tor-browser

hb-ot-layout-common.hh (148478B)

---

/*
* Copyright © 2007,2008,2009  Red Hat, Inc.
* Copyright © 2010,2012  Google, Inc.
*
*  This is part of HarfBuzz, a text shaping library.
*
* Permission is hereby granted, without written agreement and without
* license or royalty fees, to use, copy, modify, and distribute this
* software and its documentation for any purpose, provided that the
* above copyright notice and the following two paragraphs appear in
* 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_COMMON_HH
#define HB_OT_LAYOUT_COMMON_HH

#include "hb.hh"
#include "hb-ot-layout.hh"
#include "hb-open-type.hh"
#include "hb-set.hh"
#include "hb-bimap.hh"
#include "hb-cache.hh"

#include "OT/Layout/Common/Coverage.hh"
#include "OT/Layout/types.hh"

// TODO(garretrieger): cleanup these after migration.
using OT::Layout::Common::Coverage;
using OT::Layout::Common::RangeRecord;
using OT::Layout::SmallTypes;
using OT::Layout::MediumTypes;


namespace OT {

template<typename Iterator>
static inline bool ClassDef_serialize (hb_serialize_context_t *c,
			       Iterator it);

static bool ClassDef_remap_and_serialize (
   hb_serialize_context_t *c,
   const hb_set_t &klasses,
   bool use_class_zero,
   hb_sorted_vector_t<hb_codepoint_pair_t> &glyph_and_klass, /* IN/OUT */
   hb_map_t *klass_map /*IN/OUT*/);

struct hb_collect_feature_substitutes_with_var_context_t
{
 const hb_map_t *axes_index_tag_map;
 const hb_hashmap_t<hb_tag_t, Triple> *axes_location;
 hb_hashmap_t<unsigned, hb::shared_ptr<hb_set_t>> *record_cond_idx_map;
 hb_hashmap_t<unsigned, const Feature*> *feature_substitutes_map;
 hb_set_t& catch_all_record_feature_idxes;

 // not stored in subset_plan
 hb_set_t *feature_indices;
 bool apply;
 bool variation_applied;
 bool universal;
 unsigned cur_record_idx;
 hb_hashmap_t<hb::shared_ptr<hb_map_t>, unsigned> *conditionset_map;
};

struct hb_prune_langsys_context_t
{
 hb_prune_langsys_context_t (const void         *table_,
                             hb_hashmap_t<unsigned, hb::unique_ptr<hb_set_t>> *script_langsys_map_,
                             const hb_map_t     *duplicate_feature_map_,
                             hb_set_t           *new_collected_feature_indexes_)
     :table (table_),
     script_langsys_map (script_langsys_map_),
     duplicate_feature_map (duplicate_feature_map_),
     new_feature_indexes (new_collected_feature_indexes_),
     script_count (0),langsys_feature_count (0) {}

 bool visitScript ()
 { return script_count++ < HB_MAX_SCRIPTS; }

 bool visitLangsys (unsigned feature_count)
 {
   langsys_feature_count += feature_count;
   return langsys_feature_count < HB_MAX_LANGSYS_FEATURE_COUNT;
 }

 public:
 const void *table;
 hb_hashmap_t<unsigned, hb::unique_ptr<hb_set_t>> *script_langsys_map;
 const hb_map_t     *duplicate_feature_map;
 hb_set_t           *new_feature_indexes;

 private:
 unsigned script_count;
 unsigned langsys_feature_count;
};

struct hb_subset_layout_context_t :
 hb_dispatch_context_t<hb_subset_layout_context_t, hb_empty_t, HB_DEBUG_SUBSET>
{
 const char *get_name () { return "SUBSET_LAYOUT"; }
 static return_t default_return_value () { return hb_empty_t (); }

 bool visitScript ()
 {
   return script_count++ < HB_MAX_SCRIPTS;
 }

 bool visitLangSys ()
 {
   return langsys_count++ < HB_MAX_LANGSYS;
 }

 bool visitFeatureIndex (int count)
 {
   feature_index_count += count;
   return feature_index_count < HB_MAX_FEATURE_INDICES;
 }

 bool visitLookupIndex()
 {
   lookup_index_count++;
   return lookup_index_count < HB_MAX_LOOKUP_VISIT_COUNT;
 }

 hb_subset_context_t *subset_context;
 const hb_tag_t table_tag;
 const hb_map_t *lookup_index_map;
 const hb_hashmap_t<unsigned, hb::unique_ptr<hb_set_t>> *script_langsys_map;
 const hb_map_t *feature_index_map;
 const hb_map_t *feature_map_w_duplicates;
 const hb_hashmap_t<unsigned, const Feature*> *feature_substitutes_map;
 hb_hashmap_t<unsigned, hb::shared_ptr<hb_set_t>> *feature_record_cond_idx_map;
 const hb_set_t *catch_all_record_feature_idxes;
 const hb_hashmap_t<unsigned, hb_pair_t<const void*, const void*>> *feature_idx_tag_map;

 unsigned cur_script_index;
 unsigned cur_feature_var_record_idx;

 hb_subset_layout_context_t (hb_subset_context_t *c_,
		      hb_tag_t tag_) :
			subset_context (c_),
			table_tag (tag_),
			cur_script_index (0xFFFFu),
			cur_feature_var_record_idx (0u),
			script_count (0),
			langsys_count (0),
			feature_index_count (0),
			lookup_index_count (0)
 {
   if (tag_ == HB_OT_TAG_GSUB)
   {
     lookup_index_map = &c_->plan->gsub_lookups;
     script_langsys_map = &c_->plan->gsub_langsys;
     feature_index_map = &c_->plan->gsub_features;
     feature_map_w_duplicates = &c_->plan->gsub_features_w_duplicates;
     feature_substitutes_map = &c_->plan->gsub_feature_substitutes_map;
     feature_record_cond_idx_map = c_->plan->user_axes_location.is_empty () ? nullptr : &c_->plan->gsub_feature_record_cond_idx_map;
     catch_all_record_feature_idxes = &c_->plan->gsub_old_features;
     feature_idx_tag_map = &c_->plan->gsub_old_feature_idx_tag_map;
   }
   else
   {
     lookup_index_map = &c_->plan->gpos_lookups;
     script_langsys_map = &c_->plan->gpos_langsys;
     feature_index_map = &c_->plan->gpos_features;
     feature_map_w_duplicates = &c_->plan->gpos_features_w_duplicates;
     feature_substitutes_map = &c_->plan->gpos_feature_substitutes_map;
     feature_record_cond_idx_map = c_->plan->user_axes_location.is_empty () ? nullptr : &c_->plan->gpos_feature_record_cond_idx_map;
     catch_all_record_feature_idxes = &c_->plan->gpos_old_features;
     feature_idx_tag_map = &c_->plan->gpos_old_feature_idx_tag_map;
   }
 }

 private:
 unsigned script_count;
 unsigned langsys_count;
 unsigned feature_index_count;
 unsigned lookup_index_count;
};

struct ItemVariationStore;
struct hb_collect_variation_indices_context_t :
      hb_dispatch_context_t<hb_collect_variation_indices_context_t>
{
 template <typename T>
 return_t dispatch (const T &obj) { obj.collect_variation_indices (this); return hb_empty_t (); }
 static return_t default_return_value () { return hb_empty_t (); }

 hb_set_t *layout_variation_indices;
 const hb_set_t *glyph_set;
 const hb_map_t *gpos_lookups;

 hb_collect_variation_indices_context_t (hb_set_t *layout_variation_indices_,
				  const hb_set_t *glyph_set_,
				  const hb_map_t *gpos_lookups_) :
				layout_variation_indices (layout_variation_indices_),
				glyph_set (glyph_set_),
				gpos_lookups (gpos_lookups_) {}
};

template<typename OutputArray>
struct subset_offset_array_t
{
 subset_offset_array_t (hb_subset_context_t *subset_context_,
		 OutputArray& out_,
		 const void *base_) : subset_context (subset_context_),
				      out (out_), base (base_) {}

 template <typename T>
 bool operator () (T&& offset)
 {
   auto snap = subset_context->serializer->snapshot ();
   auto *o = out.serialize_append (subset_context->serializer);
   if (unlikely (!o)) return false;
   bool ret = o->serialize_subset (subset_context, offset, base);
   if (!ret)
   {
     out.pop ();
     subset_context->serializer->revert (snap);
   }
   return ret;
 }

 private:
 hb_subset_context_t *subset_context;
 OutputArray &out;
 const void *base;
};


template<typename OutputArray, typename Arg>
struct subset_offset_array_arg_t
{
 subset_offset_array_arg_t (hb_subset_context_t *subset_context_,
		     OutputArray& out_,
		     const void *base_,
		     Arg &&arg_) : subset_context (subset_context_), out (out_),
				  base (base_), arg (arg_) {}

 template <typename T>
 bool operator () (T&& offset)
 {
   auto snap = subset_context->serializer->snapshot ();
   auto *o = out.serialize_append (subset_context->serializer);
   if (unlikely (!o)) return false;
   bool ret = o->serialize_subset (subset_context, offset, base, arg);
   if (!ret)
   {
     out.pop ();
     subset_context->serializer->revert (snap);
   }
   return ret;
 }

 private:
 hb_subset_context_t *subset_context;
 OutputArray &out;
 const void *base;
 Arg &&arg;
};

/*
* Helper to subset an array of offsets. Subsets the thing pointed to by each offset
* and discards the offset in the array if the subset operation results in an empty
* thing.
*/
struct
{
 template<typename OutputArray>
 subset_offset_array_t<OutputArray>
 operator () (hb_subset_context_t *subset_context, OutputArray& out,
       const void *base) const
 { return subset_offset_array_t<OutputArray> (subset_context, out, base); }

 /* Variant with one extra argument passed to serialize_subset */
 template<typename OutputArray, typename Arg>
 subset_offset_array_arg_t<OutputArray, Arg>
 operator () (hb_subset_context_t *subset_context, OutputArray& out,
       const void *base, Arg &&arg) const
 { return subset_offset_array_arg_t<OutputArray, Arg> (subset_context, out, base, arg); }
}
HB_FUNCOBJ (subset_offset_array);

template<typename OutputArray>
struct subset_record_array_t
{
 subset_record_array_t (hb_subset_layout_context_t *c_, OutputArray* out_,
		 const void *base_) : subset_layout_context (c_),
				      out (out_), base (base_) {}

 template <typename T>
 void
 operator () (T&& record)
 {
   auto snap = subset_layout_context->subset_context->serializer->snapshot ();
   bool ret = record.subset (subset_layout_context, base);
   if (!ret) subset_layout_context->subset_context->serializer->revert (snap);
   else out->len++;
 }

 private:
 hb_subset_layout_context_t *subset_layout_context;
 OutputArray *out;
 const void *base;
};

template<typename OutputArray, typename Arg>
struct subset_record_array_arg_t
{
 subset_record_array_arg_t (hb_subset_layout_context_t *c_, OutputArray* out_,
		     const void *base_,
		     Arg &&arg_) : subset_layout_context (c_),
				   out (out_), base (base_), arg (arg_) {}

 template <typename T>
 void
 operator () (T&& record)
 {
   auto snap = subset_layout_context->subset_context->serializer->snapshot ();
   bool ret = record.subset (subset_layout_context, base, arg);
   if (!ret) subset_layout_context->subset_context->serializer->revert (snap);
   else out->len++;
 }

 private:
 hb_subset_layout_context_t *subset_layout_context;
 OutputArray *out;
 const void *base;
 Arg &&arg;
};

/*
* Helper to subset a RecordList/record array. Subsets each Record in the array and
* discards the record if the subset operation returns false.
*/
struct
{
 template<typename OutputArray>
 subset_record_array_t<OutputArray>
 operator () (hb_subset_layout_context_t *c, OutputArray* out,
       const void *base) const
 { return subset_record_array_t<OutputArray> (c, out, base); }

 /* Variant with one extra argument passed to subset */
 template<typename OutputArray, typename Arg>
 subset_record_array_arg_t<OutputArray, Arg>
 operator () (hb_subset_layout_context_t *c, OutputArray* out,
              const void *base, Arg &&arg) const
 { return subset_record_array_arg_t<OutputArray, Arg> (c, out, base, arg); }
}
HB_FUNCOBJ (subset_record_array);


template<typename OutputArray>
struct serialize_math_record_array_t
{
 serialize_math_record_array_t (hb_serialize_context_t *serialize_context_,
                        OutputArray& out_,
                        const void *base_) : serialize_context (serialize_context_),
                                             out (out_), base (base_) {}

 template <typename T>
 bool operator () (T&& record)
 {
   if (!serialize_context->copy (record, base)) return false;
   out.len++;
   return true;
 }

 private:
 hb_serialize_context_t *serialize_context;
 OutputArray &out;
 const void *base;
};

/*
* Helper to serialize an array of MATH records.
*/
struct
{
 template<typename OutputArray>
 serialize_math_record_array_t<OutputArray>
 operator () (hb_serialize_context_t *serialize_context, OutputArray& out,
              const void *base) const
 { return serialize_math_record_array_t<OutputArray> (serialize_context, out, base); }

}
HB_FUNCOBJ (serialize_math_record_array);

/*
*
* OpenType Layout Common Table Formats
*
*/


/*
* Script, ScriptList, LangSys, Feature, FeatureList, Lookup, LookupList
*/

struct IndexArray : Array16Of<Index>
{
 bool intersects (const hb_map_t *indexes) const
 { return hb_any (*this, indexes); }

 template <typename Iterator,
    hb_requires (hb_is_iterator (Iterator))>
 void serialize (hb_serialize_context_t *c,
	  hb_subset_layout_context_t *l,
	  Iterator it)
 {
   if (!it) return;
   if (unlikely (!c->extend_min ((*this)))) return;

   for (const auto _ : it)
   {
     if (!l->visitLookupIndex()) break;

     Index i;
     i = _;
     c->copy (i);
     this->len++;
   }
 }

 unsigned int get_indexes (unsigned int start_offset,
		    unsigned int *_count /* IN/OUT */,
		    unsigned int *_indexes /* OUT */) const
 {
   if (_count)
   {
     + this->as_array ().sub_array (start_offset, _count)
     | hb_sink (hb_array (_indexes, *_count))
     ;
   }
   return this->len;
 }

 void add_indexes_to (hb_set_t* output /* OUT */) const
 {
   output->add_array (as_array ());
 }
};


/* https://docs.microsoft.com/en-us/typography/opentype/spec/features_pt#size */
struct FeatureParamsSize
{
 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   if (unlikely (!c->check_struct (this))) return_trace (false);
   hb_barrier ();

