Add m-esr52 at 52.6.0

1 files changed, 1654 insertions, 0 deletions

diff --git a/gfx/harfbuzz/src/hb-ot-layout-gpos-table.hh b/gfx/harfbuzz/src/hb-ot-layout-gpos-table.hh
new file mode 100644
index 000000000..952fd60fe
--- /dev/null
+++ b/gfx/harfbuzz/src/hb-ot-layout-gpos-table.hh
@@ -0,0 +1,1654 @@
+/*
+ * Copyright © 2007,2008,2009,2010  Red Hat, Inc.
+ * Copyright © 2010,2012,2013  Google, Inc.
+ *
+ *  This is part of HarfBuzz, a text shaping library.
+ *
+ * Permission is hereby granted, without written agreement and without
+ * license or royalty fees, to use, copy, modify, and distribute this
+ * software and its documentation for any purpose, provided that the
+ * above copyright notice and the following two paragraphs appear in
+ * all copies of this software.
+ *
+ * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
+ * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
+ * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Red Hat Author(s): Behdad Esfahbod
+ * Google Author(s): Behdad Esfahbod
+ */
+
+#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_chain() var.i16[0] /* glyph to which this attaches to, relative to current glyphs; negative for going back, positive for forward. */
+#define attach_type() var.u8[2] /* attachment type */
+/* Note! if attach_chain() is zero, the value of attach_type() is irrelevant. */
+
+enum attach_type_t {
+  ATTACH_TYPE_NONE	= 0X00,
+
+  /* Each attachment should be either a mark or a cursive; can't be both. */
+  ATTACH_TYPE_MARK	= 0X01,
+  ATTACH_TYPE_CURSIVE	= 0X02,
+};
+
+
+/* Shared Tables: ValueRecord, Anchor Table, and MarkArray */
+
+typedef USHORT Value;
+
+typedef Value ValueRecord[VAR];
+
+struct ValueFormat : USHORT
+{
+  enum Flags {
+    xPlacement	= 0x0001u,	/* Includes horizontal adjustment for placement */
+    yPlacement	= 0x0002u,	/* Includes vertical adjustment for placement */
+    xAdvance	= 0x0004u,	/* Includes horizontal adjustment for advance */
+    yAdvance	= 0x0008u,	/* Includes vertical adjustment for advance */
+    xPlaDevice	= 0x0010u,	/* Includes horizontal Device table for placement */
+    yPlaDevice	= 0x0020u,	/* Includes vertical Device table for placement */
+    xAdvDevice	= 0x0040u,	/* Includes horizontal Device table for advance */
+    yAdvDevice	= 0x0080u,	/* Includes vertical Device table for advance */
+    ignored	= 0x0F00u,	/* Was used in TrueType Open for MM fonts */
+    reserved	= 0xF000u,	/* For future use */
+
+    devices	= 0x00F0u	/* Mask for having any Device table */
+  };
+
+/* All fields are options.  Only those available advance the value pointer. */
+#if 0
+  SHORT		xPlacement;		/* Horizontal adjustment for
+					 * placement--in design units */
+  SHORT		yPlacement;		/* Vertical adjustment for
+					 * placement--in design units */
+  SHORT		xAdvance;		/* Horizontal adjustment for
+					 * advance--in design units (only used
+					 * for horizontal writing) */
+  SHORT		yAdvance;		/* Vertical adjustment for advance--in
+					 * design units (only used for vertical
+					 * writing) */
+  Offset	xPlaDevice;		/* Offset to Device table for
+					 * horizontal placement--measured from
+					 * beginning of PosTable (may be NULL) */
+  Offset	yPlaDevice;		/* Offset to Device table for vertical
+					 * placement--measured from beginning
+					 * of PosTable (may be NULL) */
+  Offset	xAdvDevice;		/* Offset to Device table for
+					 * horizontal advance--measured from
+					 * beginning of PosTable (may be NULL) */
+  Offset	yAdvDevice;		/* Offset to Device table for vertical
+					 * advance--measured from beginning of
+					 * PosTable (may be NULL) */
+#endif
+
+  inline unsigned int get_len (void) const
+  { return _hb_popcount32 ((unsigned int) *this); }
+  inline unsigned int get_size (void) const
+  { return get_len () * Value::static_size; }
+
+  void apply_value (hb_apply_context_t   *c,
+		    const void           *base,
+		    const Value          *values,
+		    hb_glyph_position_t  &glyph_pos) const
+  {
+    unsigned int format = *this;
+    if (!format) return;
+
+    hb_font_t *font = c->font;
+    hb_bool_t horizontal = HB_DIRECTION_IS_HORIZONTAL (c->direction);
+
+    if (format & xPlacement) glyph_pos.x_offset  += font->em_scale_x (get_short (values++));
+    if (format & yPlacement) glyph_pos.y_offset  += font->em_scale_y (get_short (values++));
+    if (format & xAdvance) {
+      if (likely (horizontal)) glyph_pos.x_advance += font->em_scale_x (get_short (values));
+      values++;
+    }
+    /* y_advance values grow downward but font-space grows upward, hence negation */
+    if (format & yAdvance) {
+      if (unlikely (!horizontal)) glyph_pos.y_advance -= font->em_scale_y (get_short (values));
+      values++;
+    }
+
+    if (!has_device ()) return;
+
+    bool use_x_device = font->x_ppem || font->num_coords;
+    bool use_y_device = font->y_ppem || font->num_coords;
+
+    if (!use_x_device && !use_y_device) return;
+
+    const VariationStore &store = c->var_store;
+
+    /* pixel -> fractional pixel */
+    if (format & xPlaDevice) {
+      if (use_x_device) glyph_pos.x_offset  += (base + get_device (values)).get_x_delta (font, store);
+      values++;
+    }
+    if (format & yPlaDevice) {
+      if (use_y_device) glyph_pos.y_offset  += (base + get_device (values)).get_y_delta (font, store);
