harfbuzz-ng roll

third_party/harfbuzz-ng/src/hb-ot-layout-gpos-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_GPOS_TABLE_HH
 #define HB_OT_LAYOUT_GPOS_TABLE_HH
 
 #include "hb-ot-layout-gsubgpos-private.hh"
 
 
+namespace OT {
+
 
 /* buffer **position** var allocations */
 #define attach_lookback() var.u16[0] /* number of glyphs to go back to attach this glyph to its base */
 #define cursive_chain() var.i16[1] /* character to which this connects, may be positive or negative */
 
 
 /* Shared Tables: ValueRecord, Anchor Table, and MarkArray */
 
 typedef USHORT Value;
 
@@ skipping 173 matching lines @@
   {
       *x = font->em_scale_x (xCoordinate);
       *y = font->em_scale_y (yCoordinate);
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   SHORT         xCoordinate;            /* Horizontal value--in design units */
   SHORT         yCoordinate;            /* Vertical value--in design units */
   public:
   DEFINE_SIZE_STATIC (6);
 };
 
 struct AnchorFormat2
 {
   friend struct Anchor;
 
   private:
   inline void get_anchor (hb_font_t *font, hb_codepoint_t glyph_id,
                           hb_position_t *x, hb_position_t *y) const
   {
       unsigned int x_ppem = font->x_ppem;
       unsigned int y_ppem = font->y_ppem;
       hb_position_t cx, cy;
       hb_bool_t ret = false;
 
       if (x_ppem || y_ppem)
-        ret = hb_font_get_glyph_contour_point_for_origin (font, glyph_id, anchorPoint, HB_DIRECTION_LTR, &cx, &cy);
+        ret = font->get_glyph_contour_point_for_origin (glyph_id, anchorPoint, HB_DIRECTION_LTR, &cx, &cy);
       *x = x_ppem && ret ? cx : font->em_scale_x (xCoordinate);
       *y = y_ppem && ret ? cy : font->em_scale_y (yCoordinate);
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 2 */
   SHORT         xCoordinate;            /* Horizontal value--in design units */
   SHORT         yCoordinate;            /* Vertical value--in design units */
   USHORT        anchorPoint;            /* Index to glyph contour point */
   public:
   DEFINE_SIZE_STATIC (8);
 };
 
 struct AnchorFormat3
 {
@@ skipping 10 matching lines @@
         *x += (this+xDeviceTable).get_x_delta (font);
       if (font->y_ppem)
         *y += (this+yDeviceTable).get_x_delta (font);
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this) && xDeviceTable.sanitize (c, this) && yDeviceTable.sanitize (c, this));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 3 */
   SHORT         xCoordinate;            /* Horizontal value--in design units */
   SHORT         yCoordinate;            /* Vertical value--in design units */
   OffsetTo<Device>
                 xDeviceTable;           /* Offset to Device table for X
                                          * coordinate-- from beginning of
                                          * Anchor table (may be NULL) */
   OffsetTo<Device>
                 yDeviceTable;           /* Offset to Device table for Y
                                          * coordinate-- from beginning of
@@ skipping 20 matching lines @@
     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));
     case 3: return TRACE_RETURN (u.format3.sanitize (c));
     default:return TRACE_RETURN (true);
     }
   }
 
-  private:
+  protected:
   union {
   USHORT                format;         /* Format identifier */
   AnchorFormat1         format1;
   AnchorFormat2         format2;
   AnchorFormat3         format3;
   } u;
   public:
   DEFINE_SIZE_UNION (2, format);
 };
 
@@ skipping 10 matching lines @@
     if (!c->check_struct (this)) return TRACE_RETURN (false);
     if (unlikely (rows > 0 && cols >= ((unsigned int) -1) / rows)) return TRACE_RETURN (false);
     unsigned int count = rows * cols;
     if (!c->check_array (matrix, matrix[0].static_size, count)) return TRACE_RETURN (false);
     for (unsigned int i = 0; i < count; i++)
       if (!matrix[i].sanitize (c, this)) return TRACE_RETURN (false);
     return TRACE_RETURN (true);
   }
 