   /* This subtable has some "history", if you will.  Some earlier versions of
    * Adobe tools calculated the offset of the FeatureParams subtable from the
    * beginning of the FeatureList table!  Now, that is dealt with in the
    * Feature implementation.  But we still need to be able to tell junk from
    * real data.  Note: We don't check that the nameID actually exists.
    *
    * Read Roberts wrote on 9/15/06 on opentype-list@indx.co.uk :
    *
    * Yes, it is correct that a new version of the AFDKO (version 2.0) will be
    * coming out soon, and that the makeotf program will build a font with a
    * 'size' feature that is correct by the specification.
    *
    * The specification for this feature tag is in the "OpenType Layout Tag
    * Registry". You can see a copy of this at:
    * https://docs.microsoft.com/en-us/typography/opentype/spec/features_pt#tag-size
    *
    * Here is one set of rules to determine if the 'size' feature is built
    * correctly, or as by the older versions of MakeOTF. You may be able to do
    * better.
    *
    * Assume that the offset to the size feature is according to specification,
    * and make the following value checks. If it fails, assume the size
    * feature is calculated as versions of MakeOTF before the AFDKO 2.0 built it.
    * If this fails, reject the 'size' feature. The older makeOTF's calculated the
    * offset from the beginning of the FeatureList table, rather than from the
    * beginning of the 'size' Feature table.
    *
    * If "design size" == 0:
    *     fails check
    *
    * Else if ("subfamily identifier" == 0 and
    *     "range start" == 0 and
    *     "range end" == 0 and
    *     "range start" == 0 and
    *     "menu name ID" == 0)
    *     passes check: this is the format used when there is a design size
    * specified, but there is no recommended size range.
    *
    * Else if ("design size" <  "range start" or
    *     "design size" >   "range end" or
    *     "range end" <= "range start" or
    *     "menu name ID"  < 256 or
    *     "menu name ID"  > 32767 or
    *     menu name ID is not a name ID which is actually in the name table)
    *     fails test
    * Else
    *     passes test.
    */

   if (!designSize)
     return_trace (false);
   else if (subfamilyID == 0 &&
     subfamilyNameID == 0 &&
     rangeStart == 0 &&
     rangeEnd == 0)
     return_trace (true);
   else if (designSize < rangeStart ||
     designSize > rangeEnd ||
     subfamilyNameID < 256 ||
     subfamilyNameID > 32767)
     return_trace (false);
   else
     return_trace (true);
 }

 void collect_name_ids (hb_set_t *nameids_to_retain /* OUT */) const
 { nameids_to_retain->add (subfamilyNameID); }

 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   return_trace ((bool) c->serializer->embed (*this));
 }

 HBUINT16	designSize;	/* Represents the design size in 720/inch
			 * units (decipoints).  The design size entry
			 * must be non-zero.  When there is a design
			 * size but no recommended size range, the
			 * rest of the array will consist of zeros. */
 HBUINT16	subfamilyID;	/* Has no independent meaning, but serves
			 * as an identifier that associates fonts
			 * in a subfamily. All fonts which share a
			 * Preferred or Font Family name and which
			 * differ only by size range shall have the
			 * same subfamily value, and no fonts which
			 * differ in weight or style shall have the
			 * same subfamily value. If this value is
			 * zero, the remaining fields in the array
			 * will be ignored. */
 NameID	subfamilyNameID;/* If the preceding value is non-zero, this
			 * value must be set in the range 256 - 32767
			 * (inclusive). It records the value of a
			 * field in the name table, which must
			 * contain English-language strings encoded
			 * in Windows Unicode and Macintosh Roman,
			 * and may contain additional strings
			 * localized to other scripts and languages.
			 * Each of these strings is the name an
			 * application should use, in combination
			 * with the family name, to represent the
			 * subfamily in a menu.  Applications will
			 * choose the appropriate version based on
			 * their selection criteria. */
 HBUINT16	rangeStart;	/* Large end of the recommended usage range
			 * (inclusive), stored in 720/inch units
			 * (decipoints). */
 HBUINT16	rangeEnd;	/* Small end of the recommended usage range
			   (exclusive), stored in 720/inch units
			 * (decipoints). */
 public:
 DEFINE_SIZE_STATIC (10);
};

/* https://docs.microsoft.com/en-us/typography/opentype/spec/features_pt#ssxx */
struct FeatureParamsStylisticSet
{
 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   /* Right now minorVersion is at zero.  Which means, any table supports
    * the uiNameID field. */
   return_trace (c->check_struct (this));
 }

 void collect_name_ids (hb_set_t *nameids_to_retain /* OUT */) const
 { nameids_to_retain->add (uiNameID); }

 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   return_trace ((bool) c->serializer->embed (*this));
 }

 HBUINT16	version;	/* (set to 0): This corresponds to a “minor”
			 * version number. Additional data may be
			 * added to the end of this Feature Parameters
			 * table in the future. */

 NameID	uiNameID;	/* The 'name' table name ID that specifies a
			 * string (or strings, for multiple languages)
			 * for a user-interface label for this
			 * feature.  The values of uiLabelNameId and
			 * sampleTextNameId are expected to be in the
			 * font-specific name ID range (256-32767),
			 * though that is not a requirement in this
			 * Feature Parameters specification. The
			 * user-interface label for the feature can
			 * be provided in multiple languages. An
			 * English string should be included as a
			 * fallback. The string should be kept to a
			 * minimal length to fit comfortably with
			 * different application interfaces. */
 public:
 DEFINE_SIZE_STATIC (4);
};

/* https://docs.microsoft.com/en-us/typography/opentype/spec/features_ae#cv01-cv99 */
struct FeatureParamsCharacterVariants
{
 unsigned
 get_characters (unsigned start_offset, unsigned *char_count, hb_codepoint_t *chars) const
 {
   if (char_count)
   {
     + characters.as_array ().sub_array (start_offset, char_count)
     | hb_sink (hb_array (chars, *char_count))
     ;
   }
   return characters.len;
 }

 unsigned get_size () const
 { return min_size + characters.len * HBUINT24::static_size; }

 void collect_name_ids (hb_set_t *nameids_to_retain /* OUT */) const
 {
   if (featUILableNameID) nameids_to_retain->add (featUILableNameID);
   if (featUITooltipTextNameID) nameids_to_retain->add (featUITooltipTextNameID);
   if (sampleTextNameID) nameids_to_retain->add (sampleTextNameID);

   if (!firstParamUILabelNameID || !numNamedParameters || numNamedParameters >= 0x7FFF)
     return;

   unsigned last_name_id = (unsigned) firstParamUILabelNameID + (unsigned) numNamedParameters - 1;
   nameids_to_retain->add_range (firstParamUILabelNameID, last_name_id);
 }

 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   return_trace ((bool) c->serializer->embed (*this));
 }

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

 HBUINT16	format;			/* Format number is set to 0. */
 NameID	featUILableNameID;	/* The ‘name’ table name ID that
				 * specifies a string (or strings,
				 * for multiple languages) for a
				 * user-interface label for this
				 * feature. (May be NULL.) */
 NameID	featUITooltipTextNameID;/* The ‘name’ table name ID that
				 * specifies a string (or strings,
				 * for multiple languages) that an
				 * application can use for tooltip
				 * text for this feature. (May be
				 * nullptr.) */
 NameID	sampleTextNameID;	/* The ‘name’ table name ID that
				 * specifies sample text that
				 * illustrates the effect of this
				 * feature. (May be NULL.) */
 HBUINT16	numNamedParameters;	/* Number of named parameters. (May
				 * be zero.) */
 NameID	firstParamUILabelNameID;/* The first ‘name’ table name ID
				 * used to specify strings for
				 * user-interface labels for the
				 * feature parameters. (Must be zero
				 * if numParameters is zero.) */
 Array16Of<HBUINT24>
	characters;		/* Array of the Unicode Scalar Value
				 * of the characters for which this
				 * feature provides glyph variants.
				 * (May be zero.) */
 public:
 DEFINE_SIZE_ARRAY (14, characters);
};

struct FeatureParams
{
 bool sanitize (hb_sanitize_context_t *c, hb_tag_t tag) const
 {
#ifdef HB_NO_LAYOUT_FEATURE_PARAMS
   return true;
#endif
   TRACE_SANITIZE (this);
   if (tag == HB_TAG ('s','i','z','e'))
     return_trace (u.size.sanitize (c));
   if ((tag & 0xFFFF0000u) == HB_TAG ('s','s','\0','\0')) /* ssXX */
     return_trace (u.stylisticSet.sanitize (c));
   if ((tag & 0xFFFF0000u) == HB_TAG ('c','v','\0','\0')) /* cvXX */
     return_trace (u.characterVariants.sanitize (c));
   return_trace (true);
 }

 void collect_name_ids (hb_tag_t tag, hb_set_t *nameids_to_retain /* OUT */) const
 {
#ifdef HB_NO_LAYOUT_FEATURE_PARAMS
   return;
#endif
   if (tag == HB_TAG ('s','i','z','e'))
     return (u.size.collect_name_ids (nameids_to_retain));
   if ((tag & 0xFFFF0000u) == HB_TAG ('s','s','\0','\0')) /* ssXX */
     return (u.stylisticSet.collect_name_ids (nameids_to_retain));
   if ((tag & 0xFFFF0000u) == HB_TAG ('c','v','\0','\0')) /* cvXX */
     return (u.characterVariants.collect_name_ids (nameids_to_retain));
 }

 bool subset (hb_subset_context_t *c, const Tag* tag) const
 {
   TRACE_SUBSET (this);
   if (!tag) return_trace (false);
   if (*tag == HB_TAG ('s','i','z','e'))
     return_trace (u.size.subset (c));
   if ((*tag & 0xFFFF0000u) == HB_TAG ('s','s','\0','\0')) /* ssXX */
     return_trace (u.stylisticSet.subset (c));
   if ((*tag & 0xFFFF0000u) == HB_TAG ('c','v','\0','\0')) /* cvXX */
     return_trace (u.characterVariants.subset (c));
   return_trace (false);
 }

#ifndef HB_NO_LAYOUT_FEATURE_PARAMS
 const FeatureParamsSize& get_size_params (hb_tag_t tag) const
 {
   if (tag == HB_TAG ('s','i','z','e'))
     return u.size;
   return Null (FeatureParamsSize);
 }
 const FeatureParamsStylisticSet& get_stylistic_set_params (hb_tag_t tag) const
 {
   if ((tag & 0xFFFF0000u) == HB_TAG ('s','s','\0','\0')) /* ssXX */
     return u.stylisticSet;
   return Null (FeatureParamsStylisticSet);
 }
 const FeatureParamsCharacterVariants& get_character_variants_params (hb_tag_t tag) const
 {
   if ((tag & 0xFFFF0000u) == HB_TAG ('c','v','\0','\0')) /* cvXX */
     return u.characterVariants;
   return Null (FeatureParamsCharacterVariants);
 }
#endif

 private:
 union {
 FeatureParamsSize			size;
 FeatureParamsStylisticSet		stylisticSet;
 FeatureParamsCharacterVariants	characterVariants;
 } u;
 public:
 DEFINE_SIZE_MIN (0);
};

struct Record_sanitize_closure_t {
 hb_tag_t tag;
 const void *list_base;
};

struct Feature
{
 unsigned int get_lookup_count () const
 { return lookupIndex.len; }
 hb_tag_t get_lookup_index (unsigned int i) const
 { return lookupIndex[i]; }
 unsigned int get_lookup_indexes (unsigned int start_index,
			   unsigned int *lookup_count /* IN/OUT */,
			   unsigned int *lookup_tags /* OUT */) const
 { return lookupIndex.get_indexes (start_index, lookup_count, lookup_tags); }
 void add_lookup_indexes_to (hb_set_t *lookup_indexes) const
 { lookupIndex.add_indexes_to (lookup_indexes); }

 const FeatureParams &get_feature_params () const
 { return this+featureParams; }

 bool intersects_lookup_indexes (const hb_map_t *lookup_indexes) const
 { return lookupIndex.intersects (lookup_indexes); }

 void collect_name_ids (hb_tag_t tag, hb_set_t *nameids_to_retain /* OUT */) const
 {
   if (featureParams)
     get_feature_params ().collect_name_ids (tag, nameids_to_retain);
 }

 bool subset (hb_subset_context_t         *c,
       hb_subset_layout_context_t  *l,
       const Tag                   *tag = nullptr) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

   out->featureParams.serialize_subset (c, featureParams, this, tag);

   auto it =
   + hb_iter (lookupIndex)
   | hb_filter (l->lookup_index_map)
   | hb_map (l->lookup_index_map)
   ;

   out->lookupIndex.serialize (c->serializer, l, it);
   // The decision to keep or drop this feature is already made before we get here
   // so always retain it.
   return_trace (true);
 }

 bool sanitize (hb_sanitize_context_t *c,
	 const Record_sanitize_closure_t *closure = nullptr) const
 {
   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) &&
	  featureParams.sanitize (c, this, closure ? closure->tag : HB_TAG_NONE) &&
	  lookupIndex.sanitize (c));
 }

 Offset16To<FeatureParams>
	 featureParams;	/* Offset to Feature Parameters table (if one
			 * has been defined for the feature), relative
			 * to the beginning of the Feature Table; = Null
			 * if not required */
 IndexArray	 lookupIndex;	/* Array of LookupList indices */
 public:
 DEFINE_SIZE_ARRAY_SIZED (4, lookupIndex);
};

template <typename Type>
struct Record
{
 int cmp (hb_tag_t a) const { return tag.cmp (a); }

 bool subset (hb_subset_layout_context_t *c, const void *base, const void *f_sub = nullptr) const
 {
   TRACE_SUBSET (this);
   auto *out = c->subset_context->serializer->embed (this);
   if (unlikely (!out)) return_trace (false);

   if (!f_sub)
     return_trace (out->offset.serialize_subset (c->subset_context, offset, base, c, &tag));

   const Feature& f = *reinterpret_cast<const Feature *> (f_sub);
   auto *s = c->subset_context->serializer;
   s->push ();

   out->offset = 0;
   bool ret = f.subset (c->subset_context, c, &tag);
   if (ret)
     s->add_link (out->offset, s->pop_pack ());
   else
     s->pop_discard ();

   return_trace (ret);
 }

 bool sanitize (hb_sanitize_context_t *c, const void *base) const
 {
   TRACE_SANITIZE (this);
   const Record_sanitize_closure_t closure = {tag, base};
   return_trace (c->check_struct (this) &&
	  offset.sanitize (c, base, &closure));
 }

 Tag           tag;            /* 4-byte Tag identifier */
 Offset16To<Type>
               offset;         /* Offset from beginning of object holding
                                * the Record */
 public:
 DEFINE_SIZE_STATIC (6);
};

template <typename Type>
struct RecordArrayOf : SortedArray16Of<Record<Type>>
{
 const Offset16To<Type>& get_offset (unsigned int i) const
 { return (*this)[i].offset; }
 Offset16To<Type>& get_offset (unsigned int i)
 { return (*this)[i].offset; }
 const Tag& get_tag (unsigned int i) const
 { return (*this)[i].tag; }
 unsigned int get_tags (unsigned int start_offset,
                        unsigned int *record_count /* IN/OUT */,
                        hb_tag_t     *record_tags /* OUT */) const
 {
   if (record_count)
   {
     + this->as_array ().sub_array (start_offset, record_count)
     | hb_map (&Record<Type>::tag)
     | hb_sink (hb_array (record_tags, *record_count))
     ;
   }
   return this->len;
 }
 bool find_index (hb_tag_t tag, unsigned int *index) const
 {
   return this->bfind (tag, index, HB_NOT_FOUND_STORE, Index::NOT_FOUND_INDEX);
 }
};

template <typename Type>
struct RecordListOf : RecordArrayOf<Type>
{
 const Type& operator [] (unsigned int i) const
 { return this+this->get_offset (i); }

 bool subset (hb_subset_context_t *c,
              hb_subset_layout_context_t *l) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