+      values++;
+    }
+    if (format & xAdvDevice) {
+      if (horizontal && use_x_device) glyph_pos.x_advance += (base + get_device (values)).get_x_delta (font, store);
+      values++;
+    }
+    if (format & yAdvDevice) {
+      /* y_advance values grow downward but font-space grows upward, hence negation */
+      if (!horizontal && use_y_device) glyph_pos.y_advance -= (base + get_device (values)).get_y_delta (font, store);
+      values++;
+    }
+  }
+
+  private:
+  inline bool sanitize_value_devices (hb_sanitize_context_t *c, const void *base, const Value *values) const
+  {
+    unsigned int format = *this;
+
+    if (format & xPlacement) values++;
+    if (format & yPlacement) values++;
+    if (format & xAdvance)   values++;
+    if (format & yAdvance)   values++;
+
+    if ((format & xPlaDevice) && !get_device (values++).sanitize (c, base)) return false;
+    if ((format & yPlaDevice) && !get_device (values++).sanitize (c, base)) return false;
+    if ((format & xAdvDevice) && !get_device (values++).sanitize (c, base)) return false;
+    if ((format & yAdvDevice) && !get_device (values++).sanitize (c, base)) return false;
+
+    return true;
+  }
+
+  static inline OffsetTo<Device>& get_device (Value* value)
+  { return *CastP<OffsetTo<Device> > (value); }
+  static inline const OffsetTo<Device>& get_device (const Value* value)
+  { return *CastP<OffsetTo<Device> > (value); }
+
+  static inline const SHORT& get_short (const Value* value)
+  { return *CastP<SHORT> (value); }
+
+  public:
+
+  inline bool has_device (void) const {
+    unsigned int format = *this;
+    return (format & devices) != 0;
+  }
+
+  inline bool sanitize_value (hb_sanitize_context_t *c, const void *base, const Value *values) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_range (values, get_size ()) && (!has_device () || sanitize_value_devices (c, base, values)));
+  }
+
+  inline bool sanitize_values (hb_sanitize_context_t *c, const void *base, const Value *values, unsigned int count) const
+  {
+    TRACE_SANITIZE (this);
+    unsigned int len = get_len ();
+
+    if (!c->check_array (values, get_size (), count)) return_trace (false);
+
+    if (!has_device ()) return_trace (true);
+
+    for (unsigned int i = 0; i < count; i++) {
+      if (!sanitize_value_devices (c, base, values))
+        return_trace (false);
+      values += len;
+    }
+
+    return_trace (true);
+  }
+
+  /* Just sanitize referenced Device tables.  Doesn't check the values themselves. */
+  inline bool sanitize_values_stride_unsafe (hb_sanitize_context_t *c, const void *base, const Value *values, unsigned int count, unsigned int stride) const
+  {
+    TRACE_SANITIZE (this);
+
+    if (!has_device ()) return_trace (true);
+
+    for (unsigned int i = 0; i < count; i++) {
+      if (!sanitize_value_devices (c, base, values))
+        return_trace (false);
+      values += stride;
+    }
+
+    return_trace (true);
+  }
+};
+
+
+struct AnchorFormat1
+{
+  inline void get_anchor (hb_apply_context_t *c, hb_codepoint_t glyph_id HB_UNUSED,
+			  hb_position_t *x, hb_position_t *y) const
+  {
+    hb_font_t *font = c->font;
+    *x = font->em_scale_x (xCoordinate);
+    *y = font->em_scale_y (yCoordinate);
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this));
+  }
+
+  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
+{
+  inline void get_anchor (hb_apply_context_t *c, hb_codepoint_t glyph_id,
+			  hb_position_t *x, hb_position_t *y) const
+  {
+    hb_font_t *font = c->font;
+    unsigned int x_ppem = font->x_ppem;
+    unsigned int y_ppem = font->y_ppem;
+    hb_position_t cx, cy;
+    hb_bool_t ret;
+
+    ret = (x_ppem || y_ppem) &&
+	   font->get_glyph_contour_point_for_origin (glyph_id, anchorPoint, HB_DIRECTION_LTR, &cx, &cy);
+    *x = ret && x_ppem ? cx : font->em_scale_x (xCoordinate);
+    *y = ret && y_ppem ? cy : font->em_scale_y (yCoordinate);
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this));
+  }
+
+  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
+{
+  inline void get_anchor (hb_apply_context_t *c, hb_codepoint_t glyph_id HB_UNUSED,
+			  hb_position_t *x, hb_position_t *y) const
+  {
+    hb_font_t *font = c->font;
+    *x = font->em_scale_x (xCoordinate);
+    *y = font->em_scale_y (yCoordinate);
+
+    if (font->x_ppem || font->num_coords)
+      *x += (this+xDeviceTable).get_x_delta (font, c->var_store);
+    if (font->y_ppem || font->num_coords)
+      *y += (this+yDeviceTable).get_y_delta (font, c->var_store);
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) && xDeviceTable.sanitize (c, this) && yDeviceTable.sanitize (c, this));
+  }
+
+  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
+					 * Anchor table (may be NULL) */
+  public:
+  DEFINE_SIZE_STATIC (10);
+};
+
+struct Anchor
+{
+  inline void get_anchor (hb_apply_context_t *c, hb_codepoint_t glyph_id,
+			  hb_position_t *x, hb_position_t *y) const
+  {
+    *x = *y = 0;
+    switch (u.format) {
+    case 1: u.format1.get_anchor (c, glyph_id, x, y); return;
+    case 2: u.format2.get_anchor (c, glyph_id, x, y); return;
+    case 3: u.format3.get_anchor (c, glyph_id, x, y); return;
+    default:						 return;
+    }
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    if (!u.format.sanitize (c)) return_trace (false);