   USHORT        rows;                   /* Number of rows */
-  private:
+  protected:
   OffsetTo<Anchor>
                 matrix[VAR];            /* Matrix of offsets to Anchor tables--
                                          * from beginning of AnchorMatrix table */
   public:
   DEFINE_SIZE_ARRAY (2, matrix);
 };
 
 
 struct MarkRecord
 {
   friend struct MarkArray;
 
   inline bool sanitize (hb_sanitize_context_t *c, void *base) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this) && markAnchor.sanitize (c, base));
   }
 
-  private:
+  protected:
   USHORT        klass;                  /* Class defined for this mark */
   OffsetTo<Anchor>
                 markAnchor;             /* Offset to Anchor table--from
                                          * beginning of MarkArray table */
   public:
   DEFINE_SIZE_STATIC (4);
 };
 
 struct MarkArray : ArrayOf<MarkRecord>  /* Array of MarkRecords--in Coverage order */
 {
@@ skipping 30 matching lines @@
 };
 
 
 /* Lookups */
 
 struct SinglePosFormat1
 {
   friend struct SinglePos;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    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);
 
     valueFormat.apply_value (c->font, c->direction, this,
                              values, c->buffer->cur_pos());
 
     c->buffer->idx++;
     return TRACE_RETURN (true);
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this) && coverage.sanitize (c, this) && valueFormat.sanitize_value (c, this, values));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of subtable */
   ValueFormat   valueFormat;            /* Defines the types of data in the
                                          * ValueRecord */
   ValueRecord   values;                 /* Defines positioning
                                          * value(s)--applied to all glyphs in
                                          * the Coverage table */
   public:
   DEFINE_SIZE_ARRAY (6, values);
 };
 
 struct SinglePosFormat2
 {
   friend struct SinglePos;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    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);
 
     if (likely (index >= valueCount)) return TRACE_RETURN (false);
 
     valueFormat.apply_value (c->font, c->direction, this,
                              &values[index * valueFormat.get_len ()],
                              c->buffer->cur_pos());
 
     c->buffer->idx++;
     return TRACE_RETURN (true);
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this) && coverage.sanitize (c, this) && valueFormat.sanitize_values (c, this, values, valueCount));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 2 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of subtable */
   ValueFormat   valueFormat;            /* Defines the types of data in the
                                          * ValueRecord */
   USHORT        valueCount;             /* Number of ValueRecords */
   ValueRecord   values;                 /* Array of ValueRecords--positioning
                                          * values applied to glyphs */
   public:
   DEFINE_SIZE_ARRAY (8, values);
 };
 
 struct SinglePos
 {
   friend struct PosLookupSubTable;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    switch (u.format) {
+    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 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 */
   SinglePosFormat1      format1;
   SinglePosFormat2      format2;
   } u;
 };
 
 
 struct PairValueRecord
 {
   friend struct PairSet;
 
-  private:
+  protected:
   GlyphID       secondGlyph;            /* GlyphID of second glyph in the
                                          * pair--first glyph is listed in the
                                          * Coverage table */
   ValueRecord   values;                 /* Positioning data for the first glyph
                                          * followed by for second glyph */
   public:
   DEFINE_SIZE_ARRAY (2, values);
 };
 
 struct PairSet
@@ skipping 41 matching lines @@
     TRACE_SANITIZE ();
     if (!(c->check_struct (this)
        && c->check_array (array, USHORT::static_size * closure->stride, len))) return TRACE_RETURN (false);
 
     unsigned int count = len;
     PairValueRecord *record = CastP<PairValueRecord> (array);
     return TRACE_RETURN (closure->valueFormats[0].sanitize_values_stride_unsafe (c, closure->base, &record->values[0], count, closure->stride)
                       && closure->valueFormats[1].sanitize_values_stride_unsafe (c, closure->base, &record->values[closure->len1], count, closure->stride));
   }
 
