LANGUAGE, script_index))
     return false;

   if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
   return false;
 }

 hb_bool_t
 hb_ot_layout_table_choose_script (hb_face_t      *face,
 				  hb_tag_t        table_tag,
 				  const hb_tag_t *script_tags,
 				  unsigned int   *script_index,
 				  hb_tag_t       *chosen_script)
 {
   ASSERT_STATIC (Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
   const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);

   while (*script_tags)
   {
     if (g.find_script_index (*script_tags, script_index)) {
       if (chosen_script)
         *chosen_script = *script_tags;
       return true;
     }
     script_tags++;
   }

   /* try finding 'DFLT' */
   if (g.find_script_index (HB_OT_TAG_DEFAULT_SCRIPT, script_index)) {
     if (chosen_script)
       *chosen_script = HB_OT_TAG_DEFAULT_SCRIPT;
     return false;
   }

   /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
   if (g.find_script_index (HB_OT_TAG_DEFAULT_LANGUAGE, script_index)) {
     if (chosen_script)
       *chosen_script = HB_OT_TAG_DEFAULT_LANGUAGE;
     return false;
   }

   /* try with 'latn'; some old fonts put their features there even though
      they're really trying to support Thai, for example :( */
 #define HB_OT_TAG_LATIN_SCRIPT		HB_TAG ('l', 'a', 't', 'n')
   if (g.find_script_index (HB_OT_TAG_LATIN_SCRIPT, script_index)) {
     if (chosen_script)
       *chosen_script = HB_OT_TAG_LATIN_SCRIPT;
     return false;
   }

   if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
   if (chosen_script)
     *chosen_script = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
   return false;
 }

 unsigned int
 hb_ot_layout_table_get_feature_tags (hb_face_t    *face,
 				     hb_tag_t      table_tag,
 				     unsigned int  start_offset,
 				     unsigned int *feature_count /* IN/OUT */,
 				     hb_tag_t     *feature_tags /* OUT */)
 {
   const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);

   return g.get_feature_tags (start_offset, feature_count, feature_tags);
 }


 unsigned int
 hb_ot_layout_script_get_language_tags (hb_face_t    *face,
 				       hb_tag_t      table_tag,
 				       unsigned int  script_index,
 				       unsigned int  start_offset,
 				       unsigned int *language_count /* IN/OUT */,
 				       hb_tag_t     *language_tags /* OUT */)
 {
   const Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);

   return s.get_lang_sys_tags (start_offset, language_count, language_tags);
 }

 hb_bool_t
 hb_ot_layout_script_find_language (hb_face_t    *face,
 				   hb_tag_t      table_tag,
 				   unsigned int  script_index,
 				   hb_tag_t      language_tag,
 				   unsigned int *language_index)
 {
   ASSERT_STATIC (Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX);
   const Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);

   if (s.find_lang_sys_index (language_tag, language_index))
     return true;

   /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
   if (s.find_lang_sys_index (HB_OT_TAG_DEFAULT_LANGUAGE, language_index))
     return false;

   if (language_index) *language_index = HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX;
   return false;
 }

 hb_bool_t
 hb_ot_layout_language_get_required_feature_index (hb_face_t    *face,
 						  hb_tag_t      table_tag,
 						  unsigned int  script_index,
 						  unsigned int  language_index,
 						  unsigned int *feature_index)
 {
   const LangSys &l = get_gsubgpos_table (face, table_tag).get_script (script_index).get_lang_sys (language_index);

   if (feature_index) *feature_index = l.get_required_feature_index ();

   return l.has_required_feature ();
 }

 unsigned int
 hb_ot_layout_language_get_feature_indexes (hb_face_t    *face,
 					   hb_tag_t      table_tag,
 					   unsigned int  script_index,
 					   unsigned int  language_index,
 					   unsigned int  start_offset,
 					   unsigned int *feature_count /* IN/OUT */,
 					   unsigned int *feature_indexes /* OUT */)
 {
   const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);

   return l.get_feature_indexes (start_offset, feature_count, feature_indexes);
 }

 unsigned int
 hb_ot_layout_language_get_feature_tags (hb_face_t    *face,
 					hb_tag_t      table_tag,
 					unsigned int  script_index,
 					unsigned int  language_index,
 					unsigned int  start_offset,
 					unsigned int *feature_count /* IN/OUT */,
 					hb_tag_t     *feature_tags /* OUT */)
 {
   const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);