   + this->iter ()
   | hb_apply (subset_record_array (l, out, this))
   ;
   return_trace (true);
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (RecordArrayOf<Type>::sanitize (c, this));
 }
};

struct RecordListOfFeature : RecordListOf<Feature>
{
 bool subset (hb_subset_context_t *c,
       hb_subset_layout_context_t *l) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

   + hb_enumerate (*this)
   | hb_filter (l->feature_index_map, hb_first)
   | hb_apply ([l, out, this] (const hb_pair_t<unsigned, const Record<Feature>&>& _)
               {
                 const Feature *f_sub = nullptr;
                 const Feature **f = nullptr;
                 if (l->feature_substitutes_map->has (_.first, &f))
                   f_sub = *f;

                 subset_record_array (l, out, this, f_sub) (_.second);
               })
   ;

   return_trace (true);
 }
};

typedef RecordListOf<Feature> FeatureList;


struct LangSys
{
 unsigned int get_feature_count () const
 { return featureIndex.len; }
 hb_tag_t get_feature_index (unsigned int i) const
 { return featureIndex[i]; }
 unsigned int get_feature_indexes (unsigned int start_offset,
			    unsigned int *feature_count /* IN/OUT */,
			    unsigned int *feature_indexes /* OUT */) const
 { return featureIndex.get_indexes (start_offset, feature_count, feature_indexes); }
 void add_feature_indexes_to (hb_set_t *feature_indexes) const
 { featureIndex.add_indexes_to (feature_indexes); }

 bool has_required_feature () const { return reqFeatureIndex != 0xFFFFu; }
 unsigned int get_required_feature_index () const
 {
   if (reqFeatureIndex == 0xFFFFu)
     return Index::NOT_FOUND_INDEX;
  return reqFeatureIndex;
 }

 LangSys* copy (hb_serialize_context_t *c) const
 {
   TRACE_SERIALIZE (this);
   return_trace (c->embed (*this));
 }

 bool compare (const LangSys& o, const hb_map_t *feature_index_map) const
 {
   if (reqFeatureIndex != o.reqFeatureIndex)
     return false;

   auto iter =
   + hb_iter (featureIndex)
   | hb_filter (feature_index_map)
   | hb_map (feature_index_map)
   ;

   auto o_iter =
   + hb_iter (o.featureIndex)
   | hb_filter (feature_index_map)
   | hb_map (feature_index_map)
   ;

   for (; iter && o_iter; iter++, o_iter++)
   {
     unsigned a = *iter;
     unsigned b = *o_iter;
     if (a != b) return false;
   }

   if (iter || o_iter) return false;

   return true;
 }

 void collect_features (hb_prune_langsys_context_t *c) const
 {
   if (!has_required_feature () && !get_feature_count ()) return;
   if (has_required_feature () &&
       c->duplicate_feature_map->has (reqFeatureIndex))
     c->new_feature_indexes->add (get_required_feature_index ());

   + hb_iter (featureIndex)
   | hb_filter (c->duplicate_feature_map)
   | hb_sink (c->new_feature_indexes)
   ;
 }

 bool subset (hb_subset_context_t        *c,
       hb_subset_layout_context_t *l,
       const Tag                  *tag = nullptr) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

   const uint32_t *v;
   out->reqFeatureIndex = l->feature_map_w_duplicates->has (reqFeatureIndex, &v) ? *v : 0xFFFFu;

   if (!l->visitFeatureIndex (featureIndex.len))
     return_trace (false);

   auto it =
   + hb_iter (featureIndex)
   | hb_filter (l->feature_map_w_duplicates)
   | hb_map (l->feature_map_w_duplicates)
   ;

   bool ret = bool (it);
   out->featureIndex.serialize (c->serializer, l, it);
   return_trace (ret);
 }

 bool sanitize (hb_sanitize_context_t *c,
	 const Record_sanitize_closure_t * = nullptr) const
 {
   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) && featureIndex.sanitize (c));
 }

 Offset16	lookupOrderZ;	/* = Null (reserved for an offset to a
			 * reordering table) */
 HBUINT16	reqFeatureIndex;/* Index of a feature required for this
			 * language system--if no required features
			 * = 0xFFFFu */
 IndexArray	featureIndex;	/* Array of indices into the FeatureList */
 public:
 DEFINE_SIZE_ARRAY_SIZED (6, featureIndex);
};
DECLARE_NULL_NAMESPACE_BYTES (OT, LangSys);

struct Script
{
 unsigned int get_lang_sys_count () const
 { return langSys.len; }
 const Tag& get_lang_sys_tag (unsigned int i) const
 { return langSys.get_tag (i); }
 unsigned int get_lang_sys_tags (unsigned int start_offset,
			  unsigned int *lang_sys_count /* IN/OUT */,
			  hb_tag_t     *lang_sys_tags /* OUT */) const
 { return langSys.get_tags (start_offset, lang_sys_count, lang_sys_tags); }
 const LangSys& get_lang_sys (unsigned int i) const
 {
   if (i == Index::NOT_FOUND_INDEX) return get_default_lang_sys ();
   return this+langSys[i].offset;
 }
 bool find_lang_sys_index (hb_tag_t tag, unsigned int *index) const
 { return langSys.find_index (tag, index); }

 bool has_default_lang_sys () const           { return defaultLangSys != 0; }
 const LangSys& get_default_lang_sys () const { return this+defaultLangSys; }

 void prune_langsys (hb_prune_langsys_context_t *c,
                     unsigned script_index) const
 {
   if (!has_default_lang_sys () && !get_lang_sys_count ()) return;
   if (!c->visitScript ()) return;

   if (!c->script_langsys_map->has (script_index))
   {
     if (unlikely (!c->script_langsys_map->set (script_index, hb::unique_ptr<hb_set_t> {hb_set_create ()})))
return;
   }

   if (has_default_lang_sys ())
   {
     //only collect features from non-redundant langsys
     const LangSys& d = get_default_lang_sys ();
     if (c->visitLangsys (d.get_feature_count ())) {
       d.collect_features (c);
     }

     for (auto _ : + hb_enumerate (langSys))
     {
       const LangSys& l = this+_.second.offset;
       if (!c->visitLangsys (l.get_feature_count ())) continue;
       if (l.compare (d, c->duplicate_feature_map)) continue;

       l.collect_features (c);
       c->script_langsys_map->get (script_index)->add (_.first);
     }
   }
   else
   {
     for (auto _ : + hb_enumerate (langSys))
     {
       const LangSys& l = this+_.second.offset;
       if (!c->visitLangsys (l.get_feature_count ())) continue;
       l.collect_features (c);
       c->script_langsys_map->get (script_index)->add (_.first);
     }
   }
 }

 bool subset (hb_subset_context_t         *c,
       hb_subset_layout_context_t  *l,
       const Tag                   *tag) const
 {
   TRACE_SUBSET (this);
   if (!l->visitScript ()) return_trace (false);
   if (tag && !c->plan->layout_scripts.has (*tag))
     return false;

   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

   bool defaultLang = false;
   if (has_default_lang_sys ())
   {
     c->serializer->push ();
     const LangSys& ls = this+defaultLangSys;
     bool ret = ls.subset (c, l);
     if (!ret && tag && *tag != HB_TAG ('D', 'F', 'L', 'T'))
     {
c->serializer->pop_discard ();
out->defaultLangSys = 0;
     }
     else
     {
c->serializer->add_link (out->defaultLangSys, c->serializer->pop_pack ());
defaultLang = true;
     }
   }

   const hb_set_t *active_langsys = l->script_langsys_map->get (l->cur_script_index);
   if (active_langsys)
   {
     + hb_enumerate (langSys)
     | hb_filter (active_langsys, hb_first)
     | hb_map (hb_second)
     | hb_filter ([=] (const Record<LangSys>& record) {return l->visitLangSys (); })
     | hb_apply (subset_record_array (l, &(out->langSys), this))
     ;
   }

   return_trace (bool (out->langSys.len) || defaultLang || l->table_tag == HB_OT_TAG_GSUB);
 }

 bool sanitize (hb_sanitize_context_t *c,
	 const Record_sanitize_closure_t * = nullptr) const
 {
   TRACE_SANITIZE (this);
   return_trace (defaultLangSys.sanitize (c, this) && langSys.sanitize (c, this));
 }

 protected:
 Offset16To<LangSys>
	defaultLangSys;	/* Offset to DefaultLangSys table--from
			 * beginning of Script table--may be Null */
 RecordArrayOf<LangSys>
	langSys;	/* Array of LangSysRecords--listed
			 * alphabetically by LangSysTag */
 public:
 DEFINE_SIZE_ARRAY_SIZED (4, langSys);
};

struct RecordListOfScript : RecordListOf<Script>
{
 bool subset (hb_subset_context_t *c,
              hb_subset_layout_context_t *l) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

   for (auto _ : + hb_enumerate (*this))
   {
     auto snap = c->serializer->snapshot ();
     l->cur_script_index = _.first;
     bool ret = _.second.subset (l, this);
     if (!ret) c->serializer->revert (snap);
     else out->len++;
   }

   return_trace (true);
 }
};

typedef RecordListOfScript ScriptList;



struct LookupFlag : HBUINT16
{
 enum Flags {
   RightToLeft		= 0x0001u,
   IgnoreBaseGlyphs	= 0x0002u,
   IgnoreLigatures	= 0x0004u,
   IgnoreMarks		= 0x0008u,
   IgnoreFlags		= 0x000Eu,
   UseMarkFilteringSet	= 0x0010u,
   Reserved		= 0x00E0u,
   MarkAttachmentType	= 0xFF00u
 };
 public:
 DEFINE_SIZE_STATIC (2);
};

} /* namespace OT */
/* This has to be outside the namespace. */
HB_MARK_AS_FLAG_T (OT::LookupFlag::Flags);
namespace OT {

struct Lookup
{
 unsigned int get_subtable_count () const { return subTable.len; }

 template <typename TSubTable>
 const Array16OfOffset16To<TSubTable>& get_subtables () const
 { return reinterpret_cast<const Array16OfOffset16To<TSubTable> &> (subTable); }
 template <typename TSubTable>
 Array16OfOffset16To<TSubTable>& get_subtables ()
 { return reinterpret_cast<Array16OfOffset16To<TSubTable> &> (subTable); }

 template <typename TSubTable>
 const TSubTable& get_subtable (unsigned int i) const
 { return this+get_subtables<TSubTable> ()[i]; }
 template <typename TSubTable>
 TSubTable& get_subtable (unsigned int i)
 { return this+get_subtables<TSubTable> ()[i]; }

 unsigned int get_size () const
 {
   const HBUINT16 &markFilteringSet = StructAfter<const HBUINT16> (subTable);
   if (lookupFlag & LookupFlag::UseMarkFilteringSet)
     return (const char *) &StructAfter<const char> (markFilteringSet) - (const char *) this;
   return (const char *) &markFilteringSet - (const char *) this;
 }

 unsigned int get_type () const { return lookupType; }

 /* lookup_props is a 32-bit integer where the lower 16-bit is LookupFlag and
  * higher 16-bit is mark-filtering-set if the lookup uses one.
  * Not to be confused with glyph_props which is very similar. */
 uint32_t get_props () const
 {
   unsigned int flag = lookupFlag;
   if (unlikely (flag & LookupFlag::UseMarkFilteringSet))
   {
     const HBUINT16 &markFilteringSet = StructAfter<HBUINT16> (subTable);
     flag += (markFilteringSet << 16);
   }
   return flag;
 }

 template <typename TSubTable, typename context_t, typename ...Ts>
 typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const
 {
   unsigned int lookup_type = get_type ();
   TRACE_DISPATCH (this, lookup_type);
   unsigned int count = get_subtable_count ();
   for (unsigned int i = 0; i < count; i++) {
     typename context_t::return_t r = get_subtable<TSubTable> (i).dispatch (c, lookup_type, ds...);
     if (c->stop_sublookup_iteration (r))
return_trace (r);
   }
   return_trace (c->default_return_value ());
 }

 bool serialize (hb_serialize_context_t *c,
	  unsigned int lookup_type,
	  uint32_t lookup_props,
	  unsigned int num_subtables)
 {
   TRACE_SERIALIZE (this);
   if (unlikely (!c->extend_min (this))) return_trace (false);
   lookupType = lookup_type;
   lookupFlag = lookup_props & 0xFFFFu;
   if (unlikely (!subTable.serialize (c, num_subtables))) return_trace (false);
   if (lookupFlag & LookupFlag::UseMarkFilteringSet)
   {
     if (unlikely (!c->extend (this))) return_trace (false);
     HBUINT16 &markFilteringSet = StructAfter<HBUINT16> (subTable);
     markFilteringSet = lookup_props >> 16;
   }
   return_trace (true);
 }

 template <typename TSubTable>
 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!c->serializer->extend_min (out))) return_trace (false);
   out->lookupType = lookupType;
   out->lookupFlag = lookupFlag;

   const hb_set_t *glyphset = c->plan->glyphset_gsub ();
   unsigned int lookup_type = get_type ();
   + hb_iter (get_subtables <TSubTable> ())
   | hb_filter ([this, glyphset, lookup_type] (const Offset16To<TSubTable> &_) { return (this+_).intersects (glyphset, lookup_type); })
   | hb_apply (subset_offset_array (c, out->get_subtables<TSubTable> (), this, lookup_type))
   ;

   if (lookupFlag & LookupFlag::UseMarkFilteringSet)
   {
     const HBUINT16 &markFilteringSet = StructAfter<HBUINT16> (subTable);
     hb_codepoint_t *idx;
     if (!c->plan->used_mark_sets_map.has (markFilteringSet, &idx))
     {
       unsigned new_flag = lookupFlag;
       new_flag &= ~LookupFlag::UseMarkFilteringSet;
       // https://github.com/harfbuzz/harfbuzz/issues/5499
       // If we remove UseMarkFilteringSet flag because the set is now empty,
       // we need to add IgnoreMarks flag, otherwise the lookup will not
       // ignore any marks, which changes the behavior.
       new_flag |= LookupFlag::IgnoreMarks;
       out->lookupFlag = new_flag;
     }
     else
     {
       if (unlikely (!c->serializer->extend (out))) return_trace (false);
       HBUINT16 &outMarkFilteringSet = StructAfter<HBUINT16> (out->subTable);
       outMarkFilteringSet = *idx;
     }
   }

