src/hb-ot-kern-table.hh - third_party/harfbuzz - Git at Google

 /*
  * Copyright © 2017  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.
  *
  * Google Author(s): Behdad Esfahbod
  */

 #ifndef HB_OT_KERN_TABLE_HH
 #define HB_OT_KERN_TABLE_HH

 #include "hb-open-type.hh"
 #include "hb-ot-shape.hh"
 #include "hb-ot-layout-gsubgpos.hh"
 #include "hb-aat-layout-common.hh"


 template <typename Driver>
 struct hb_kern_machine_t
 {
   hb_kern_machine_t (const Driver &driver_) : driver (driver_) {}

   HB_NO_SANITIZE_SIGNED_INTEGER_OVERFLOW
   inline void kern (hb_font_t   *font,
 		    hb_buffer_t *buffer,
 		    hb_mask_t    kern_mask,
 		    bool         scale = true) const
   {
     OT::hb_ot_apply_context_t c (1, font, buffer);
     c.set_lookup_mask (kern_mask);
     c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
     OT::hb_ot_apply_context_t::skipping_iterator_t &skippy_iter = c.iter_input;
     skippy_iter.init (&c);

     bool horizontal = HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction);
     unsigned int count = buffer->len;
     hb_glyph_info_t *info = buffer->info;
     hb_glyph_position_t *pos = buffer->pos;
     for (unsigned int idx = 0; idx < count;)
     {
       if (!(info[idx].mask & kern_mask))
       {
 	idx++;
 	continue;
       }

       skippy_iter.reset (idx, 1);
       if (!skippy_iter.next ())
       {
 	idx++;
 	continue;
       }

       unsigned int i = idx;
       unsigned int j = skippy_iter.idx;

       hb_position_t kern = driver.get_kerning (info[i].codepoint,
 					       info[j].codepoint);


       if (likely (!kern))
         goto skip;


       if (horizontal)
       {
         if (scale)
 	  kern = font->em_scale_x (kern);
 	hb_position_t kern1 = kern >> 1;
 	hb_position_t kern2 = kern - kern1;
 	pos[i].x_advance += kern1;
 	pos[j].x_advance += kern2;
 	pos[j].x_offset += kern2;
       }
       else
       {
         if (scale)
 	  kern = font->em_scale_y (kern);
 	hb_position_t kern1 = kern >> 1;
 	hb_position_t kern2 = kern - kern1;
 	pos[i].y_advance += kern1;
 	pos[j].y_advance += kern2;
 	pos[j].y_offset += kern2;
       }

       buffer->unsafe_to_break (i, j + 1);

     skip:
       idx = skippy_iter.idx;
     }
   }

   const Driver &driver;
 };


 /*
  * kern -- Kerning
  * https://docs.microsoft.com/en-us/typography/opentype/spec/kern
  * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6kern.html
  */
 #define HB_OT_TAG_kern HB_TAG('k','e','r','n')


 namespace OT {


 struct hb_glyph_pair_t
 {
   hb_codepoint_t left;
   hb_codepoint_t right;
 };

 struct KernPair
 {
   inline int get_kerning (void) const
   { return value; }

   inline int cmp (const hb_glyph_pair_t &o) const
   {
     int ret = left.cmp (o.left);
     if (ret) return ret;
     return right.cmp (o.right);
   }

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     return_trace (c->check_struct (this));
   }

   protected:
   GlyphID	left;
   GlyphID	right;
   FWORD		value;
   public:
   DEFINE_SIZE_STATIC (6);
 };

 struct KernSubTableFormat0
 {
   inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
   {
     hb_glyph_pair_t pair = {left, right};
     int i = pairs.bsearch (pair);
     if (i == -1)
       return 0;
     return pairs[i].get_kerning ();
   }

   inline bool apply (AAT::hb_aat_apply_context_t *c) const
   {
     TRACE_APPLY (this);

     if (!c->plan->requested_kerning)
       return false;

     hb_kern_machine_t<KernSubTableFormat0> machine (*this);
     machine.kern (c->font, c->buffer, c->plan->kern_mask);

     return_trace (true);
   }

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     return_trace (pairs.sanitize (c));
   }

   protected:
   BinSearchArrayOf<KernPair> pairs;	/* Array of kerning pairs. */
   public:
   DEFINE_SIZE_ARRAY (8, pairs);
 };

 struct KernSubTableFormat1
 {
   typedef void EntryData;

   struct driver_context_t
   {
     static const bool in_place = true;
     enum Flags
     {
       Push		= 0x8000,	/* If set, push this glyph on the kerning stack. */
       DontAdvance	= 0x4000,	/* If set, don't advance to the next glyph
 					 * before going to the new state. */
       Offset		= 0x3FFF,	/* Byte offset from beginning of subtable to the
 					 * value table for the glyphs on the kerning stack. */
     };

     inline driver_context_t (const KernSubTableFormat1 *table_,
 			     AAT::hb_aat_apply_context_t *c_) :
 	c (c_),
 	table (table_),
 	/* Apparently the offset kernAction is from the beginning of the state-machine,
 	 * similar to offsets in morx table, NOT from beginning of this table, like
 	 * other subtables in kerx.  Discovered via testing. */
 	kernAction (&table->machine + table->kernAction),
 	depth (0) {}

     inline bool is_actionable (AAT::StateTableDriver<AAT::MortTypes, EntryData> *driver HB_UNUSED,
 			       const AAT::Entry<EntryData> *entry)
     {
       return entry->flags & Offset;
     }
     inline bool transition (AAT::StateTableDriver<AAT::MortTypes, EntryData> *driver,
 			    const AAT::Entry<EntryData> *entry)
     {
       hb_buffer_t *buffer = driver->buffer;
       unsigned int flags = entry->flags;