   ASSERT_STATIC (sizeof (unsigned int) == sizeof (hb_tag_t));
   unsigned int ret = l.get_feature_indexes (start_offset, feature_count, (unsigned int *) feature_tags);

   if (feature_tags) {
     unsigned int count = *feature_count;
     for (unsigned int i = 0; i < count; i++)
       feature_tags[i] = g.get_feature_tag ((unsigned int) feature_tags[i]);
   }

   return ret;
 }


 hb_bool_t
 hb_ot_layout_language_find_feature (hb_face_t    *face,
 				    hb_tag_t      table_tag,
 				    unsigned int  script_index,
 				    unsigned int  language_index,
 				    hb_tag_t      feature_tag,
 				    unsigned int *feature_index)
 {
   ASSERT_STATIC (Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
   const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);

   unsigned int num_features = l.get_feature_count ();
   for (unsigned int i = 0; i < num_features; i++) {
     unsigned int f_index = l.get_feature_index (i);

     if (feature_tag == g.get_feature_tag (f_index)) {
       if (feature_index) *feature_index = f_index;
       return true;
     }
   }

   if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
   return false;
 }

 unsigned int
 hb_ot_layout_feature_get_lookup_indexes (hb_face_t    *face,
 					 hb_tag_t      table_tag,
 					 unsigned int  feature_index,
 					 unsigned int  start_offset,
 					 unsigned int *lookup_count /* IN/OUT */,
 					 unsigned int *lookup_indexes /* OUT */)
 {
   const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
   const Feature &f = g.get_feature (feature_index);

   return f.get_lookup_indexes (start_offset, lookup_count, lookup_indexes);
 }


 /*
  * GSUB
  */

 hb_bool_t
 hb_ot_layout_has_substitution (hb_face_t *face)
 {
   return &_get_gsub (face) != &Null(GSUB);
 }

 hb_bool_t
 hb_ot_layout_would_substitute_lookup (hb_face_t            *face,
 				      const hb_codepoint_t *glyphs,
 				      unsigned int          glyphs_length,
 				      unsigned int          lookup_index)
 {
   if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return false;
   return hb_ot_layout_would_substitute_lookup_fast (face, glyphs, glyphs_length, lookup_index);
 }

 hb_bool_t
 hb_ot_layout_would_substitute_lookup_fast (hb_face_t            *face,
 					   const hb_codepoint_t *glyphs,
 					   unsigned int          glyphs_length,
 					   unsigned int          lookup_index)
 {
   if (unlikely (lookup_index >= hb_ot_layout_from_face (face)->gsub_lookup_count)) return false;
   hb_would_apply_context_t c (face, glyphs, glyphs_length, &hb_ot_layout_from_face (face)->gsub_digests[lookup_index]);
   return hb_ot_layout_from_face (face)->gsub->would_substitute_lookup (&c, lookup_index);
 }

 void
 hb_ot_layout_substitute_start (hb_font_t *font, hb_buffer_t *buffer)
 {
   GSUB::substitute_start (font, buffer);
 }

 hb_bool_t
 hb_ot_layout_substitute_lookup (hb_font_t    *font,
 				hb_buffer_t  *buffer,
 				unsigned int  lookup_index,
 				hb_mask_t     mask)
 {
   if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gsub_lookup_count)) return false;
   hb_apply_context_t c (font, buffer, mask, &hb_ot_layout_from_face (font->face)->gsub_digests[lookup_index]);
   return hb_ot_layout_from_face (font->face)->gsub->substitute_lookup (&c, lookup_index);
 }

 void
 hb_ot_layout_substitute_finish (hb_font_t *font, hb_buffer_t *buffer)
 {
   GSUB::substitute_finish (font, buffer);
 }

 void
 hb_ot_layout_substitute_closure_lookup (hb_face_t    *face,
 				        hb_set_t     *glyphs,
 				        unsigned int  lookup_index)
 {
   hb_closure_context_t c (face, glyphs);
   _get_gsub (face).closure_lookup (&c, lookup_index);
 }