   // Always keep the lookup even if it's empty. The rest of layout subsetting depends on lookup
   // indices being consistent with those computed during planning. So if an empty lookup is
   // discarded during the subset phase it will invalidate all subsequent lookup indices.
   // Generally we shouldn't end up with an empty lookup as we pre-prune them during the planning
   // phase, but it can happen in rare cases such as when during closure subtable is considered
   // degenerate (see: https://github.com/harfbuzz/harfbuzz/issues/3853)
   return_trace (true);
 }

 template <typename TSubTable>
 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   if (!(c->check_struct (this) && subTable.sanitize (c))) return_trace (false);
   hb_barrier ();

   unsigned subtables = get_subtable_count ();
   if (unlikely (!c->visit_subtables (subtables))) return_trace (false);

   if (lookupFlag & LookupFlag::UseMarkFilteringSet)
   {
     const HBUINT16 &markFilteringSet = StructAfter<HBUINT16> (subTable);
     if (!markFilteringSet.sanitize (c)) return_trace (false);
   }

   if (unlikely (!get_subtables<TSubTable> ().sanitize (c, this, get_type ())))
     return_trace (false);

   if (unlikely (get_type () == TSubTable::Extension))
   {
     hb_barrier ();

     /* The spec says all subtables of an Extension lookup should
      * have the same type, which shall not be the Extension type
      * itself (but we already checked for that).
      * This is specially important if one has a reverse type!
      */
     unsigned int type = get_subtable<TSubTable> (0).u.extension.get_type ();
     for (unsigned int i = 1; i < subtables; i++)
if (get_subtable<TSubTable> (i).u.extension.get_type () != type)
  return_trace (false);
   }
   return_trace (true);
 }

 protected:
 HBUINT16	lookupType;		/* Different enumerations for GSUB and GPOS */
 HBUINT16	lookupFlag;		/* Lookup qualifiers */
 Array16Of<Offset16>
	subTable;		/* Array of SubTables */
/*HBUINT16	markFilteringSetX[HB_VAR_ARRAY];*//* Index (base 0) into GDEF mark glyph sets
				 * structure. This field is only present if bit
				 * UseMarkFilteringSet of lookup flags is set. */
 public:
 DEFINE_SIZE_ARRAY (6, subTable);
};

template <typename Types>
using LookupList = List16OfOffsetTo<Lookup, typename Types::HBUINT>;

template <typename TLookup, typename OffsetType>
struct LookupOffsetList : List16OfOffsetTo<TLookup, OffsetType>
{
 bool subset (hb_subset_context_t        *c,
       hb_subset_layout_context_t *l) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (this);
   if (unlikely (!c->serializer->extend_min (out))) return_trace (false);

   + hb_enumerate (*this)
   | hb_filter (l->lookup_index_map, hb_first)
   | hb_map (hb_second)
   | hb_apply (subset_offset_array (c, *out, this))
   ;
   return_trace (true);
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (List16OfOffset16To<TLookup>::sanitize (c, this));
 }
};


/*
* Coverage Table
*/


static bool ClassDef_remap_and_serialize (hb_serialize_context_t *c,
				  const hb_set_t &klasses,
                                         bool use_class_zero,
                                         hb_sorted_vector_t<hb_codepoint_pair_t> &glyph_and_klass, /* IN/OUT */
				  hb_map_t *klass_map /*IN/OUT*/)
{
 if (!klass_map)
   return ClassDef_serialize (c, glyph_and_klass.iter ());

 /* any glyph not assigned a class value falls into Class zero (0),
  * if any glyph assigned to class 0, remapping must start with 0->0*/
 if (!use_class_zero)
   klass_map->set (0, 0);

 unsigned idx = klass_map->has (0) ? 1 : 0;
 for (const unsigned k: klasses)
 {
   if (klass_map->has (k)) continue;
   klass_map->set (k, idx);
   idx++;
 }


 for (unsigned i = 0; i < glyph_and_klass.length; i++)
 {
   hb_codepoint_t klass = glyph_and_klass[i].second;
   glyph_and_klass[i].second = klass_map->get (klass);
 }

 c->propagate_error (glyph_and_klass, klasses);
 return ClassDef_serialize (c, glyph_and_klass.iter ());
}

/*
* Class Definition Table
*/

template <typename Types>
struct ClassDefFormat1_3
{
 friend struct ClassDef;

 private:
 unsigned int get_class (hb_codepoint_t glyph_id) const
 {
   return classValue[(unsigned int) (glyph_id - startGlyph)];
 }

 unsigned get_population () const
 {
   return classValue.len;
 }

 template<typename Iterator,
   hb_requires (hb_is_sorted_source_of (Iterator, hb_codepoint_t))>
 bool serialize (hb_serialize_context_t *c,
	  Iterator it)
 {
   TRACE_SERIALIZE (this);
   if (unlikely (!c->extend_min (this))) return_trace (false);

   if (unlikely (!it))
   {
     classFormat = 1;
     startGlyph = 0;
     classValue.len = 0;
     return_trace (true);
   }

   hb_codepoint_t glyph_min = (*it).first;
   hb_codepoint_t glyph_max = + it
		       | hb_map (hb_first)
		       | hb_reduce (hb_max, 0u);
   unsigned glyph_count = glyph_max - glyph_min + 1;

   startGlyph = glyph_min;
   if (unlikely (!classValue.serialize (c, glyph_count))) return_trace (false);
   for (const hb_pair_t<hb_codepoint_t, uint32_t> gid_klass_pair : + it)
   {
     unsigned idx = gid_klass_pair.first - glyph_min;
     classValue[idx] = gid_klass_pair.second;
   }
   return_trace (true);
 }

 bool subset (hb_subset_context_t *c,
       hb_map_t *klass_map = nullptr /*OUT*/,
              bool keep_empty_table = true,
              bool use_class_zero = true,
              const Coverage* glyph_filter = nullptr) const
 {
   TRACE_SUBSET (this);
   const hb_map_t &glyph_map = c->plan->glyph_map_gsub;

   hb_sorted_vector_t<hb_codepoint_pair_t> glyph_and_klass;
   hb_set_t orig_klasses;

   hb_codepoint_t start = startGlyph;
   hb_codepoint_t end   = start + classValue.len;

   for (const hb_codepoint_t gid : + hb_range (start, end))
   {
     hb_codepoint_t new_gid = glyph_map[gid];
     if (new_gid == HB_MAP_VALUE_INVALID) continue;
     if (glyph_filter && !glyph_filter->has(gid)) continue;

     unsigned klass = classValue[gid - start];
     if (!klass) continue;

     glyph_and_klass.push (hb_pair (new_gid, klass));
     orig_klasses.add (klass);
   }

   if (use_class_zero)
   {
     unsigned glyph_count = glyph_filter
		     ? hb_len (hb_iter (glyph_map.keys()) | hb_filter (glyph_filter))
		     : glyph_map.get_population ();
     use_class_zero = glyph_count <= glyph_and_klass.length;
   }
   if (!ClassDef_remap_and_serialize (c->serializer,
                                      orig_klasses,
                                      use_class_zero,
                                      glyph_and_klass,
                                      klass_map))
     return_trace (false);
   return_trace (keep_empty_table || (bool) glyph_and_klass);
 }

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

 unsigned cost () const { return 1; }

 template <typename set_t>
 bool collect_coverage (set_t *glyphs) const
 {
   unsigned int start = 0;
   unsigned int count = classValue.len;
   for (unsigned int i = 0; i < count; i++)
   {
     if (classValue[i])
continue;

     if (start != i)
if (unlikely (!glyphs->add_range (startGlyph + start, startGlyph + i)))
  return false;

     start = i + 1;
   }
   if (start != count)
     if (unlikely (!glyphs->add_range (startGlyph + start, startGlyph + count)))
return false;

   return true;
 }

 template <typename set_t>
 bool collect_class (set_t *glyphs, unsigned klass) const
 {
   unsigned int count = classValue.len;
   for (unsigned int i = 0; i < count; i++)
     if (classValue[i] == klass) glyphs->add (startGlyph + i);
   return true;
 }

 bool intersects (const hb_set_t *glyphs) const
 {
   hb_codepoint_t start = startGlyph;
   hb_codepoint_t end = startGlyph + classValue.len;
   for (hb_codepoint_t iter = startGlyph - 1;
 glyphs->next (&iter) && iter < end;)
     if (classValue[iter - start]) return true;
   return false;
 }
 bool intersects_class (const hb_set_t *glyphs, uint16_t klass) const
 {
   unsigned int count = classValue.len;
   if (klass == 0)
   {
     /* Match if there's any glyph that is not listed! */
     hb_codepoint_t g = HB_SET_VALUE_INVALID;
     if (!glyphs->next (&g)) return false;
     if (g < startGlyph) return true;
     g = startGlyph + count - 1;
     if (glyphs->next (&g)) return true;
     /* Fall through. */
   }
   /* TODO Speed up, using set overlap first? */
   /* TODO(iter) Rewrite as dagger. */
   const HBUINT16 *arr = classValue.arrayZ;
   for (unsigned int i = 0; i < count; i++)
     if (arr[i] == klass && glyphs->has (startGlyph + i))
return true;
   return false;
 }

 void intersected_class_glyphs (const hb_set_t *glyphs, unsigned klass, hb_set_t *intersect_glyphs) const
 {
   unsigned count = classValue.len;
   if (klass == 0)
   {
     unsigned start_glyph = startGlyph;
     for (uint32_t g = HB_SET_VALUE_INVALID;
   glyphs->next (&g) && g < start_glyph;)
intersect_glyphs->add (g);

     for (uint32_t g = startGlyph + count - 1;
   glyphs-> next (&g);)
intersect_glyphs->add (g);

     return;
   }

   for (unsigned i = 0; i < count; i++)
     if (classValue[i] == klass && glyphs->has (startGlyph + i))
intersect_glyphs->add (startGlyph + i);

#if 0
   /* The following implementation is faster asymptotically, but slower
    * in practice. */
   unsigned start_glyph = startGlyph;
   unsigned end_glyph = start_glyph + count;
   for (unsigned g = startGlyph - 1;
 glyphs->next (&g) && g < end_glyph;)
     if (classValue.arrayZ[g - start_glyph] == klass)
       intersect_glyphs->add (g);
#endif
 }

 void intersected_classes (const hb_set_t *glyphs, hb_set_t *intersect_classes) const
 {
   if (glyphs->is_empty ()) return;
   hb_codepoint_t end_glyph = startGlyph + classValue.len - 1;
   if (glyphs->get_min () < startGlyph ||
       glyphs->get_max () > end_glyph)
     intersect_classes->add (0);

   for (const auto& _ : + hb_enumerate (classValue))
   {
     hb_codepoint_t g = startGlyph + _.first;
     if (glyphs->has (g))
       intersect_classes->add (_.second);
   }
 }

 protected:
 HBUINT16	classFormat;	/* Format identifier--format = 1 */
 typename Types::HBGlyphID
	 startGlyph;	/* First GlyphID of the classValueArray */
 typename Types::template ArrayOf<HBUINT16>
	classValue;	/* Array of Class Values--one per GlyphID */
 public:
 DEFINE_SIZE_ARRAY (2 + 2 * Types::size, classValue);
};

template <typename Types>
struct ClassDefFormat2_4
{
 friend struct ClassDef;

 private:
 unsigned int get_class (hb_codepoint_t glyph_id) const
 {
   return rangeRecord.bsearch (glyph_id).value;
 }

 unsigned get_population () const
 {
   typename Types::large_int ret = 0;
   for (const auto &r : rangeRecord)
     ret += r.get_population ();
   return ret > UINT_MAX ? UINT_MAX : (unsigned) ret;
 }

 template<typename Iterator,
   hb_requires (hb_is_sorted_source_of (Iterator, hb_codepoint_t))>
 bool serialize (hb_serialize_context_t *c,
	  Iterator it)
 {
   TRACE_SERIALIZE (this);
   if (unlikely (!c->extend_min (this))) return_trace (false);

   if (unlikely (!it))
   {
     classFormat = 2;
     rangeRecord.len = 0;
     return_trace (true);
   }

   unsigned unsorted = false;
   unsigned num_ranges = 1;
   hb_codepoint_t prev_gid = (*it).first;
   unsigned prev_klass = (*it).second;

   RangeRecord<Types> range_rec;
   range_rec.first = prev_gid;
   range_rec.last = prev_gid;
   range_rec.value = prev_klass;

   auto *record = c->copy (range_rec);
   if (unlikely (!record)) return_trace (false);

   for (const auto gid_klass_pair : + (++it))
   {
     hb_codepoint_t cur_gid = gid_klass_pair.first;
     unsigned cur_klass = gid_klass_pair.second;

     if (cur_gid != prev_gid + 1 ||
  cur_klass != prev_klass)
     {

if (unlikely (cur_gid < prev_gid))
  unsorted = true;

if (unlikely (!record)) break;
record->last = prev_gid;
num_ranges++;

range_rec.first = cur_gid;
range_rec.last = cur_gid;
range_rec.value = cur_klass;

record = c->copy (range_rec);
     }

     prev_klass = cur_klass;
     prev_gid = cur_gid;
   }

   if (unlikely (c->in_error ())) return_trace (false);

   if (likely (record)) record->last = prev_gid;
   rangeRecord.len = num_ranges;

   if (unlikely (unsorted))
     rangeRecord.as_array ().qsort (RangeRecord<Types>::cmp_range);

   return_trace (true);
 }

 bool subset (hb_subset_context_t *c,
       hb_map_t *klass_map = nullptr /*OUT*/,
              bool keep_empty_table = true,
              bool use_class_zero = true,
              const Coverage* glyph_filter = nullptr) const
 {
   TRACE_SUBSET (this);
   const hb_map_t &glyph_map = c->plan->glyph_map_gsub;
   const hb_set_t &glyph_set = *c->plan->glyphset_gsub ();

   hb_sorted_vector_t<hb_codepoint_pair_t> glyph_and_klass;
   hb_set_t orig_klasses;

   if (glyph_set.get_population () * hb_bit_storage ((unsigned) rangeRecord.len)
< get_population ())
   {
     for (hb_codepoint_t g : glyph_set)
     {
unsigned klass = get_class (g);
if (!klass) continue;
hb_codepoint_t new_gid = glyph_map[g];
if (new_gid == HB_MAP_VALUE_INVALID) continue;
if (glyph_filter && !glyph_filter->has (g)) continue;
glyph_and_klass.push (hb_pair (new_gid, klass));
orig_klasses.add (klass);
     }
   }
   else
   {
     unsigned num_source_glyphs = c->plan->source->get_num_glyphs ();
     for (auto &range : rangeRecord)
     {
unsigned klass = range.value;
if (!klass) continue;
hb_codepoint_t start = range.first;
hb_codepoint_t end   = hb_min (range.last + 1, num_source_glyphs);
for (hb_codepoint_t g = start; g < end; g++)
{
  hb_codepoint_t new_gid = glyph_map[g];
  if (new_gid == HB_MAP_VALUE_INVALID) continue;
  if (glyph_filter && !glyph_filter->has (g)) continue;

  glyph_and_klass.push (hb_pair (new_gid, klass));
  orig_klasses.add (klass);
}
     }
   }

   const hb_set_t& glyphset = *c->plan->glyphset_gsub ();
   unsigned glyph_count = glyph_filter
                          ? hb_len (hb_iter (glyphset) | hb_filter (glyph_filter))
                          : glyph_map.get_population ();
   use_class_zero = use_class_zero && glyph_count <= glyph_and_klass.length;
   if (!ClassDef_remap_and_serialize (c->serializer,
                                      orig_klasses,
                                      use_class_zero,
                                      glyph_and_klass,
                                      klass_map))
     return_trace (false);
   return_trace (keep_empty_table || (bool) glyph_and_klass);
 }