-  private:
+  protected:
   USHORT        len;                    /* Number of PairValueRecords */
   USHORT        array[VAR];             /* Array of PairValueRecords--ordered
                                          * by GlyphID of the second glyph */
   public:
   DEFINE_SIZE_ARRAY (2, array);
 };
 
 struct PairPosFormat1
 {
   friend struct PairPos;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     hb_apply_context_t::mark_skipping_forward_iterator_t skippy_iter (c, c->buffer->idx, 1);
     if (skippy_iter.has_no_chance ()) return TRACE_RETURN (false);
 
     unsigned int index = (this+coverage) (c->buffer->cur().codepoint);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
     if (!skippy_iter.next ()) return TRACE_RETURN (false);
 
     return TRACE_RETURN ((this+pairSet[index]).apply (c, &valueFormat1, skippy_iter.idx));
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
 
     unsigned int len1 = valueFormat1.get_len ();
     unsigned int len2 = valueFormat2.get_len ();
     PairSet::sanitize_closure_t closure = {
       this,
       &valueFormat1,
       len1,
       1 + len1 + len2
     };
 
     return TRACE_RETURN (c->check_struct (this) && coverage.sanitize (c, this) && pairSet.sanitize (c, this, &closure));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of subtable */
   ValueFormat   valueFormat1;           /* Defines the types of data in
                                          * ValueRecord1--for the first glyph
                                          * in the pair--may be zero (0) */
   ValueFormat   valueFormat2;           /* Defines the types of data in
                                          * ValueRecord2--for the second glyph
                                          * in the pair--may be zero (0) */
   OffsetArrayOf<PairSet>
                 pairSet;                /* Array of PairSet tables
                                          * ordered by Coverage Index */
   public:
   DEFINE_SIZE_ARRAY (10, pairSet);
 };
 
 struct PairPosFormat2
 {
   friend struct PairPos;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     hb_apply_context_t::mark_skipping_forward_iterator_t skippy_iter (c, c->buffer->idx, 1);
     if (skippy_iter.has_no_chance ()) return TRACE_RETURN (false);
 
     unsigned int index = (this+coverage) (c->buffer->cur().codepoint);
     if (likely (index == NOT_COVERED)) return TRACE_RETURN (false);
 
     if (!skippy_iter.next ()) return TRACE_RETURN (false);
@@ skipping 29 matching lines @@
     unsigned int len1 = valueFormat1.get_len ();
     unsigned int len2 = valueFormat2.get_len ();
     unsigned int stride = len1 + len2;
     unsigned int record_size = valueFormat1.get_size () + valueFormat2.get_size ();
     unsigned int count = (unsigned int) class1Count * (unsigned int) class2Count;
     return TRACE_RETURN (c->check_array (values, record_size, count) &&
                          valueFormat1.sanitize_values_stride_unsafe (c, this, &values[0], count, stride) &&
                          valueFormat2.sanitize_values_stride_unsafe (c, this, &values[len1], count, stride));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 2 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of subtable */
   ValueFormat   valueFormat1;           /* ValueRecord definition--for the
                                          * first glyph of the pair--may be zero
                                          * (0) */
   ValueFormat   valueFormat2;           /* ValueRecord definition--for the
                                          * second glyph of the pair--may be
                                          * zero (0) */
@@ skipping 14 matching lines @@
                                          * Each entry has value1 and value2 */
   public:
   DEFINE_SIZE_ARRAY (16, values);
 };
 
 struct PairPos
 {
   friend struct PosLookupSubTable;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    switch (u.format) {
+    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 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 */
   PairPosFormat1        format1;
   PairPosFormat2        format2;
   } u;
 };
 
 
 struct EntryExitRecord
 {
   friend struct CursivePosFormat1;
 
   inline bool sanitize (hb_sanitize_context_t *c, void *base) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (entryAnchor.sanitize (c, base) && exitAnchor.sanitize (c, base));
   }
 
-  private:
+  protected:
   OffsetTo<Anchor>
                 entryAnchor;            /* Offset to EntryAnchor table--from
                                          * beginning of CursivePos
                                          * subtable--may be NULL */
   OffsetTo<Anchor>
                 exitAnchor;             /* Offset to ExitAnchor table--from
                                          * beginning of CursivePos
                                          * subtable--may be NULL */
   public:
   DEFINE_SIZE_STATIC (4);
 };
 
 struct CursivePosFormat1
 {
   friend struct CursivePos;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
 
     /* We don't handle mark glyphs here. */
     if (c->property & HB_OT_LAYOUT_GLYPH_CLASS_MARK) return TRACE_RETURN (false);
 
     hb_apply_context_t::mark_skipping_forward_iterator_t skippy_iter (c, c->buffer->idx, 1);
     if (skippy_iter.has_no_chance ()) return TRACE_RETURN (false);
 