+    switch (u.format) {
+    case 1: return_trace (u.format1.sanitize (c));
+    case 2: return_trace (u.format2.sanitize (c));
+    case 3: return_trace (u.format3.sanitize (c));
+    default:return_trace (true);
+    }
+  }
+
+  protected:
+  union {
+  USHORT		format;		/* Format identifier */
+  AnchorFormat1		format1;
+  AnchorFormat2		format2;
+  AnchorFormat3		format3;
+  } u;
+  public:
+  DEFINE_SIZE_UNION (2, format);
+};
+
+
+struct AnchorMatrix
+{
+  inline const Anchor& get_anchor (unsigned int row, unsigned int col, unsigned int cols, bool *found) const {
+    *found = false;
+    if (unlikely (row >= rows || col >= cols)) return Null(Anchor);
+    *found = !matrixZ[row * cols + col].is_null ();
+    return this+matrixZ[row * cols + col];
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c, unsigned int cols) const
+  {
+    TRACE_SANITIZE (this);
+    if (!c->check_struct (this)) return_trace (false);
+    if (unlikely (_hb_unsigned_int_mul_overflows (rows, cols))) return_trace (false);
+    unsigned int count = rows * cols;
+    if (!c->check_array (matrixZ, matrixZ[0].static_size, count)) return_trace (false);
+    for (unsigned int i = 0; i < count; i++)
+      if (!matrixZ[i].sanitize (c, this)) return_trace (false);
+    return_trace (true);
+  }
+
+  USHORT	rows;			/* Number of rows */
+  protected:
+  OffsetTo<Anchor>
+		matrixZ[VAR];		/* Matrix of offsets to Anchor tables--
+					 * from beginning of AnchorMatrix table */
+  public:
+  DEFINE_SIZE_ARRAY (2, matrixZ);
+};
+
+
+struct MarkRecord
+{
+  friend struct MarkArray;
+
+  inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) && markAnchor.sanitize (c, base));
+  }
+
+  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 */
+{
+  inline bool apply (hb_apply_context_t *c,
+		     unsigned int mark_index, unsigned int glyph_index,
+		     const AnchorMatrix &anchors, unsigned int class_count,
+		     unsigned int glyph_pos) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    const MarkRecord &record = ArrayOf<MarkRecord>::operator[](mark_index);
+    unsigned int mark_class = record.klass;
+
+    const Anchor& mark_anchor = this + record.markAnchor;
+    bool found;
+    const Anchor& glyph_anchor = anchors.get_anchor (glyph_index, mark_class, class_count, &found);
+    /* If this subtable doesn't have an anchor for this base and this class,
+     * return false such that the subsequent subtables have a chance at it. */
+    if (unlikely (!found)) return_trace (false);
+
+    hb_position_t mark_x, mark_y, base_x, base_y;
+
+    mark_anchor.get_anchor (c, buffer->cur().codepoint, &mark_x, &mark_y);
+    glyph_anchor.get_anchor (c, buffer->info[glyph_pos].codepoint, &base_x, &base_y);
+
+    hb_glyph_position_t &o = buffer->cur_pos();
+    o.x_offset = base_x - mark_x;
+    o.y_offset = base_y - mark_y;
+    o.attach_type() = ATTACH_TYPE_MARK;
+    o.attach_chain() = (int) glyph_pos - (int) buffer->idx;
+    buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
+
+    buffer->idx++;
+    return_trace (true);
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (ArrayOf<MarkRecord>::sanitize (c, this));
+  }
+};
+
+
+/* Lookups */
+
+struct SinglePosFormat1
+{
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    (this+coverage).add_coverage (c->input);
+  }
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint);
+    if (likely (index == NOT_COVERED)) return_trace (false);
+
+    valueFormat.apply_value (c, this, values, buffer->cur_pos());
+
+    buffer->idx++;
+    return_trace (true);
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) &&
+		  coverage.sanitize (c, this) &&
+		  valueFormat.sanitize_value (c, this, values));
+  }
+
+  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
+{
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    (this+coverage).add_coverage (c->input);
+  }
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint);
+    if (likely (index == NOT_COVERED)) return_trace (false);
+
+    if (likely (index >= valueCount)) return_trace (false);
+
+    valueFormat.apply_value (c, this,
+			     &values[index * valueFormat.get_len ()],
+			     buffer->cur_pos());
+
+    buffer->idx++;
+    return_trace (true);
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) &&
+		  coverage.sanitize (c, this) &&
+		  valueFormat.sanitize_values (c, this, values, valueCount));
+  }
+
+  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
+{
+  template <typename context_t>
+  inline typename context_t::return_t dispatch (context_t *c) const
+  {
+    TRACE_DISPATCH (this, u.format);
+    if (unlikely (!c->may_dispatch (this, &u.format))) return_trace (c->no_dispatch_return_value ());
+    switch (u.format) {
+    case 1: return_trace (c->dispatch (u.format1));
+    case 2: return_trace (c->dispatch (u.format2));
+    default:return_trace (c->default_return_value ());
+    }
+  }
+
+  protected:
+  union {
+  USHORT		format;		/* Format identifier */
+  SinglePosFormat1	format1;
+  SinglePosFormat2	format2;
+  } u;
+};
+
+
+struct PairValueRecord
+{
+  friend struct PairSet;
+
+  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
+{
+  friend struct PairPosFormat1;
+
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c,
+			      const ValueFormat *valueFormats) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    unsigned int len1 = valueFormats[0].get_len ();
