text: /*
   * 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_AAT_LAYOUT_MORX_TABLE_HH
  #define HB_AAT_LAYOUT_MORX_TABLE_HH
  
  #include "hb-open-type.hh"
  #include "hb-aat-layout-common.hh"
  #include "hb-ot-layout-common.hh"
  #include "hb-aat-map.hh"
  
  /*
   * morx -- Extended Glyph Metamorphosis
   * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6morx.html
   * https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6mort.html
   */
  #define HB_AAT_TAG_morx HB_TAG('m','o','r','x')
  #define HB_AAT_TAG_mort HB_TAG('m','o','r','t')
  
  
  namespace AAT {
  
  using namespace OT;
  
  template <typename Types>
  struct RearrangementSubtable
  {
    typedef typename Types::HBUINT HBUINT;
  
    typedef void EntryData;
  
    struct driver_context_t
    {
      static constexpr bool in_place = true;
      enum Flags
      {
        MarkFirst		= 0x8000,	/* If set, make the current glyph the first
  					 * glyph to be rearranged. */
        DontAdvance	= 0x4000,	/* If set, don't advance to the next glyph
  					 * before going to the new state. This means
  					 * that the glyph index doesn't change, even
  					 * if the glyph at that index has changed. */
        MarkLast		= 0x2000,	/* If set, make the current glyph the last
  					 * glyph to be rearranged. */
        Reserved		= 0x1FF0,	/* These bits are reserved and should be set to 0. */
        Verb		= 0x000F,	/* The type of rearrangement specified. */
      };
  
      driver_context_t (const RearrangementSubtable *table HB_UNUSED) :
  	ret (false),
  	start (0), end (0) {}
  
      bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED,
  			const Entry<EntryData> &entry)
      {
        return (entry.flags & Verb) && start < end;
      }
      void transition (StateTableDriver<Types, EntryData> *driver,
  		     const Entry<EntryData> &entry)
      {
        hb_buffer_t *buffer = driver->buffer;
        unsigned int flags = entry.flags;
  
        if (flags & MarkFirst)
  	start = buffer->idx;
  
        if (flags & MarkLast)
  	end = hb_min (buffer->idx + 1, buffer->len);
  
        if ((flags & Verb) && start < end)
        {
  	/* The following map has two nibbles, for start-side
  	 * and end-side. Values of 0,1,2 mean move that many
  	 * to the other side. Value of 3 means move 2 and
  	 * flip them. */
  	const unsigned char map[16] =
  	{
  	  0x00,	/* 0	no change */
  	  0x10,	/* 1	Ax => xA */
  	  0x01,	/* 2	xD => Dx */
  	  0x11,	/* 3	AxD => DxA */
  	  0x20,	/* 4	ABx => xAB */
  	  0x30,	/* 5	ABx => xBA */
  	  0x02,	/* 6	xCD => CDx */
  	  0x03,	/* 7	xCD => DCx */
  	  0x12,	/* 8	AxCD => CDxA */
  	  0x13,	/* 9	AxCD => DCxA */
  	  0x21,	/* 10	ABxD => DxAB */
  	  0x31,	/* 11	ABxD => DxBA */
  	  0x22,	/* 12	ABxCD => CDxAB */
  	  0x32,	/* 13	ABxCD => CDxBA */
  	  0x23,	/* 14	ABxCD => DCxAB */
  	  0x33,	/* 15	ABxCD => DCxBA */
  	};
  
  	unsigned int m = map[flags & Verb];
  	unsigned int l = hb_min (2u, m >> 4);
  	unsigned int r = hb_min (2u, m & 0x0F);
  	bool reverse_l = 3 == (m >> 4);
  	bool reverse_r = 3 == (m & 0x0F);
  
  	if (end - start >= l + r)
  	{
  	  buffer->merge_clusters (start, hb_min (buffer->idx + 1, buffer->len));
  	  buffer->merge_clusters (start, end);
  
  	  hb_glyph_info_t *info = buffer->info;
  	  hb_glyph_info_t buf[4];
  
  	  memcpy (buf, info + start, l * sizeof (buf[0]));
  	  memcpy (buf + 2, info + end - r, r * sizeof (buf[0]));
  
  	  if (l != r)
  	    memmove (info + start + r, info + start + l, (end - start - l - r) * sizeof (buf[0]));
  
  	  memcpy (info + start, buf + 2, r * sizeof (buf[0]));
  	  memcpy (info + end - l, buf, l * sizeof (buf[0]));
  	  if (reverse_l)
  	  {
  	    buf[0] = info[end - 1];
  	    info[end - 1] = info[end - 2];
  	    info[end - 2] = buf[0];
  	  }
  	  if (reverse_r)
  	  {
  	    buf[0] = info[start];
  	    info[start] = info[start + 1];
  	    info[start + 1] = buf[0];
  	  }
  	}
        }
      }
  
      public:
      bool ret;
      private:
      unsigned int start;
      unsigned int end;
    };
  
    bool apply (hb_aat_apply_context_t *c) const
    {
      TRACE_APPLY (this);
  
      driver_context_t dc (this);
  