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

 unsigned cost () const { return hb_bit_storage ((unsigned) rangeRecord.len); /* bsearch cost */ }

 template <typename set_t>
 bool collect_coverage (set_t *glyphs) const
 {
   for (auto &range : rangeRecord)
     if (range.value)
if (unlikely (!range.collect_coverage (glyphs)))
  return false;
   return true;
 }

 template <typename set_t>
 bool collect_class (set_t *glyphs, unsigned int klass) const
 {
   for (auto &range : rangeRecord)
   {
     if (range.value == klass)
if (unlikely (!range.collect_coverage (glyphs)))
  return false;
   }
   return true;
 }

 bool intersects (const hb_set_t *glyphs) const
 {
   if (rangeRecord.len > glyphs->get_population () * hb_bit_storage ((unsigned) rangeRecord.len))
   {
     for (auto g : *glyphs)
       if (get_class (g))
  return true;
     return false;
   }

   return hb_any (+ hb_iter (rangeRecord)
                  | hb_map ([glyphs] (const RangeRecord<Types> &range) { return range.intersects (*glyphs) && range.value; }));
 }
 bool intersects_class (const hb_set_t *glyphs, uint16_t klass) const
 {
   if (klass == 0)
   {
     /* Match if there's any glyph that is not listed! */
     hb_codepoint_t g = HB_SET_VALUE_INVALID;
     hb_codepoint_t last = HB_SET_VALUE_INVALID;
     auto it = hb_iter (rangeRecord);
     for (auto &range : it)
     {
       if (it->first == last + 1)
{
  it++;
  continue;
}

if (!glyphs->next (&g))
  break;
if (g < range.first)
  return true;
g = range.last;
last = g;
     }
     if (g != HB_SET_VALUE_INVALID && glyphs->next (&g))
return true;
     /* Fall through. */
   }
   for (const auto &range : rangeRecord)
     if (range.value == klass && range.intersects (*glyphs))
return true;
   return false;
 }

 void intersected_class_glyphs (const hb_set_t *glyphs, unsigned klass, hb_set_t *intersect_glyphs) const
 {
   if (klass == 0)
   {
     hb_codepoint_t g = HB_SET_VALUE_INVALID;
     for (auto &range : rangeRecord)
     {
if (!glyphs->next (&g))
  goto done;
while (g < range.first)
{
  intersect_glyphs->add (g);
  if (!glyphs->next (&g))
    goto done;
       }
       g = range.last;
     }
     while (glyphs->next (&g))
intersect_glyphs->add (g);
     done:

     return;
   }

   unsigned count = rangeRecord.len;
   if (count > glyphs->get_population () * hb_bit_storage (count))
   {
     for (auto g : *glyphs)
     {
       unsigned i;
       if (rangeRecord.as_array ().bfind (g, &i) &&
    rangeRecord.arrayZ[i].value == klass)
  intersect_glyphs->add (g);
     }
     return;
   }

   for (auto &range : rangeRecord)
   {
     if (range.value != klass) continue;

     unsigned end = range.last + 1;
     for (hb_codepoint_t g = range.first - 1;
   glyphs->next (&g) && g < end;)
intersect_glyphs->add (g);
   }
 }

 void intersected_classes (const hb_set_t *glyphs, hb_set_t *intersect_classes) const
 {
   if (glyphs->is_empty ()) return;

   hb_codepoint_t g = HB_SET_VALUE_INVALID;
   for (auto &range : rangeRecord)
   {
     if (!glyphs->next (&g))
       break;
     if (g < range.first)
     {
       intersect_classes->add (0);
       break;
     }
     g = range.last;
   }
   if (g != HB_SET_VALUE_INVALID && glyphs->next (&g))
     intersect_classes->add (0);

   for (const auto& range : rangeRecord)
     if (range.intersects (*glyphs))
       intersect_classes->add (range.value);
 }

 protected:
 HBUINT16	classFormat;	/* Format identifier--format = 2 */
 typename Types::template SortedArrayOf<RangeRecord<Types>>
	rangeRecord;	/* Array of glyph ranges--ordered by
			 * Start GlyphID */
 public:
 DEFINE_SIZE_ARRAY (2 + Types::size, rangeRecord);
};

struct ClassDef
{
 /* Has interface. */
 unsigned operator [] (hb_codepoint_t k) const { return get (k); }
 bool has (hb_codepoint_t k) const { return (*this)[k]; }
 /* Projection. */
 hb_codepoint_t operator () (hb_codepoint_t k) const { return get (k); }

 unsigned int get (hb_codepoint_t k) const { return get_class (k); }
 unsigned int get_class (hb_codepoint_t glyph_id) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.get_class (glyph_id);
   case 2: hb_barrier (); return u.format2.get_class (glyph_id);
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.get_class (glyph_id);
   case 4: hb_barrier (); return u.format4.get_class (glyph_id);
#endif
   default:return 0;
   }
 }
 unsigned int get_class (hb_codepoint_t glyph_id,
		  hb_ot_layout_mapping_cache_t *cache) const
 {
   unsigned klass;
   if (cache && cache->get (glyph_id, &klass)) return klass;
   klass = get_class (glyph_id);
   if (cache) cache->set (glyph_id, klass);
   return klass;
 }

 unsigned get_population () const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.get_population ();
   case 2: hb_barrier (); return u.format2.get_population ();
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.get_population ();
   case 4: hb_barrier (); return u.format4.get_population ();
#endif
   default:return NOT_COVERED;
   }
 }

 template<typename Iterator,
   hb_requires (hb_is_sorted_source_of (Iterator, hb_codepoint_t))>
 bool serialize (hb_serialize_context_t *c, Iterator it_with_class_zero)
 {
   TRACE_SERIALIZE (this);
   if (unlikely (!c->extend_min (this))) return_trace (false);

   auto it = + it_with_class_zero | hb_filter (hb_second);

   unsigned format = 2;
   hb_codepoint_t glyph_max = 0;
   if (likely (it))
   {
     hb_codepoint_t glyph_min = (*it).first;
     glyph_max = glyph_min;

     unsigned num_glyphs = 0;
     unsigned num_ranges = 1;
     hb_codepoint_t prev_gid = glyph_min;
     unsigned prev_klass = (*it).second;

     for (const auto gid_klass_pair : it)
     {
hb_codepoint_t cur_gid = gid_klass_pair.first;
unsigned cur_klass = gid_klass_pair.second;
       num_glyphs++;
if (cur_gid == glyph_min) continue;
       if (cur_gid > glyph_max) glyph_max = cur_gid;
if (cur_gid != prev_gid + 1 ||
    cur_klass != prev_klass)
  num_ranges++;

prev_gid = cur_gid;
prev_klass = cur_klass;
     }

     if (num_glyphs && 1 + (glyph_max - glyph_min + 1) <= num_ranges * 3)
format = 1;
   }

#ifndef HB_NO_BEYOND_64K
   if (glyph_max > 0xFFFFu)
     u.format.v += 2;
   if (unlikely (glyph_max > 0xFFFFFFu))
#else
   if (unlikely (glyph_max > 0xFFFFu))
#endif
   {
     c->check_success (false, HB_SERIALIZE_ERROR_INT_OVERFLOW);
     return_trace (false);
   }

   u.format.v = format;

   switch (u.format.v)
   {
   case 1: hb_barrier (); return_trace (u.format1.serialize (c, it));
   case 2: hb_barrier (); return_trace (u.format2.serialize (c, it));
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return_trace (u.format3.serialize (c, it));
   case 4: hb_barrier (); return_trace (u.format4.serialize (c, it));
#endif
   default:return_trace (false);
   }
 }

 bool subset (hb_subset_context_t *c,
       hb_map_t *klass_map = nullptr /*OUT*/,
              bool keep_empty_table = true,
              bool use_class_zero = true,
              const Coverage* glyph_filter = nullptr) const
 {
   TRACE_SUBSET (this);
   switch (u.format.v) {
   case 1: hb_barrier (); return_trace (u.format1.subset (c, klass_map, keep_empty_table, use_class_zero, glyph_filter));
   case 2: hb_barrier (); return_trace (u.format2.subset (c, klass_map, keep_empty_table, use_class_zero, glyph_filter));
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return_trace (u.format3.subset (c, klass_map, keep_empty_table, use_class_zero, glyph_filter));
   case 4: hb_barrier (); return_trace (u.format4.subset (c, klass_map, keep_empty_table, use_class_zero, glyph_filter));
#endif
   default:return_trace (false);
   }
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   if (!u.format.v.sanitize (c)) return_trace (false);
   hb_barrier ();
   switch (u.format.v) {
   case 1: hb_barrier (); return_trace (u.format1.sanitize (c));
   case 2: hb_barrier (); return_trace (u.format2.sanitize (c));
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return_trace (u.format3.sanitize (c));
   case 4: hb_barrier (); return_trace (u.format4.sanitize (c));
#endif
   default:return_trace (true);
   }
 }

 unsigned cost () const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.cost ();
   case 2: hb_barrier (); return u.format2.cost ();
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.cost ();
   case 4: hb_barrier (); return u.format4.cost ();
#endif
   default:return 0u;
   }
 }

 /* Might return false if array looks unsorted.
  * Used for faster rejection of corrupt data. */
 template <typename set_t>
 bool collect_coverage (set_t *glyphs) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.collect_coverage (glyphs);
   case 2: hb_barrier (); return u.format2.collect_coverage (glyphs);
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.collect_coverage (glyphs);
   case 4: hb_barrier (); return u.format4.collect_coverage (glyphs);
#endif
   default:return false;
   }
 }

 /* Might return false if array looks unsorted.
  * Used for faster rejection of corrupt data. */
 template <typename set_t>
 bool collect_class (set_t *glyphs, unsigned int klass) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.collect_class (glyphs, klass);
   case 2: hb_barrier (); return u.format2.collect_class (glyphs, klass);
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.collect_class (glyphs, klass);
   case 4: hb_barrier (); return u.format4.collect_class (glyphs, klass);
#endif
   default:return false;
   }
 }

 bool intersects (const hb_set_t *glyphs) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.intersects (glyphs);
   case 2: hb_barrier (); return u.format2.intersects (glyphs);
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.intersects (glyphs);
   case 4: hb_barrier (); return u.format4.intersects (glyphs);
#endif
   default:return false;
   }
 }
 bool intersects_class (const hb_set_t *glyphs, unsigned int klass) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.intersects_class (glyphs, klass);
   case 2: hb_barrier (); return u.format2.intersects_class (glyphs, klass);
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.intersects_class (glyphs, klass);
   case 4: hb_barrier (); return u.format4.intersects_class (glyphs, klass);
#endif
   default:return false;
   }
 }

 void intersected_class_glyphs (const hb_set_t *glyphs, unsigned klass, hb_set_t *intersect_glyphs) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.intersected_class_glyphs (glyphs, klass, intersect_glyphs);
   case 2: hb_barrier (); return u.format2.intersected_class_glyphs (glyphs, klass, intersect_glyphs);
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.intersected_class_glyphs (glyphs, klass, intersect_glyphs);
   case 4: hb_barrier (); return u.format4.intersected_class_glyphs (glyphs, klass, intersect_glyphs);
#endif
   default:return;
   }
 }

 void intersected_classes (const hb_set_t *glyphs, hb_set_t *intersect_classes) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.intersected_classes (glyphs, intersect_classes);
   case 2: hb_barrier (); return u.format2.intersected_classes (glyphs, intersect_classes);
#ifndef HB_NO_BEYOND_64K
   case 3: hb_barrier (); return u.format3.intersected_classes (glyphs, intersect_classes);
   case 4: hb_barrier (); return u.format4.intersected_classes (glyphs, intersect_classes);
#endif
   default:return;
   }
 }


 protected:
 union {
 struct { HBUINT16 v; }	format;		/* Format identifier */
 ClassDefFormat1_3<SmallTypes>	format1;
 ClassDefFormat2_4<SmallTypes>	format2;
#ifndef HB_NO_BEYOND_64K
 ClassDefFormat1_3<MediumTypes>format3;
 ClassDefFormat2_4<MediumTypes>format4;
#endif
 } u;
 public:
 DEFINE_SIZE_UNION (2, format.v);
};

template<typename Iterator>
static inline bool ClassDef_serialize (hb_serialize_context_t *c,
			       Iterator it)
{ return (c->start_embed<ClassDef> ()->serialize (c, it)); }


/*
* Item Variation Store
*/

/* ported from fonttools (class _Encoding) */
struct delta_row_encoding_t
{
 /* each byte represents a region, value is one of 0/1/2/4, which means bytes
  * needed for this region */
 struct chars_t : hb_vector_t<uint8_t>
 {
   int cmp (const chars_t& other) const
   {
     return as_array ().cmp (other.as_array ());
   }

   hb_pair_t<unsigned, unsigned> get_width ()
   {
     unsigned width = 0;
     unsigned columns = 0;
     for (unsigned i = 0; i < length; i++)
     {
unsigned v = arrayZ[i];
width += v;
columns += (v != 0);
     }
     return hb_pair (width, columns);
   }

   HB_HOT
   hb_pair_t<unsigned, unsigned> combine_width (const chars_t& other) const
   {
     unsigned combined_width = 0;
     unsigned combined_columns = 0;
     for (unsigned i = 0; i < length; i++)
     {
       unsigned v = hb_max (arrayZ[i], other.arrayZ[i]);
combined_width += v;
combined_columns += (v != 0);
     }
     return hb_pair (combined_width, combined_columns);
   }
 };

 hb_pair_t<unsigned, unsigned> combine_width (const delta_row_encoding_t& other_encoding) const { return chars.combine_width (other_encoding.chars); }

 // Actual data

 chars_t chars;
 unsigned width = 0;
 unsigned overhead = 0;
 hb_vector_t<const hb_vector_t<int>*> items;

 delta_row_encoding_t () = default;
 delta_row_encoding_t (hb_vector_t<const hb_vector_t<int>*> &&rows, unsigned num_cols)
 {
   assert (rows);

   items = std::move (rows);

   if (unlikely (!chars.resize (num_cols)))
     return;

   calculate_chars ();
 }

 void merge (const delta_row_encoding_t& other)
 {
   items.alloc (items.length + other.items.length);
   for (auto &row : other.items)
     add_row (row);