+    unsigned int len2 = valueFormats[1].get_len ();
+    unsigned int record_size = USHORT::static_size * (1 + len1 + len2);
+
+    const PairValueRecord *record = CastP<PairValueRecord> (arrayZ);
+    unsigned int count = len;
+    for (unsigned int i = 0; i < count; i++)
+    {
+      c->input->add (record->secondGlyph);
+      record = &StructAtOffset<PairValueRecord> (record, record_size);
+    }
+  }
+
+  inline bool apply (hb_apply_context_t *c,
+		     const ValueFormat *valueFormats,
+		     unsigned int pos) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    unsigned int len1 = valueFormats[0].get_len ();
+    unsigned int len2 = valueFormats[1].get_len ();
+    unsigned int record_size = USHORT::static_size * (1 + len1 + len2);
+
+    const PairValueRecord *record_array = CastP<PairValueRecord> (arrayZ);
+    unsigned int count = len;
+
+    /* Hand-coded bsearch. */
+    if (unlikely (!count))
+      return_trace (false);
+    hb_codepoint_t x = buffer->info[pos].codepoint;
+    int min = 0, max = (int) count - 1;
+    while (min <= max)
+    {
+      int mid = (min + max) / 2;
+      const PairValueRecord *record = &StructAtOffset<PairValueRecord> (record_array, record_size * mid);
+      hb_codepoint_t mid_x = record->secondGlyph;
+      if (x < mid_x)
+        max = mid - 1;
+      else if (x > mid_x)
+        min = mid + 1;
+      else
+      {
+	valueFormats[0].apply_value (c, this, &record->values[0], buffer->cur_pos());
+	valueFormats[1].apply_value (c, this, &record->values[len1], buffer->pos[pos]);
+	if (len2)
+	  pos++;
+	buffer->idx = pos;
+	return_trace (true);
+      }
+    }
+
+    return_trace (false);
+  }
+
+  struct sanitize_closure_t {
+    const void *base;
+    const ValueFormat *valueFormats;
+    unsigned int len1; /* valueFormats[0].get_len() */
+    unsigned int stride; /* 1 + len1 + len2 */
+  };
+
+  inline bool sanitize (hb_sanitize_context_t *c, const sanitize_closure_t *closure) const
+  {
+    TRACE_SANITIZE (this);
+    if (!(c->check_struct (this)
+       && c->check_array (arrayZ, USHORT::static_size * closure->stride, len))) return_trace (false);
+
+    unsigned int count = len;
+    const PairValueRecord *record = CastP<PairValueRecord> (arrayZ);
+    return_trace (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));
+  }
+
+  protected:
+  USHORT	len;			/* Number of PairValueRecords */
+  USHORT	arrayZ[VAR];		/* Array of PairValueRecords--ordered
+					 * by GlyphID of the second glyph */
+  public:
+  DEFINE_SIZE_ARRAY (2, arrayZ);
+};
+
+struct PairPosFormat1
+{
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    (this+coverage).add_coverage (c->input);
+    unsigned int count = pairSet.len;
+    for (unsigned int i = 0; i < count; i++)
+      (this+pairSet[i]).collect_glyphs (c, valueFormat);
+  }
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint);
+    if (likely (index == NOT_COVERED)) return_trace (false);
+
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
+    skippy_iter.reset (buffer->idx, 1);
+    if (!skippy_iter.next ()) return_trace (false);
+
+    return_trace ((this+pairSet[index]).apply (c, valueFormat, skippy_iter.idx));
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+
+    if (!c->check_struct (this)) return_trace (false);
+
+    unsigned int len1 = valueFormat[0].get_len ();
+    unsigned int len2 = valueFormat[1].get_len ();
+    PairSet::sanitize_closure_t closure = {
+      this,
+      valueFormat,
+      len1,
+      1 + len1 + len2
+    };
+
+    return_trace (coverage.sanitize (c, this) && pairSet.sanitize (c, this, &closure));
+  }
+
+  protected:
+  USHORT	format;			/* Format identifier--format = 1 */
+  OffsetTo<Coverage>
+		coverage;		/* Offset to Coverage table--from
+					 * beginning of subtable */
+  ValueFormat	valueFormat[2];		/* [0] Defines the types of data in
+					 * ValueRecord1--for the first glyph
+					 * in the pair--may be zero (0) */
+					/* [1] 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
+{
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    (this+coverage).add_coverage (c->input);
+
+    unsigned int count1 = class1Count;
+    const ClassDef &klass1 = this+classDef1;
+    for (unsigned int i = 0; i < count1; i++)
+      klass1.add_class (c->input, i);
+
+    unsigned int count2 = class2Count;
+    const ClassDef &klass2 = this+classDef2;
+    for (unsigned int i = 0; i < count2; i++)
+      klass2.add_class (c->input, i);
+  }
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    unsigned int index = (this+coverage).get_coverage  (buffer->cur().codepoint);
+    if (likely (index == NOT_COVERED)) return_trace (false);
+
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
+    skippy_iter.reset (buffer->idx, 1);
+    if (!skippy_iter.next ()) return_trace (false);
+
+    unsigned int len1 = valueFormat1.get_len ();
+    unsigned int len2 = valueFormat2.get_len ();
+    unsigned int record_len = len1 + len2;
+
+    unsigned int klass1 = (this+classDef1).get_class (buffer->cur().codepoint);
+    unsigned int klass2 = (this+classDef2).get_class (buffer->info[skippy_iter.idx].codepoint);
+    if (unlikely (klass1 >= class1Count || klass2 >= class2Count)) return_trace (false);
+