      StateTableDriver<Types, EntryData> driver (machine, c->buffer, c->face);
      driver.drive (&dc);
  
      return_trace (dc.ret);
    }
  
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (machine.sanitize (c));
    }
  
    protected:
    StateTable<Types, EntryData>	machine;
    public:
    DEFINE_SIZE_STATIC (16);
  };
  
  template <typename Types>
  struct ContextualSubtable
  {
    typedef typename Types::HBUINT HBUINT;
  
    struct EntryData
    {
      HBUINT16	markIndex;	/* Index of the substitution table for the
  				 * marked glyph (use 0xFFFF for none). */
      HBUINT16	currentIndex;	/* Index of the substitution table for the
  				 * current glyph (use 0xFFFF for none). */
      public:
      DEFINE_SIZE_STATIC (4);
    };
  
    struct driver_context_t
    {
      static constexpr bool in_place = true;
      enum Flags
      {
        SetMark		= 0x8000,	/* If set, make the current glyph the marked glyph. */
        DontAdvance	= 0x4000,	/* If set, don't advance to the next glyph before
  					 * going to the new state. */
        Reserved		= 0x3FFF,	/* These bits are reserved and should be set to 0. */
      };
  
      driver_context_t (const ContextualSubtable *table_,
  			     hb_aat_apply_context_t *c_) :
  	ret (false),
  	c (c_),
  	mark_set (false),
  	mark (0),
  	table (table_),
  	subs (table+table->substitutionTables) {}
  
      bool is_actionable (StateTableDriver<Types, EntryData> *driver,
  			const Entry<EntryData> &entry)
      {
        hb_buffer_t *buffer = driver->buffer;
  
        if (buffer->idx == buffer->len && !mark_set)
  	return false;
  
        return entry.data.markIndex != 0xFFFF || entry.data.currentIndex != 0xFFFF;
      }
      void transition (StateTableDriver<Types, EntryData> *driver,
  		     const Entry<EntryData> &entry)
      {
        hb_buffer_t *buffer = driver->buffer;
  
        /* Looks like CoreText applies neither mark nor current substitution for
         * end-of-text if mark was not explicitly set. */
        if (buffer->idx == buffer->len && !mark_set)
  	return;
  
        const HBGlyphID *replacement;
  
        replacement = nullptr;
        if (Types::extended)
        {
  	if (entry.data.markIndex != 0xFFFF)
  	{
  	  const Lookup<HBGlyphID> &lookup = subs[entry.data.markIndex];
  	  replacement = lookup.get_value (buffer->info[mark].codepoint, driver->num_glyphs);
  	}
        }
        else
        {
  	unsigned int offset = entry.data.markIndex + buffer->info[mark].codepoint;
  	const UnsizedArrayOf<HBGlyphID> &subs_old = (const UnsizedArrayOf<HBGlyphID> &) subs;
  	replacement = &subs_old[Types::wordOffsetToIndex (offset, table, subs_old.arrayZ)];
  	if (!replacement->sanitize (&c->sanitizer) || !*replacement)
  	  replacement = nullptr;
        }
        if (replacement)
        {
  	buffer->unsafe_to_break (mark, hb_min (buffer->idx + 1, buffer->len));
  	buffer->info[mark].codepoint = *replacement;
  	ret = true;
        }
  
        replacement = nullptr;
        unsigned int idx = hb_min (buffer->idx, buffer->len - 1);
        if (Types::extended)
        {
  	if (entry.data.currentIndex != 0xFFFF)
  	{
  	  const Lookup<HBGlyphID> &lookup = subs[entry.data.currentIndex];
  	  replacement = lookup.get_value (buffer->info[idx].codepoint, driver->num_glyphs);
  	}
        }
        else
        {
  	unsigned int offset = entry.data.currentIndex + buffer->info[idx].codepoint;
  	const UnsizedArrayOf<HBGlyphID> &subs_old = (const UnsizedArrayOf<HBGlyphID> &) subs;
  	replacement = &subs_old[Types::wordOffsetToIndex (offset, table, subs_old.arrayZ)];
  	if (!replacement->sanitize (&c->sanitizer) || !*replacement)
  	  replacement = nullptr;
        }
        if (replacement)
        {
  	buffer->info[idx].codepoint = *replacement;
  	ret = true;
        }
  
        if (entry.flags & SetMark)
        {
  	mark_set = true;
  	mark = buffer->idx;
        }
      }
  
      public:
      bool ret;
      private:
      hb_aat_apply_context_t *c;
      bool mark_set;
      unsigned int mark;
      const ContextualSubtable *table;
      const UnsizedOffsetListOf<Lookup<HBGlyphID>, HBUINT, false> &subs;
    };
  
    bool apply (hb_aat_apply_context_t *c) const
    {
      TRACE_APPLY (this);
  
      driver_context_t dc (this, c);
  