 /*
  * GPOS
  */

 hb_bool_t
 hb_ot_layout_has_positioning (hb_face_t *face)
 {
   return &_get_gpos (face) != &Null(GPOS);
 }

 void
 hb_ot_layout_position_start (hb_font_t *font, hb_buffer_t *buffer)
 {
   GPOS::position_start (font, buffer);
 }

 hb_bool_t
 hb_ot_layout_position_lookup (hb_font_t    *font,
 			      hb_buffer_t  *buffer,
 			      unsigned int  lookup_index,
 			      hb_mask_t     mask)
 {
   if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gpos_lookup_count)) return false;
   hb_apply_context_t c (font, buffer, mask, &hb_ot_layout_from_face (font->face)->gpos_digests[lookup_index]);
   return hb_ot_layout_from_face (font->face)->gpos->position_lookup (&c, lookup_index);
 }

 void
 hb_ot_layout_position_finish (hb_font_t *font, hb_buffer_t *buffer, hb_bool_t zero_width_attached_marks)
 {
   GPOS::position_finish (font, buffer, zero_width_attached_marks);
 }
	/*
	* Copyright © 1998-2004 David Turner and Werner Lemberg
	* Copyright © 2006 Behdad Esfahbod
	* Copyright © 2007,2008,2009 Red Hat, Inc.
	* 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.
	*
	* Red Hat Author(s): Behdad Esfahbod
	* Google Author(s): Behdad Esfahbod
	*/

	#include "hb-ot-layout-private.hh"

	#include "hb-ot-layout-gdef-table.hh"
	#include "hb-ot-layout-gsub-table.hh"
	#include "hb-ot-layout-gpos-table.hh"
	#include "hb-ot-maxp-table.hh"


	#include <stdlib.h>
	#include <string.h>


	HB_SHAPER_DATA_ENSURE_DECLARE(ot, face)

	hb_ot_layout_t *
	_hb_ot_layout_create (hb_face_t *face)
	{
	hb_ot_layout_t layout = (hb_ot_layout_t ) calloc (1, sizeof (hb_ot_layout_t));
	if (unlikely (!layout))
	return NULL;

	layout->gdef_blob = Sanitizer<GDEF>::sanitize (face->reference_table (HB_OT_TAG_GDEF));
	layout->gdef = Sanitizer<GDEF>::lock_instance (layout->gdef_blob);

	layout->gsub_blob = Sanitizer<GSUB>::sanitize (face->reference_table (HB_OT_TAG_GSUB));
	layout->gsub = Sanitizer<GSUB>::lock_instance (layout->gsub_blob);

	layout->gpos_blob = Sanitizer<GPOS>::sanitize (face->reference_table (HB_OT_TAG_GPOS));
	layout->gpos = Sanitizer<GPOS>::lock_instance (layout->gpos_blob);

	layout->gsub_lookup_count = layout->gsub->get_lookup_count ();
	layout->gpos_lookup_count = layout->gpos->get_lookup_count ();

	layout->gsub_digests = (hb_set_digest_t *) calloc (layout->gsub->get_lookup_count (), sizeof (hb_set_digest_t));
	layout->gpos_digests = (hb_set_digest_t *) calloc (layout->gpos->get_lookup_count (), sizeof (hb_set_digest_t));

	if (unlikely ((layout->gsub_lookup_count && !layout->gsub_digests) \|\|
	(layout->gpos_lookup_count && !layout->gpos_digests)))
	{
	_hb_ot_layout_destroy (layout);
	return NULL;
	}

	for (unsigned int i = 0; i < layout->gsub_lookup_count; i++)
	layout->gsub->add_coverage (&layout->gsub_digests[i], i);
	for (unsigned int i = 0; i < layout->gpos_lookup_count; i++)
	layout->gpos->add_coverage (&layout->gpos_digests[i], i);