+    const Value *v = &values[record_len * (klass1 * class2Count + klass2)];
+    valueFormat1.apply_value (c, this, v, buffer->cur_pos());
+    valueFormat2.apply_value (c, this, v + len1, buffer->pos[skippy_iter.idx]);
+
+    buffer->idx = skippy_iter.idx;
+    if (len2)
+      buffer->idx++;
+
+    return_trace (true);
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    if (!(c->check_struct (this)
+       && coverage.sanitize (c, this)
+       && classDef1.sanitize (c, this)
+       && classDef2.sanitize (c, this))) return_trace (false);
+
+    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 (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));
+  }
+
+  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) */
+  OffsetTo<ClassDef>
+		classDef1;		/* Offset to ClassDef table--from
+					 * beginning of PairPos subtable--for
+					 * the first glyph of the pair */
+  OffsetTo<ClassDef>
+		classDef2;		/* Offset to ClassDef table--from
+					 * beginning of PairPos subtable--for
+					 * the second glyph of the pair */
+  USHORT	class1Count;		/* Number of classes in ClassDef1
+					 * table--includes Class0 */
+  USHORT	class2Count;		/* Number of classes in ClassDef2
+					 * table--includes Class0 */
+  ValueRecord	values;			/* Matrix of value pairs:
+					 * class1-major, class2-minor,
+					 * Each entry has value1 and value2 */
+  public:
+  DEFINE_SIZE_ARRAY (16, values);
+};
+
+struct PairPos
+{
+  template <typename context_t>
+  inline typename context_t::return_t dispatch (context_t *c) const
+  {
+    TRACE_DISPATCH (this, u.format);
+    if (unlikely (!c->may_dispatch (this, &u.format))) return_trace (c->no_dispatch_return_value ());
+    switch (u.format) {
+    case 1: return_trace (c->dispatch (u.format1));
+    case 2: return_trace (c->dispatch (u.format2));
+    default:return_trace (c->default_return_value ());
+    }
+  }
+
+  protected:
+  union {
+  USHORT		format;		/* Format identifier */
+  PairPosFormat1	format1;
+  PairPosFormat2	format2;
+  } u;
+};
+
+
+struct EntryExitRecord
+{
+  friend struct CursivePosFormat1;
+
+  inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (entryAnchor.sanitize (c, base) && exitAnchor.sanitize (c, base));
+  }
+
+  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);
+};
+
+static void
+reverse_cursive_minor_offset (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction, unsigned int new_parent);
+
+struct CursivePosFormat1
+{
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    (this+coverage).add_coverage (c->input);
+  }
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+coverage;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+
+    const EntryExitRecord &this_record = entryExitRecord[(this+coverage).get_coverage  (buffer->cur().codepoint)];
+    if (!this_record.exitAnchor) return_trace (false);
+
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
+    skippy_iter.reset (buffer->idx, 1);
+    if (!skippy_iter.next ()) return_trace (false);
+
+    const EntryExitRecord &next_record = entryExitRecord[(this+coverage).get_coverage  (buffer->info[skippy_iter.idx].codepoint)];
+    if (!next_record.entryAnchor) return_trace (false);
+
+    unsigned int i = buffer->idx;
+    unsigned int j = skippy_iter.idx;
+
+    hb_position_t entry_x, entry_y, exit_x, exit_y;
+    (this+this_record.exitAnchor).get_anchor (c, buffer->info[i].codepoint, &exit_x, &exit_y);
+    (this+next_record.entryAnchor).get_anchor (c, buffer->info[j].codepoint, &entry_x, &entry_y);
+
+    hb_glyph_position_t *pos = buffer->pos;
+
+    hb_position_t d;
+    /* Main-direction adjustment */
+    switch (c->direction) {
+      case HB_DIRECTION_LTR:
+	pos[i].x_advance  =  exit_x + pos[i].x_offset;
+
+	d = entry_x + pos[j].x_offset;
+	pos[j].x_advance -= d;
+	pos[j].x_offset  -= d;
+	break;
+      case HB_DIRECTION_RTL:
+	d = exit_x + pos[i].x_offset;
+	pos[i].x_advance -= d;
+	pos[i].x_offset  -= d;
+
+	pos[j].x_advance  =  entry_x + pos[j].x_offset;
+	break;
+      case HB_DIRECTION_TTB:
+	pos[i].y_advance  =  exit_y + pos[i].y_offset;
+
+	d = entry_y + pos[j].y_offset;
+	pos[j].y_advance -= d;
+	pos[j].y_offset  -= d;
+	break;
+      case HB_DIRECTION_BTT:
+	d = exit_y + pos[i].y_offset;
+	pos[i].y_advance -= d;
+	pos[i].y_offset  -= d;
+
+	pos[j].y_advance  =  entry_y;
+	break;
+      case HB_DIRECTION_INVALID:
+      default:
+	break;
+    }
+
+    /* Cross-direction adjustment */
+
+    /* We attach child to parent (think graph theory and rooted trees whereas
+     * the root stays on baseline and each node aligns itself against its
+     * parent.
+     *
+     * Optimize things for the case of RightToLeft, as that's most common in
+     * Arabinc. */
+    unsigned int child  = i;
+    unsigned int parent = j;
+    hb_position_t x_offset = entry_x - exit_x;
+    hb_position_t y_offset = entry_y - exit_y;
+    if  (!(c->lookup_props & LookupFlag::RightToLeft))
+    {
+      unsigned int k = child;
+      child = parent;
+      parent = k;
+      x_offset = -x_offset;
+      y_offset = -y_offset;
+    }
+
+    /* If child was already connected to someone else, walk through its old
+     * chain and reverse the link direction, such that the whole tree of its
+     * previous connection now attaches to new parent.  Watch out for case
+     * where new parent is on the path from old chain...
