harfbuzz-ng roll

third_party/harfbuzz-ng/src/hb-ot-layout-gsub-table.hh

 /*
  * Copyright © 2007,2008,2009,2010  Red Hat, Inc.
  * 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
@@ skipping 14 matching lines @@
  * Red Hat Author(s): Behdad Esfahbod
  * Google Author(s): Behdad Esfahbod
  */
 
 #ifndef HB_OT_LAYOUT_GSUB_TABLE_HH
 #define HB_OT_LAYOUT_GSUB_TABLE_HH
 
 #include "hb-ot-layout-gsubgpos-private.hh"
 
 
+namespace OT {
+
 
 struct SingleSubstFormat1
 {
   friend struct SingleSubst;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     Coverage::Iter iter;
     for (iter.init (this+coverage); iter.more (); iter.next ()) {
       hb_codepoint_t glyph_id = iter.get_glyph ();
       if (c->glyphs->has (glyph_id))
         c->glyphs->add ((glyph_id + deltaGlyphID) & 0xFFFF);
     }
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id) const
+  inline const Coverage &get_coverage (void) const
   {
-    return (this+coverage) (glyph_id) != NOT_COVERED;
+    return this+coverage;
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     hb_codepoint_t glyph_id = c->buffer->cur().codepoint;
     unsigned int index = (this+coverage) (glyph_id);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
     /* According to the Adobe Annotated OpenType Suite, result is always
      * limited to 16bit. */
     glyph_id = (glyph_id + deltaGlyphID) & 0xFFFF;
     c->replace_glyph (glyph_id);
 
     return TRACE_RETURN (true);
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &glyphs,
+                         unsigned int num_glyphs,
+                         int delta)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    if (unlikely (!coverage.serialize (c, this).serialize (c, glyphs, num_glyphs))) return TRACE_RETURN (false);
+    deltaGlyphID.set (delta); /* TODO(serilaize) overflow? */
+    return TRACE_RETURN (true);
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (coverage.sanitize (c, this) && deltaGlyphID.sanitize (c));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of Substitution table */
   SHORT         deltaGlyphID;           /* Add to original GlyphID to get
                                          * substitute GlyphID */
   public:
   DEFINE_SIZE_STATIC (6);
 };
 
 struct SingleSubstFormat2
 {
   friend struct SingleSubst;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     Coverage::Iter iter;
     for (iter.init (this+coverage); iter.more (); iter.next ()) {
       if (c->glyphs->has (iter.get_glyph ()))
         c->glyphs->add (substitute[iter.get_coverage ()]);
     }
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id) const
+  inline const Coverage &get_coverage (void) const
   {
-    return (this+coverage) (glyph_id) != NOT_COVERED;
+    return this+coverage;
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     hb_codepoint_t glyph_id = c->buffer->cur().codepoint;
     unsigned int index = (this+coverage) (glyph_id);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
     if (unlikely (index >= substitute.len)) return TRACE_RETURN (false);
 
     glyph_id = substitute[index];
     c->replace_glyph (glyph_id);
 
     return TRACE_RETURN (true);
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &glyphs,
+                         Supplier<GlyphID> &substitutes,
+                         unsigned int num_glyphs)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    if (unlikely (!substitute.serialize (c, substitutes, num_glyphs))) return TRACE_RETURN (false);
+    if (unlikely (!coverage.serialize (c, this).serialize (c, glyphs, num_glyphs))) return TRACE_RETURN (false);
+    return TRACE_RETURN (true);
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (coverage.sanitize (c, this) && substitute.sanitize (c));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 2 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of Substitution table */
   ArrayOf<GlyphID>
                 substitute;             /* Array of substitute
                                          * GlyphIDs--ordered by Coverage Index */
   public:
   DEFINE_SIZE_ARRAY (6, substitute);
 };
 
 struct SingleSubst
 {
   friend struct SubstLookupSubTable;
+  friend struct SubstLookup;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     switch (u.format) {
     case 1: u.format1.closure (c); break;
     case 2: u.format2.closure (c); break;
     default:                       break;
     }
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id) const
+  inline const Coverage &get_coverage (void) const
   {
     switch (u.format) {
-    case 1: return u.format1.would_apply (glyph_id);
-    case 2: return u.format2.would_apply (glyph_id);
-    default:return false;
+    case 1: return u.format1.get_coverage ();
+    case 2: return u.format2.get_coverage ();
+    default:return Null(Coverage);
     }
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.apply (c));
     case 2: return TRACE_RETURN (u.format2.apply (c));
     default:return TRACE_RETURN (false);
     }
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &glyphs,
+                         Supplier<GlyphID> &substitutes,
+                         unsigned int num_glyphs)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (u.format))) return TRACE_RETURN (false);
+    unsigned int format = 2;
+    int delta;
+    if (num_glyphs) {
+      format = 1;
+      /* TODO(serialize) check for wrap-around */
+      delta = substitutes[0] - glyphs[0];
+      for (unsigned int i = 1; i < num_glyphs; i++)
+        if (delta != substitutes[i] - glyphs[i]) {
+          format = 2;
+          break;
+        }
+    }
+    u.format.set (format);
+    switch (u.format) {
+    case 1: return TRACE_RETURN (u.format1.serialize (c, glyphs, num_glyphs, delta));
+    case 2: return TRACE_RETURN (u.format2.serialize (c, glyphs, substitutes, num_glyphs));
+    default:return TRACE_RETURN (false);
+    }
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (!u.format.sanitize (c)) return TRACE_RETURN (false);
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.sanitize (c));
     case 2: return TRACE_RETURN (u.format2.sanitize (c));
     default:return TRACE_RETURN (true);
     }
   }
 