      StateTableDriver<Types, EntryData> driver (machine, c->buffer, c->face);
      driver.drive (&dc);
  
      return_trace (dc.ret);
    }
  
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
  
      unsigned int num_entries = 0;
      if (unlikely (!machine.sanitize (c, &num_entries))) return_trace (false);
  
      if (!Types::extended)
        return_trace (substitutionTables.sanitize (c, this, 0));
  
      unsigned int num_lookups = 0;
  
      const Entry<EntryData> *entries = machine.get_entries ();
      for (unsigned int i = 0; i < num_entries; i++)
      {
        const EntryData &data = entries[i].data;
  
        if (data.markIndex != 0xFFFF)
  	num_lookups = hb_max (num_lookups, 1 + data.markIndex);
        if (data.currentIndex != 0xFFFF)
  	num_lookups = hb_max (num_lookups, 1 + data.currentIndex);
      }
  
      return_trace (substitutionTables.sanitize (c, this, num_lookups));
    }
  
    protected:
    StateTable<Types, EntryData>
  		machine;
    NNOffsetTo<UnsizedOffsetListOf<Lookup<HBGlyphID>, HBUINT, false>, HBUINT>
  		substitutionTables;
    public:
    DEFINE_SIZE_STATIC (20);
  };
  
  
  template <bool extended>
  struct LigatureEntry;
  
  template <>
  struct LigatureEntry<true>
  {
    enum Flags
    {
      SetComponent	= 0x8000,	/* Push this glyph onto the component stack for
  					 * eventual processing. */
      DontAdvance		= 0x4000,	/* Leave the glyph pointer at this glyph for the
  					   next iteration. */
      PerformAction	= 0x2000,	/* Use the ligActionIndex to process a ligature
  					 * group. */
      Reserved		= 0x1FFF,	/* These bits are reserved and should be set to 0. */
    };
  
    struct EntryData
    {
      HBUINT16	ligActionIndex;	/* Index to the first ligActionTable entry
  				 * for processing this group, if indicated
  				 * by the flags. */
      public:
      DEFINE_SIZE_STATIC (2);
    };
  
    static bool performAction (const Entry<EntryData> &entry)
    { return entry.flags & PerformAction; }
  
    static unsigned int ligActionIndex (const Entry<EntryData> &entry)
    { return entry.data.ligActionIndex; }
  };
  template <>
  struct LigatureEntry<false>
  {
    enum Flags
    {
      SetComponent	= 0x8000,	/* Push this glyph onto the component stack for
  					 * eventual processing. */
      DontAdvance		= 0x4000,	/* Leave the glyph pointer at this glyph for the
  					   next iteration. */
      Offset		= 0x3FFF,	/* Byte offset from beginning of subtable to the
  					 * ligature action list. This value must be a
  					 * multiple of 4. */
    };
  
    typedef void EntryData;
  
    static bool performAction (const Entry<EntryData> &entry)
    { return entry.flags & Offset; }
  
    static unsigned int ligActionIndex (const Entry<EntryData> &entry)
    { return entry.flags & Offset; }
  };
  
  
  template <typename Types>
  struct LigatureSubtable
  {
    typedef typename Types::HBUINT HBUINT;
  
    typedef LigatureEntry<Types::extended> LigatureEntryT;
    typedef typename LigatureEntryT::EntryData EntryData;
  
    struct driver_context_t
    {
      static constexpr bool in_place = false;
      enum
      {
        DontAdvance	= LigatureEntryT::DontAdvance,
      };
      enum LigActionFlags
      {
        LigActionLast	= 0x80000000,	/* This is the last action in the list. This also
  					 * implies storage. */
        LigActionStore	= 0x40000000,	/* Store the ligature at the current cumulated index
  					 * in the ligature table in place of the marked
  					 * (i.e. currently-popped) glyph. */
        LigActionOffset	= 0x3FFFFFFF,	/* A 30-bit value which is sign-extended to 32-bits
  					 * and added to the glyph ID, resulting in an index
  					 * into the component table. */
      };
  
      driver_context_t (const LigatureSubtable *table_,
  		      hb_aat_apply_context_t *c_) :
  	ret (false),
  	c (c_),
  	table (table_),
  	ligAction (table+table->ligAction),
  	component (table+table->component),
  	ligature (table+table->ligature),
  	match_length (0) {}
  
      bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED,
  			const Entry<EntryData> &entry)
      {
        return LigatureEntryT::performAction (entry);
      }
      void transition (StateTableDriver<Types, EntryData> *driver,
  		     const Entry<EntryData> &entry)
      {
        hb_buffer_t *buffer = driver->buffer;
  