       if (flags & Push)
       {
 	if (likely (depth < ARRAY_LENGTH (stack)))
 	  stack[depth++] = buffer->idx;
 	else
 	  depth = 0; /* Probably not what CoreText does, but better? */
       }

       if (entry->flags & Offset)
       {
 	unsigned int kernIndex = AAT::MortTypes::offsetToIndex (entry->flags & Offset, &table->machine, kernAction.arrayZ);
 	const FWORD *actions = &kernAction[kernIndex];
 	if (!c->sanitizer.check_array (actions, depth))
 	{
 	  depth = 0;
 	  return false;
 	}

 	hb_mask_t kern_mask = c->plan->kern_mask;
 	for (unsigned int i = 0; i < depth; i++)
 	{
 	  /* Apparently, when spec says "Each pops one glyph from the kerning stack
 	   * and applies the kerning value to it.", it doesn't mean it in that order.
 	   * The deepest item in the stack corresponds to the first item in the action
 	   * list.  Discovered by testing. */
 	  unsigned int idx = stack[i];
 	  int v = *actions++;
 	  if (idx < buffer->len && buffer->info[idx].mask & kern_mask)
 	  {
 	    if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
 	    {
 	      buffer->pos[idx].x_advance += c->font->em_scale_x (v);
 	      if (HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
 		buffer->pos[idx].x_offset += c->font->em_scale_x (v);
 	    }
 	    else
 	    {
 	      buffer->pos[idx].y_advance += c->font->em_scale_y (v);
 	      if (HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
 		buffer->pos[idx].y_offset += c->font->em_scale_y (v);
 	    }
 	  }
 	}
 	depth = 0;
       }

       return true;
     }

     private:
     AAT::hb_aat_apply_context_t *c;
     const KernSubTableFormat1 *table;
     const UnsizedArrayOf<FWORD> &kernAction;
     unsigned int stack[8];
     unsigned int depth;
   };

   inline bool apply (AAT::hb_aat_apply_context_t *c) const
   {
     TRACE_APPLY (this);

     if (!c->plan->requested_kerning)
       return false;

     driver_context_t dc (this, c);

     AAT::StateTableDriver<AAT::MortTypes, EntryData> driver (machine, c->buffer, c->font->face);
     driver.drive (&dc);

     return_trace (true);
   }

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     /* The rest of array sanitizations are done at run-time. */
     return_trace (likely (c->check_struct (this) &&
 			  machine.sanitize (c)));
   }

   protected:
   AAT::StateTable<AAT::MortTypes, EntryData>		machine;
   OffsetTo<UnsizedArrayOf<FWORD>, HBUINT16, false>	kernAction;
   public:
   DEFINE_SIZE_STATIC (10);
 };

 struct KernClassTable
 {
   inline unsigned int get_class (hb_codepoint_t g) const { return classes[g - firstGlyph]; }

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     return_trace (c->check_struct (this) &&
 		  classes.sanitize (c));
   }

   protected:
   HBUINT16		firstGlyph;	/* First glyph in class range. */
   ArrayOf<HBUINT16>	classes;	/* Glyph classes. */
   public:
   DEFINE_SIZE_ARRAY (4, classes);
 };

 struct KernSubTableFormat2
 {
   inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right,
 			  AAT::hb_aat_apply_context_t *c) const
   {
     /* This subtable is disabled.  It's not cleaer to me *exactly* where the offests are
      * based from.  I *think* they should be based from beginning of kern subtable wrapper,
      * *NOT* "this".  Since we know of no fonts that use this subtable, we are disabling
      * it.  Someday fix it and re-enable. */
     return 0;
     unsigned int l = (this+leftClassTable).get_class (left);
     unsigned int r = (this+rightClassTable).get_class (right);
     unsigned int offset = l + r;
     const FWORD *v = &StructAtOffset<FWORD> (&(this+array), offset);
 #if 0
     if (unlikely ((const char *) v < (const char *) &array ||
 		  (const char *) v > (const char *) end - 2))
 #endif
       return 0;
     return *v;
   }

   inline bool apply (AAT::hb_aat_apply_context_t *c) const
   {
     TRACE_APPLY (this);

     if (!c->plan->requested_kerning)
       return false;

     accelerator_t accel (*this, c);
     hb_kern_machine_t<accelerator_t> machine (accel);
     machine.kern (c->font, c->buffer, c->plan->kern_mask);

     return_trace (true);
   }

   struct accelerator_t
   {
     const KernSubTableFormat2 &table;
     AAT::hb_aat_apply_context_t *c;

     inline accelerator_t (const KernSubTableFormat2 &table_,
 			  AAT::hb_aat_apply_context_t *c_) :
 			    table (table_), c (c_) {}

     inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
     { return table.get_kerning (left, right, c); }
   };