-  private:
+  protected:
   union {
   USHORT                format;         /* Format identifier */
   SingleSubstFormat1    format1;
   SingleSubstFormat2    format2;
   } u;
 };
 
 
 struct Sequence
 {
   friend struct MultipleSubstFormat1;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     unsigned int count = substitute.len;
     for (unsigned int i = 0; i < count; i++)
       c->glyphs->add (substitute[i]);
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     if (unlikely (!substitute.len)) return TRACE_RETURN (false);
 
     unsigned int klass = c->property & HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE ? HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH : 0;
-    c->replace_glyphs_be16 (1, substitute.len, (const char *) substitute.array, klass);
+    unsigned int count = substitute.len;
+    for (unsigned int i = 0; i < count; i++) {
+      set_lig_props_for_component (c->buffer->cur(), i);
+      c->output_glyph (substitute.array[i], klass);
+    }
+    c->buffer->skip_glyph ();
 
     return TRACE_RETURN (true);
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &glyphs,
+                         unsigned int num_glyphs)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    if (unlikely (!substitute.serialize (c, glyphs, num_glyphs))) return TRACE_RETURN (false);
+    return TRACE_RETURN (true);
+  }
+
   public:
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (substitute.sanitize (c));
   }
 
-  private:
+  protected:
   ArrayOf<GlyphID>
                 substitute;             /* String of GlyphIDs to substitute */
   public:
   DEFINE_SIZE_ARRAY (2, substitute);
 };
 
 struct MultipleSubstFormat1
 {
   friend struct MultipleSubst;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     Coverage::Iter iter;
     for (iter.init (this+coverage); iter.more (); iter.next ()) {
       if (c->glyphs->has (iter.get_glyph ()))
         (this+sequence[iter.get_coverage ()]).closure (c);
     }
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id) const
+  inline const Coverage &get_coverage (void) const
   {
-    return (this+coverage) (glyph_id) != NOT_COVERED;
+    return this+coverage;
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
 
     unsigned int index = (this+coverage) (c->buffer->cur().codepoint);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
     return TRACE_RETURN ((this+sequence[index]).apply (c));
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &glyphs,
+                         Supplier<unsigned int> &substitute_len_list,
+                         unsigned int num_glyphs,
+                         Supplier<GlyphID> &substitute_glyphs_list)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    if (unlikely (!sequence.serialize (c, num_glyphs))) return TRACE_RETURN (false);
+    for (unsigned int i = 0; i < num_glyphs; i++)
+      if (unlikely (!sequence[i].serialize (c, this).serialize (c,
+                                                                substitute_glyphs_list,
+                                                                substitute_len_list[i]))) return TRACE_RETURN (false);
+    substitute_len_list.advance (num_glyphs);
+    if (unlikely (!coverage.serialize (c, this).serialize (c, glyphs, num_glyphs))) return TRACE_RETURN (false);
+    return TRACE_RETURN (true);
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (coverage.sanitize (c, this) && sequence.sanitize (c, this));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of Substitution table */
   OffsetArrayOf<Sequence>
                 sequence;               /* Array of Sequence tables
                                          * ordered by Coverage Index */
   public:
   DEFINE_SIZE_ARRAY (6, sequence);
 };
 
 struct MultipleSubst
 {
   friend struct SubstLookupSubTable;
+  friend struct SubstLookup;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     switch (u.format) {
     case 1: u.format1.closure (c); break;
     default:                       break;
     }
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id) const
+  inline const Coverage &get_coverage (void) const
   {
     switch (u.format) {
-    case 1: return u.format1.would_apply (glyph_id);
-    default:return false;
+    case 1: return u.format1.get_coverage ();
+    default:return Null(Coverage);
     }
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.apply (c));
     default:return TRACE_RETURN (false);
     }
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &glyphs,
+                         Supplier<unsigned int> &substitute_len_list,
+                         unsigned int num_glyphs,
+                         Supplier<GlyphID> &substitute_glyphs_list)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (u.format))) return TRACE_RETURN (false);
+    unsigned int format = 1;
+    u.format.set (format);
+    switch (u.format) {
+    case 1: return TRACE_RETURN (u.format1.serialize (c, glyphs, substitute_len_list, num_glyphs, substitute_glyphs_list));
+    default:return TRACE_RETURN (false);
+    }
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (!u.format.sanitize (c)) return TRACE_RETURN (false);
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.sanitize (c));
     default:return TRACE_RETURN (true);
     }
   }
 
-  private:
+  protected:
   union {
   USHORT                format;         /* Format identifier */
   MultipleSubstFormat1  format1;
   } u;
 };
 
 
 typedef ArrayOf<GlyphID> AlternateSet;  /* Array of alternate GlyphIDs--in
                                          * arbitrary order */
 
@@ skipping 10 matching lines @@
     for (iter.init (this+coverage); iter.more (); iter.next ()) {
       if (c->glyphs->has (iter.get_glyph ())) {
         const AlternateSet &alt_set = this+alternateSet[iter.get_coverage ()];
         unsigned int count = alt_set.len;
         for (unsigned int i = 0; i < count; i++)
           c->glyphs->add (alt_set[i]);
       }
     }
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id) const
+  inline const Coverage &get_coverage (void) const
   {
-    return (this+coverage) (glyph_id) != NOT_COVERED;
+    return this+coverage;
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     hb_codepoint_t glyph_id = c->buffer->cur().codepoint;
 
     unsigned int index = (this+coverage) (glyph_id);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
@@ skipping 10 matching lines @@
 
     if (unlikely (alt_index > alt_set.len || alt_index == 0)) return TRACE_RETURN (false);
 
     glyph_id = alt_set[alt_index - 1];
 
     c->replace_glyph (glyph_id);
 
     return TRACE_RETURN (true);
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &glyphs,
+                         Supplier<unsigned int> &alternate_len_list,
+                         unsigned int num_glyphs,
+                         Supplier<GlyphID> &alternate_glyphs_list)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    if (unlikely (!alternateSet.serialize (c, num_glyphs))) return TRACE_RETURN (false);
+    for (unsigned int i = 0; i < num_glyphs; i++)
+      if (unlikely (!alternateSet[i].serialize (c, this).serialize (c,
+                                                                    alternate_glyphs_list,
+                                                                    alternate_len_list[i]))) return TRACE_RETURN (false);
+    alternate_len_list.advance (num_glyphs);
+    if (unlikely (!coverage.serialize (c, this).serialize (c, glyphs, num_glyphs))) return TRACE_RETURN (false);
+    return TRACE_RETURN (true);
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (coverage.sanitize (c, this) && alternateSet.sanitize (c, this));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of Substitution table */
   OffsetArrayOf<AlternateSet>
                 alternateSet;           /* Array of AlternateSet tables
                                          * ordered by Coverage Index */
   public:
   DEFINE_SIZE_ARRAY (6, alternateSet);
 };
 