@@ skipping 67 matching lines @@
 
     c->buffer->idx = j;
     return TRACE_RETURN (true);
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (coverage.sanitize (c, this) && entryExitRecord.sanitize (c, this));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 coverage;               /* Offset to Coverage table--from
                                          * beginning of subtable */
   ArrayOf<EntryExitRecord>
                 entryExitRecord;        /* Array of EntryExit records--in
                                          * Coverage Index order */
   public:
   DEFINE_SIZE_ARRAY (6, entryExitRecord);
 };
 
 struct CursivePos
 {
   friend struct PosLookupSubTable;
 
   private:
+
+  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 */
   CursivePosFormat1     format1;
   } u;
 };
 
 
 typedef AnchorMatrix BaseArray;         /* base-major--
                                          * in order of BaseCoverage Index--,
                                          * mark-minor--
                                          * ordered by class--zero-based. */
 
 struct MarkBasePosFormat1
 {
   friend struct MarkBasePos;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+markCoverage;
+  }
+
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     unsigned int mark_index = (this+markCoverage) (c->buffer->cur().codepoint);
     if (likely (mark_index == NOT_COVERED)) return TRACE_RETURN (false);
 
     /* now we search backwards for a non-mark glyph */
     unsigned int property;
     hb_apply_context_t::mark_skipping_backward_iterator_t skippy_iter (c, c->buffer->idx, 1);
-    if (!skippy_iter.prev (&property, LookupFlag::IgnoreMarks)) return TRACE_RETURN (false);
+    do {
+      if (!skippy_iter.prev (&property, LookupFlag::IgnoreMarks)) return TRACE_RETURN (false);
+      /* We only want to attach to the first of a MultipleSubst sequence.  Reject others. */
+      if (0 == get_lig_comp (c->buffer->info[skippy_iter.idx])) break;
+      skippy_iter.reject ();
+    } while (1);
 
     /* The following assertion is too strong, so we've disabled it. */
     if (!(property & HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH)) {/*return TRACE_RETURN (false);*/}
 
     unsigned int base_index = (this+baseCoverage) (c->buffer->info[skippy_iter.idx].codepoint);
     if (base_index == NOT_COVERED) return TRACE_RETURN (false);
 
     return TRACE_RETURN ((this+markArray).apply (c, mark_index, base_index, this+baseArray, classCount, skippy_iter.idx));
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this) && markCoverage.sanitize (c, this) && baseCoverage.sanitize (c, this) &&
                          markArray.sanitize (c, this) && baseArray.sanitize (c, this, (unsigned int) classCount));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 markCoverage;           /* Offset to MarkCoverage table--from
                                          * beginning of MarkBasePos subtable */
   OffsetTo<Coverage>
                 baseCoverage;           /* Offset to BaseCoverage table--from
                                          * beginning of MarkBasePos subtable */
   USHORT        classCount;             /* Number of classes defined for marks */
   OffsetTo<MarkArray>
                 markArray;              /* Offset to MarkArray table--from
                                          * beginning of MarkBasePos subtable */
   OffsetTo<BaseArray>
                 baseArray;              /* Offset to BaseArray table--from
                                          * beginning of MarkBasePos subtable */
   public:
   DEFINE_SIZE_STATIC (12);
 };
 
 struct MarkBasePos
 {
   friend struct PosLookupSubTable;
 
   private:
+
+  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 */
   MarkBasePosFormat1    format1;
   } u;
 };
 
 
 typedef AnchorMatrix LigatureAttach;    /* component-major--
                                          * in order of writing direction--,
                                          * mark-minor--
                                          * ordered by class--zero-based. */
 
 typedef OffsetListOf<LigatureAttach> LigatureArray;
                                         /* Array of LigatureAttach
                                          * tables ordered by
                                          * LigatureCoverage Index */
 
 struct MarkLigPosFormat1
 {
   friend struct MarkLigPos;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+markCoverage;
+  }
+
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     unsigned int mark_index = (this+markCoverage) (c->buffer->cur().codepoint);
     if (likely (mark_index == NOT_COVERED)) return TRACE_RETURN (false);
 