        DEBUG_MSG (APPLY, nullptr, "Ligature transition at %u", buffer->idx);
        if (entry.flags & LigatureEntryT::SetComponent)
        {
  	/* Never mark same index twice, in case DontAdvance was used... */
  	if (match_length && match_positions[(match_length - 1u) % ARRAY_LENGTH (match_positions)] == buffer->out_len)
  	  match_length--;
  
  	match_positions[match_length++ % ARRAY_LENGTH (match_positions)] = buffer->out_len;
  	DEBUG_MSG (APPLY, nullptr, "Set component at %u", buffer->out_len);
        }
  
        if (LigatureEntryT::performAction (entry))
        {
  	DEBUG_MSG (APPLY, nullptr, "Perform action with %u", match_length);
  	unsigned int end = buffer->out_len;
  
  	if (unlikely (!match_length))
  	  return;
  
  	if (buffer->idx >= buffer->len)
  	  return; /* TODO Work on previous instead? */
  
  	unsigned int cursor = match_length;
  
  	unsigned int action_idx = LigatureEntryT::ligActionIndex (entry);
  	action_idx = Types::offsetToIndex (action_idx, table, ligAction.arrayZ);
  	const HBUINT32 *actionData = &ligAction[action_idx];
  
  	unsigned int ligature_idx = 0;
  	unsigned int action;
  	do
  	{
  	  if (unlikely (!cursor))
  	  {
  	    /* Stack underflow.  Clear the stack. */
  	    DEBUG_MSG (APPLY, nullptr, "Stack underflow");
  	    match_length = 0;
  	    break;
  	  }
  
  	  DEBUG_MSG (APPLY, nullptr, "Moving to stack position %u", cursor - 1);
  	  buffer->move_to (match_positions[--cursor % ARRAY_LENGTH (match_positions)]);
  
  	  if (unlikely (!actionData->sanitize (&c->sanitizer))) break;
  	  action = *actionData;
  
  	  uint32_t uoffset = action & LigActionOffset;
  	  if (uoffset & 0x20000000)
  	    uoffset |= 0xC0000000; /* Sign-extend. */
  	  int32_t offset = (int32_t) uoffset;
  	  unsigned int component_idx = buffer->cur().codepoint + offset;
  	  component_idx = Types::wordOffsetToIndex (component_idx, table, component.arrayZ);
  	  const HBUINT16 &componentData = component[component_idx];
  	  if (unlikely (!componentData.sanitize (&c->sanitizer))) break;
  	  ligature_idx += componentData;
  
  	  DEBUG_MSG (APPLY, nullptr, "Action store %u last %u",
  		     bool (action & LigActionStore),
  		     bool (action & LigActionLast));
  	  if (action & (LigActionStore | LigActionLast))
  	  {
  	    ligature_idx = Types::offsetToIndex (ligature_idx, table, ligature.arrayZ);
  	    const HBGlyphID &ligatureData = ligature[ligature_idx];
  	    if (unlikely (!ligatureData.sanitize (&c->sanitizer))) break;
  	    hb_codepoint_t lig = ligatureData;
  
  	    DEBUG_MSG (APPLY, nullptr, "Produced ligature %u", lig);
  	    buffer->replace_glyph (lig);
  
  	    unsigned int lig_end = match_positions[(match_length - 1u) % ARRAY_LENGTH (match_positions)] + 1u;
  	    /* Now go and delete all subsequent components. */
  	    while (match_length - 1u > cursor)
  	    {
  	      DEBUG_MSG (APPLY, nullptr, "Skipping ligature component");
  	      buffer->move_to (match_positions[--match_length % ARRAY_LENGTH (match_positions)]);
  	      buffer->replace_glyph (DELETED_GLYPH);
  	    }
  
  	    buffer->move_to (lig_end);
  	    buffer->merge_out_clusters (match_positions[cursor % ARRAY_LENGTH (match_positions)], buffer->out_len);
  	  }
  
  	  actionData++;
  	}
  	while (!(action & LigActionLast));
  	buffer->move_to (end);
        }
      }
  
      public:
      bool ret;
      private:
      hb_aat_apply_context_t *c;
      const LigatureSubtable *table;
      const UnsizedArrayOf<HBUINT32> &ligAction;
      const UnsizedArrayOf<HBUINT16> &component;
      const UnsizedArrayOf<HBGlyphID> &ligature;
      unsigned int match_length;
      unsigned int match_positions[HB_MAX_CONTEXT_LENGTH];
    };
  
    bool apply (hb_aat_apply_context_t *c) const
    {
      TRACE_APPLY (this);
  
      driver_context_t dc (this, c);
  
      StateTableDriver<Types, EntryData> driver (machine, c->buffer, c->face);
      driver.drive (&dc);
  
      return_trace (dc.ret);
    }
  
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      /* The rest of array sanitizations are done at run-time. */
      return_trace (c->check_struct (this) && machine.sanitize (c) &&
  		  ligAction && component && ligature);
    }
  
    protected:
    StateTable<Types, EntryData>
  		machine;
    NNOffsetTo<UnsizedArrayOf<HBUINT32>, HBUINT>
  		ligAction;	/* Offset to the ligature action table. */
    NNOffsetTo<UnsizedArrayOf<HBUINT16>, HBUINT>
  		component;	/* Offset to the component table. */
    NNOffsetTo<UnsizedArrayOf<HBGlyphID>, HBUINT>
  		ligature;	/* Offset to the actual ligature lists. */
    public:
    DEFINE_SIZE_STATIC (28);
  };
  
  template <typename Types>
  struct NoncontextualSubtable
  {
    bool apply (hb_aat_apply_context_t *c) const
    {
      TRACE_APPLY (this);
  