	return layout;
	}

	void
	_hb_ot_layout_destroy (hb_ot_layout_t *layout)
	{
	hb_blob_destroy (layout->gdef_blob);
	hb_blob_destroy (layout->gsub_blob);
	hb_blob_destroy (layout->gpos_blob);

	free (layout->gsub_digests);
	free (layout->gpos_digests);

	free (layout);
	}

	static inline const GDEF&
	_get_gdef (hb_face_t *face)
	{
	if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(GDEF);
	return *hb_ot_layout_from_face (face)->gdef;
	}
	static inline const GSUB&
	_get_gsub (hb_face_t *face)
	{
	if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(GSUB);
	return *hb_ot_layout_from_face (face)->gsub;
	}
	static inline const GPOS&
	_get_gpos (hb_face_t *face)
	{
	if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return Null(GPOS);
	return *hb_ot_layout_from_face (face)->gpos;
	}


	/*
	* GDEF
	*/

	hb_bool_t
	hb_ot_layout_has_glyph_classes (hb_face_t *face)
	{
	return _get_gdef (face).has_glyph_classes ();
	}


	unsigned int
	hb_ot_layout_get_attach_points (hb_face_t *face,
	hb_codepoint_t glyph,
	unsigned int start_offset,
	unsigned int point_count / IN/OUT */,
	unsigned int point_array / OUT */)
	{
	return _get_gdef (face).get_attach_points (glyph, start_offset, point_count, point_array);
	}

	unsigned int
	hb_ot_layout_get_ligature_carets (hb_font_t *font,
	hb_direction_t direction,
	hb_codepoint_t glyph,
	unsigned int start_offset,
	unsigned int caret_count / IN/OUT */,
	int caret_array / OUT */)
	{
	return _get_gdef (font->face).get_lig_carets (font, direction, glyph, start_offset, caret_count, caret_array);
	}


	/*
	* GSUB/GPOS
	*/

	static const GSUBGPOS&
	get_gsubgpos_table (hb_face_t *face,
	hb_tag_t table_tag)
	{
	switch (table_tag) {
	case HB_OT_TAG_GSUB: return _get_gsub (face);
	case HB_OT_TAG_GPOS: return _get_gpos (face);
	default: return Null(GSUBGPOS);
	}
	}


	unsigned int
	hb_ot_layout_table_get_script_tags (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int start_offset,
	unsigned int script_count / IN/OUT */,
	hb_tag_t script_tags / OUT */)
	{
	const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);

	return g.get_script_tags (start_offset, script_count, script_tags);
	}

	hb_bool_t
	hb_ot_layout_table_find_script (hb_face_t *face,
	hb_tag_t table_tag,
	hb_tag_t script_tag,
	unsigned int *script_index)
	{
	ASSERT_STATIC (Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
	const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);

	if (g.find_script_index (script_tag, script_index))
	return true;

	/* try finding 'DFLT' */
	if (g.find_script_index (HB_OT_TAG_DEFAULT_SCRIPT, script_index))
	return false;

	/* try with 'dflt'; MS site has had typos and many fonts use it now :(.
	* including many versions of DejaVu Sans Mono! */
	if (g.find_script_index (HB_OT_TAG_DEFAULT_LANGUAGE, script_index))
	return false;

	if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
	return false;
	}

	hb_bool_t
	hb_ot_layout_table_choose_script (hb_face_t *face,
	hb_tag_t table_tag,
	const hb_tag_t *script_tags,
	unsigned int *script_index,
	hb_tag_t *chosen_script)
	{
	ASSERT_STATIC (Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
	const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);

	while (*script_tags)
	{
	if (g.find_script_index (*script_tags, script_index)) {
	if (chosen_script)
	chosen_script = script_tags;
	return true;
	}
	script_tags++;
	}

	/* try finding 'DFLT' */
	if (g.find_script_index (HB_OT_TAG_DEFAULT_SCRIPT, script_index)) {
	if (chosen_script)
	*chosen_script = HB_OT_TAG_DEFAULT_SCRIPT;
	return false;
	}