     /* now we search backwards for a non-mark glyph */
     unsigned int property;
     hb_apply_context_t::mark_skipping_backward_iterator_t skippy_iter (c, c->buffer->idx, 1);
     if (!skippy_iter.prev (&property, LookupFlag::IgnoreMarks)) return TRACE_RETURN (false);
 
     /* The following assertion is too strong, so we've disabled it. */
     if (!(property & HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE)) {/*return TRACE_RETURN (false);*/}
 
     unsigned int j = skippy_iter.idx;
     unsigned int lig_index = (this+ligatureCoverage) (c->buffer->info[j].codepoint);
     if (lig_index == NOT_COVERED) return TRACE_RETURN (false);
 
     const LigatureArray& lig_array = this+ligatureArray;
     const LigatureAttach& lig_attach = lig_array[lig_index];
 
     /* Find component to attach to */
     unsigned int comp_count = lig_attach.rows;
     if (unlikely (!comp_count)) return TRACE_RETURN (false);
 
-    unsigned int comp_index;
     /* We must now check whether the ligature ID of the current mark glyph
      * is identical to the ligature ID of the found ligature.  If yes, we
      * can directly use the component index.  If not, we attach the mark
      * glyph to the last component of the ligature. */
-    if (get_lig_id (c->buffer->info[j]) &&
-        get_lig_id (c->buffer->cur()) &&
-        get_lig_comp (c->buffer->cur()) > 0)
-    {
-      comp_index = get_lig_comp (c->buffer->cur()) - 1;
-      if (comp_index >= comp_count)
-        comp_index = comp_count - 1;
-    }
+    unsigned int comp_index;
+    unsigned int lig_id = get_lig_id (c->buffer->info[j]);
+    unsigned int mark_id = get_lig_id (c->buffer->cur());
+    unsigned int mark_comp = get_lig_comp (c->buffer->cur());
+    if (lig_id && lig_id == mark_id && mark_comp > 0)
+      comp_index = MIN (comp_count, get_lig_comp (c->buffer->cur())) - 1;
     else
       comp_index = comp_count - 1;
 
     return TRACE_RETURN ((this+markArray).apply (c, mark_index, comp_index, lig_attach, classCount, j));
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this) && markCoverage.sanitize (c, this) && ligatureCoverage.sanitize (c, this) &&
                          markArray.sanitize (c, this) && ligatureArray.sanitize (c, this, (unsigned int) classCount));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 markCoverage;           /* Offset to Mark Coverage table--from
                                          * beginning of MarkLigPos subtable */
   OffsetTo<Coverage>
                 ligatureCoverage;       /* Offset to Ligature Coverage
                                          * table--from beginning of MarkLigPos
                                          * subtable */
   USHORT        classCount;             /* Number of defined mark classes */
   OffsetTo<MarkArray>
                 markArray;              /* Offset to MarkArray table--from
                                          * beginning of MarkLigPos subtable */
   OffsetTo<LigatureArray>
                 ligatureArray;          /* Offset to LigatureArray table--from
                                          * beginning of MarkLigPos subtable */
   public:
   DEFINE_SIZE_STATIC (12);
 };
 
 struct MarkLigPos
 {
   friend struct PosLookupSubTable;
 
   private:
+
+  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 */
   MarkLigPosFormat1     format1;
   } u;
 };
 
 
 typedef AnchorMatrix Mark2Array;        /* mark2-major--
                                          * in order of Mark2Coverage Index--,
                                          * mark1-minor--
                                          * ordered by class--zero-based. */
 
 struct MarkMarkPosFormat1
 {
   friend struct MarkMarkPos;
 
   private:
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+mark1Coverage;
+  }
+
   inline bool apply (hb_apply_context_t *c) const
   {
     TRACE_APPLY ();
     unsigned int mark1_index = (this+mark1Coverage) (c->buffer->cur().codepoint);
     if (likely (mark1_index == NOT_COVERED)) return TRACE_RETURN (false);
 
     /* now we search backwards for a suitable mark glyph until a non-mark glyph */
     unsigned int property;
     hb_apply_context_t::mark_skipping_backward_iterator_t skippy_iter (c, c->buffer->idx, 1);
     if (!skippy_iter.prev (&property)) return TRACE_RETURN (false);
 
     if (!(property & HB_OT_LAYOUT_GLYPH_CLASS_MARK)) return TRACE_RETURN (false);
 
     unsigned int j = skippy_iter.idx;
 