      bool ret = false;
      unsigned int num_glyphs = c->face->get_num_glyphs ();
  
      hb_glyph_info_t *info = c->buffer->info;
      unsigned int count = c->buffer->len;
      for (unsigned int i = 0; i < count; i++)
      {
        const HBGlyphID *replacement = substitute.get_value (info[i].codepoint, num_glyphs);
        if (replacement)
        {
  	info[i].codepoint = *replacement;
  	ret = true;
        }
      }
  
      return_trace (ret);
    }
  
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (substitute.sanitize (c));
    }
  
    protected:
    Lookup<HBGlyphID>	substitute;
    public:
    DEFINE_SIZE_MIN (2);
  };
  
  template <typename Types>
  struct InsertionSubtable
  {
    typedef typename Types::HBUINT HBUINT;
  
    struct EntryData
    {
      HBUINT16	currentInsertIndex;	/* Zero-based index into the insertion glyph table.
  					 * The number of glyphs to be inserted is contained
  					 * in the currentInsertCount field in the flags.
  					 * A value of 0xFFFF indicates no insertion is to
  					 * be done. */
      HBUINT16	markedInsertIndex;	/* Zero-based index into the insertion glyph table.
  					 * The number of glyphs to be inserted is contained
  					 * in the markedInsertCount field in the flags.
  					 * A value of 0xFFFF indicates no insertion is to
  					 * be done. */
      public:
      DEFINE_SIZE_STATIC (4);
    };
  
    struct driver_context_t
    {
      static constexpr bool in_place = false;
      enum Flags
      {
        SetMark		= 0x8000,	/* If set, mark the current glyph. */
        DontAdvance	= 0x4000,	/* If set, don't advance to the next glyph before
  					 * going to the new state.  This does not mean
  					 * that the glyph pointed to is the same one as
  					 * before. If you've made insertions immediately
  					 * downstream of the current glyph, the next glyph
  					 * processed would in fact be the first one
  					 * inserted. */
        CurrentIsKashidaLike= 0x2000,	/* If set, and the currentInsertList is nonzero,
  					 * then the specified glyph list will be inserted
  					 * as a kashida-like insertion, either before or
  					 * after the current glyph (depending on the state
  					 * of the currentInsertBefore flag). If clear, and
  					 * the currentInsertList is nonzero, then the
  					 * specified glyph list will be inserted as a
  					 * split-vowel-like insertion, either before or
  					 * after the current glyph (depending on the state
  					 * of the currentInsertBefore flag). */
        MarkedIsKashidaLike= 0x1000,	/* If set, and the markedInsertList is nonzero,
  					 * then the specified glyph list will be inserted
  					 * as a kashida-like insertion, either before or
  					 * after the marked glyph (depending on the state
  					 * of the markedInsertBefore flag). If clear, and
  					 * the markedInsertList is nonzero, then the
  					 * specified glyph list will be inserted as a
  					 * split-vowel-like insertion, either before or
  					 * after the marked glyph (depending on the state
  					 * of the markedInsertBefore flag). */
        CurrentInsertBefore= 0x0800,	/* If set, specifies that insertions are to be made
  					 * to the left of the current glyph. If clear,
  					 * they're made to the right of the current glyph. */
        MarkedInsertBefore= 0x0400,	/* If set, specifies that insertions are to be
  					 * made to the left of the marked glyph. If clear,
  					 * they're made to the right of the marked glyph. */
        CurrentInsertCount= 0x3E0,	/* This 5-bit field is treated as a count of the
  					 * number of glyphs to insert at the current
  					 * position. Since zero means no insertions, the
  					 * largest number of insertions at any given
  					 * current location is 31 glyphs. */
        MarkedInsertCount= 0x001F,	/* This 5-bit field is treated as a count of the
  					 * number of glyphs to insert at the marked
  					 * position. Since zero means no insertions, the
  					 * largest number of insertions at any given
  					 * marked location is 31 glyphs. */
      };
  
      driver_context_t (const InsertionSubtable *table,
  		      hb_aat_apply_context_t *c_) :
  	ret (false),
  	c (c_),
  	mark (0),
  	insertionAction (table+table->insertionAction) {}
  
      bool is_actionable (StateTableDriver<Types, EntryData> *driver HB_UNUSED,
  			const Entry<EntryData> &entry)
      {
        return (entry.flags & (CurrentInsertCount | MarkedInsertCount)) &&
  	     (entry.data.currentInsertIndex != 0xFFFF ||entry.data.markedInsertIndex != 0xFFFF);
      }
      void transition (StateTableDriver<Types, EntryData> *driver,
  		     const Entry<EntryData> &entry)
      {
        hb_buffer_t *buffer = driver->buffer;
        unsigned int flags = entry.flags;
  
        unsigned mark_loc = buffer->out_len;
  
        if (entry.data.markedInsertIndex != 0xFFFF)
        {
  	unsigned int count = (flags & MarkedInsertCount);
  	unsigned int start = entry.data.markedInsertIndex;
  	const HBGlyphID *glyphs = &insertionAction[start];
  	if (unlikely (!c->sanitizer.check_array (glyphs, count))) count = 0;
  