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     return_trace (true); /* Disabled.  See above. */
     return_trace (c->check_struct (this) &&
 		  leftClassTable.sanitize (c, this) &&
 		  rightClassTable.sanitize (c, this) &&
 		  array.sanitize (c, this));
   }

   protected:
   HBUINT16	rowWidth;	/* The width, in bytes, of a row in the table. */
   OffsetTo<KernClassTable>
 		leftClassTable;	/* Offset from beginning of this subtable to
 				 * left-hand class table. */
   OffsetTo<KernClassTable>
 		rightClassTable;/* Offset from beginning of this subtable to
 				 * right-hand class table. */
   OffsetTo<FWORD>
 		array;		/* Offset from beginning of this subtable to
 				 * the start of the kerning array. */
   public:
   DEFINE_SIZE_MIN (8);
 };

 struct KernSubTableFormat3
 {
   inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
   {
     hb_array_t<const FWORD> kernValue = kernValueZ.as_array (kernValueCount);
     hb_array_t<const HBUINT8> leftClass = StructAfter<const UnsizedArrayOf<HBUINT8> > (kernValue).as_array (glyphCount);
     hb_array_t<const HBUINT8> rightClass = StructAfter<const UnsizedArrayOf<HBUINT8> > (leftClass).as_array (glyphCount);
     hb_array_t<const HBUINT8> kernIndex = StructAfter<const UnsizedArrayOf<HBUINT8> > (rightClass).as_array (leftClassCount * rightClassCount);

     unsigned int leftC = leftClass[left];
     unsigned int rightC = rightClass[right];
     if (unlikely (leftC >= leftClassCount || rightC >= rightClassCount))
       return 0;
     unsigned int i = leftC * rightClassCount + rightC;
     return kernValue[kernIndex[i]];
   }

   inline bool apply (AAT::hb_aat_apply_context_t *c) const
   {
     TRACE_APPLY (this);

     if (!c->plan->requested_kerning)
       return false;

     hb_kern_machine_t<KernSubTableFormat3> machine (*this);
     machine.kern (c->font, c->buffer, c->plan->kern_mask);

     return_trace (true);
   }

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     return_trace (c->check_struct (this) &&
 		  c->check_range (kernValueZ,
 				  kernValueCount * sizeof (FWORD) +
 				  glyphCount * 2 +
 				  leftClassCount * rightClassCount));
   }

   protected:
   HBUINT16	glyphCount;	/* The number of glyphs in this font. */
   HBUINT8	kernValueCount;	/* The number of kerning values. */
   HBUINT8	leftClassCount;	/* The number of left-hand classes. */
   HBUINT8	rightClassCount;/* The number of right-hand classes. */
   HBUINT8	flags;		/* Set to zero (reserved for future use). */
   UnsizedArrayOf<FWORD>
 		kernValueZ;	/* The kerning values.
 				 * Length kernValueCount. */
 #if 0
   UnsizedArrayOf<HBUINT8>
 		leftClass;	/* The left-hand classes.
 				 * Length glyphCount. */
   UnsizedArrayOf<HBUINT8>
 		RightClass;	/* The right-hand classes.
 				 * Length glyphCount. */
   UnsizedArrayOf<HBUINT8>
 		kernIndex;	/* The indices into the kernValue array.
 				 * Length leftClassCount * rightClassCount */
 #endif
   public:
   DEFINE_SIZE_ARRAY (6, kernValueZ);
 };

 struct KernSubTable
 {
   inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right, unsigned int format) const
   {
     switch (format) {
     /* This method hooks up to hb_font_t's get_h_kerning.  Only support Format0. */
     case 0: return u.format0.get_kerning (left, right);
     default:return 0;
     }
   }

   inline void apply (AAT::hb_aat_apply_context_t *c, unsigned int format) const
   {
     /* TODO Switch to dispatch(). */
     switch (format) {
     case 0: u.format0.apply (c); return;
     case 1: u.format1.apply (c); return;
     case 2: u.format2.apply (c); return;
     case 3: u.format3.apply (c); return;
     default:			 return;
     }
   }

   inline bool sanitize (hb_sanitize_context_t *c, unsigned int format) const
   {
     TRACE_SANITIZE (this);
     switch (format) {
     case 0: return_trace (u.format0.sanitize (c));
     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 {
   KernSubTableFormat0	format0;
   KernSubTableFormat1	format1;
   KernSubTableFormat2	format2;
   KernSubTableFormat3	format3;
   } u;
   public:
   DEFINE_SIZE_MIN (0);
 };


 template <typename T>
 struct KernSubTableWrapper
 {
   /* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
   inline const T* thiz (void) const { return static_cast<const T *> (this); }

   inline bool is_supported (void) const
   { return !(thiz()->coverage & T::CheckFlags); }

   inline bool is_horizontal (void) const
   { return (thiz()->coverage & T::Direction) == T::CheckHorizontal; }

   inline bool is_override (void) const
   { return bool (thiz()->coverage & T::Override); }

   inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
   { return thiz()->subtable.get_kerning (left, right, thiz()->format); }

   inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const
   { return is_supported () && is_horizontal () ? get_kerning (left, right) : 0; }

   inline void apply (AAT::hb_aat_apply_context_t *c) const
   { thiz()->subtable.apply (c, thiz()->format); }

   inline unsigned int get_size (void) const { return thiz()->length; }

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     return_trace (c->check_struct (thiz()) &&
 		  thiz()->length >= T::min_size &&
 		  c->check_range (thiz(), thiz()->length) &&
 		  thiz()->subtable.sanitize (c, thiz()->format));
   }
 };

 template <typename T>
 struct KernTable
 {
   /* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
   inline const T* thiz (void) const { return static_cast<const T *> (this); }

   inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const
   {
     int v = 0;
     const typename T::SubTableWrapper *st = CastP<typename T::SubTableWrapper> (&thiz()->dataZ);
     unsigned int count = thiz()->nTables;
     for (unsigned int i = 0; i < count; i++)
     {
       if (st->is_supported () && st->is_override ())
         v = 0;
       v += st->get_h_kerning (left, right);
       st = &StructAfter<typename T::SubTableWrapper> (*st);
     }
     return v;
   }