+     */
+    reverse_cursive_minor_offset (pos, child, c->direction, parent);
+
+    pos[child].attach_type() = ATTACH_TYPE_CURSIVE;
+    pos[child].attach_chain() = (int) parent - (int) child;
+    buffer->scratch_flags |= HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT;
+    if (likely (HB_DIRECTION_IS_HORIZONTAL (c->direction)))
+      pos[child].y_offset = y_offset;
+    else
+      pos[child].x_offset = x_offset;
+
+    buffer->idx = j;
+    return_trace (true);
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (coverage.sanitize (c, this) && entryExitRecord.sanitize (c, this));
+  }
+
+  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
+{
+  template <typename context_t>
+  inline typename context_t::return_t dispatch (context_t *c) const
+  {
+    TRACE_DISPATCH (this, u.format);
+    if (unlikely (!c->may_dispatch (this, &u.format))) return_trace (c->no_dispatch_return_value ());
+    switch (u.format) {
+    case 1: return_trace (c->dispatch (u.format1));
+    default:return_trace (c->default_return_value ());
+    }
+  }
+
+  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
+{
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    (this+markCoverage).add_coverage (c->input);
+    (this+baseCoverage).add_coverage (c->input);
+  }
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+markCoverage;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    unsigned int mark_index = (this+markCoverage).get_coverage  (buffer->cur().codepoint);
+    if (likely (mark_index == NOT_COVERED)) return_trace (false);
+
+    /* Now we search backwards for a non-mark glyph */
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
+    skippy_iter.reset (buffer->idx, 1);
+    skippy_iter.set_lookup_props (LookupFlag::IgnoreMarks);
+    do {
+      if (!skippy_iter.prev ()) return_trace (false);
+      /* We only want to attach to the first of a MultipleSubst sequence.  Reject others. */
+      if (0 == _hb_glyph_info_get_lig_comp (&buffer->info[skippy_iter.idx])) break;
+      skippy_iter.reject ();
+    } while (1);
+
+    /* Checking that matched glyph is actually a base glyph by GDEF is too strong; disabled */
+    //if (!_hb_glyph_info_is_base_glyph (&buffer->info[skippy_iter.idx])) { return_trace (false); }
+
+    unsigned int base_index = (this+baseCoverage).get_coverage  (buffer->info[skippy_iter.idx].codepoint);
+    if (base_index == NOT_COVERED) return_trace (false);
+
+    return_trace ((this+markArray).apply (c, mark_index, base_index, this+baseArray, classCount, skippy_iter.idx));
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) &&
+		  markCoverage.sanitize (c, this) &&
+		  baseCoverage.sanitize (c, this) &&
+		  markArray.sanitize (c, this) &&
+		  baseArray.sanitize (c, this, (unsigned int) classCount));
+  }
+
+  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
+{
+  template <typename context_t>
+  inline typename context_t::return_t dispatch (context_t *c) const
+  {
+    TRACE_DISPATCH (this, u.format);
+    if (unlikely (!c->may_dispatch (this, &u.format))) return_trace (c->no_dispatch_return_value ());
+    switch (u.format) {
+    case 1: return_trace (c->dispatch (u.format1));
+    default:return_trace (c->default_return_value ());
+    }
+  }
+
+  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
+{
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    (this+markCoverage).add_coverage (c->input);
+    (this+ligatureCoverage).add_coverage (c->input);
+  }
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+markCoverage;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    unsigned int mark_index = (this+markCoverage).get_coverage  (buffer->cur().codepoint);
+    if (likely (mark_index == NOT_COVERED)) return_trace (false);
+
+    /* Now we search backwards for a non-mark glyph */
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
+    skippy_iter.reset (buffer->idx, 1);
+    skippy_iter.set_lookup_props (LookupFlag::IgnoreMarks);
+    if (!skippy_iter.prev ()) return_trace (false);
+
+    /* Checking that matched glyph is actually a ligature by GDEF is too strong; disabled */
+    //if (!_hb_glyph_info_is_ligature (&buffer->info[skippy_iter.idx])) { return_trace (false); }
+
+    unsigned int j = skippy_iter.idx;
+    unsigned int lig_index = (this+ligatureCoverage).get_coverage  (buffer->info[j].codepoint);
+    if (lig_index == NOT_COVERED) return_trace (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 (false);
+
+    /* 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. */
+    unsigned int comp_index;
+    unsigned int lig_id = _hb_glyph_info_get_lig_id (&buffer->info[j]);
+    unsigned int mark_id = _hb_glyph_info_get_lig_id (&buffer->cur());
+    unsigned int mark_comp = _hb_glyph_info_get_lig_comp (&buffer->cur());
+    if (lig_id && lig_id == mark_id && mark_comp > 0)
+      comp_index = MIN (comp_count, _hb_glyph_info_get_lig_comp (&buffer->cur())) - 1;
+    else
+      comp_index = comp_count - 1;
+
+    return_trace ((this+markArray).apply (c, mark_index, comp_index, lig_attach, classCount, j));
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) &&