  	bool before = flags & MarkedInsertBefore;
  
  	unsigned int end = buffer->out_len;
  	buffer->move_to (mark);
  
  	if (buffer->idx < buffer->len && !before)
  	  buffer->copy_glyph ();
  	/* TODO We ignore KashidaLike setting. */
  	for (unsigned int i = 0; i < count; i++)
  	  buffer->output_glyph (glyphs[i]);
  	if (buffer->idx < buffer->len && !before)
  	  buffer->skip_glyph ();
  
  	buffer->move_to (end + count);
  
  	buffer->unsafe_to_break_from_outbuffer (mark, hb_min (buffer->idx + 1, buffer->len));
        }
  
        if (flags & SetMark)
  	mark = mark_loc;
  
        if (entry.data.currentInsertIndex != 0xFFFF)
        {
  	unsigned int count = (flags & CurrentInsertCount) >> 5;
  	unsigned int start = entry.data.currentInsertIndex;
  	const HBGlyphID *glyphs = &insertionAction[start];
  	if (unlikely (!c->sanitizer.check_array (glyphs, count))) count = 0;
  
  	bool before = flags & CurrentInsertBefore;
  
  	unsigned int end = buffer->out_len;
  
  	if (buffer->idx < buffer->len && !before)
  	  buffer->copy_glyph ();
  	/* TODO We ignore KashidaLike setting. */
  	for (unsigned int i = 0; i < count; i++)
  	  buffer->output_glyph (glyphs[i]);
  	if (buffer->idx < buffer->len && !before)
  	  buffer->skip_glyph ();
  
  	/* Humm. Not sure where to move to.  There's this wording under
  	 * DontAdvance flag:
  	 *
  	 * "If set, don't update the glyph index before going to the new state.
  	 * This does not mean that the glyph pointed to is the same one as
  	 * before. If you've made insertions immediately downstream of the
  	 * current glyph, the next glyph processed would in fact be the first
  	 * one inserted."
  	 *
  	 * This suggests that if DontAdvance is NOT set, we should move to
  	 * end+count.  If it *was*, then move to end, such that newly inserted
  	 * glyphs are now visible.
  	 *
  	 * https://github.com/harfbuzz/harfbuzz/issues/1224#issuecomment-427691417
  	 */
  	buffer->move_to ((flags & DontAdvance) ? end : end + count);
        }
      }
  
      public:
      bool ret;
      private:
      hb_aat_apply_context_t *c;
      unsigned int mark;
      const UnsizedArrayOf<HBGlyphID> &insertionAction;
    };
  
    bool apply (hb_aat_apply_context_t *c) const
    {
      TRACE_APPLY (this);
  
      driver_context_t dc (this, c);
  
      StateTableDriver<Types, EntryData> driver (machine, c->buffer, c->face);
      driver.drive (&dc);
  
      return_trace (dc.ret);
    }
  
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      /* The rest of array sanitizations are done at run-time. */
      return_trace (c->check_struct (this) && machine.sanitize (c) &&
  		  insertionAction);
    }
  
    protected:
    StateTable<Types, EntryData>
  		machine;
    NNOffsetTo<UnsizedArrayOf<HBGlyphID>, HBUINT>
  		insertionAction;	/* Byte offset from stateHeader to the start of
  					 * the insertion glyph table. */
    public:
    DEFINE_SIZE_STATIC (20);
  };
  
  
  struct Feature
  {
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (c->check_struct (this));
    }
  
    public:
    HBUINT16	featureType;	/* The type of feature. */
    HBUINT16	featureSetting;	/* The feature's setting (aka selector). */
    HBUINT32	enableFlags;	/* Flags for the settings that this feature
  				 * and setting enables. */
    HBUINT32	disableFlags;	/* Complement of flags for the settings that this
  				 * feature and setting disable. */
  
    public:
    DEFINE_SIZE_STATIC (12);
  };
  
  template <typename Types>
  struct ChainSubtable
  {
    typedef typename Types::HBUINT HBUINT;
  
    template <typename T>
    friend struct Chain;
  
    unsigned int get_size () const     { return length; }
    unsigned int get_type () const     { return coverage & 0xFF; }
    unsigned int get_coverage () const { return coverage >> (sizeof (HBUINT) * 8 - 8); }
  
    enum Coverage
    {
      Vertical		= 0x80,	/* If set, this subtable will only be applied
  				 * to vertical text. If clear, this subtable
  				 * will only be applied to horizontal text. */
      Backwards		= 0x40,	/* If set, this subtable will process glyphs
  				 * in descending order. If clear, it will
  				 * process the glyphs in ascending order. */
      AllDirections	= 0x20,	/* If set, this subtable will be applied to
  				 * both horizontal and vertical text (i.e.
  				 * the state of bit 0x80000000 is ignored). */
      Logical		= 0x10,	/* If set, this subtable will process glyphs
  				 * in logical order (or reverse logical order,
  				 * depending on the value of bit 0x80000000). */
    };
    enum Type
    {
      Rearrangement	= 0,
      Contextual		= 1,
      Ligature		= 2,
      Noncontextual	= 4,
      Insertion		= 5
    };
  