-    /* Two marks match only if they belong to the same base, or same component
-     * of the same ligature.  That is, the component numbers must match, and
-     * if those are non-zero, the ligid number should also match. */
-    if ((get_lig_comp (c->buffer->cur())) ||
-        (get_lig_comp (c->buffer->info[j]) > 0 &&
-         get_lig_id (c->buffer->cur())))
-      return TRACE_RETURN (false);
+    unsigned int id1 = get_lig_id (c->buffer->cur());
+    unsigned int id2 = get_lig_id (c->buffer->info[j]);
+    unsigned int comp1 = get_lig_comp (c->buffer->cur());
+    unsigned int comp2 = get_lig_comp (c->buffer->info[j]);
 
+    if (likely (id1 == id2)) {
+      if (id1 == 0) /* Marks belonging to the same base. */
+        goto good;
+      else if (comp1 == comp2) /* Marks belonging to the same ligature component. */
+        goto good;
+    } else {
+      /* If ligature ids don't match, it may be the case that one of the marks
+       * itself is a ligature.  In which case match. */
+      if ((id1 > 0 && !comp1) || (id2 > 0 && !comp2))
+        goto good;
+    }
+
+    /* Didn't match. */
+    return TRACE_RETURN (false);
+
+    good:
     unsigned int mark2_index = (this+mark2Coverage) (c->buffer->info[j].codepoint);
     if (mark2_index == NOT_COVERED) return TRACE_RETURN (false);
 
     return TRACE_RETURN ((this+mark1Array).apply (c, mark1_index, mark2_index, this+mark2Array, classCount, j));
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     return TRACE_RETURN (c->check_struct (this) && mark1Coverage.sanitize (c, this) &&
                          mark2Coverage.sanitize (c, this) && mark1Array.sanitize (c, this)
                          && mark2Array.sanitize (c, this, (unsigned int) classCount));
   }
 
-  private:
+  protected:
   USHORT        format;                 /* Format identifier--format = 1 */
   OffsetTo<Coverage>
                 mark1Coverage;          /* Offset to Combining Mark1 Coverage
                                          * table--from beginning of MarkMarkPos
                                          * subtable */
   OffsetTo<Coverage>
                 mark2Coverage;          /* Offset to Combining Mark2 Coverage
                                          * table--from beginning of MarkMarkPos
                                          * subtable */
   USHORT        classCount;             /* Number of defined mark classes */
   OffsetTo<MarkArray>
                 mark1Array;             /* Offset to Mark1Array table--from
                                          * beginning of MarkMarkPos subtable */
   OffsetTo<Mark2Array>
                 mark2Array;             /* Offset to Mark2Array table--from
                                          * beginning of MarkMarkPos subtable */
   public:
   DEFINE_SIZE_STATIC (12);
 };
 
 struct MarkMarkPos
 {
   friend struct PosLookupSubTable;
 
   private:
+
+  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 */
   MarkMarkPosFormat1    format1;
   } u;
 };
 
 
 static inline bool position_lookup (hb_apply_context_t *c, unsigned int lookup_index);
 
 struct ContextPos : Context
@@ skipping 26 matching lines @@
   friend struct PosLookupSubTable;
 
   private:
   inline const struct PosLookupSubTable& get_subtable (void) const
   {
     unsigned int offset = get_offset ();
     if (unlikely (!offset)) return Null(PosLookupSubTable);
     return StructAtOffset<PosLookupSubTable> (this, offset);
   }
 
+  inline const Coverage &get_coverage (void) const;
+
   inline bool apply (hb_apply_context_t *c) const;
 
   inline bool sanitize (hb_sanitize_context_t *c);
 };
 
 
 
 /*
  * PosLookup
  */
 
 
 struct PosLookupSubTable
 {
   friend struct PosLookup;
 
   enum Type {
     Single              = 1,
     Pair                = 2,
     Cursive             = 3,
     MarkBase            = 4,
     MarkLig             = 5,
     MarkMark            = 6,
     Context             = 7,
     ChainContext        = 8,
     Extension           = 9
   };
 