   inline void apply (AAT::hb_aat_apply_context_t *c) const
   {
     c->set_lookup_index (0);
     const typename T::SubTableWrapper *st = CastP<typename T::SubTableWrapper> (&thiz()->dataZ);
     unsigned int count = thiz()->nTables;
     /* If there's an override subtable, skip subtables before that. */
     unsigned int last_override = 0;
     for (unsigned int i = 0; i < count; i++)
     {
       if (st->is_supported () && st->is_override ())
         last_override = i;
       st = &StructAfter<typename T::SubTableWrapper> (*st);
     }
     st = CastP<typename T::SubTableWrapper> (&thiz()->dataZ);
     for (unsigned int i = 0; i < count; i++)
     {
       if (!st->is_supported ())
         goto skip;

       if (HB_DIRECTION_IS_HORIZONTAL (c->buffer->props.direction) != st->is_horizontal ())
 	goto skip;

       if (i < last_override)
 	goto skip;

       if (!c->buffer->message (c->font, "start kern subtable %d", c->lookup_index))
 	goto skip;

       c->sanitizer.set_object (*st);

       st->apply (c);

       (void) c->buffer->message (c->font, "end kern subtable %d", c->lookup_index);

     skip:
       st = &StructAfter<typename T::SubTableWrapper> (*st);
     }
   }

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     if (unlikely (!c->check_struct (thiz()) ||
 		  thiz()->version != T::VERSION))
       return_trace (false);

     const typename T::SubTableWrapper *st = CastP<typename T::SubTableWrapper> (&thiz()->dataZ);
     unsigned int count = thiz()->nTables;
     for (unsigned int i = 0; i < count; i++)
     {
       if (unlikely (!st->sanitize (c)))
 	return_trace (false);
       st = &StructAfter<typename T::SubTableWrapper> (*st);
     }

     return_trace (true);
   }
 };

 struct KernOT : KernTable<KernOT>
 {
   friend struct KernTable<KernOT>;

   static const uint16_t VERSION = 0x0000u;

   struct SubTableWrapper : KernSubTableWrapper<SubTableWrapper>
   {
     friend struct KernTable<KernOT>;
     friend struct KernSubTableWrapper<SubTableWrapper>;

     enum Coverage
     {
       Direction		= 0x01u,
       Minimum		= 0x02u,
       CrossStream	= 0x04u,
       Override		= 0x08u,

       Variation		= 0x00u, /* Not supported. */

       CheckFlags	= 0x06u,
       CheckHorizontal	= 0x01u
     };

     protected:
     HBUINT16	versionZ;	/* Unused. */
     HBUINT16	length;		/* Length of the subtable (including this header). */
     HBUINT8	format;		/* Subtable format. */
     HBUINT8	coverage;	/* Coverage bits. */
     KernSubTable subtable;	/* Subtable data. */
     public:
     DEFINE_SIZE_MIN (6);
   };

   protected:
   HBUINT16			version;	/* Version--0x0000u */
   HBUINT16			nTables;	/* Number of subtables in the kerning table. */
   UnsizedArrayOf<HBUINT8>	dataZ;
   public:
   DEFINE_SIZE_ARRAY (4, dataZ);
 };

 struct KernAAT : KernTable<KernAAT>
 {
   friend struct KernTable<KernAAT>;

   static const uint32_t VERSION = 0x00010000u;

   struct SubTableWrapper : KernSubTableWrapper<SubTableWrapper>
   {
     friend struct KernTable<KernAAT>;
     friend struct KernSubTableWrapper<SubTableWrapper>;

     enum Coverage
     {
       Direction		= 0x80u,
       CrossStream	= 0x40u,
       Variation		= 0x20u,

       Override		= 0x00u, /* Not supported. */

       CheckFlags	= 0x60u,
       CheckHorizontal	= 0x00u
     };

     protected:
     HBUINT32	length;		/* Length of the subtable (including this header). */
     HBUINT8	coverage;	/* Coverage bits. */
     HBUINT8	format;		/* Subtable format. */
     HBUINT16	tupleIndex;	/* The tuple index (used for variations fonts).
 				 * This value specifies which tuple this subtable covers. */
     KernSubTable subtable;	/* Subtable data. */
     public:
     DEFINE_SIZE_MIN (8);
   };

   protected:
   HBUINT32			version;	/* Version--0x00010000u */
   HBUINT32			nTables;	/* Number of subtables in the kerning table. */
   UnsizedArrayOf<HBUINT8>	dataZ;
   public:
   DEFINE_SIZE_ARRAY (8, dataZ);
 };

 struct kern
 {
   static const hb_tag_t tableTag = HB_OT_TAG_kern;

   inline bool has_data (void) const
   { return u.version32 != 0; }

   inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const
   {
     switch (u.major) {
     case 0: return u.ot.get_h_kerning (left, right);
     case 1: return u.aat.get_h_kerning (left, right);
     default:return 0;
     }
   }

   inline void apply (AAT::hb_aat_apply_context_t *c) const
   {
     /* TODO Switch to dispatch(). */
     switch (u.major) {
     case 0: u.ot.apply (c);  return;
     case 1: u.aat.apply (c); return;
     default:		     return;
     }
   }

   inline bool sanitize (hb_sanitize_context_t *c) const
   {
     TRACE_SANITIZE (this);
     if (!u.version32.sanitize (c)) return_trace (false);
     switch (u.major) {
     case 0: return_trace (u.ot.sanitize (c));
     case 1: return_trace (u.aat.sanitize (c));
     default:return_trace (true);
     }
   }

   protected:
   union {
   HBUINT32		version32;
   HBUINT16		major;
   KernOT		ot;
   KernAAT		aat;
   } u;
   public:
   DEFINE_SIZE_UNION (4, version32);
 };