    template <typename context_t, typename ...Ts>
    typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const
    {
      unsigned int subtable_type = get_type ();
      TRACE_DISPATCH (this, subtable_type);
      switch (subtable_type) {
      case Rearrangement:		return_trace (c->dispatch (u.rearrangement, hb_forward<Ts> (ds)...));
      case Contextual:		return_trace (c->dispatch (u.contextual, hb_forward<Ts> (ds)...));
      case Ligature:		return_trace (c->dispatch (u.ligature, hb_forward<Ts> (ds)...));
      case Noncontextual:		return_trace (c->dispatch (u.noncontextual, hb_forward<Ts> (ds)...));
      case Insertion:		return_trace (c->dispatch (u.insertion, hb_forward<Ts> (ds)...));
      default:			return_trace (c->default_return_value ());
      }
    }
  
    bool apply (hb_aat_apply_context_t *c) const
    {
      TRACE_APPLY (this);
      hb_sanitize_with_object_t with (&c->sanitizer, this);
      return_trace (dispatch (c));
    }
  
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      if (!length.sanitize (c) ||
  	length <= min_size ||
  	!c->check_range (this, length))
        return_trace (false);
  
      hb_sanitize_with_object_t with (c, this);
      return_trace (dispatch (c));
    }
  
    protected:
    HBUINT	length;		/* Total subtable length, including this header. */
    HBUINT	coverage;	/* Coverage flags and subtable type. */
    HBUINT32	subFeatureFlags;/* The 32-bit mask identifying which subtable this is. */
    union {
    RearrangementSubtable<Types>	rearrangement;
    ContextualSubtable<Types>	contextual;
    LigatureSubtable<Types>	ligature;
    NoncontextualSubtable<Types>	noncontextual;
    InsertionSubtable<Types>	insertion;
    } u;
    public:
    DEFINE_SIZE_MIN (2 * sizeof (HBUINT) + 4);
  };
  
  template <typename Types>
  struct Chain
  {
    typedef typename Types::HBUINT HBUINT;
  
    hb_mask_t compile_flags (const hb_aat_map_builder_t *map) const
    {
      hb_mask_t flags = defaultFlags;
      {
        unsigned int count = featureCount;
        for (unsigned i = 0; i < count; i++)
        {
  	const Feature &feature = featureZ[i];
  	hb_aat_layout_feature_type_t type = (hb_aat_layout_feature_type_t) (unsigned int) feature.featureType;
  	hb_aat_layout_feature_selector_t setting = (hb_aat_layout_feature_selector_t) (unsigned int) feature.featureSetting;
        retry:
  	const hb_aat_map_builder_t::feature_info_t *info = map->features.bsearch (type);
  	if (info && info->setting == setting)
  	{
  	  flags &= feature.disableFlags;
  	  flags |= feature.enableFlags;
  	}
  	else if (type == HB_AAT_LAYOUT_FEATURE_TYPE_LETTER_CASE && setting == HB_AAT_LAYOUT_FEATURE_SELECTOR_SMALL_CAPS)
  	{
  	  /* Deprecated. https://github.com/harfbuzz/harfbuzz/issues/1342 */
  	  type = HB_AAT_LAYOUT_FEATURE_TYPE_LOWER_CASE;
  	  setting = HB_AAT_LAYOUT_FEATURE_SELECTOR_LOWER_CASE_SMALL_CAPS;
  	  goto retry;
  	}
        }
      }
      return flags;
    }
  
    void apply (hb_aat_apply_context_t *c,
  		     hb_mask_t flags) const
    {
      const ChainSubtable<Types> *subtable = &StructAfter<ChainSubtable<Types>> (featureZ.as_array (featureCount));
      unsigned int count = subtableCount;
      for (unsigned int i = 0; i < count; i++)
      {
        bool reverse;
  
        if (!(subtable->subFeatureFlags & flags))
  	goto skip;
  
        if (!(subtable->get_coverage() & ChainSubtable<Types>::AllDirections) &&
  	  HB_DIRECTION_IS_VERTICAL (c->buffer->props.direction) !=
  	  bool (subtable->get_coverage() & ChainSubtable<Types>::Vertical))
  	goto skip;
  
        /* Buffer contents is always in logical direction.  Determine if
         * we need to reverse before applying this subtable.  We reverse
         * back after if we did reverse indeed.
         *
         * Quoting the spac:
         * """
         * Bits 28 and 30 of the coverage field control the order in which
         * glyphs are processed when the subtable is run by the layout engine.
         * Bit 28 is used to indicate if the glyph processing direction is
         * the same as logical order or layout order. Bit 30 is used to
         * indicate whether glyphs are processed forwards or backwards within
         * that order.
  