	/* try with 'dflt'; MS site has had typos and many fonts use it now :( */
	if (g.find_script_index (HB_OT_TAG_DEFAULT_LANGUAGE, script_index)) {
	if (chosen_script)
	*chosen_script = HB_OT_TAG_DEFAULT_LANGUAGE;
	return false;
	}

	/* try with 'latn'; some old fonts put their features there even though
	they're really trying to support Thai, for example :( */
	#define HB_OT_TAG_LATIN_SCRIPT HB_TAG ('l', 'a', 't', 'n')
	if (g.find_script_index (HB_OT_TAG_LATIN_SCRIPT, script_index)) {
	if (chosen_script)
	*chosen_script = HB_OT_TAG_LATIN_SCRIPT;
	return false;
	}

	if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
	if (chosen_script)
	*chosen_script = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
	return false;
	}

	unsigned int
	hb_ot_layout_table_get_feature_tags (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int start_offset,
	unsigned int feature_count / IN/OUT */,
	hb_tag_t feature_tags / OUT */)
	{
	const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);

	return g.get_feature_tags (start_offset, feature_count, feature_tags);
	}


	unsigned int
	hb_ot_layout_script_get_language_tags (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int script_index,
	unsigned int start_offset,
	unsigned int language_count / IN/OUT */,
	hb_tag_t language_tags / OUT */)
	{
	const Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);

	return s.get_lang_sys_tags (start_offset, language_count, language_tags);
	}

	hb_bool_t
	hb_ot_layout_script_find_language (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int script_index,
	hb_tag_t language_tag,
	unsigned int *language_index)
	{
	ASSERT_STATIC (Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX);
	const Script &s = get_gsubgpos_table (face, table_tag).get_script (script_index);

	if (s.find_lang_sys_index (language_tag, language_index))
	return true;

	/* try with 'dflt'; MS site has had typos and many fonts use it now :( */
	if (s.find_lang_sys_index (HB_OT_TAG_DEFAULT_LANGUAGE, language_index))
	return false;

	if (language_index) *language_index = HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX;
	return false;
	}

	hb_bool_t
	hb_ot_layout_language_get_required_feature_index (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int script_index,
	unsigned int language_index,
	unsigned int *feature_index)
	{
	const LangSys &l = get_gsubgpos_table (face, table_tag).get_script (script_index).get_lang_sys (language_index);

	if (feature_index) *feature_index = l.get_required_feature_index ();

	return l.has_required_feature ();
	}

	unsigned int
	hb_ot_layout_language_get_feature_indexes (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int script_index,
	unsigned int language_index,
	unsigned int start_offset,
	unsigned int feature_count / IN/OUT */,
	unsigned int feature_indexes / OUT */)
	{
	const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
	const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);

	return l.get_feature_indexes (start_offset, feature_count, feature_indexes);
	}

	unsigned int
	hb_ot_layout_language_get_feature_tags (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int script_index,
	unsigned int language_index,
	unsigned int start_offset,
	unsigned int feature_count / IN/OUT */,
	hb_tag_t feature_tags / OUT */)
	{
	const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
	const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);

	ASSERT_STATIC (sizeof (unsigned int) == sizeof (hb_tag_t));
	unsigned int ret = l.get_feature_indexes (start_offset, feature_count, (unsigned int *) feature_tags);

	if (feature_tags) {
	unsigned int count = *feature_count;
	for (unsigned int i = 0; i < count; i++)
	feature_tags[i] = g.get_feature_tag ((unsigned int) feature_tags[i]);
	}

	return ret;
	}


	hb_bool_t
	hb_ot_layout_language_find_feature (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int script_index,
	unsigned int language_index,
	hb_tag_t feature_tag,
	unsigned int *feature_index)
	{
	ASSERT_STATIC (Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
	const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
	const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);

	unsigned int num_features = l.get_feature_count ();
	for (unsigned int i = 0; i < num_features; i++) {
	unsigned int f_index = l.get_feature_index (i);