 struct AlternateSubst
 {
   friend struct SubstLookupSubTable;
+  friend struct SubstLookup;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     switch (u.format) {
     case 1: u.format1.closure (c); break;
     default:                       break;
     }
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id) const
+  inline const Coverage &get_coverage (void) const
   {
     switch (u.format) {
-    case 1: return u.format1.would_apply (glyph_id);
-    default:return false;
+    case 1: return u.format1.get_coverage ();
+    default:return Null(Coverage);
     }
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.apply (c));
     default:return TRACE_RETURN (false);
     }
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &glyphs,
+                         Supplier<unsigned int> &alternate_len_list,
+                         unsigned int num_glyphs,
+                         Supplier<GlyphID> &alternate_glyphs_list)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (u.format))) return TRACE_RETURN (false);
+    unsigned int format = 1;
+    u.format.set (format);
+    switch (u.format) {
+    case 1: return TRACE_RETURN (u.format1.serialize (c, glyphs, alternate_len_list, num_glyphs, alternate_glyphs_list));
+    default:return TRACE_RETURN (false);
+    }
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (!u.format.sanitize (c)) return TRACE_RETURN (false);
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.sanitize (c));
     default:return TRACE_RETURN (true);
     }
   }
 
-  private:
+  protected:
   union {
   USHORT                format;         /* Format identifier */
   AlternateSubstFormat1 format1;
   } u;
 };
 
 
 struct Ligature
 {
   friend struct LigatureSet;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     unsigned int count = component.len;
     for (unsigned int i = 1; i < count; i++)
       if (!c->glyphs->has (component[i]))
         return;
     c->glyphs->add (ligGlyph);
   }
 
-  inline bool would_apply (hb_codepoint_t second) const
+  inline bool would_apply (hb_would_apply_context_t *c) const
   {
-    return component.len == 2 && component[1] == second;
+    if (c->len != component.len)
+      return false;
+
+    for (unsigned int i = 1; i < c->len; i++)
+      if (likely (c->glyphs[i] != component[i]))
+        return false;
+
+    return true;
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     unsigned int count = component.len;
-    if (unlikely (count < 2)) return TRACE_RETURN (false);
+    if (unlikely (count < 1)) return TRACE_RETURN (false);
 
-    hb_apply_context_t::mark_skipping_forward_iterator_t skippy_iter (c, c->buffer->idx, count - 1);
-    if (skippy_iter.has_no_chance ()) return TRACE_RETURN (false);
+    unsigned int end_offset;
+    bool is_mark_ligature;
+    unsigned int total_component_count;
 
-    bool first_was_mark = (c->property & HB_OT_LAYOUT_GLYPH_CLASS_MARK);
-    bool found_non_mark = false;
+    if (likely (!match_input (c, count,
+                              &component[1],
+                              match_glyph,
+                              NULL,
+                              &end_offset,
+                              &is_mark_ligature,
+                              &total_component_count)))
+      return TRACE_RETURN (false);
 
-    for (unsigned int i = 1; i < count; i++)
-    {
-      unsigned int property;
+    /* Deal, we are forming the ligature. */
+    c->buffer->merge_clusters (c->buffer->idx, c->buffer->idx + end_offset);
 
-      if (!skippy_iter.next (&property)) return TRACE_RETURN (false);
-
-      found_non_mark |= !(property & HB_OT_LAYOUT_GLYPH_CLASS_MARK);
-
-      if (likely (c->buffer->info[skippy_iter.idx].codepoint != component[i])) return TRACE_RETURN (false);
-    }
-
-    unsigned int klass = first_was_mark && found_non_mark ? HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE : 0;
-
-    /* Allocate new ligature id */
-    unsigned int lig_id = allocate_lig_id (c->buffer);
-    set_lig_props (c->buffer->cur(), lig_id, 0);
-
-    if (skippy_iter.idx < c->buffer->idx + count) /* No input glyphs skipped */
-    {
-      c->replace_glyphs_be16 (count, 1, (const char *) &ligGlyph, klass);
-    }
-    else
-    {
-      c->replace_glyph (ligGlyph);
-
-      /* Now we must do a second loop to copy the skipped glyphs to
-         `out' and assign component values to it.  We start with the
-         glyph after the first component.  Glyphs between component
-         i and i+1 belong to component i.  Together with the lig_id
-         value it is later possible to check whether a specific
-         component value really belongs to a given ligature. */
-
-      for (unsigned int i = 1; i < count; i++)
-      {
-        while (c->should_mark_skip_current_glyph ())
-        {
-          set_lig_props (c->buffer->cur(),  lig_id, i);
-          c->replace_glyph (c->buffer->cur().codepoint);
-        }
-
-        /* Skip the base glyph */
-        c->buffer->idx++;
-      }
-    }
+    ligate_input (c,
+                  count,
+                  &component[1],
+                  ligGlyph,
+                  match_glyph,
+                  NULL,
+                  is_mark_ligature,
+                  total_component_count);
 
     return TRACE_RETURN (true);
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         GlyphID ligature,
+                         Supplier<GlyphID> &components, /* Starting from second */
+                         unsigned int num_components /* Including first component */)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    ligGlyph = ligature;
+    if (unlikely (!component.serialize (c, components, num_components))) return TRACE_RETURN (false);
+    return TRACE_RETURN (true);
+  }
+
   public:
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (ligGlyph.sanitize (c) && component.sanitize (c));
   }
 
-  private:
+  protected:
   GlyphID       ligGlyph;               /* GlyphID of ligature to substitute */
   HeadlessArrayOf<GlyphID>
                 component;              /* Array of component GlyphIDs--start
                                          * with the second  component--ordered
                                          * in writing direction */
   public:
   DEFINE_SIZE_ARRAY (4, component);
 };
 
 struct LigatureSet
 {
   friend struct LigatureSubstFormat1;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     unsigned int num_ligs = ligature.len;
     for (unsigned int i = 0; i < num_ligs; i++)
       (this+ligature[i]).closure (c);
   }
 