 } /* namespace OT */


 #endif /* HB_OT_KERN_TABLE_HH */
	/*
	* Copyright © 2017 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.
	*
	* Google Author(s): Behdad Esfahbod
	*/

	#ifndef HB_OT_KERN_TABLE_HH
	#define HB_OT_KERN_TABLE_HH

	#include "hb-open-type.hh"
	#include "hb-ot-shape.hh"
	#include "hb-ot-layout-gsubgpos.hh"
	#include "hb-aat-layout-common.hh"


	template <typename Driver>
	struct hb_kern_machine_t
	{
	hb_kern_machine_t (const Driver &driver_) : driver (driver_) {}

	HB_NO_SANITIZE_SIGNED_INTEGER_OVERFLOW
	inline void kern (hb_font_t *font,
	hb_buffer_t *buffer,
	hb_mask_t kern_mask,
	bool scale = true) const
	{
	OT::hb_ot_apply_context_t c (1, font, buffer);
	c.set_lookup_mask (kern_mask);
	c.set_lookup_props (OT::LookupFlag::IgnoreMarks);
	OT::hb_ot_apply_context_t::skipping_iterator_t &skippy_iter = c.iter_input;
	skippy_iter.init (&c);

	bool horizontal = HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction);
	unsigned int count = buffer->len;
	hb_glyph_info_t *info = buffer->info;
	hb_glyph_position_t *pos = buffer->pos;
	for (unsigned int idx = 0; idx < count;)
	{
	if (!(info[idx].mask & kern_mask))
	{
	idx++;
	continue;
	}

	skippy_iter.reset (idx, 1);
	if (!skippy_iter.next ())
	{
	idx++;
	continue;
	}

	unsigned int i = idx;
	unsigned int j = skippy_iter.idx;

	hb_position_t kern = driver.get_kerning (info[i].codepoint,
	info[j].codepoint);


	if (likely (!kern))
	goto skip;


	if (horizontal)
	{
	if (scale)
	kern = font->em_scale_x (kern);
	hb_position_t kern1 = kern >> 1;
	hb_position_t kern2 = kern - kern1;
	pos[i].x_advance += kern1;
	pos[j].x_advance += kern2;
	pos[j].x_offset += kern2;
	}
	else
	{
	if (scale)
	kern = font->em_scale_y (kern);
	hb_position_t kern1 = kern >> 1;
	hb_position_t kern2 = kern - kern1;
	pos[i].y_advance += kern1;
	pos[j].y_advance += kern2;
	pos[j].y_offset += kern2;
	}

	buffer->unsafe_to_break (i, j + 1);

	skip:
	idx = skippy_iter.idx;
	}
	}

	const Driver &driver;
	};


	/*
	* kern -- Kerning
	* https://docs.microsoft.com/en-us/typography/opentype/spec/kern
	* https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6kern.html
	*/
	#define HB_OT_TAG_kern HB_TAG('k','e','r','n')


	namespace OT {


	struct hb_glyph_pair_t
	{
	hb_codepoint_t left;
	hb_codepoint_t right;
	};

	struct KernPair
	{
	inline int get_kerning (void) const
	{ return value; }

	inline int cmp (const hb_glyph_pair_t &o) const
	{
	int ret = left.cmp (o.left);
	if (ret) return ret;
	return right.cmp (o.right);
	}

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	return_trace (c->check_struct (this));
	}

	protected:
	GlyphID left;
	GlyphID right;
	FWORD value;
	public:
	DEFINE_SIZE_STATIC (6);
	};

	struct KernSubTableFormat0
	{
	inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
	{
	hb_glyph_pair_t pair = {left, right};
	int i = pairs.bsearch (pair);
	if (i == -1)
	return 0;
	return pairs[i].get_kerning ();
	}

	inline bool apply (AAT::hb_aat_apply_context_t *c) const
	{
	TRACE_APPLY (this);

	if (!c->plan->requested_kerning)
	return false;

	hb_kern_machine_t<KernSubTableFormat0> machine (*this);
	machine.kern (c->font, c->buffer, c->plan->kern_mask);

	return_trace (true);
	}

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	return_trace (pairs.sanitize (c));
	}

	protected:
	BinSearchArrayOf<KernPair> pairs; /* Array of kerning pairs. */
	public:
	DEFINE_SIZE_ARRAY (8, pairs);
	};

	struct KernSubTableFormat1
	{
	typedef void EntryData;

	struct driver_context_t
	{
	static const bool in_place = true;
	enum Flags
	{
	Push = 0x8000, /* If set, push this glyph on the kerning stack. */
	DontAdvance = 0x4000, /* If set, don't advance to the next glyph
	* before going to the new state. */
	Offset = 0x3FFF, /* Byte offset from beginning of subtable to the
	* value table for the glyphs on the kerning stack. */
	};

	inline driver_context_t (const KernSubTableFormat1 *table_,
	AAT::hb_aat_apply_context_t *c_) :
	c (c_),
	table (table_),
	/* Apparently the offset kernAction is from the beginning of the state-machine,
	* similar to offsets in morx table, NOT from beginning of this table, like
	* other subtables in kerx. Discovered via testing. */
	kernAction (&table->machine + table->kernAction),
	depth (0) {}

	inline bool is_actionable (AAT::StateTableDriver<AAT::MortTypes, EntryData> *driver HB_UNUSED,
	const AAT::Entry<EntryData> *entry)
	{
	return entry->flags & Offset;
	}
	inline bool transition (AAT::StateTableDriver<AAT::MortTypes, EntryData> *driver,
	const AAT::Entry<EntryData> *entry)
	{
	hb_buffer_t *buffer = driver->buffer;
	unsigned int flags = entry->flags;

