harfbuzz-ng roll

third_party/harfbuzz-ng/src/hb-ot-layout.cc

 /*
  * 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)
 {
-  /* TODO Remove this object altogether */
   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 (hb_face_reference_table (face, HB_OT_TAG_GDEF));
-  layout->gdef = Sanitizer<GDEF>::lock_instance (layout->gdef_blob);
+  layout->gdef_blob = OT::Sanitizer<OT::GDEF>::sanitize (face->reference_table (HB_OT_TAG_GDEF));
+  layout->gdef = OT::Sanitizer<OT::GDEF>::lock_instance (layout->gdef_blob);
 
-  layout->gsub_blob = Sanitizer<GSUB>::sanitize (hb_face_reference_table (face, HB_OT_TAG_GSUB));
-  layout->gsub = Sanitizer<GSUB>::lock_instance (layout->gsub_blob);
+  layout->gsub_blob = OT::Sanitizer<OT::GSUB>::sanitize (face->reference_table (HB_OT_TAG_GSUB));
+  layout->gsub = OT::Sanitizer<OT::GSUB>::lock_instance (layout->gsub_blob);
 
-  layout->gpos_blob = Sanitizer<GPOS>::sanitize (hb_face_reference_table (face, HB_OT_TAG_GPOS));
-  layout->gpos = Sanitizer<GPOS>::lock_instance (layout->gpos_blob);
+  layout->gpos_blob = OT::Sanitizer<OT::GPOS>::sanitize (face->reference_table (HB_OT_TAG_GPOS));
+  layout->gpos = OT::Sanitizer<OT::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&
+static inline const OT::GDEF&
 _get_gdef (hb_face_t *face)
 {
-  return likely (face->ot_layout && face->ot_layout->gdef) ? *face->ot_layout->gdef : Null(GDEF);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GDEF);
+  return *hb_ot_layout_from_face (face)->gdef;
 }
-static inline const GSUB&
+static inline const OT::GSUB&
 _get_gsub (hb_face_t *face)
 {
-  return likely (face->ot_layout && face->ot_layout->gsub) ? *face->ot_layout->gsub : Null(GSUB);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::GSUB);
+  return *hb_ot_layout_from_face (face)->gsub;
 }
-static inline const GPOS&
+static inline const OT::GPOS&
 _get_gpos (hb_face_t *face)
 {
-  return likely (face->ot_layout && face->ot_layout->gpos) ? *face->ot_layout->gpos : Null(GPOS);
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return OT::Null(OT::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_glyph_property (hb_face_t       *face,
-                                  hb_glyph_info_t *info)
-{
-  if (!info->props_cache())
-  {
-    const GDEF &gdef = _get_gdef (face);
-    info->props_cache() = gdef.get_glyph_props (info->codepoint);
-  }
-
-  return info->props_cache();
-}
-
-static hb_bool_t
-_hb_ot_layout_match_properties (hb_face_t      *face,
-                                hb_codepoint_t  codepoint,
-                                unsigned int    glyph_props,
-                                unsigned int    lookup_props)
-{
-  /* Not covered, if, for example, glyph class is ligature and
-   * lookup_props includes LookupFlags::IgnoreLigatures
-   */
-  if (glyph_props & lookup_props & LookupFlag::IgnoreFlags)
-    return false;
-
-  if (glyph_props & HB_OT_LAYOUT_GLYPH_CLASS_MARK)
-  {
-    /* If using mark filtering sets, the high short of
-     * lookup_props has the set index.
-     */
-    if (lookup_props & LookupFlag::UseMarkFilteringSet)
-      return _get_gdef (face).mark_set_covers (lookup_props >> 16, codepoint);
-
-    /* The second byte of lookup_props has the meaning
-     * "ignore marks of attachment type different than
-     * the attachment type specified."
-     */
-    if (lookup_props & LookupFlag::MarkAttachmentType && glyph_props & LookupFlag::MarkAttachmentType)
-      return (lookup_props & LookupFlag::MarkAttachmentType) == (glyph_props & LookupFlag::MarkAttachmentType);
-  }
-
-  return true;
-}
-
-hb_bool_t
-_hb_ot_layout_check_glyph_property (hb_face_t    *face,
-                                    hb_glyph_info_t *ginfo,
-                                    unsigned int  lookup_props,
-                                    unsigned int *property_out)
-{
-  unsigned int property;
-
-  property = _hb_ot_layout_get_glyph_property (face, ginfo);
-  (void) (property_out && (*property_out = property));
-
-  return _hb_ot_layout_match_properties (face, ginfo->codepoint, property, lookup_props);
-}
-
-hb_bool_t
-_hb_ot_layout_skip_mark (hb_face_t    *face,
-                         hb_glyph_info_t *ginfo,
-                         unsigned int  lookup_props,
-                         unsigned int *property_out)
-{
-  unsigned int property;
-
-  property = _hb_ot_layout_get_glyph_property (face, ginfo);
-  (void) (property_out && (*property_out = property));
-
-  /* If it's a mark, skip it we don't accept it. */
-  if (unlikely (property & HB_OT_LAYOUT_GLYPH_CLASS_MARK))
-    return !_hb_ot_layout_match_properties (face, ginfo->codepoint, property, lookup_props);
-
-  /* If not a mark, don't skip. */
-  return false;
-}
-
-
 