-  inline bool would_apply (hb_codepoint_t second) const
+  inline bool would_apply (hb_would_apply_context_t *c) const
   {
     unsigned int num_ligs = ligature.len;
     for (unsigned int i = 0; i < num_ligs; i++)
     {
       const Ligature &lig = this+ligature[i];
-      if (lig.would_apply (second))
+      if (lig.would_apply (c))
         return true;
     }
     return false;
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     unsigned int num_ligs = ligature.len;
     for (unsigned int i = 0; i < num_ligs; i++)
     {
       const Ligature &lig = this+ligature[i];
       if (lig.apply (c)) return TRACE_RETURN (true);
     }
 
     return TRACE_RETURN (false);
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &ligatures,
+                         Supplier<unsigned int> &component_count_list,
+                         unsigned int num_ligatures,
+                         Supplier<GlyphID> &component_list /* Starting from second for each ligature */)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    if (unlikely (!ligature.serialize (c, num_ligatures))) return TRACE_RETURN (false);
+    for (unsigned int i = 0; i < num_ligatures; i++)
+      if (unlikely (!ligature[i].serialize (c, this).serialize (c,
+                                                                ligatures[i],
+                                                                component_list,
+                                                                component_count_list[i]))) return TRACE_RETURN (false);
+    ligatures.advance (num_ligatures);
+    component_count_list.advance (num_ligatures);
+    return TRACE_RETURN (true);
+  }
+
   public:
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (ligature.sanitize (c, this));
   }
 
-  private:
+  protected:
   OffsetArrayOf<Ligature>
                 ligature;               /* Array LigatureSet tables
                                          * ordered by preference */
   public:
   DEFINE_SIZE_ARRAY (2, ligature);
 };
 
 struct LigatureSubstFormat1
 {
   friend struct LigatureSubst;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     Coverage::Iter iter;
     for (iter.init (this+coverage); iter.more (); iter.next ()) {
       if (c->glyphs->has (iter.get_glyph ()))
         (this+ligatureSet[iter.get_coverage ()]).closure (c);
     }
   }
 
-  inline bool would_apply (hb_codepoint_t first, hb_codepoint_t second) const
+  inline const Coverage &get_coverage (void) const
   {
-    unsigned int index;
-    return (index = (this+coverage) (first)) != NOT_COVERED &&
-           (this+ligatureSet[index]).would_apply (second);
+    return this+coverage;
+  }
+
+  inline bool would_apply (hb_would_apply_context_t *c) const
+  {
+    return (this+ligatureSet[(this+coverage) (c->glyphs[0])]).would_apply (c);
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     hb_codepoint_t glyph_id = c->buffer->cur().codepoint;
 
     unsigned int index = (this+coverage) (glyph_id);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
     const LigatureSet &lig_set = this+ligatureSet[index];
     return TRACE_RETURN (lig_set.apply (c));
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &first_glyphs,
+                         Supplier<unsigned int> &ligature_per_first_glyph_count_list,
+                         unsigned int num_first_glyphs,
+                         Supplier<GlyphID> &ligatures_list,
+                         Supplier<unsigned int> &component_count_list,
+                         Supplier<GlyphID> &component_list /* Starting from second for each ligature */)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (*this))) return TRACE_RETURN (false);
+    if (unlikely (!ligatureSet.serialize (c, num_first_glyphs))) return TRACE_RETURN (false);
+    for (unsigned int i = 0; i < num_first_glyphs; i++)
+      if (unlikely (!ligatureSet[i].serialize (c, this).serialize (c,
+                                                                   ligatures_list,
+                                                                   component_count_list,
+                                                                   ligature_per_first_glyph_count_list[i],
+                                                                   component_list))) return TRACE_RETURN (false);
+    ligature_per_first_glyph_count_list.advance (num_first_glyphs);
+    if (unlikely (!coverage.serialize (c, this).serialize (c, first_glyphs, num_first_glyphs))) return TRACE_RETURN (false);
+    return TRACE_RETURN (true);
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (coverage.sanitize (c, this) && ligatureSet.sanitize (c, this));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of Substitution table */
   OffsetArrayOf<LigatureSet>
                 ligatureSet;            /* Array LigatureSet tables
                                          * ordered by Coverage Index */
   public:
   DEFINE_SIZE_ARRAY (6, ligatureSet);
 };
 
 struct LigatureSubst
 {
   friend struct SubstLookupSubTable;
+  friend struct SubstLookup;
 
   private:
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     switch (u.format) {
     case 1: u.format1.closure (c); break;
     default:                       break;
     }
   }
 
-  inline bool would_apply (hb_codepoint_t first, hb_codepoint_t second) const
+  inline const Coverage &get_coverage (void) const
   {
     switch (u.format) {
-    case 1: return u.format1.would_apply (first, second);
+    case 1: return u.format1.get_coverage ();
+    default:return Null(Coverage);
+    }
+  }
+
+  inline bool would_apply (hb_would_apply_context_t *c) const
+  {
+    switch (u.format) {
+    case 1: return u.format1.would_apply (c);
     default:return false;
     }
   }
 
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.apply (c));
     default:return TRACE_RETURN (false);
     }
   }
 
+  inline bool serialize (hb_serialize_context_t *c,
+                         Supplier<GlyphID> &first_glyphs,
+                         Supplier<unsigned int> &ligature_per_first_glyph_count_list,
+                         unsigned int num_first_glyphs,
+                         Supplier<GlyphID> &ligatures_list,
+                         Supplier<unsigned int> &component_count_list,
+                         Supplier<GlyphID> &component_list /* Starting from second for each ligature */)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!c->extend_min (u.format))) return TRACE_RETURN (false);
+    unsigned int format = 1;
+    u.format.set (format);
+    switch (u.format) {
+    case 1: return TRACE_RETURN (u.format1.serialize (c, first_glyphs, ligature_per_first_glyph_count_list, num_first_glyphs,
+                                                      ligatures_list, component_count_list, component_list));
+    default:return TRACE_RETURN (false);
+    }
+  }
+
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (!u.format.sanitize (c)) return TRACE_RETURN (false);
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.sanitize (c));
     default:return TRACE_RETURN (true);
     }
   }
 
-  private:
+  protected:
   union {
   USHORT                format;         /* Format identifier */
   LigatureSubstFormat1  format1;
   } u;
 };
 
 
 static inline bool substitute_lookup (hb_apply_context_t *c, unsigned int lookup_index);
 static inline void closure_lookup (hb_closure_context_t *c, unsigned int lookup_index);
 