	if (feature_tag == g.get_feature_tag (f_index)) {
	if (feature_index) *feature_index = f_index;
	return true;
	}
	}

	if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
	return false;
	}

	unsigned int
	hb_ot_layout_feature_get_lookup_indexes (hb_face_t *face,
	hb_tag_t table_tag,
	unsigned int feature_index,
	unsigned int start_offset,
	unsigned int lookup_count / IN/OUT */,
	unsigned int lookup_indexes / OUT */)
	{
	const GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
	const Feature &f = g.get_feature (feature_index);

	return f.get_lookup_indexes (start_offset, lookup_count, lookup_indexes);
	}


	/*
	* GSUB
	*/

	hb_bool_t
	hb_ot_layout_has_substitution (hb_face_t *face)
	{
	return &_get_gsub (face) != &Null(GSUB);
	}

	hb_bool_t
	hb_ot_layout_would_substitute_lookup (hb_face_t *face,
	const hb_codepoint_t *glyphs,
	unsigned int glyphs_length,
	unsigned int lookup_index)
	{
	if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return false;
	return hb_ot_layout_would_substitute_lookup_fast (face, glyphs, glyphs_length, lookup_index);
	}

	hb_bool_t
	hb_ot_layout_would_substitute_lookup_fast (hb_face_t *face,
	const hb_codepoint_t *glyphs,
	unsigned int glyphs_length,
	unsigned int lookup_index)
	{
	if (unlikely (lookup_index >= hb_ot_layout_from_face (face)->gsub_lookup_count)) return false;
	hb_would_apply_context_t c (face, glyphs, glyphs_length, &hb_ot_layout_from_face (face)->gsub_digests[lookup_index]);
	return hb_ot_layout_from_face (face)->gsub->would_substitute_lookup (&c, lookup_index);
	}

	void
	hb_ot_layout_substitute_start (hb_font_t font, hb_buffer_t buffer)
	{
	GSUB::substitute_start (font, buffer);
	}

	hb_bool_t
	hb_ot_layout_substitute_lookup (hb_font_t *font,
	hb_buffer_t *buffer,
	unsigned int lookup_index,
	hb_mask_t mask)
	{
	if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gsub_lookup_count)) return false;
	hb_apply_context_t c (font, buffer, mask, &hb_ot_layout_from_face (font->face)->gsub_digests[lookup_index]);
	return hb_ot_layout_from_face (font->face)->gsub->substitute_lookup (&c, lookup_index);
	}

	void
	hb_ot_layout_substitute_finish (hb_font_t font, hb_buffer_t buffer)
	{
	GSUB::substitute_finish (font, buffer);
	}

	void
	hb_ot_layout_substitute_closure_lookup (hb_face_t *face,
	hb_set_t *glyphs,
	unsigned int lookup_index)
	{
	hb_closure_context_t c (face, glyphs);
	_get_gsub (face).closure_lookup (&c, lookup_index);
	}

	/*
	* GPOS
	*/

	hb_bool_t
	hb_ot_layout_has_positioning (hb_face_t *face)
	{
	return &_get_gpos (face) != &Null(GPOS);
	}

	void
	hb_ot_layout_position_start (hb_font_t font, hb_buffer_t buffer)
	{
	GPOS::position_start (font, buffer);
	}

	hb_bool_t
	hb_ot_layout_position_lookup (hb_font_t *font,
	hb_buffer_t *buffer,
	unsigned int lookup_index,
	hb_mask_t mask)
	{
	if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gpos_lookup_count)) return false;
	hb_apply_context_t c (font, buffer, mask, &hb_ot_layout_from_face (font->face)->gpos_digests[lookup_index]);
	return hb_ot_layout_from_face (font->face)->gpos->position_lookup (&c, lookup_index);
	}

	void
	hb_ot_layout_position_finish (hb_font_t font, hb_buffer_t buffer, hb_bool_t zero_width_attached_marks)
	{
	GPOS::position_finish (font, buffer, zero_width_attached_marks);
	}