   // Merge chars
   assert (chars.length == other.chars.length);
   for (unsigned i = 0; i < chars.length; i++)
     chars.arrayZ[i] = hb_max (chars.arrayZ[i], other.chars.arrayZ[i]);
   chars_changed ();
 }

 void chars_changed ()
 {
   auto _ = chars.get_width ();
   width = _.first;
   overhead = get_chars_overhead (_.second);
 }

 void calculate_chars ()
 {
   assert (items);

   bool long_words = false;

   for (auto &row : items)
   {
     assert (row->length == chars.length);

     /* 0/1/2 byte encoding */
     for (unsigned i = 0; i < row->length; i++)
     {
int v =  row->arrayZ[i];
if (v == 0)
  continue;
else if (v > 32767 || v < -32768)
{
  long_words = true;
  chars.arrayZ[i] = hb_max (chars.arrayZ[i], 4);
}
else if (v > 127 || v < -128)
  chars.arrayZ[i] = hb_max (chars.arrayZ[i], 2);
else
  chars.arrayZ[i] = hb_max (chars.arrayZ[i], 1);
     }
   }

   if (long_words)
   {
     // Convert 1s to 2s
     for (auto &v : chars)
if (v == 1)
  v = 2;
   }

   chars_changed ();
 }

 bool is_empty () const
 { return !items; }

 static inline unsigned get_chars_overhead (unsigned num_columns)
 {
   unsigned c = 4 + 6; // 4 bytes for LOffset, 6 bytes for VarData header
   return c + num_columns * 2;
 }

 unsigned get_gain (unsigned additional_bytes_per_rows = 1) const
 {
   int count = items.length;
   return hb_max (0, (int) overhead - count * (int) additional_bytes_per_rows);
 }

 int gain_from_merging (const delta_row_encoding_t& other_encoding) const
 {
   // Back of the envelope calculations to reject early.
   signed additional_bytes_per_rows = other_encoding.width - width;
   if (additional_bytes_per_rows > 0)
   {
     if (get_gain (additional_bytes_per_rows) == 0)
       return 0;
   }
   else
   {
     if (other_encoding.get_gain (-additional_bytes_per_rows) == 0)
return 0;
   }

   auto pair = combine_width (other_encoding);
   unsigned combined_width = pair.first;
   unsigned combined_columns = pair.second;

   int combined_gain = (int) overhead + (int) other_encoding.overhead;
   combined_gain -= (combined_width - (int) width) * items.length;
   combined_gain -= (combined_width - (int) other_encoding.width) * other_encoding.items.length;
   combined_gain -= get_chars_overhead (combined_columns);

   return combined_gain;
 }

 bool add_row (const hb_vector_t<int>* row)
 { return items.push (row); }

 static int cmp (const void *pa, const void *pb)
 {
   const delta_row_encoding_t *a = (const delta_row_encoding_t *)pa;
   const delta_row_encoding_t *b = (const delta_row_encoding_t *)pb;

   if (a->width != b->width)
     return (int) a->width - (int) b->width;

   return b->chars.cmp (a->chars);
 }
};

struct VarRegionAxis
{
 float evaluate (int coord) const
 {
   int peak = peakCoord.to_int ();
   if (peak == 0 || coord == peak)
     return 1.f;
   else if (coord == 0) // Faster
     return 0.f;

   int start = startCoord.to_int (), end = endCoord.to_int ();

   /* TODO Move these to sanitize(). */
   if (unlikely (start > peak || peak > end))
     return 1.f;
   if (unlikely (start < 0 && end > 0 && peak != 0))
     return 1.f;

   if (coord <= start || end <= coord)
     return 0.f;

   /* Interpolate */
   if (coord < peak)
     return float (coord - start) / (peak - start);
   else
     return float (end - coord) / (end - peak);
 }

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

 bool serialize (hb_serialize_context_t *c) const
 {
   TRACE_SERIALIZE (this);
   return_trace (c->embed (this));
 }

 public:
 F2DOT14	startCoord;
 F2DOT14	peakCoord;
 F2DOT14	endCoord;
 public:
 DEFINE_SIZE_STATIC (6);
};
struct SparseVarRegionAxis
{
 float evaluate (const int *coords, unsigned int coord_len) const
 {
   unsigned i = axisIndex;
   int coord = i < coord_len ? coords[i] : 0;
   return axis.evaluate (coord);
 }

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

 bool serialize (hb_serialize_context_t *c) const
 {
   TRACE_SERIALIZE (this);
   return_trace (c->embed (this));
 }

 public:
 HBUINT16 axisIndex;
 VarRegionAxis axis;
 public:
 DEFINE_SIZE_STATIC (8);
};

struct hb_scalar_cache_t
{
 private:
 static constexpr unsigned STATIC_LENGTH = 16;
 static constexpr int INVALID = INT_MIN;
 static constexpr float MULTIPLIER = 1 << ((sizeof (int) * 8) - 2);
 static constexpr float DIVISOR = 1.f / MULTIPLIER;

 public:
 hb_scalar_cache_t () : length (STATIC_LENGTH) { clear (); }

 hb_scalar_cache_t (const hb_scalar_cache_t&) = delete;
 hb_scalar_cache_t (hb_scalar_cache_t&&) = delete;
 hb_scalar_cache_t& operator= (const hb_scalar_cache_t&) = delete;
 hb_scalar_cache_t& operator= (hb_scalar_cache_t&&) = delete;

 static hb_scalar_cache_t *create (unsigned int count,
			    hb_scalar_cache_t *scratch_cache = nullptr)
 {
   if (!count) return (hb_scalar_cache_t *) &Null(hb_scalar_cache_t);

   if (scratch_cache && count <= scratch_cache->length)
   {
     scratch_cache->clear ();
     return scratch_cache;
   }

   auto *cache = (hb_scalar_cache_t *) hb_malloc (sizeof (hb_scalar_cache_t) - sizeof (static_values) + sizeof (static_values[0]) * count);
   if (unlikely (!cache)) return (hb_scalar_cache_t *) &Null(hb_scalar_cache_t);

   cache->length = count;
   cache->clear ();

   return cache;
 }

 static void destroy (hb_scalar_cache_t *cache,
	       hb_scalar_cache_t *scratch_cache = nullptr)
 {
   if (cache != &Null(hb_scalar_cache_t) && cache != scratch_cache)
     hb_free (cache);
 }

 void clear ()
 {
   auto *values = &static_values[0];
   unsigned i = 0;
#ifndef HB_OPTIMIZE_SIZE
   for (; i + 3 < length; i += 4)
   {
     values[i + 0] = INVALID;
     values[i + 1] = INVALID;
     values[i + 2] = INVALID;
     values[i + 3] = INVALID;
   }
#endif
   for (; i < length; i++)
     values[i] = INVALID;
 }

 HB_ALWAYS_INLINE
 bool get (unsigned i, float *value) const
 {
   if (unlikely (i >= length))
   {
     *value = 0.f;
     return true;
   }
   auto *values = &static_values[0];
   auto *cached_value = &values[i];
   // Super hot. Most common path is that we have a cached value of 0.
   int v = *cached_value;
   if (likely (!v))
   {
     *value = 0.f;
     return true;
   }
   if (v == INVALID)
     return false;
   *value = v * DIVISOR;
   return true;
 }

 HB_ALWAYS_INLINE
 void set (unsigned i, float value)
 {
   if (unlikely (i >= length)) return;
   auto *values = &static_values[0];
   auto *cached_value = &values[i];
   *cached_value = roundf(value * MULTIPLIER);
 }

 private:
 unsigned length;
 mutable hb_atomic_t<int> static_values[STATIC_LENGTH];
};

struct VarRegionList
{
 private:
 float evaluate_impl (unsigned int region_index,
	       const int *coords, unsigned int coord_len) const
 {
   const VarRegionAxis *axes = axesZ.arrayZ + (region_index * axisCount);
   float v = 1.f;

   unsigned int count = axisCount;
   for (unsigned int i = 0; i < count; i++)
   {
     int coord = i < coord_len ? coords[i] : 0;
     float factor = axes[i].evaluate (coord);
     if (factor == 0.f)
     {
v = 0.f;
break;
     }
     v *= factor;
   }

   return v;
 }

 public:
 HB_ALWAYS_INLINE
 float evaluate (unsigned int region_index,
	  const int *coords, unsigned int coord_len,
	  hb_scalar_cache_t *cache = nullptr) const
 {
   if (unlikely (region_index >= regionCount))
     return 0.;

   float v;
   if (cache && cache->get (region_index, &v))
     return v;

   v = evaluate_impl (region_index, coords, coord_len);

   if (cache)
     cache->set (region_index, v);
   return v;
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) &&
	  hb_barrier () &&
	  axesZ.sanitize (c, axisCount * regionCount));
 }

 bool serialize (hb_serialize_context_t *c,
                 const hb_vector_t<hb_tag_t>& axis_tags,
                 const hb_vector_t<const hb_hashmap_t<hb_tag_t, Triple>*>& regions)
 {
   TRACE_SERIALIZE (this);
   unsigned axis_count = axis_tags.length;
   unsigned region_count = regions.length;
   if (!axis_count || !region_count) return_trace (false);
   if (unlikely (hb_unsigned_mul_overflows (axis_count * region_count,
                                            VarRegionAxis::static_size))) return_trace (false);
   if (unlikely (!c->extend_min (this))) return_trace (false);
   axisCount = axis_count;
   regionCount = region_count;

   for (unsigned r = 0; r < region_count; r++)
   {
     const auto& region = regions[r];
     for (unsigned i = 0; i < axis_count; i++)
     {
       hb_tag_t tag = axis_tags.arrayZ[i];
       VarRegionAxis var_region_rec;
       Triple *coords;
       if (region->has (tag, &coords))
       {
         var_region_rec.startCoord.set_float (coords->minimum);
         var_region_rec.peakCoord.set_float (coords->middle);
         var_region_rec.endCoord.set_float (coords->maximum);
       }
       else
       {
         var_region_rec.startCoord.set_int (0);
         var_region_rec.peakCoord.set_int (0);
         var_region_rec.endCoord.set_int (0);
       }
       if (!var_region_rec.serialize (c))
         return_trace (false);
     }
   }
   return_trace (true);
 }

 bool serialize (hb_serialize_context_t *c, const VarRegionList *src, const hb_inc_bimap_t &region_map)
 {
   TRACE_SERIALIZE (this);
   if (unlikely (!c->extend_min (this))) return_trace (false);
   axisCount = src->axisCount;
   regionCount = region_map.get_population ();
   if (unlikely (hb_unsigned_mul_overflows (axisCount * regionCount,
				     VarRegionAxis::static_size))) return_trace (false);
   if (unlikely (!c->extend (this))) return_trace (false);
   unsigned int region_count = src->regionCount;
   for (unsigned int r = 0; r < regionCount; r++)
   {
     unsigned int backward = region_map.backward (r);
     if (backward >= region_count) return_trace (false);
     hb_memcpy (&axesZ[axisCount * r], &src->axesZ[axisCount * backward], VarRegionAxis::static_size * axisCount);
   }

   return_trace (true);
 }

 bool get_var_region (unsigned region_index,
                      const hb_map_t& axes_old_index_tag_map,
                      hb_hashmap_t<hb_tag_t, Triple>& axis_tuples /* OUT */) const
 {
   if (region_index >= regionCount) return false;
   const VarRegionAxis* axis_region = axesZ.arrayZ + (region_index * axisCount);
   for (unsigned i = 0; i < axisCount; i++)
   {
     hb_tag_t *axis_tag;
     if (!axes_old_index_tag_map.has (i, &axis_tag))
       return false;

     float min_val = axis_region->startCoord.to_float ();
     float def_val = axis_region->peakCoord.to_float ();
     float max_val = axis_region->endCoord.to_float ();

     if (def_val != 0.f)
       axis_tuples.set (*axis_tag, Triple ((double) min_val, (double) def_val, (double) max_val));
     axis_region++;
   }
   return !axis_tuples.in_error ();
 }

 bool get_var_regions (const hb_map_t& axes_old_index_tag_map,
                       hb_vector_t<hb_hashmap_t<hb_tag_t, Triple>>& regions /* OUT */) const
 {
   if (!regions.alloc (regionCount))
     return false;

   for (unsigned i = 0; i < regionCount; i++)
   {
     hb_hashmap_t<hb_tag_t, Triple> axis_tuples;
     if (!get_var_region (i, axes_old_index_tag_map, axis_tuples))
       return false;
     regions.push (std::move (axis_tuples));
   }
   return !regions.in_error ();
 }

 unsigned int get_size () const { return min_size + VarRegionAxis::static_size * axisCount * regionCount; }

 public:
 HBUINT16	axisCount;
 HBUINT15	regionCount;
 protected:
 UnsizedArrayOf<VarRegionAxis>
	axesZ;
 public:
 DEFINE_SIZE_ARRAY (4, axesZ);
};

struct SparseVariationRegion : Array16Of<SparseVarRegionAxis>
{
 float evaluate (const int *coords, unsigned int coord_len) const
 {
   float v = 1.f;
   unsigned int count = len;
   for (unsigned int i = 0; i < count; i++)
   {
     float factor = arrayZ[i].evaluate (coords, coord_len);
     if (factor == 0.f)
return 0.;
     v *= factor;
   }
   return v;
 }
};

struct SparseVarRegionList
{
 HB_ALWAYS_INLINE
 float evaluate (unsigned int region_index,
	  const int *coords, unsigned int coord_len,
	  hb_scalar_cache_t *cache = nullptr) const
 {
   if (unlikely (region_index >= regions.len))
     return 0.;

   float v;
   if (cache && cache->get (region_index, &v))
     return v;

   const SparseVariationRegion &region = this+regions[region_index];

   v = region.evaluate (coords, coord_len);
   if (cache)
     cache->set (region_index, v);

   return v;
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (regions.sanitize (c, this));
 }

 public:
 Array16Of<Offset32To<SparseVariationRegion>>
	regions;
 public:
 DEFINE_SIZE_ARRAY (2, regions);
};


struct VarData
{
 unsigned int get_item_count () const
 { return itemCount; }

 unsigned int get_region_index_count () const
 { return regionIndices.len; }

 unsigned get_region_index (unsigned i) const
 { return i >= regionIndices.len ? -1 : regionIndices[i]; }

 unsigned int get_row_size () const
 { return (wordCount () + regionIndices.len) * (longWords () ? 2 : 1); }

 unsigned int get_size () const
 { return min_size
 - regionIndices.min_size + regionIndices.get_size ()
 + itemCount * get_row_size ();
 }

 float _get_delta (unsigned int inner,
	    const int *coords, unsigned int coord_count,
	    const VarRegionList &regions,
	    hb_scalar_cache_t *cache = nullptr) const
 {
   if (unlikely (inner >= itemCount))
     return 0.;
   bool is_long = longWords ();
   unsigned int count = regionIndices.len;
   unsigned word_count = wordCount ();
   unsigned int scount = is_long ? count : word_count;
   unsigned int lcount = is_long ? word_count : 0;