@@ skipping 43 matching lines @@
 
   private:
   inline const struct SubstLookupSubTable& get_subtable (void) const
   {
     unsigned int offset = get_offset ();
     if (unlikely (!offset)) return Null(SubstLookupSubTable);
     return StructAtOffset<SubstLookupSubTable> (this, offset);
   }
 
   inline void closure (hb_closure_context_t *c) const;
-  inline bool would_apply (hb_codepoint_t glyph_id) const;
-  inline bool would_apply (hb_codepoint_t first, hb_codepoint_t second) const;
+
+  inline const Coverage &get_coverage (void) const;
+
+  inline bool would_apply (hb_would_apply_context_t *c) const;
 
   inline bool apply (hb_apply_context_t *c) const;
 
   inline bool sanitize (hb_sanitize_context_t *c);
 
   inline bool is_reverse (void) const;
 };
 
 
 struct ReverseChainSingleSubstFormat1
@@ skipping 20 matching lines @@
         return;
 
     const ArrayOf<GlyphID> &substitute = StructAfter<ArrayOf<GlyphID> > (lookahead);
     Coverage::Iter iter;
     for (iter.init (this+coverage); iter.more (); iter.next ()) {
       if (c->glyphs->has (iter.get_glyph ()))
         c->glyphs->add (substitute[iter.get_coverage ()]);
     }
   }
 
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     if (unlikely (c->nesting_level_left != MAX_NESTING_LEVEL))
       return TRACE_RETURN (false); /* No chaining to this type */
 
     unsigned int index = (this+coverage) (c->buffer->cur().codepoint);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
     const OffsetArrayOf<Coverage> &lookahead = StructAfter<OffsetArrayOf<Coverage> > (backtrack);
     const ArrayOf<GlyphID> &substitute = StructAfter<ArrayOf<GlyphID> > (lookahead);
 
     if (match_backtrack (c,
                          backtrack.len, (USHORT *) backtrack.array,
                          match_coverage, this) &&
         match_lookahead (c,
                          lookahead.len, (USHORT *) lookahead.array,
                          match_coverage, this,
                          1))
     {
-      c->buffer->cur().codepoint = substitute[index];
+      c->replace_glyph_inplace (substitute[index]);
       c->buffer->idx--; /* Reverse! */
       return TRACE_RETURN (true);
     }
 
     return TRACE_RETURN (false);
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (!(coverage.sanitize (c, this) && backtrack.sanitize (c, this)))
       return TRACE_RETURN (false);
     OffsetArrayOf<Coverage> &lookahead = StructAfter<OffsetArrayOf<Coverage> > (backtrack);
     if (!lookahead.sanitize (c, this))
       return TRACE_RETURN (false);
     ArrayOf<GlyphID> &substitute = StructAfter<ArrayOf<GlyphID> > (lookahead);
     return TRACE_RETURN (substitute.sanitize (c));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of table */
   OffsetArrayOf<Coverage>
                 backtrack;              /* Array of coverage tables
                                          * in backtracking sequence, in  glyph
                                          * sequence order */
   OffsetArrayOf<Coverage>
                 lookaheadX;             /* Array of coverage tables
@@ skipping 14 matching lines @@
 
   inline void closure (hb_closure_context_t *c) const
   {
     TRACE_CLOSURE ();
     switch (u.format) {
     case 1: u.format1.closure (c); break;
     default:                       break;
     }
   }
 
+  inline const Coverage &get_coverage (void) const
+  {
+    switch (u.format) {
+    case 1: return u.format1.get_coverage ();
+    default:return Null(Coverage);
+    }
+  }
+
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.apply (c));
     default:return TRACE_RETURN (false);
     }
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (!u.format.sanitize (c)) return TRACE_RETURN (false);
     switch (u.format) {
     case 1: return TRACE_RETURN (u.format1.sanitize (c));
     default:return TRACE_RETURN (true);
     }
   }
 
-  private:
+  protected:
   union {
   USHORT                                format;         /* Format identifier */
   ReverseChainSingleSubstFormat1        format1;
   } u;
 };
 
 
 
 /*
  * SubstLookup
@@ skipping 16 matching lines @@
 
   inline void closure (hb_closure_context_t *c,
                        unsigned int    lookup_type) const
   {
     TRACE_CLOSURE ();
     switch (lookup_type) {
     case Single:                u.single.closure (c); break;
     case Multiple:              u.multiple.closure (c); break;
     case Alternate:             u.alternate.closure (c); break;
     case Ligature:              u.ligature.closure (c); break;
-    case Context:               u.c.closure (c); break;
+    case Context:               u.context.closure (c); break;
     case ChainContext:          u.chainContext.closure (c); break;
     case Extension:             u.extension.closure (c); break;
     case ReverseChainSingle:    u.reverseChainContextSingle.closure (c); break;
     default:                    break;
     }
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id,
+  inline const Coverage &get_coverage (unsigned int lookup_type) const
+  {
+    switch (lookup_type) {
+    case Single:                return u.single.get_coverage ();
+    case Multiple:              return u.multiple.get_coverage ();
+    case Alternate:             return u.alternate.get_coverage ();
+    case Ligature:              return u.ligature.get_coverage ();
+    case Context:               return u.context.get_coverage ();
+    case ChainContext:          return u.chainContext.get_coverage ();
+    case Extension:             return u.extension.get_coverage ();
+    case ReverseChainSingle:    return u.reverseChainContextSingle.get_coverage ();
+    default:                    return Null(Coverage);
+    }
+  }
+
+  inline bool would_apply (hb_would_apply_context_t *c,
                            unsigned int lookup_type) const
   {
+    TRACE_WOULD_APPLY ();
+    if (get_coverage (lookup_type).get_coverage (c->glyphs[0]) == NOT_COVERED) return false;
+    if (c->len == 1) {
+      switch (lookup_type) {
+      case Single:
+      case Multiple:
+      case Alternate:
+      case ReverseChainSingle:
+        return true;
+      }
+    }
+
+    /* Only need to look further for lookups that support substitutions
+     * of input longer than 1. */
     switch (lookup_type) {
-    case Single:                return u.single.would_apply (glyph_id);
-    case Multiple:              return u.multiple.would_apply (glyph_id);
-    case Alternate:             return u.alternate.would_apply (glyph_id);
-    case Extension:             return u.extension.would_apply (glyph_id);
+    case Ligature:              return u.ligature.would_apply (c);
+    case Context:               return u.context.would_apply (c);
+    case ChainContext:          return u.chainContext.would_apply (c);
+    case Extension:             return u.extension.would_apply (c);
     default:                    return false;
     }
   }
-  inline bool would_apply (hb_codepoint_t first,
-                           hb_codepoint_t second,
-                           unsigned int lookup_type) const
-  {
-    switch (lookup_type) {
-    case Ligature:              return u.ligature.would_apply (first, second);
-    case Extension:             return u.extension.would_apply (first, second);
-    default:                    return false;
-    }
-  }
 