	if (flags & Push)
	{
	if (likely (depth < ARRAY_LENGTH (stack)))
	stack[depth++] = buffer->idx;
	else
	depth = 0; /* Probably not what CoreText does, but better? */
	}

	if (entry->flags & Offset)
	{
	unsigned int kernIndex = AAT::MortTypes::offsetToIndex (entry->flags & Offset, &table->machine, kernAction.arrayZ);
	const FWORD *actions = &kernAction[kernIndex];
	if (!c->sanitizer.check_array (actions, depth))
	{
	depth = 0;
	return false;
	}

	hb_mask_t kern_mask = c->plan->kern_mask;
	for (unsigned int i = 0; i < depth; i++)
	{
	/* Apparently, when spec says "Each pops one glyph from the kerning stack
	* and applies the kerning value to it.", it doesn't mean it in that order.
	* The deepest item in the stack corresponds to the first item in the action
	* list. Discovered by testing. */
	unsigned int idx = stack[i];
	int v = *actions++;
	if (idx < buffer->len && buffer->info[idx].mask & kern_mask)
	{
	if (HB_DIRECTION_IS_HORIZONTAL (buffer->props.direction))
	{
	buffer->pos[idx].x_advance += c->font->em_scale_x (v);
	if (HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
	buffer->pos[idx].x_offset += c->font->em_scale_x (v);
	}
	else
	{
	buffer->pos[idx].y_advance += c->font->em_scale_y (v);
	if (HB_DIRECTION_IS_BACKWARD (buffer->props.direction))
	buffer->pos[idx].y_offset += c->font->em_scale_y (v);
	}
	}
	}
	depth = 0;
	}

	return true;
	}

	private:
	AAT::hb_aat_apply_context_t *c;
	const KernSubTableFormat1 *table;
	const UnsizedArrayOf<FWORD> &kernAction;
	unsigned int stack[8];
	unsigned int depth;
	};

	inline bool apply (AAT::hb_aat_apply_context_t *c) const
	{
	TRACE_APPLY (this);

	if (!c->plan->requested_kerning)
	return false;

	driver_context_t dc (this, c);

	AAT::StateTableDriver<AAT::MortTypes, EntryData> driver (machine, c->buffer, c->font->face);
	driver.drive (&dc);

	return_trace (true);
	}

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	/* The rest of array sanitizations are done at run-time. */
	return_trace (likely (c->check_struct (this) &&
	machine.sanitize (c)));
	}

	protected:
	AAT::StateTable<AAT::MortTypes, EntryData> machine;
	OffsetTo<UnsizedArrayOf<FWORD>, HBUINT16, false> kernAction;
	public:
	DEFINE_SIZE_STATIC (10);
	};

	struct KernClassTable
	{
	inline unsigned int get_class (hb_codepoint_t g) const { return classes[g - firstGlyph]; }

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	return_trace (c->check_struct (this) &&
	classes.sanitize (c));
	}

	protected:
	HBUINT16 firstGlyph; /* First glyph in class range. */
	ArrayOf<HBUINT16> classes; /* Glyph classes. */
	public:
	DEFINE_SIZE_ARRAY (4, classes);
	};

	struct KernSubTableFormat2
	{
	inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right,
	AAT::hb_aat_apply_context_t *c) const
	{
	/* This subtable is disabled. It's not cleaer to me exactly where the offests are
	* based from. I think they should be based from beginning of kern subtable wrapper,
	* NOT "this". Since we know of no fonts that use this subtable, we are disabling
	* it. Someday fix it and re-enable. */
	return 0;
	unsigned int l = (this+leftClassTable).get_class (left);
	unsigned int r = (this+rightClassTable).get_class (right);
	unsigned int offset = l + r;
	const FWORD *v = &StructAtOffset<FWORD> (&(this+array), offset);
	#if 0
	if (unlikely ((const char ) v < (const char ) &array \|\|
	(const char ) v > (const char ) end - 2))
	#endif
	return 0;
	return *v;
	}

	inline bool apply (AAT::hb_aat_apply_context_t *c) const
	{
	TRACE_APPLY (this);

	if (!c->plan->requested_kerning)
	return false;

	accelerator_t accel (*this, c);
	hb_kern_machine_t<accelerator_t> machine (accel);
	machine.kern (c->font, c->buffer, c->plan->kern_mask);

	return_trace (true);
	}

	struct accelerator_t
	{
	const KernSubTableFormat2 &table;
	AAT::hb_aat_apply_context_t *c;

	inline accelerator_t (const KernSubTableFormat2 &table_,
	AAT::hb_aat_apply_context_t *c_) :
	table (table_), c (c_) {}

	inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
	{ return table.get_kerning (left, right, c); }
	};