  		Bit 30	Bit 28	Interpretation for Horizontal Text
  		0	0	The subtable is processed in layout order
  				(the same order as the glyphs, which is
  				always left-to-right).
  		1	0	The subtable is processed in reverse layout order
  				(the order opposite that of the glyphs, which is
  				always right-to-left).
  		0	1	The subtable is processed in logical order
  				(the same order as the characters, which may be
  				left-to-right or right-to-left).
  		1	1	The subtable is processed in reverse logical order
  				(the order opposite that of the characters, which
  				may be right-to-left or left-to-right).
         */
        reverse = subtable->get_coverage () & ChainSubtable<Types>::Logical ?
  		bool (subtable->get_coverage () & ChainSubtable<Types>::Backwards) :
  		bool (subtable->get_coverage () & ChainSubtable<Types>::Backwards) !=
  		HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction);
  
        if (!c->buffer->message (c->font, "start chain subtable %d", c->lookup_index))
  	goto skip;
  
        if (reverse)
  	c->buffer->reverse ();
  
        subtable->apply (c);
  
        if (reverse)
  	c->buffer->reverse ();
  
        (void) c->buffer->message (c->font, "end chain subtable %d", c->lookup_index);
  
        if (unlikely (!c->buffer->successful)) return;
  
      skip:
        subtable = &StructAfter<ChainSubtable<Types>> (*subtable);
        c->set_lookup_index (c->lookup_index + 1);
      }
    }
  
    unsigned int get_size () const { return length; }
  
    bool sanitize (hb_sanitize_context_t *c, unsigned int version HB_UNUSED) const
    {
      TRACE_SANITIZE (this);
      if (!length.sanitize (c) ||
  	length < min_size ||
  	!c->check_range (this, length))
        return_trace (false);
  
      if (!c->check_array (featureZ.arrayZ, featureCount))
        return_trace (false);
  
      const ChainSubtable<Types> *subtable = &StructAfter<ChainSubtable<Types>> (featureZ.as_array (featureCount));
      unsigned int count = subtableCount;
      for (unsigned int i = 0; i < count; i++)
      {
        if (!subtable->sanitize (c))
  	return_trace (false);
        subtable = &StructAfter<ChainSubtable<Types>> (*subtable);
      }
  
      return_trace (true);
    }
  
    protected:
    HBUINT32	defaultFlags;	/* The default specification for subtables. */
    HBUINT32	length;		/* Total byte count, including this header. */
    HBUINT	featureCount;	/* Number of feature subtable entries. */
    HBUINT	subtableCount;	/* The number of subtables in the chain. */
  
    UnsizedArrayOf<Feature>	featureZ;	/* Features. */
  /*ChainSubtable	firstSubtable;*//* Subtables. */
  /*subtableGlyphCoverageArray*/	/* Only if version >= 3. We don't use. */
  
    public:
    DEFINE_SIZE_MIN (8 + 2 * sizeof (HBUINT));
  };
  
  
  /*
   * The 'mort'/'morx' Table
   */
  
  template <typename Types, hb_tag_t TAG>
  struct mortmorx
  {
    static constexpr hb_tag_t tableTag = TAG;
  
    bool has_data () const { return version != 0; }
  
    void compile_flags (const hb_aat_map_builder_t *mapper,
  		      hb_aat_map_t *map) const
    {
      const Chain<Types> *chain = &firstChain;
      unsigned int count = chainCount;
      for (unsigned int i = 0; i < count; i++)
      {
        map->chain_flags.push (chain->compile_flags (mapper));
        chain = &StructAfter<Chain<Types>> (*chain);
      }
    }
  
    void apply (hb_aat_apply_context_t *c) const
    {
      if (unlikely (!c->buffer->successful)) return;
      c->set_lookup_index (0);
      const Chain<Types> *chain = &firstChain;
      unsigned int count = chainCount;
      for (unsigned int i = 0; i < count; i++)
      {
        chain->apply (c, c->plan->aat_map.chain_flags[i]);
        if (unlikely (!c->buffer->successful)) return;
        chain = &StructAfter<Chain<Types>> (*chain);
      }
    }
  
    bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      if (!version.sanitize (c) || !version || !chainCount.sanitize (c))
        return_trace (false);
  
      const Chain<Types> *chain = &firstChain;
      unsigned int count = chainCount;
      for (unsigned int i = 0; i < count; i++)
      {
        if (!chain->sanitize (c, version))
  	return_trace (false);
        chain = &StructAfter<Chain<Types>> (*chain);
      }
  
      return_trace (true);
    }
  
    protected:
    HBUINT16	version;	/* Version number of the glyph metamorphosis table.
  				 * 1, 2, or 3. */
    HBUINT16	unused;		/* Set to 0. */
    HBUINT32	chainCount;	/* Number of metamorphosis chains contained in this
  				 * table. */
    Chain<Types>	firstChain;	/* Chains. */
  
    public:
    DEFINE_SIZE_MIN (8);
  };
  
  struct morx : mortmorx<ExtendedTypes, HB_AAT_TAG_morx> {};
  struct mort : mortmorx<ObsoleteTypes, HB_AAT_TAG_mort> {};
  
  
  } /* namespace AAT */
  
  
  #endif /* HB_AAT_LAYOUT_MORX_TABLE_HH */
  