 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&
+static const OT::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);
+    default:             return OT::Null(OT::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);
+  const OT::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);
+  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
+  const OT::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);
+  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
+  const OT::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++;
   }
@@ skipping 27 matching lines @@
   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);
+  const OT::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);
+  const OT::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);
+  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX);
+  const OT::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);
+  const OT::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);
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+  const OT::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);
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+  const OT::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);
+  ASSERT_STATIC (OT::Index::NOT_FOUND_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+  const OT::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);
+  const OT::GSUBGPOS &g = get_gsubgpos_table (face, table_tag);
+  const OT::Feature &f = g.get_feature (feature_index);
 
   return f.get_lookup_indexes (start_offset, lookup_count, lookup_indexes);
 }
 
 
 /*
- * GSUB
+ * OT::GSUB
  */
 
 hb_bool_t
 hb_ot_layout_has_substitution (hb_face_t *face)
 {
-  return &_get_gsub (face) != &Null(GSUB);
+  return &_get_gsub (face) != &OT::Null(OT::GSUB);
+}
+
+hb_bool_t
+hb_ot_layout_would_substitute_lookup (hb_face_t            *face,
+                                      unsigned int          lookup_index,
+                                      const hb_codepoint_t *glyphs,
+                                      unsigned int          glyphs_length,
+                                      hb_bool_t             zero_context)
+{
+  if (unlikely (!hb_ot_shaper_face_data_ensure (face))) return false;
+  return hb_ot_layout_would_substitute_lookup_fast (face, lookup_index, glyphs, glyphs_length, zero_context);
+}
+
+hb_bool_t
+hb_ot_layout_would_substitute_lookup_fast (hb_face_t            *face,
+                                           unsigned int          lookup_index,
+                                           const hb_codepoint_t *glyphs,
+                                           unsigned int          glyphs_length,
+                                           hb_bool_t             zero_context)
+{
+  if (unlikely (lookup_index >= hb_ot_layout_from_face (face)->gsub_lookup_count)) return false;
+  OT::hb_would_apply_context_t c (face, glyphs, glyphs_length, zero_context);
+
+  const OT::SubstLookup& l = hb_ot_layout_from_face (face)->gsub->get_lookup (lookup_index);
+
+  return l.would_apply (&c, &hb_ot_layout_from_face (face)->gsub_digests[lookup_index]);
 }
 
 void
-hb_ot_layout_substitute_start (hb_buffer_t  *buffer)
+hb_ot_layout_substitute_start (hb_font_t *font, hb_buffer_t *buffer)
 {
-  GSUB::substitute_start (buffer);
+  OT::GSUB::substitute_start (font, buffer);
 }
 
 hb_bool_t
-hb_ot_layout_substitute_lookup (hb_face_t    *face,
+hb_ot_layout_substitute_lookup (hb_font_t    *font,
                                 hb_buffer_t  *buffer,
                                 unsigned int  lookup_index,
                                 hb_mask_t     mask)
 {
-  hb_apply_context_t c (NULL, face, buffer, mask);
-  return _get_gsub (face).substitute_lookup (&c, lookup_index);
+  if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gsub_lookup_count)) return false;
+
+  OT::hb_apply_context_t c (font, buffer, mask);
+
+  const OT::SubstLookup& l = hb_ot_layout_from_face (font->face)->gsub->get_lookup (lookup_index);
+
+  return l.apply_string (&c, &hb_ot_layout_from_face (font->face)->gsub_digests[lookup_index]);
 }
 
 void
-hb_ot_layout_substitute_finish (hb_buffer_t  *buffer HB_UNUSED)
+hb_ot_layout_substitute_finish (hb_font_t *font, hb_buffer_t *buffer)
 {
-  GSUB::substitute_finish (buffer);
+  OT::GSUB::substitute_finish (font, buffer);
 }
 
 void
 hb_ot_layout_substitute_closure_lookup (hb_face_t    *face,
-                                        hb_set_t     *glyphs,
-                                        unsigned int  lookup_index)
+                                        unsigned int  lookup_index,
+                                        hb_set_t     *glyphs)
 {
-  hb_closure_context_t c (face, glyphs);
+  OT::hb_closure_context_t c (face, glyphs);
   _get_gsub (face).closure_lookup (&c, lookup_index);
 }
 
 /*
- * GPOS
+ * OT::GPOS
  */
 
 hb_bool_t
 hb_ot_layout_has_positioning (hb_face_t *face)
 {
-  return &_get_gpos (face) != &Null(GPOS);
+  return &_get_gpos (face) != &OT::Null(OT::GPOS);
 }
 
 void
-hb_ot_layout_position_start (hb_buffer_t  *buffer)
+hb_ot_layout_position_start (hb_font_t *font, hb_buffer_t *buffer)
 {
-  GPOS::position_start (buffer);
+  OT::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)
+hb_ot_layout_position_lookup (hb_font_t    *font,
+                              hb_buffer_t  *buffer,
+                              unsigned int  lookup_index,
+                              hb_mask_t     mask)
 {
-  hb_apply_context_t c (font, font->face, buffer, mask);
-  return _get_gpos (font->face).position_lookup (&c, lookup_index);
+  if (unlikely (lookup_index >= hb_ot_layout_from_face (font->face)->gpos_lookup_count)) return false;
+
+  OT::hb_apply_context_t c (font, buffer, mask);
+
+  const OT::PosLookup& l = hb_ot_layout_from_face (font->face)->gpos->get_lookup (lookup_index);
+
+  return l.apply_string (&c, &hb_ot_layout_from_face (font->face)->gpos_digests[lookup_index]);
 }
 
 void
-hb_ot_layout_position_finish (hb_buffer_t  *buffer)
+hb_ot_layout_position_finish (hb_font_t *font, hb_buffer_t *buffer, hb_bool_t zero_width_attached_marks)
 {
-  GPOS::position_finish (buffer);
+  OT::GPOS::position_finish (font, buffer, zero_width_attached_marks);
 }
-
-