+		  markCoverage.sanitize (c, this) &&
+		  ligatureCoverage.sanitize (c, this) &&
+		  markArray.sanitize (c, this) &&
+		  ligatureArray.sanitize (c, this, (unsigned int) classCount));
+  }
+
+  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
+{
+  template <typename context_t>
+  inline typename context_t::return_t dispatch (context_t *c) const
+  {
+    TRACE_DISPATCH (this, u.format);
+    if (unlikely (!c->may_dispatch (this, &u.format))) return_trace (c->no_dispatch_return_value ());
+    switch (u.format) {
+    case 1: return_trace (c->dispatch (u.format1));
+    default:return_trace (c->default_return_value ());
+    }
+  }
+
+  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
+{
+  inline void collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    (this+mark1Coverage).add_coverage (c->input);
+    (this+mark2Coverage).add_coverage (c->input);
+  }
+
+  inline const Coverage &get_coverage (void) const
+  {
+    return this+mark1Coverage;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    hb_buffer_t *buffer = c->buffer;
+    unsigned int mark1_index = (this+mark1Coverage).get_coverage  (buffer->cur().codepoint);
+    if (likely (mark1_index == NOT_COVERED)) return_trace (false);
+
+    /* now we search backwards for a suitable mark glyph until a non-mark glyph */
+    hb_apply_context_t::skipping_iterator_t &skippy_iter = c->iter_input;
+    skippy_iter.reset (buffer->idx, 1);
+    skippy_iter.set_lookup_props (c->lookup_props & ~LookupFlag::IgnoreFlags);
+    if (!skippy_iter.prev ()) return_trace (false);
+
+    if (!_hb_glyph_info_is_mark (&buffer->info[skippy_iter.idx])) { return_trace (false); }
+
+    unsigned int j = skippy_iter.idx;
+
+    unsigned int id1 = _hb_glyph_info_get_lig_id (&buffer->cur());
+    unsigned int id2 = _hb_glyph_info_get_lig_id (&buffer->info[j]);
+    unsigned int comp1 = _hb_glyph_info_get_lig_comp (&buffer->cur());
+    unsigned int comp2 = _hb_glyph_info_get_lig_comp (&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 (false);
+
+    good:
+    unsigned int mark2_index = (this+mark2Coverage).get_coverage  (buffer->info[j].codepoint);
+    if (mark2_index == NOT_COVERED) return_trace (false);
+
+    return_trace ((this+mark1Array).apply (c, mark1_index, mark2_index, this+mark2Array, classCount, j));
+  }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) &&
+		  mark1Coverage.sanitize (c, this) &&
+		  mark2Coverage.sanitize (c, this) &&
+		  mark1Array.sanitize (c, this) &&
+		  mark2Array.sanitize (c, this, (unsigned int) classCount));
+  }
+
+  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
+{
+  template <typename context_t>
+  inline typename context_t::return_t dispatch (context_t *c) const
+  {
+    TRACE_DISPATCH (this, u.format);
+    if (unlikely (!c->may_dispatch (this, &u.format))) return_trace (c->no_dispatch_return_value ());
+    switch (u.format) {
+    case 1: return_trace (c->dispatch (u.format1));
+    default:return_trace (c->default_return_value ());
+    }
+  }
+
+  protected:
+  union {
+  USHORT		format;		/* Format identifier */
+  MarkMarkPosFormat1	format1;
+  } u;
+};
+
+
+struct ContextPos : Context {};
+
+struct ChainContextPos : ChainContext {};
+
+struct ExtensionPos : Extension<ExtensionPos>
+{
+  typedef struct PosLookupSubTable LookupSubTable;
+};
+
+
+
+/*
+ * 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
+  };
+
+  template <typename context_t>
+  inline typename context_t::return_t dispatch (context_t *c, unsigned int lookup_type) const
+  {
+    TRACE_DISPATCH (this, lookup_type);
+    if (unlikely (!c->may_dispatch (this, &u.sub_format))) return_trace (c->no_dispatch_return_value ());
+    switch (lookup_type) {
+    case Single:		return_trace (u.single.dispatch (c));
+    case Pair:			return_trace (u.pair.dispatch (c));
+    case Cursive:		return_trace (u.cursive.dispatch (c));
+    case MarkBase:		return_trace (u.markBase.dispatch (c));
+    case MarkLig:		return_trace (u.markLig.dispatch (c));
+    case MarkMark:		return_trace (u.markMark.dispatch (c));
+    case Context:		return_trace (u.context.dispatch (c));
+    case ChainContext:		return_trace (u.chainContext.dispatch (c));
+    case Extension:		return_trace (u.extension.dispatch (c));
+    default:			return_trace (c->default_return_value ());
+    }
+  }
+
+  protected:
+  union {
+  USHORT		sub_format;
+  SinglePos		single;
+  PairPos		pair;
+  CursivePos		cursive;
+  MarkBasePos		markBase;
+  MarkLigPos		markLig;
+  MarkMarkPos		markMark;
+  ContextPos		context;
+  ChainContextPos	chainContext;
+  ExtensionPos		extension;
+  } u;
+  public:
+  DEFINE_SIZE_UNION (2, sub_format);
+};
+
+
+struct PosLookup : Lookup
+{
+  inline const PosLookupSubTable& get_subtable (unsigned int i) const
+  { return Lookup::get_subtable<PosLookupSubTable> (i); }
+
+  inline bool is_reverse (void) const
+  {
+    return false;
+  }
+
+  inline bool apply (hb_apply_context_t *c) const
+  {
+    TRACE_APPLY (this);
+    return_trace (dispatch (c));
+  }
+
+  inline hb_collect_glyphs_context_t::return_t collect_glyphs (hb_collect_glyphs_context_t *c) const
+  {
+    TRACE_COLLECT_GLYPHS (this);