   inline bool apply (hb_apply_context_t *c, unsigned int lookup_type) const
   {
     TRACE_APPLY ();
     switch (lookup_type) {
     case Single:                return TRACE_RETURN (u.single.apply (c));
     case Multiple:              return TRACE_RETURN (u.multiple.apply (c));
     case Alternate:             return TRACE_RETURN (u.alternate.apply (c));
     case Ligature:              return TRACE_RETURN (u.ligature.apply (c));
-    case Context:               return TRACE_RETURN (u.c.apply (c));
+    case Context:               return TRACE_RETURN (u.context.apply (c));
     case ChainContext:          return TRACE_RETURN (u.chainContext.apply (c));
     case Extension:             return TRACE_RETURN (u.extension.apply (c));
     case ReverseChainSingle:    return TRACE_RETURN (u.reverseChainContextSingle.apply (c));
     default:                    return TRACE_RETURN (false);
     }
   }
 
   inline bool sanitize (hb_sanitize_context_t *c, unsigned int lookup_type) {
     TRACE_SANITIZE ();
+    if (!u.header.sub_format.sanitize (c))
+      return TRACE_RETURN (false);
     switch (lookup_type) {
     case Single:                return TRACE_RETURN (u.single.sanitize (c));
     case Multiple:              return TRACE_RETURN (u.multiple.sanitize (c));
     case Alternate:             return TRACE_RETURN (u.alternate.sanitize (c));
     case Ligature:              return TRACE_RETURN (u.ligature.sanitize (c));
-    case Context:               return TRACE_RETURN (u.c.sanitize (c));
+    case Context:               return TRACE_RETURN (u.context.sanitize (c));
     case ChainContext:          return TRACE_RETURN (u.chainContext.sanitize (c));
     case Extension:             return TRACE_RETURN (u.extension.sanitize (c));
     case ReverseChainSingle:    return TRACE_RETURN (u.reverseChainContextSingle.sanitize (c));
     default:                    return TRACE_RETURN (true);
     }
   }
 
-  private:
+  protected:
   union {
-  USHORT                        sub_format;
+  struct {
+    USHORT                      sub_format;
+  } header;
   SingleSubst                   single;
   MultipleSubst                 multiple;
   AlternateSubst                alternate;
   LigatureSubst                 ligature;
-  ContextSubst                  c;
+  ContextSubst                  context;
   ChainContextSubst             chainContext;
   ExtensionSubst                extension;
   ReverseChainSingleSubst       reverseChainContextSingle;
   } u;
   public:
-  DEFINE_SIZE_UNION (2, sub_format);
+  DEFINE_SIZE_UNION (2, header.sub_format);
 };
 
 
 struct SubstLookup : Lookup
 {
   inline const SubstLookupSubTable& get_subtable (unsigned int i) const
   { return this+CastR<OffsetArrayOf<SubstLookupSubTable> > (subTable)[i]; }
 
   inline static bool lookup_type_is_reverse (unsigned int lookup_type)
   { return lookup_type == SubstLookupSubTable::ReverseChainSingle; }
 
   inline bool is_reverse (void) const
   {
     unsigned int type = get_type ();
     if (unlikely (type == SubstLookupSubTable::Extension))
       return CastR<ExtensionSubst> (get_subtable(0)).is_reverse ();
     return lookup_type_is_reverse (type);
   }
 
   inline void closure (hb_closure_context_t *c) const
   {
     unsigned int lookup_type = get_type ();
     unsigned int count = get_subtable_count ();
     for (unsigned int i = 0; i < count; i++)
       get_subtable (i).closure (c, lookup_type);
   }
 
-  inline bool would_apply (hb_codepoint_t glyph_id) const
+  template <typename set_t>
+  inline void add_coverage (set_t *glyphs) const
   {
+    const Coverage *last = NULL;
+    unsigned int count = get_subtable_count ();
+    for (unsigned int i = 0; i < count; i++) {
+      const Coverage *c = &get_subtable (i).get_coverage (get_type ());
+      if (c != last) {
+        c->add_coverage (glyphs);
+        last = c;
+      }
+    }
+  }
+
+  inline bool would_apply (hb_would_apply_context_t *c, const hb_set_digest_t *digest) const
+  {
+    if (unlikely (!c->len)) return false;
+    if (!digest->may_have (c->glyphs[0])) return false;
     unsigned int lookup_type = get_type ();
     unsigned int count = get_subtable_count ();
     for (unsigned int i = 0; i < count; i++)
-      if (get_subtable (i).would_apply (glyph_id, lookup_type))
+      if (get_subtable (i).would_apply (c, lookup_type))
         return true;
     return false;
   }
-  inline bool would_apply (hb_codepoint_t first, hb_codepoint_t second) const
-  {
-    unsigned int lookup_type = get_type ();
-    unsigned int count = get_subtable_count ();
-    for (unsigned int i = 0; i < count; i++)
-      if (get_subtable (i).would_apply (first, second, lookup_type))
-        return true;
-    return false;
-  }
 
   inline bool apply_once (hb_apply_context_t *c) const
   {
     unsigned int lookup_type = get_type ();
 
-    if (!_hb_ot_layout_check_glyph_property (c->face, &c->buffer->cur(), c->lookup_props, &c->property))
+    if (!c->check_glyph_property (&c->buffer->cur(), c->lookup_props, &c->property))
       return false;
 