   const HBUINT8 *bytes = get_delta_bytes ();
   const HBUINT8 *row = bytes + inner * get_row_size ();

   float delta = 0.;
   unsigned int i = 0;

   const HBINT32 *lcursor = reinterpret_cast<const HBINT32 *> (row);
   for (; i < lcount; i++)
   {
     float scalar = regions.evaluate (regionIndices.arrayZ[i], coords, coord_count, cache);
     if (scalar)
       delta += scalar * *lcursor;
     lcursor++;
   }
   const HBINT16 *scursor = reinterpret_cast<const HBINT16 *> (lcursor);
   for (; i < scount; i++)
   {
     float scalar = regions.evaluate (regionIndices.arrayZ[i], coords, coord_count, cache);
     if (scalar)
      delta += scalar * *scursor;
     scursor++;
   }
   const HBINT8 *bcursor = reinterpret_cast<const HBINT8 *> (scursor);
   for (; i < count; i++)
   {
     float scalar = regions.evaluate (regionIndices.arrayZ[i], coords, coord_count, cache);
     if (scalar)
       delta += scalar * *bcursor;
     bcursor++;
   }

   return delta;
 }

 HB_ALWAYS_INLINE
 float get_delta (unsigned int inner,
	   const int *coords, unsigned int coord_count,
	   const VarRegionList &regions,
	   hb_scalar_cache_t *cache = nullptr) const
 {
   unsigned int count = regionIndices.len;
   if (!count) return 0.f; // This is quite common, so optimize it.
   return _get_delta (inner, coords, coord_count, regions, cache);
 }

 void get_region_scalars (const int *coords, unsigned int coord_count,
		   const VarRegionList &regions,
		   float *scalars /*OUT */,
		   unsigned int num_scalars) const
 {
   unsigned count = hb_min (num_scalars, regionIndices.len);
   for (unsigned int i = 0; i < count; i++)
     scalars[i] = regions.evaluate (regionIndices.arrayZ[i], coords, coord_count);
   for (unsigned int i = count; i < num_scalars; i++)
     scalars[i] = 0.f;
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) &&
	  regionIndices.sanitize (c) &&
	  hb_barrier () &&
	  wordCount () <= regionIndices.len &&
	  c->check_range (get_delta_bytes (),
			  itemCount,
			  get_row_size ()));
 }

 bool serialize (hb_serialize_context_t *c,
                 bool has_long,
                 const hb_vector_t<const hb_vector_t<int>*>& rows)
 {
   TRACE_SERIALIZE (this);
   unsigned row_count = rows.length;
   if (!row_count) {
     // Nothing to serialize, will be empty.
     return false;
   }

   if (unlikely (!c->extend_min (this))) return_trace (false);
   itemCount = row_count;

   int min_threshold = has_long ? -65536 : -128;
   int max_threshold = has_long ? +65535 : +127;
   enum delta_size_t { kZero=0, kNonWord, kWord };
   hb_vector_t<delta_size_t> delta_sz;
   unsigned num_regions = rows[0]->length;
   if (!delta_sz.resize (num_regions))
     return_trace (false);

   unsigned word_count = 0;
   for (unsigned r = 0; r < num_regions; r++)
   {
     for (unsigned i = 0; i < row_count; i++)
     {
       int delta = rows[i]->arrayZ[r];
       if (delta < min_threshold || delta > max_threshold)
       {
         delta_sz[r] = kWord;
         word_count++;
         break;
       }
       else if (delta != 0)
       {
         delta_sz[r] = kNonWord;
       }
     }
   }

   /* reorder regions: words and then non-words*/
   unsigned word_index = 0;
   unsigned non_word_index = word_count;
   hb_map_t ri_map;
   for (unsigned r = 0; r < num_regions; r++)
   {
     if (!delta_sz[r]) continue;
     unsigned new_r = (delta_sz[r] == kWord)? word_index++ : non_word_index++;
     if (!ri_map.set (new_r, r))
       return_trace (false);
   }

   wordSizeCount = word_count | (has_long ? 0x8000u /* LONG_WORDS */ : 0);

   unsigned ri_count = ri_map.get_population ();
   regionIndices.len = ri_count;
   if (unlikely (!c->extend (this))) return_trace (false);

   for (unsigned r = 0; r < ri_count; r++)
   {
     hb_codepoint_t *idx;
     if (!ri_map.has (r, &idx))
       return_trace (false);
     regionIndices[r] = *idx;
   }

   HBUINT8 *delta_bytes = get_delta_bytes ();
   unsigned row_size = get_row_size ();
   for (unsigned int i = 0; i < row_count; i++)
   {
     for (unsigned int r = 0; r < ri_count; r++)
     {
       int delta = rows[i]->arrayZ[ri_map[r]];
       set_item_delta_fast (i, r, delta, delta_bytes, row_size);
     }
   }
   return_trace (true);
 }

 bool serialize (hb_serialize_context_t *c,
	  const VarData *src,
	  const hb_inc_bimap_t &inner_map,
	  const hb_inc_bimap_t &region_map)
 {
   TRACE_SERIALIZE (this);
   if (unlikely (!c->extend_min (this))) return_trace (false);
   itemCount = inner_map.get_next_value ();

   /* Optimize word count */
   unsigned ri_count = src->regionIndices.len;
   enum delta_size_t { kZero=0, kNonWord, kWord };
   hb_vector_t<delta_size_t> delta_sz;
   hb_vector_t<unsigned int> ri_map;	/* maps new index to old index */
   delta_sz.resize (ri_count);
   ri_map.resize (ri_count);
   unsigned int new_word_count = 0;
   unsigned int r;

   const HBUINT8 *src_delta_bytes = src->get_delta_bytes ();
   unsigned src_row_size = src->get_row_size ();
   unsigned src_word_count = src->wordCount ();
   bool     src_long_words = src->longWords ();

   bool has_long = false;
   if (src_long_words)
   {
     for (r = 0; r < src_word_count; r++)
     {
       for (unsigned old_gid : inner_map.keys())
{
  int32_t delta = src->get_item_delta_fast (old_gid, r, src_delta_bytes, src_row_size);
  if (delta < -65536 || 65535 < delta)
  {
    has_long = true;
    break;
  }
       }
     }
   }

   signed min_threshold = has_long ? -65536 : -128;
   signed max_threshold = has_long ? +65535 : +127;
   for (r = 0; r < ri_count; r++)
   {
     bool short_circuit = src_long_words == has_long && src_word_count <= r;

     delta_sz[r] = kZero;
     for (unsigned old_gid : inner_map.keys())
     {
int32_t delta = src->get_item_delta_fast (old_gid, r, src_delta_bytes, src_row_size);
if (delta < min_threshold || max_threshold < delta)
{
  delta_sz[r] = kWord;
  new_word_count++;
  break;
}
else if (delta != 0)
{
  delta_sz[r] = kNonWord;
  if (short_circuit)
    break;
}
     }
   }

   unsigned int word_index = 0;
   unsigned int non_word_index = new_word_count;
   unsigned int new_ri_count = 0;
   for (r = 0; r < ri_count; r++)
     if (delta_sz[r])
     {
unsigned new_r = (delta_sz[r] == kWord)? word_index++ : non_word_index++;
ri_map[new_r] = r;
new_ri_count++;
     }

   wordSizeCount = new_word_count | (has_long ? 0x8000u /* LONG_WORDS */ : 0);

   regionIndices.len = new_ri_count;

   if (unlikely (!c->extend (this))) return_trace (false);

   for (r = 0; r < new_ri_count; r++)
     regionIndices[r] = region_map[src->regionIndices[ri_map[r]]];

   HBUINT8 *delta_bytes = get_delta_bytes ();
   unsigned row_size = get_row_size ();
   unsigned count = itemCount;
   for (unsigned int i = 0; i < count; i++)
   {
     unsigned int old = inner_map.backward (i);
     for (unsigned int r = 0; r < new_ri_count; r++)
set_item_delta_fast (i, r,
		     src->get_item_delta_fast (old, ri_map[r],
					       src_delta_bytes, src_row_size),
		     delta_bytes, row_size);
   }

   return_trace (true);
 }

 void collect_region_refs (hb_set_t &region_indices, const hb_inc_bimap_t &inner_map) const
 {
   const HBUINT8 *delta_bytes = get_delta_bytes ();
   unsigned row_size = get_row_size ();

   for (unsigned int r = 0; r < regionIndices.len; r++)
   {
     unsigned int region = regionIndices.arrayZ[r];
     if (region_indices.has (region)) continue;
     for (hb_codepoint_t old_gid : inner_map.keys())
if (get_item_delta_fast (old_gid, r, delta_bytes, row_size) != 0)
{
  region_indices.add (region);
  break;
}
   }
 }

 public:
 const HBUINT8 *get_delta_bytes () const
 { return &StructAfter<HBUINT8> (regionIndices); }

 protected:
 HBUINT8 *get_delta_bytes ()
 { return &StructAfter<HBUINT8> (regionIndices); }

 public:
 int32_t get_item_delta_fast (unsigned int item, unsigned int region,
		       const HBUINT8 *delta_bytes, unsigned row_size) const
 {
   if (unlikely (item >= itemCount || region >= regionIndices.len)) return 0;

   const HBINT8 *p = (const HBINT8 *) delta_bytes + item * row_size;
   unsigned word_count = wordCount ();
   bool is_long = longWords ();
   if (is_long)
   {
     if (region < word_count)
return ((const HBINT32 *) p)[region];
     else
return ((const HBINT16 *)(p + HBINT32::static_size * word_count))[region - word_count];
   }
   else
   {
     if (region < word_count)
return ((const HBINT16 *) p)[region];
     else
return (p + HBINT16::static_size * word_count)[region - word_count];
   }
 }
 int32_t get_item_delta (unsigned int item, unsigned int region) const
 {
    return get_item_delta_fast (item, region,
			 get_delta_bytes (),
			 get_row_size ());
 }

 protected:
 void set_item_delta_fast (unsigned int item, unsigned int region, int32_t delta,
		    HBUINT8 *delta_bytes, unsigned row_size)
 {
   HBINT8 *p = (HBINT8 *) delta_bytes + item * row_size;
   unsigned word_count = wordCount ();
   bool is_long = longWords ();
   if (is_long)
   {
     if (region < word_count)
((HBINT32 *) p)[region] = delta;
     else
((HBINT16 *)(p + HBINT32::static_size * word_count))[region - word_count] = delta;
   }
   else
   {
     if (region < word_count)
((HBINT16 *) p)[region] = delta;
     else
(p + HBINT16::static_size * word_count)[region - word_count] = delta;
   }
 }
 void set_item_delta (unsigned int item, unsigned int region, int32_t delta)
 {
   set_item_delta_fast (item, region, delta,
		 get_delta_bytes (),
		 get_row_size ());
 }

 bool longWords () const { return wordSizeCount & 0x8000u /* LONG_WORDS */; }
 unsigned wordCount () const { return wordSizeCount & 0x7FFFu /* WORD_DELTA_COUNT_MASK */; }

 protected:
 HBUINT16		itemCount;
 HBUINT16		wordSizeCount;
 Array16Of<HBUINT16>	regionIndices;
/*UnsizedArrayOf<HBUINT8>bytesX;*/
 public:
 DEFINE_SIZE_ARRAY (6, regionIndices);
};

struct MultiVarData
{
 unsigned int get_size () const
 { return min_size
 - regionIndices.min_size + regionIndices.get_size ()
 + StructAfter<CFF2Index> (regionIndices).get_size ();
 }

 void get_delta (unsigned int inner,
	  const int *coords, unsigned int coord_count,
	  const SparseVarRegionList &regions,
	  hb_array_t<float> out,
	  hb_scalar_cache_t *cache = nullptr) const
 {
   auto &deltaSets = StructAfter<decltype (deltaSetsX)> (regionIndices);

   auto values_iter = deltaSets.fetcher (inner);
   unsigned regionCount = regionIndices.len;
   for (unsigned regionIndex = 0; regionIndex < regionCount; regionIndex++)
   {
     float scalar = regions.evaluate (regionIndices.arrayZ[regionIndex],
			       coords, coord_count,
			       cache);
     values_iter.add_to (out, scalar);
   }
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (format.sanitize (c) &&
	  hb_barrier () &&
	  format == 1 &&
	  regionIndices.sanitize (c) &&
	  hb_barrier () &&
	  StructAfter<decltype (deltaSetsX)> (regionIndices).sanitize (c));
 }

 protected:
 HBUINT8	      format; // 1
 Array16Of<HBUINT16> regionIndices;
 TupleList	      deltaSetsX;
 public:
 DEFINE_SIZE_MIN (8);
};

struct ItemVariationStore
{
 friend struct item_variations_t;

 hb_scalar_cache_t *create_cache () const
 {
#ifdef HB_NO_VAR
   return hb_scalar_cache_t::create (0);
#endif
   return hb_scalar_cache_t::create ((this+regions).regionCount);
 }

 static void destroy_cache (hb_scalar_cache_t *cache)
 {
   hb_scalar_cache_t::destroy (cache);
 }

 private:
 float get_delta (unsigned int outer, unsigned int inner,
	   const int *coords, unsigned int coord_count,
	   hb_scalar_cache_t *cache = nullptr) const
 {
#ifdef HB_NO_VAR
   return 0.f;
#endif

   if (unlikely (outer >= dataSets.len))
     return 0.f;

   return (this+dataSets[outer]).get_delta (inner,
				     coords, coord_count,
				     this+regions,
				     cache);
 }

 public:
 float get_delta (unsigned int index,
	   const int *coords, unsigned int coord_count,
	   hb_scalar_cache_t *cache = nullptr) const
 {
   unsigned int outer = index >> 16;
   unsigned int inner = index & 0xFFFF;
   return get_delta (outer, inner, coords, coord_count, cache);
 }
 float get_delta (unsigned int index,
	   hb_array_t<const int> coords,
	   hb_scalar_cache_t *cache = nullptr) const
 {
   return get_delta (index,
	      coords.arrayZ, coords.length,
	      cache);
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
#ifdef HB_NO_VAR
   return true;
#endif