+  inline const Coverage &get_coverage (unsigned int lookup_type) const
+  {
+    switch (lookup_type) {
+    case Single:                return u.single.get_coverage ();
+    case Pair:                  return u.pair.get_coverage ();
+    case Cursive:               return u.cursive.get_coverage ();
+    case MarkBase:              return u.markBase.get_coverage ();
+    case MarkLig:               return u.markLig.get_coverage ();
+    case MarkMark:              return u.markMark.get_coverage ();
+    case Context:               return u.context.get_coverage ();
+    case ChainContext:          return u.chainContext.get_coverage ();
+    case Extension:             return u.extension.get_coverage ();
+    default:                    return Null(Coverage);
+    }
+  }
+
   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 Pair:                  return TRACE_RETURN (u.pair.apply (c));
     case Cursive:               return TRACE_RETURN (u.cursive.apply (c));
     case MarkBase:              return TRACE_RETURN (u.markBase.apply (c));
     case MarkLig:               return TRACE_RETURN (u.markLig.apply (c));
     case MarkMark:              return TRACE_RETURN (u.markMark.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));
     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 Pair:                  return TRACE_RETURN (u.pair.sanitize (c));
     case Cursive:               return TRACE_RETURN (u.cursive.sanitize (c));
     case MarkBase:              return TRACE_RETURN (u.markBase.sanitize (c));
     case MarkLig:               return TRACE_RETURN (u.markLig.sanitize (c));
     case MarkMark:              return TRACE_RETURN (u.markMark.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));
     default:                    return TRACE_RETURN (true);
     }
   }
 
-  private:
+  protected:
   union {
-  USHORT                sub_format;
+  struct {
+    USHORT                      sub_format;
+  } header;
   SinglePos             single;
   PairPos               pair;
   CursivePos            cursive;
   MarkBasePos           markBase;
   MarkLigPos            markLig;
   MarkMarkPos           markMark;
-  ContextPos            c;
+  ContextPos            context;
   ChainContextPos       chainContext;
   ExtensionPos          extension;
   } u;
   public:
-  DEFINE_SIZE_UNION (2, sub_format);
+  DEFINE_SIZE_UNION (2, header.sub_format);
 };
 
 
 struct PosLookup : Lookup
 {
   inline const PosLookupSubTable& get_subtable (unsigned int i) const
   { return this+CastR<OffsetArrayOf<PosLookupSubTable> > (subTable)[i]; }
 
+  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 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;
 
-    for (unsigned int i = 0; i < get_subtable_count (); i++)
+    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);
 
     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->idx++;
     }
 
     return ret;
   }
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (unlikely (!Lookup::sanitize (c))) return TRACE_RETURN (false);
     OffsetArrayOf<PosLookupSubTable> &list = CastR<OffsetArrayOf<PosLookupSubTable> > (subTable);
     return TRACE_RETURN (list.sanitize (c, this, get_type ()));
   }
 };
 
 typedef OffsetListOf<PosLookup> PosLookupList;
 
 /*
  * GPOS -- The Glyph Positioning Table
  */
 
 struct GPOS : GSUBGPOS
 {
   static const hb_tag_t Tag     = HB_OT_TAG_GPOS;
 
   inline const PosLookup& get_lookup (unsigned int i) const
   { return CastR<PosLookup> (GSUBGPOS::get_lookup (i)); }
 
-  inline bool position_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 position_start (hb_buffer_t *buffer);
-  static inline void position_finish (hb_buffer_t *buffer);
+  static inline void position_start (hb_font_t *font, hb_buffer_t *buffer);
+  static inline void position_finish (hb_font_t *font, hb_buffer_t *buffer, hb_bool_t zero_width_attahced_marks);
 
   inline bool sanitize (hb_sanitize_context_t *c) {
     TRACE_SANITIZE ();
     if (unlikely (!GSUBGPOS::sanitize (c))) return TRACE_RETURN (false);
     OffsetTo<PosLookupList> &list = CastR<OffsetTo<PosLookupList> > (lookupList);
     return TRACE_RETURN (list.sanitize (c, this));
   }
   public:
   DEFINE_SIZE_STATIC (10);
 };
 
 
 static void
 fix_cursive_minor_offset (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction)
 {
-    unsigned int j = pos[i].cursive_chain();
-    if (likely (!j))
-      return;
+  unsigned int j = pos[i].cursive_chain();
+  if (likely (!j))
+    return;
 