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	return_trace (true); /* Disabled. See above. */
	return_trace (c->check_struct (this) &&
	leftClassTable.sanitize (c, this) &&
	rightClassTable.sanitize (c, this) &&
	array.sanitize (c, this));
	}

	protected:
	HBUINT16 rowWidth; /* The width, in bytes, of a row in the table. */
	OffsetTo<KernClassTable>
	leftClassTable; /* Offset from beginning of this subtable to
	* left-hand class table. */
	OffsetTo<KernClassTable>
	rightClassTable;/* Offset from beginning of this subtable to
	* right-hand class table. */
	OffsetTo<FWORD>
	array; /* Offset from beginning of this subtable to
	* the start of the kerning array. */
	public:
	DEFINE_SIZE_MIN (8);
	};

	struct KernSubTableFormat3
	{
	inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
	{
	hb_array_t<const FWORD> kernValue = kernValueZ.as_array (kernValueCount);
	hb_array_t<const HBUINT8> leftClass = StructAfter<const UnsizedArrayOf<HBUINT8> > (kernValue).as_array (glyphCount);
	hb_array_t<const HBUINT8> rightClass = StructAfter<const UnsizedArrayOf<HBUINT8> > (leftClass).as_array (glyphCount);
	hb_array_t<const HBUINT8> kernIndex = StructAfter<const UnsizedArrayOf<HBUINT8> > (rightClass).as_array (leftClassCount * rightClassCount);

	unsigned int leftC = leftClass[left];
	unsigned int rightC = rightClass[right];
	if (unlikely (leftC >= leftClassCount \|\| rightC >= rightClassCount))
	return 0;
	unsigned int i = leftC * rightClassCount + rightC;
	return kernValue[kernIndex[i]];
	}

	inline bool apply (AAT::hb_aat_apply_context_t *c) const
	{
	TRACE_APPLY (this);

	if (!c->plan->requested_kerning)
	return false;

	hb_kern_machine_t<KernSubTableFormat3> machine (*this);
	machine.kern (c->font, c->buffer, c->plan->kern_mask);

	return_trace (true);
	}

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	return_trace (c->check_struct (this) &&
	c->check_range (kernValueZ,
	kernValueCount * sizeof (FWORD) +
	glyphCount * 2 +
	leftClassCount * rightClassCount));
	}

	protected:
	HBUINT16 glyphCount; /* The number of glyphs in this font. */
	HBUINT8 kernValueCount; /* The number of kerning values. */
	HBUINT8 leftClassCount; /* The number of left-hand classes. */
	HBUINT8 rightClassCount;/* The number of right-hand classes. */
	HBUINT8 flags; /* Set to zero (reserved for future use). */
	UnsizedArrayOf<FWORD>
	kernValueZ; /* The kerning values.
	* Length kernValueCount. */
	#if 0
	UnsizedArrayOf<HBUINT8>
	leftClass; /* The left-hand classes.
	* Length glyphCount. */
	UnsizedArrayOf<HBUINT8>
	RightClass; /* The right-hand classes.
	* Length glyphCount. */
	UnsizedArrayOf<HBUINT8>
	kernIndex; /* The indices into the kernValue array.
	* Length leftClassCount * rightClassCount */
	#endif
	public:
	DEFINE_SIZE_ARRAY (6, kernValueZ);
	};

	struct KernSubTable
	{
	inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right, unsigned int format) const
	{
	switch (format) {
	/* This method hooks up to hb_font_t's get_h_kerning. Only support Format0. */
	case 0: return u.format0.get_kerning (left, right);
	default:return 0;
	}
	}

	inline void apply (AAT::hb_aat_apply_context_t *c, unsigned int format) const
	{
	/* TODO Switch to dispatch(). */
	switch (format) {
	case 0: u.format0.apply (c); return;
	case 1: u.format1.apply (c); return;
	case 2: u.format2.apply (c); return;
	case 3: u.format3.apply (c); return;
	default: return;
	}
	}

	inline bool sanitize (hb_sanitize_context_t *c, unsigned int format) const
	{
	TRACE_SANITIZE (this);
	switch (format) {
	case 0: return_trace (u.format0.sanitize (c));
	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 {
	KernSubTableFormat0 format0;
	KernSubTableFormat1 format1;
	KernSubTableFormat2 format2;
	KernSubTableFormat3 format3;
	} u;
	public:
	DEFINE_SIZE_MIN (0);
	};


	template <typename T>
	struct KernSubTableWrapper
	{
	/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
	inline const T* thiz (void) const { return static_cast<const T *> (this); }

	inline bool is_supported (void) const
	{ return !(thiz()->coverage & T::CheckFlags); }

	inline bool is_horizontal (void) const
	{ return (thiz()->coverage & T::Direction) == T::CheckHorizontal; }

	inline bool is_override (void) const
	{ return bool (thiz()->coverage & T::Override); }

	inline int get_kerning (hb_codepoint_t left, hb_codepoint_t right) const
	{ return thiz()->subtable.get_kerning (left, right, thiz()->format); }

	inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const
	{ return is_supported () && is_horizontal () ? get_kerning (left, right) : 0; }

	inline void apply (AAT::hb_aat_apply_context_t *c) const
	{ thiz()->subtable.apply (c, thiz()->format); }

	inline unsigned int get_size (void) const { return thiz()->length; }

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	return_trace (c->check_struct (thiz()) &&
	thiz()->length >= T::min_size &&
	c->check_range (thiz(), thiz()->length) &&
	thiz()->subtable.sanitize (c, thiz()->format));
	}
	};

	template <typename T>
	struct KernTable
	{
	/* https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern */
	inline const T* thiz (void) const { return static_cast<const T *> (this); }

	inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const
	{
	int v = 0;
	const typename T::SubTableWrapper *st = CastP<typename T::SubTableWrapper> (&thiz()->dataZ);
	unsigned int count = thiz()->nTables;
	for (unsigned int i = 0; i < count; i++)
	{
	if (st->is_supported () && st->is_override ())
	v = 0;
	v += st->get_h_kerning (left, right);
	st = &StructAfter<typename T::SubTableWrapper> (*st);
	}
	return v;
	}