-    if (unlikely (lookup_type == SubstLookupSubTable::Extension))
-    {
-      /* The spec says all subtables should have the same type.
-       * This is specially important if one has a reverse type!
-       *
-       * This is rather slow to do this here for every glyph,
-       * but it's easiest, and who uses extension lookups anyway?!*/
-      unsigned int type = get_subtable(0).u.extension.get_type ();
-      unsigned int count = get_subtable_count ();
-      for (unsigned int i = 1; i < count; i++)
-        if (get_subtable(i).u.extension.get_type () != type)
-          return false;
-    }
-
     unsigned int count = get_subtable_count ();
     for (unsigned int i = 0; i < count; i++)
       if (get_subtable (i).apply (c, lookup_type))
         return true;
 
     return false;
   }
 
-  inline bool apply_string (hb_apply_context_t *c) const
+  inline bool apply_string (hb_apply_context_t *c, const hb_set_digest_t *digest) const
   {
     bool ret = false;
 
-    if (unlikely (!c->buffer->len))
+    if (unlikely (!c->buffer->len || !c->lookup_mask))
       return false;
 
     c->set_lookup (*this);
 
     if (likely (!is_reverse ()))
     {
         /* in/out forward substitution */
         c->buffer->clear_output ();
         c->buffer->idx = 0;
+
         while (c->buffer->idx < c->buffer->len)
         {
-          if ((c->buffer->cur().mask & c->lookup_mask) && apply_once (c))
+          if ((c->buffer->cur().mask & c->lookup_mask) &&
+              digest->may_have (c->buffer->cur().codepoint) &&
+              apply_once (c))
             ret = true;
           else
             c->buffer->next_glyph ();
-
         }
         if (ret)
           c->buffer->swap_buffers ();
     }
     else
     {
         /* in-place backward substitution */
         c->buffer->idx = c->buffer->len - 1;
         do
         {
-          if ((c->buffer->cur().mask & c->lookup_mask) && apply_once (c))
+          if ((c->buffer->cur().mask & c->lookup_mask) &&
+              digest->may_have (c->buffer->cur().codepoint) &&
+              apply_once (c))
             ret = true;
           else
             c->buffer->idx--;
 
         }
         while ((int) c->buffer->idx >= 0);
     }
 
     return ret;
   }
 
-  inline bool sanitize (hb_sanitize_context_t *c) {
+  private:
+  inline SubstLookupSubTable& serialize_subtable (hb_serialize_context_t *c,
+                                                  unsigned int i)
+  { return CastR<OffsetArrayOf<SubstLookupSubTable> > (subTable)[i].serialize (c, this); }
+  public:
+
+  inline bool serialize_single (hb_serialize_context_t *c,
+                                uint32_t lookup_props,
+                                Supplier<GlyphID> &glyphs,
+                                Supplier<GlyphID> &substitutes,
+                                unsigned int num_glyphs)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!Lookup::serialize (c, SubstLookupSubTable::Single, lookup_props, 1))) return TRACE_RETURN (false);
+    return TRACE_RETURN (serialize_subtable (c, 0).u.single.serialize (c, glyphs, substitutes, num_glyphs));
+  }
+
+  inline bool serialize_multiple (hb_serialize_context_t *c,
+                                  uint32_t lookup_props,
+                                  Supplier<GlyphID> &glyphs,
+                                  Supplier<unsigned int> &substitute_len_list,
+                                  unsigned int num_glyphs,
+                                  Supplier<GlyphID> &substitute_glyphs_list)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!Lookup::serialize (c, SubstLookupSubTable::Multiple, lookup_props, 1))) return TRACE_RETURN (false);
+    return TRACE_RETURN (serialize_subtable (c, 0).u.multiple.serialize (c, glyphs, substitute_len_list, num_glyphs,
+                                                                         substitute_glyphs_list));
+  }
+
+  inline bool serialize_alternate (hb_serialize_context_t *c,
+                                   uint32_t lookup_props,
+                                   Supplier<GlyphID> &glyphs,
+                                   Supplier<unsigned int> &alternate_len_list,
+                                   unsigned int num_glyphs,
+                                   Supplier<GlyphID> &alternate_glyphs_list)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!Lookup::serialize (c, SubstLookupSubTable::Alternate, lookup_props, 1))) return TRACE_RETURN (false);
+    return TRACE_RETURN (serialize_subtable (c, 0).u.alternate.serialize (c, glyphs, alternate_len_list, num_glyphs,
+                                                                          alternate_glyphs_list));
+  }
+
+  inline bool serialize_ligature (hb_serialize_context_t *c,
+                                  uint32_t lookup_props,
+                                  Supplier<GlyphID> &first_glyphs,
+                                  Supplier<unsigned int> &ligature_per_first_glyph_count_list,
+                                  unsigned int num_first_glyphs,
+                                  Supplier<GlyphID> &ligatures_list,
+                                  Supplier<unsigned int> &component_count_list,
+                                  Supplier<GlyphID> &component_list /* Starting from second for each ligature */)
+  {
+    TRACE_SERIALIZE ();
+    if (unlikely (!Lookup::serialize (c, SubstLookupSubTable::Ligature, lookup_props, 1))) return TRACE_RETURN (false);
+    return TRACE_RETURN (serialize_subtable (c, 0).u.ligature.serialize (c, first_glyphs, ligature_per_first_glyph_count_list, num_first_glyphs,
+                                                                         ligatures_list, component_count_list, component_list));
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c)
+  {
     TRACE_SANITIZE ();
     if (unlikely (!Lookup::sanitize (c))) return TRACE_RETURN (false);
     OffsetArrayOf<SubstLookupSubTable> &list = CastR<OffsetArrayOf<SubstLookupSubTable> > (subTable);
-    return TRACE_RETURN (list.sanitize (c, this, get_type ()));
+    if (unlikely (!list.sanitize (c, this, get_type ()))) return TRACE_RETURN (false);
+
+    if (unlikely (get_type () == SubstLookupSubTable::Extension))
+    {
+      /* The spec says all subtables of an Extension lookup should
+       * have the same type.  This is specially important if one has
+       * a reverse type!
+       *
+       * We just check that they are all either forward, or reverse. */
+      unsigned int type = get_subtable (0).u.extension.get_type ();
+      unsigned int count = get_subtable_count ();
+      for (unsigned int i = 1; i < count; i++)
+        if (get_subtable (i).u.extension.get_type () != type)
+          return TRACE_RETURN (false);
+    }
+    return TRACE_RETURN (true);
   }
 };
 
 typedef OffsetListOf<SubstLookup> SubstLookupList;
 