-    j += i;
+  j += i;
 
-    pos[i].cursive_chain() = 0;
+  pos[i].cursive_chain() = 0;
 
-    fix_cursive_minor_offset (pos, j, direction);
+  fix_cursive_minor_offset (pos, j, direction);
 
-    if (HB_DIRECTION_IS_HORIZONTAL (direction))
-      pos[i].y_offset += pos[j].y_offset;
-    else
-      pos[i].x_offset += pos[j].x_offset;
+  if (HB_DIRECTION_IS_HORIZONTAL (direction))
+    pos[i].y_offset += pos[j].y_offset;
+  else
+    pos[i].x_offset += pos[j].x_offset;
 }
 
 static void
-fix_mark_attachment (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction)
+fix_mark_attachment (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction, hb_bool_t zero_width_attached_marks)
 {
   if (likely (!(pos[i].attach_lookback())))
     return;
 
   unsigned int j = i - pos[i].attach_lookback();
 
-  pos[i].x_advance = 0;
-  pos[i].y_advance = 0;
+  if (zero_width_attached_marks) {
+    pos[i].x_advance = 0;
+    pos[i].y_advance = 0;
+  }
   pos[i].x_offset += pos[j].x_offset;
   pos[i].y_offset += pos[j].y_offset;
 
   if (HB_DIRECTION_IS_FORWARD (direction))
     for (unsigned int k = j; k < i; k++) {
       pos[i].x_offset -= pos[k].x_advance;
       pos[i].y_offset -= pos[k].y_advance;
     }
   else
     for (unsigned int k = j + 1; k < i + 1; k++) {
       pos[i].x_offset += pos[k].x_advance;
       pos[i].y_offset += pos[k].y_advance;
     }
 }
 
 void
-GPOS::position_start (hb_buffer_t *buffer)
+GPOS::position_start (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer)
 {
   buffer->clear_positions ();
 
   unsigned int count = buffer->len;
   for (unsigned int i = 0; i < count; i++)
     buffer->pos[i].attach_lookback() = buffer->pos[i].cursive_chain() = 0;
 }
 
 void
-GPOS::position_finish (hb_buffer_t *buffer)
+GPOS::position_finish (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer, hb_bool_t zero_width_attached_marks)
 {
   unsigned int len;
   hb_glyph_position_t *pos = hb_buffer_get_glyph_positions (buffer, &len);
   hb_direction_t direction = buffer->props.direction;
 
   /* Handle cursive connections */
   for (unsigned int i = 0; i < len; i++)
     fix_cursive_minor_offset (pos, i, direction);
 
   /* Handle attachments */
   for (unsigned int i = 0; i < len; i++)
-    fix_mark_attachment (pos, i, direction);
+    fix_mark_attachment (pos, i, direction, zero_width_attached_marks);
 
   HB_BUFFER_DEALLOCATE_VAR (buffer, syllable);
   HB_BUFFER_DEALLOCATE_VAR (buffer, lig_props);
-  HB_BUFFER_DEALLOCATE_VAR (buffer, props_cache);
+  HB_BUFFER_DEALLOCATE_VAR (buffer, glyph_props);
 }
 
 
 /* Out-of-class implementation for methods recursing */
 
+inline const Coverage & ExtensionPos::get_coverage (void) const
+{
+  return get_subtable ().get_coverage (get_type ());
+}
+
 inline bool ExtensionPos::apply (hb_apply_context_t *c) const
 {
   TRACE_APPLY ();
   return TRACE_RETURN (get_subtable ().apply (c, get_type ()));
 }
 
 inline bool ExtensionPos::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<PosLookupSubTable> (this, offset).sanitize (c, get_type ()));
 }
 
 static inline bool position_lookup (hb_apply_context_t *c, unsigned int lookup_index)
 {
-  const GPOS &gpos = *(c->face->ot_layout->gpos);
+  const GPOS &gpos = *(hb_ot_layout_from_face (c->face)->gpos);
   const PosLookup &l = gpos.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);
 }
 
 
 #undef attach_lookback
 #undef cursive_chain
 
 
+} // namespace OT
+
 
 #endif /* HB_OT_LAYOUT_GPOS_TABLE_HH */