+    return_trace (dispatch (c));
+  }
+
+  template <typename set_t>
+  inline void add_coverage (set_t *glyphs) const
+  {
+    hb_add_coverage_context_t<set_t> c (glyphs);
+    dispatch (&c);
+  }
+
+  static bool apply_recurse_func (hb_apply_context_t *c, unsigned int lookup_index);
+
+  template <typename context_t>
+  static inline typename context_t::return_t dispatch_recurse_func (context_t *c, unsigned int lookup_index);
+
+  template <typename context_t>
+  inline typename context_t::return_t dispatch (context_t *c) const
+  { return Lookup::dispatch<PosLookupSubTable> (c); }
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    if (unlikely (!Lookup::sanitize (c))) return_trace (false);
+    return_trace (dispatch (c));
+  }
+};
+
+typedef OffsetListOf<PosLookup> PosLookupList;
+
+/*
+ * GPOS -- The Glyph Positioning Table
+ */
+
+struct GPOS : GSUBGPOS
+{
+  static const hb_tag_t tableTag	= HB_OT_TAG_GPOS;
+
+  inline const PosLookup& get_lookup (unsigned int i) const
+  { return CastR<PosLookup> (GSUBGPOS::get_lookup (i)); }
+
+  static inline void position_start (hb_font_t *font, hb_buffer_t *buffer);
+  static inline void position_finish_advances (hb_font_t *font, hb_buffer_t *buffer);
+  static inline void position_finish_offsets (hb_font_t *font, hb_buffer_t *buffer);
+
+  inline bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    if (unlikely (!GSUBGPOS::sanitize (c))) return_trace (false);
+    const OffsetTo<PosLookupList> &list = CastR<OffsetTo<PosLookupList> > (lookupList);
+    return_trace (list.sanitize (c, this));
+  }
+};
+
+
+static void
+reverse_cursive_minor_offset (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction, unsigned int new_parent)
+{
+  int chain = pos[i].attach_chain(), type = pos[i].attach_type();
+  if (likely (!chain || 0 == (type & ATTACH_TYPE_CURSIVE)))
+    return;
+
+  pos[i].attach_chain() = 0;
+
+  unsigned int j = (int) i + chain;
+
+  /* Stop if we see new parent in the chain. */
+  if (j == new_parent)
+    return;
+
+  reverse_cursive_minor_offset (pos, j, direction, new_parent);
+
+  if (HB_DIRECTION_IS_HORIZONTAL (direction))
+    pos[j].y_offset = -pos[i].y_offset;
+  else
+    pos[j].x_offset = -pos[i].x_offset;
+
+  pos[j].attach_chain() = -chain;
+  pos[j].attach_type() = type;
+}
+static void
+propagate_attachment_offsets (hb_glyph_position_t *pos, unsigned int i, hb_direction_t direction)
+{
+  /* Adjusts offsets of attached glyphs (both cursive and mark) to accumulate
+   * offset of glyph they are attached to. */
+  int chain = pos[i].attach_chain(), type = pos[i].attach_type();
+  if (likely (!chain))
+    return;
+
+  unsigned int j = (int) i + chain;
+
+  pos[i].attach_chain() = 0;
+
+  propagate_attachment_offsets (pos, j, direction);
+
+  assert (!!(type & ATTACH_TYPE_MARK) ^ !!(type & ATTACH_TYPE_CURSIVE));
+
+  if (type & ATTACH_TYPE_CURSIVE)
+  {
+    if (HB_DIRECTION_IS_HORIZONTAL (direction))
+      pos[i].y_offset += pos[j].y_offset;
+    else
+      pos[i].x_offset += pos[j].x_offset;
+  }
+  else /*if (type & ATTACH_TYPE_MARK)*/
+  {
+    pos[i].x_offset += pos[j].x_offset;
+    pos[i].y_offset += pos[j].y_offset;
+
+    assert (j < i);
+    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_font_t *font HB_UNUSED, hb_buffer_t *buffer)
+{
+  unsigned int count = buffer->len;
+  for (unsigned int i = 0; i < count; i++)
+    buffer->pos[i].attach_chain() = buffer->pos[i].attach_type() = 0;
+}
+
+void
+GPOS::position_finish_advances (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer)
+{
+  //_hb_buffer_assert_gsubgpos_vars (buffer);
+}
+
+void
+GPOS::position_finish_offsets (hb_font_t *font HB_UNUSED, hb_buffer_t *buffer)
+{
+  _hb_buffer_assert_gsubgpos_vars (buffer);
+
+  unsigned int len;
+  hb_glyph_position_t *pos = hb_buffer_get_glyph_positions (buffer, &len);
+  hb_direction_t direction = buffer->props.direction;
+
+  /* Handle attachments */
+  if (buffer->scratch_flags & HB_BUFFER_SCRATCH_FLAG_HAS_GPOS_ATTACHMENT)
+    for (unsigned int i = 0; i < len; i++)
+      propagate_attachment_offsets (pos, i, direction);
+}
+
+
+/* Out-of-class implementation for methods recursing */
+
+template <typename context_t>
+/*static*/ inline typename context_t::return_t PosLookup::dispatch_recurse_func (context_t *c, unsigned int lookup_index)
+{
+  const GPOS &gpos = *(hb_ot_layout_from_face (c->face)->gpos);
+  const PosLookup &l = gpos.get_lookup (lookup_index);
+  return l.dispatch (c);
+}
+
+/*static*/ inline bool PosLookup::apply_recurse_func (hb_apply_context_t *c, unsigned int lookup_index)
+{
+  const GPOS &gpos = *(hb_ot_layout_from_face (c->face)->gpos);
+  const PosLookup &l = gpos.get_lookup (lookup_index);
+  unsigned int saved_lookup_props = c->lookup_props;
+  unsigned int saved_lookup_index = c->lookup_index;
+  c->set_lookup_index (lookup_index);
+  c->set_lookup_props (l.get_props ());
+  bool ret = l.dispatch (c);
+  c->set_lookup_index (saved_lookup_index);
+  c->set_lookup_props (saved_lookup_props);
+  return ret;
+}
+
+
+#undef attach_chain
+#undef attach_type
+
+
+} /* namespace OT */
+
+
+#endif /* HB_OT_LAYOUT_GPOS_TABLE_HH */