 /*
  * GSUB -- The Glyph Substitution Table
  */
 
 struct GSUB : GSUBGPOS
 {
   static const hb_tag_t Tag     = HB_OT_TAG_GSUB;
 
   inline const SubstLookup& get_lookup (unsigned int i) const
   { return CastR<SubstLookup> (GSUBGPOS::get_lookup (i)); }
 
-  inline bool substitute_lookup (hb_apply_context_t *c, unsigned int lookup_index) const
-  { return get_lookup (lookup_index).apply_string (c); }
+  template <typename set_t>
+  inline void add_coverage (set_t *glyphs, unsigned int lookup_index) const
+  { get_lookup (lookup_index).add_coverage (glyphs); }
 
-  static inline void substitute_start (hb_buffer_t *buffer);
-  static inline void substitute_finish (hb_buffer_t *buffer);
+  static inline void substitute_start (hb_font_t *font, hb_buffer_t *buffer);
+  static inline void substitute_finish (hb_font_t *font, hb_buffer_t *buffer);
 
   inline void closure_lookup (hb_closure_context_t *c,
                               unsigned int          lookup_index) const
   { return get_lookup (lookup_index).closure (c); }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (unlikely (!GSUBGPOS::sanitize (c))) return TRACE_RETURN (false);
     OffsetTo<SubstLookupList> &list = CastR<OffsetTo<SubstLookupList> > (lookupList);
     return TRACE_RETURN (list.sanitize (c, this));
   }
   public:
   DEFINE_SIZE_STATIC (10);
 };
 
 
 void
-GSUB::substitute_start (hb_buffer_t *buffer)
+GSUB::substitute_start (hb_font_t *font, hb_buffer_t *buffer)
 {
-  HB_BUFFER_ALLOCATE_VAR (buffer, props_cache);
+  HB_BUFFER_ALLOCATE_VAR (buffer, glyph_props);
   HB_BUFFER_ALLOCATE_VAR (buffer, lig_props);
   HB_BUFFER_ALLOCATE_VAR (buffer, syllable);
 
+  const GDEF &gdef = *hb_ot_layout_from_face (font->face)->gdef;
   unsigned int count = buffer->len;
-  for (unsigned int i = 0; i < count; i++)
-    buffer->info[i].props_cache() = buffer->info[i].lig_props() = buffer->info[i].syllable() = 0;
+  for (unsigned int i = 0; i < count; i++) {
+    buffer->info[i].lig_props() = buffer->info[i].syllable() = 0;
+    buffer->info[i].glyph_props() = gdef.get_glyph_props (buffer->info[i].codepoint);
+  }
 }
 
 void
-GSUB::substitute_finish (hb_buffer_t *buffer HB_UNUSED)
+GSUB::substitute_finish (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer HB_UNUSED)
 {
 }
 
 
 /* Out-of-class implementation for methods recursing */
 
 inline void ExtensionSubst::closure (hb_closure_context_t *c) const
 {
   get_subtable ().closure (c, get_type ());
 }
 
-inline bool ExtensionSubst::would_apply (hb_codepoint_t glyph_id) const
+inline const Coverage & ExtensionSubst::get_coverage (void) const
 {
-  return get_subtable ().would_apply (glyph_id, get_type ());
+  return get_subtable ().get_coverage (get_type ());
 }
 
-inline bool ExtensionSubst::would_apply (hb_codepoint_t first, hb_codepoint_t second) const
+inline bool ExtensionSubst::would_apply (hb_would_apply_context_t *c) const
 {
-  return get_subtable ().would_apply (first, second, get_type ());
+  return get_subtable ().would_apply (c, get_type ());
 }
 
 inline bool ExtensionSubst::apply (hb_apply_context_t *c) const
 {
   TRACE_APPLY ();
   return TRACE_RETURN (get_subtable ().apply (c, get_type ()));
 }
 
 inline bool ExtensionSubst::sanitize (hb_sanitize_context_t *c)
 {
   TRACE_SANITIZE ();
   if (unlikely (!Extension::sanitize (c))) return TRACE_RETURN (false);
   unsigned int offset = get_offset ();
   if (unlikely (!offset)) return TRACE_RETURN (true);
   return TRACE_RETURN (StructAtOffset<SubstLookupSubTable> (this, offset).sanitize (c, get_type ()));
 }
 
 inline bool ExtensionSubst::is_reverse (void) const
 {
   unsigned int type = get_type ();
   if (unlikely (type == SubstLookupSubTable::Extension))
     return CastR<ExtensionSubst> (get_subtable()).is_reverse ();
   return SubstLookup::lookup_type_is_reverse (type);
 }
 
 static inline void closure_lookup (hb_closure_context_t *c, unsigned int lookup_index)
 {
-  const GSUB &gsub = *(c->face->ot_layout->gsub);
+  const GSUB &gsub = *(hb_ot_layout_from_face (c->face)->gsub);
   const SubstLookup &l = gsub.get_lookup (lookup_index);
 
   if (unlikely (c->nesting_level_left == 0))
     return;
 
   c->nesting_level_left--;
   l.closure (c);
   c->nesting_level_left++;
 }
 
 static inline bool substitute_lookup (hb_apply_context_t *c, unsigned int lookup_index)
 {
-  const GSUB &gsub = *(c->face->ot_layout->gsub);
+  const GSUB &gsub = *(hb_ot_layout_from_face (c->face)->gsub);
   const SubstLookup &l = gsub.get_lookup (lookup_index);
 
   if (unlikely (c->nesting_level_left == 0))
     return false;
 
   hb_apply_context_t new_c (*c);
   new_c.nesting_level_left--;
   new_c.set_lookup (l);
   return l.apply_once (&new_c);
 }
 
 
+} // namespace OT
+
 
 #endif /* HB_OT_LAYOUT_GSUB_TABLE_HH */