	inline void apply (AAT::hb_aat_apply_context_t *c) const
	{
	c->set_lookup_index (0);
	const typename T::SubTableWrapper *st = CastP<typename T::SubTableWrapper> (&thiz()->dataZ);
	unsigned int count = thiz()->nTables;
	/* If there's an override subtable, skip subtables before that. */
	unsigned int last_override = 0;
	for (unsigned int i = 0; i < count; i++)
	{
	if (st->is_supported () && st->is_override ())
	last_override = i;
	st = &StructAfter<typename T::SubTableWrapper> (*st);
	}
	st = CastP<typename T::SubTableWrapper> (&thiz()->dataZ);
	for (unsigned int i = 0; i < count; i++)
	{
	if (!st->is_supported ())
	goto skip;

	if (HB_DIRECTION_IS_HORIZONTAL (c->buffer->props.direction) != st->is_horizontal ())
	goto skip;

	if (i < last_override)
	goto skip;

	if (!c->buffer->message (c->font, "start kern subtable %d", c->lookup_index))
	goto skip;

	c->sanitizer.set_object (*st);

	st->apply (c);

	(void) c->buffer->message (c->font, "end kern subtable %d", c->lookup_index);

	skip:
	st = &StructAfter<typename T::SubTableWrapper> (*st);
	}
	}

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	if (unlikely (!c->check_struct (thiz()) \|\|
	thiz()->version != T::VERSION))
	return_trace (false);

	const typename T::SubTableWrapper *st = CastP<typename T::SubTableWrapper> (&thiz()->dataZ);
	unsigned int count = thiz()->nTables;
	for (unsigned int i = 0; i < count; i++)
	{
	if (unlikely (!st->sanitize (c)))
	return_trace (false);
	st = &StructAfter<typename T::SubTableWrapper> (*st);
	}

	return_trace (true);
	}
	};

	struct KernOT : KernTable<KernOT>
	{
	friend struct KernTable<KernOT>;

	static const uint16_t VERSION = 0x0000u;

	struct SubTableWrapper : KernSubTableWrapper<SubTableWrapper>
	{
	friend struct KernTable<KernOT>;
	friend struct KernSubTableWrapper<SubTableWrapper>;

	enum Coverage
	{
	Direction = 0x01u,
	Minimum = 0x02u,
	CrossStream = 0x04u,
	Override = 0x08u,

	Variation = 0x00u, /* Not supported. */

	CheckFlags = 0x06u,
	CheckHorizontal = 0x01u
	};

	protected:
	HBUINT16 versionZ; /* Unused. */
	HBUINT16 length; /* Length of the subtable (including this header). */
	HBUINT8 format; /* Subtable format. */
	HBUINT8 coverage; /* Coverage bits. */
	KernSubTable subtable; /* Subtable data. */
	public:
	DEFINE_SIZE_MIN (6);
	};

	protected:
	HBUINT16 version; /* Version--0x0000u */
	HBUINT16 nTables; /* Number of subtables in the kerning table. */
	UnsizedArrayOf<HBUINT8> dataZ;
	public:
	DEFINE_SIZE_ARRAY (4, dataZ);
	};

	struct KernAAT : KernTable<KernAAT>
	{
	friend struct KernTable<KernAAT>;

	static const uint32_t VERSION = 0x00010000u;

	struct SubTableWrapper : KernSubTableWrapper<SubTableWrapper>
	{
	friend struct KernTable<KernAAT>;
	friend struct KernSubTableWrapper<SubTableWrapper>;

	enum Coverage
	{
	Direction = 0x80u,
	CrossStream = 0x40u,
	Variation = 0x20u,

	Override = 0x00u, /* Not supported. */

	CheckFlags = 0x60u,
	CheckHorizontal = 0x00u
	};

	protected:
	HBUINT32 length; /* Length of the subtable (including this header). */
	HBUINT8 coverage; /* Coverage bits. */
	HBUINT8 format; /* Subtable format. */
	HBUINT16 tupleIndex; /* The tuple index (used for variations fonts).
	* This value specifies which tuple this subtable covers. */
	KernSubTable subtable; /* Subtable data. */
	public:
	DEFINE_SIZE_MIN (8);
	};

	protected:
	HBUINT32 version; /* Version--0x00010000u */
	HBUINT32 nTables; /* Number of subtables in the kerning table. */
	UnsizedArrayOf<HBUINT8> dataZ;
	public:
	DEFINE_SIZE_ARRAY (8, dataZ);
	};

	struct kern
	{
	static const hb_tag_t tableTag = HB_OT_TAG_kern;

	inline bool has_data (void) const
	{ return u.version32 != 0; }

	inline int get_h_kerning (hb_codepoint_t left, hb_codepoint_t right) const
	{
	switch (u.major) {
	case 0: return u.ot.get_h_kerning (left, right);
	case 1: return u.aat.get_h_kerning (left, right);
	default:return 0;
	}
	}

	inline void apply (AAT::hb_aat_apply_context_t *c) const
	{
	/* TODO Switch to dispatch(). */
	switch (u.major) {
	case 0: u.ot.apply (c); return;
	case 1: u.aat.apply (c); return;
	default: return;
	}
	}

	inline bool sanitize (hb_sanitize_context_t *c) const
	{
	TRACE_SANITIZE (this);
	if (!u.version32.sanitize (c)) return_trace (false);
	switch (u.major) {
	case 0: return_trace (u.ot.sanitize (c));
	case 1: return_trace (u.aat.sanitize (c));
	default:return_trace (true);
	}
	}

	protected:
	union {
	HBUINT32 version32;
	HBUINT16 major;
	KernOT ot;
	KernAAT aat;
	} u;
	public:
	DEFINE_SIZE_UNION (4, version32);
	};

	} /* namespace OT */


	#endif /* HB_OT_KERN_TABLE_HH */