   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) &&
	  hb_barrier () &&
	  format == 1 &&
	  regions.sanitize (c, this) &&
	  dataSets.sanitize (c, this));
 }

 bool serialize (hb_serialize_context_t *c,
                 bool has_long,
                 const hb_vector_t<hb_tag_t>& axis_tags,
                 const hb_vector_t<const hb_hashmap_t<hb_tag_t, Triple>*>& region_list,
                 const hb_vector_t<delta_row_encoding_t>& vardata_encodings)
 {
   TRACE_SERIALIZE (this);
#ifdef HB_NO_VAR
   return_trace (false);
#endif
   if (unlikely (!c->extend_min (this))) return_trace (false);

   format = 1;
   if (!regions.serialize_serialize (c, axis_tags, region_list))
     return_trace (false);

   unsigned num_var_data = vardata_encodings.length;
   if (!num_var_data) return_trace (false);
   if (unlikely (!c->check_assign (dataSets.len, num_var_data,
                                   HB_SERIALIZE_ERROR_INT_OVERFLOW)))
     return_trace (false);

   if (unlikely (!c->extend (dataSets))) return_trace (false);
   for (unsigned i = 0; i < num_var_data; i++)
     if (!dataSets[i].serialize_serialize (c, has_long, vardata_encodings[i].items))
       return_trace (false);

   return_trace (true);
 }

 bool serialize (hb_serialize_context_t *c,
	  const ItemVariationStore *src,
	  const hb_array_t <const hb_inc_bimap_t> &inner_maps)
 {
   TRACE_SERIALIZE (this);
#ifdef HB_NO_VAR
   return_trace (false);
#endif

   if (unlikely (!c->extend_min (this))) return_trace (false);

   unsigned int set_count = 0;
   for (unsigned int i = 0; i < inner_maps.length; i++)
     if (inner_maps[i].get_population ())
set_count++;

   format = 1;

   const auto &src_regions = src+src->regions;

   hb_set_t region_indices;
   for (unsigned int i = 0; i < inner_maps.length; i++)
     (src+src->dataSets[i]).collect_region_refs (region_indices, inner_maps[i]);

   if (region_indices.in_error ())
     return_trace (false);

   region_indices.del_range ((src_regions).regionCount, hb_set_t::INVALID);

   /* TODO use constructor when our data-structures support that. */
   hb_inc_bimap_t region_map;
   + hb_iter (region_indices)
   | hb_apply ([&region_map] (unsigned _) { region_map.add(_); })
   ;
   if (region_map.in_error())
     return_trace (false);

   if (unlikely (!regions.serialize_serialize (c, &src_regions, region_map)))
     return_trace (false);

   dataSets.len = set_count;
   if (unlikely (!c->extend (dataSets))) return_trace (false);

   /* TODO: The following code could be simplified when
    * List16OfOffset16To::subset () can take a custom param to be passed to VarData::serialize () */
   unsigned int set_index = 0;
   for (unsigned int i = 0; i < inner_maps.length; i++)
   {
     if (!inner_maps[i].get_population ()) continue;
     if (unlikely (!dataSets[set_index++]
	     .serialize_serialize (c, &(src+src->dataSets[i]), inner_maps[i], region_map)))
return_trace (false);
   }

   return_trace (true);
 }

 ItemVariationStore *copy (hb_serialize_context_t *c) const
 {
   TRACE_SERIALIZE (this);
   auto *out = c->start_embed (this);
   if (unlikely (!out)) return_trace (nullptr);

   hb_vector_t <hb_inc_bimap_t> inner_maps;
   unsigned count = dataSets.len;
   for (unsigned i = 0; i < count; i++)
   {
     hb_inc_bimap_t *map = inner_maps.push ();
     if (unlikely (!c->propagate_error(inner_maps)))
       return_trace(nullptr);
     auto &data = this+dataSets[i];

     unsigned itemCount = data.get_item_count ();
     for (unsigned j = 0; j < itemCount; j++)
map->add (j);
   }

   if (unlikely (!out->serialize (c, this, inner_maps))) return_trace (nullptr);

   return_trace (out);
 }

 bool subset (hb_subset_context_t *c, const hb_array_t<const hb_inc_bimap_t> &inner_maps) const
 {
   TRACE_SUBSET (this);
#ifdef HB_NO_VAR
   return_trace (false);
#endif

   ItemVariationStore *varstore_prime = c->serializer->start_embed<ItemVariationStore> ();
   if (unlikely (!varstore_prime)) return_trace (false);

   varstore_prime->serialize (c->serializer, this, inner_maps);

   return_trace (
       !c->serializer->in_error()
       && varstore_prime->dataSets);
 }

 unsigned int get_region_index_count (unsigned int major) const
 {
#ifdef HB_NO_VAR
   return 0;
#endif
   return (this+dataSets[major]).get_region_index_count ();
 }

 void get_region_scalars (unsigned int major,
		   const int *coords, unsigned int coord_count,
		   float *scalars /*OUT*/,
		   unsigned int num_scalars) const
 {
#ifdef HB_NO_VAR
   for (unsigned i = 0; i < num_scalars; i++)
     scalars[i] = 0.f;
   return;
#endif

   (this+dataSets[major]).get_region_scalars (coords, coord_count,
				       this+regions,
				       &scalars[0], num_scalars);
 }

 unsigned int get_sub_table_count () const
  {
#ifdef HB_NO_VAR
    return 0;
#endif
    return dataSets.len;
  }

 const VarData& get_sub_table (unsigned i) const
 {
#ifdef HB_NO_VAR
    return Null (VarData);
#endif
    return this+dataSets[i];
 }

 const VarRegionList& get_region_list () const
 {
#ifdef HB_NO_VAR
    return Null (VarRegionList);
#endif
    return this+regions;
 }

 protected:
 HBUINT16				format;
 Offset32To<VarRegionList>		regions;
 Array16OfOffset32To<VarData>		dataSets;
 public:
 DEFINE_SIZE_ARRAY_SIZED (8, dataSets);
};

struct MultiItemVariationStore
{
 hb_scalar_cache_t *create_cache (hb_scalar_cache_t *static_cache = nullptr) const
 {
#ifdef HB_NO_VAR
   return hb_scalar_cache_t::create (0);
#endif
   auto &r = this+regions;
   unsigned count = r.regions.len;

   return hb_scalar_cache_t::create (count, static_cache);
 }

 static void destroy_cache (hb_scalar_cache_t *cache,
		     hb_scalar_cache_t *static_cache = nullptr)
 {
   hb_scalar_cache_t::destroy (cache, static_cache);
 }

 private:
 void get_delta (unsigned int outer, unsigned int inner,
	  const int *coords, unsigned int coord_count,
	  hb_array_t<float> out,
	  hb_scalar_cache_t *cache = nullptr) const
 {
#ifdef HB_NO_VAR
   return;
#endif

   if (unlikely (outer >= dataSets.len))
     return;

   return (this+dataSets[outer]).get_delta (inner,
				     coords, coord_count,
				     this+regions,
				     out,
				     cache);
 }

 public:
 void get_delta (unsigned int index,
	  const int *coords, unsigned int coord_count,
	  hb_array_t<float> out,
	  hb_scalar_cache_t *cache = nullptr) const
 {
   unsigned int outer = index >> 16;
   unsigned int inner = index & 0xFFFF;
   get_delta (outer, inner, coords, coord_count, out, cache);
 }
 void get_delta (unsigned int index,
	  hb_array_t<const int> coords,
	  hb_array_t<float> out,
	  hb_scalar_cache_t *cache = nullptr) const
 {
   return get_delta (index,
	      coords.arrayZ, coords.length,
	      out,
	      cache);
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
#ifdef HB_NO_VAR
   return true;
#endif

   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) &&
	  hb_barrier () &&
	  format == 1 &&
	  regions.sanitize (c, this) &&
	  dataSets.sanitize (c, this));
 }

 protected:
 HBUINT16				format; // 1
 Offset32To<SparseVarRegionList>	regions;
 Array16OfOffset32To<MultiVarData>	dataSets;
 public:
 DEFINE_SIZE_ARRAY_SIZED (8, dataSets);
};

template <typename MapCountT>
struct DeltaSetIndexMapFormat01
{
 friend struct DeltaSetIndexMap;

 unsigned get_size () const
 { return min_size + mapCount * get_width (); }

 private:
 DeltaSetIndexMapFormat01* copy (hb_serialize_context_t *c) const
 {
   TRACE_SERIALIZE (this);
   return_trace (c->embed (this));
 }

 template <typename T>
 bool serialize (hb_serialize_context_t *c, const T &plan)
 {
   unsigned int width = plan.get_width ();
   unsigned int inner_bit_count = plan.get_inner_bit_count ();
   const hb_array_t<const uint32_t> output_map = plan.get_output_map ();

   TRACE_SERIALIZE (this);
   if (unlikely (output_map.length && ((((inner_bit_count-1)&~0xF)!=0) || (((width-1)&~0x3)!=0))))
     return_trace (false);
   if (unlikely (!c->extend_min (this))) return_trace (false);

   entryFormat = ((width-1)<<4)|(inner_bit_count-1);
   mapCount = output_map.length;
   HBUINT8 *p = c->allocate_size<HBUINT8> (width * output_map.length);
   if (unlikely (!p)) return_trace (false);
   for (unsigned int i = 0; i < output_map.length; i++)
   {
     unsigned int v = output_map.arrayZ[i];
     if (v)
     {
unsigned int outer = v >> 16;
unsigned int inner = v & 0xFFFF;
unsigned int u = (outer << inner_bit_count) | inner;
for (unsigned int w = width; w > 0;)
{
  p[--w] = u;
  u >>= 8;
}
     }
     p += width;
   }
   return_trace (true);
 }

 HB_ALWAYS_INLINE
 uint32_t map (unsigned int v) const /* Returns 16.16 outer.inner. */
 {
   /* If count is zero, pass value unchanged.  This takes
    * care of direct mapping for advance map. */
   if (!mapCount)
     return v;
   return _map (v);
 }

 HB_HOT
 uint32_t _map (unsigned int v) const /* Returns 16.16 outer.inner. */
 {
   if (v >= mapCount)
     v = mapCount - 1;

   unsigned int u = 0;
   { /* Fetch it. */
     unsigned int w = get_width ();
     const HBUINT8 *p = mapDataZ.arrayZ + w * v;
     for (; w; w--)
       u = (u << 8) + *p++;
   }

   { /* Repack it. */
     unsigned int n = get_inner_bit_count ();
     unsigned int outer = u >> n;
     unsigned int inner = u & ((1 << n) - 1);
     u = (outer<<16) | inner;
   }

   return u;
 }

 unsigned get_map_count () const       { return mapCount; }
 unsigned get_width () const           { return ((entryFormat >> 4) & 3) + 1; }
 unsigned get_inner_bit_count () const { return (entryFormat & 0xF) + 1; }


 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) &&
	  hb_barrier () &&
                 c->check_range (mapDataZ.arrayZ,
                                 mapCount,
                                 get_width ()));
 }

 protected:
 HBUINT8       format;         /* Format identifier--format = 0 */
 HBUINT8       entryFormat;    /* A packed field that describes the compressed
                                * representation of delta-set indices. */
 MapCountT     mapCount;       /* The number of mapping entries. */
 UnsizedArrayOf<HBUINT8>
               mapDataZ;       /* The delta-set index mapping data. */

 public:
 DEFINE_SIZE_ARRAY (2+MapCountT::static_size, mapDataZ);
};

struct DeltaSetIndexMap
{
 template <typename T>
 bool serialize (hb_serialize_context_t *c, const T &plan)
 {
   TRACE_SERIALIZE (this);
   unsigned length = plan.get_output_map ().length;
   u.format.v = length <= 0xFFFF ? 0 : 1;
   switch (u.format.v) {
   case 0: hb_barrier (); return_trace (u.format0.serialize (c, plan));
   case 1: hb_barrier (); return_trace (u.format1.serialize (c, plan));
   default:return_trace (false);
   }
 }

 uint32_t map (unsigned v) const
 {
   switch (u.format.v) {
   case 0: hb_barrier (); return (u.format0.map (v));
   case 1: hb_barrier (); return (u.format1.map (v));
   default:return v;
   }
 }

 unsigned get_map_count () const
 {
   switch (u.format.v) {
   case 0: hb_barrier (); return u.format0.get_map_count ();
   case 1: hb_barrier (); return u.format1.get_map_count ();
   default:return 0;
   }
 }

 unsigned get_width () const
 {
   switch (u.format.v) {
   case 0: hb_barrier (); return u.format0.get_width ();
   case 1: hb_barrier (); return u.format1.get_width ();
   default:return 0;
   }
 }

 unsigned get_inner_bit_count () const
 {
   switch (u.format.v) {
   case 0: hb_barrier (); return u.format0.get_inner_bit_count ();
   case 1: hb_barrier (); return u.format1.get_inner_bit_count ();
   default:return 0;
   }
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   if (!u.format.v.sanitize (c)) return_trace (false);
   hb_barrier ();
   switch (u.format.v) {
   case 0: hb_barrier (); return_trace (u.format0.sanitize (c));
   case 1: hb_barrier (); return_trace (u.format1.sanitize (c));
   default:return_trace (true);
   }
 }

 DeltaSetIndexMap* copy (hb_serialize_context_t *c) const
 {
   TRACE_SERIALIZE (this);
   switch (u.format.v) {
   case 0: hb_barrier (); return_trace (reinterpret_cast<DeltaSetIndexMap *> (u.format0.copy (c)));
   case 1: hb_barrier (); return_trace (reinterpret_cast<DeltaSetIndexMap *> (u.format1.copy (c)));
   default:return_trace (nullptr);
   }
 }

 protected:
 union {
 struct { HBUINT8 v; }             format;         /* Format identifier */
 DeltaSetIndexMapFormat01<HBUINT16> format0;
 DeltaSetIndexMapFormat01<HBUINT32> format1;
 } u;
 public:
 DEFINE_SIZE_UNION (1, format.v);
};


struct ItemVarStoreInstancer
{
 ItemVarStoreInstancer (const ItemVariationStore *varStore_,
		 const DeltaSetIndexMap *varIdxMap,
		 hb_array_t<const int> coords,
		 hb_scalar_cache_t *cache = nullptr) :
   varStore (varStore_), varIdxMap (varIdxMap), coords (coords), cache (cache)
 {
   if (!varStore)
     varStore = &Null(ItemVariationStore);
 }

 operator bool () const { return varStore && bool (coords); }

 float operator[] (uint32_t varIdx) const
 { return (*this) (varIdx); }

 float operator() (uint32_t varIdx, unsigned short offset = 0) const
 {
  if (!coords || varIdx == VarIdx::NO_VARIATION)
    return 0.f;

   varIdx += offset;
   if (varIdxMap)
     varIdx = varIdxMap->map (varIdx);
   return varStore->get_delta (varIdx, coords, cache);
 }

 const ItemVariationStore *varStore;
 const DeltaSetIndexMap *varIdxMap;
 hb_array_t<const int> coords;
 hb_scalar_cache_t *cache;
};

struct MultiItemVarStoreInstancer
{
 MultiItemVarStoreInstancer (const MultiItemVariationStore *varStore,
		      const DeltaSetIndexMap *varIdxMap,
		      hb_array_t<const int> coords,
		      hb_scalar_cache_t *cache = nullptr) :
   varStore (varStore), varIdxMap (varIdxMap), coords (coords), cache (cache)
 {
   if (!varStore)
     varStore = &Null(MultiItemVariationStore);
 }

 operator bool () const { return varStore && bool (coords); }

 float operator[] (uint32_t varIdx) const
 {
   float v = 0;
   (*this) (hb_array (&v, 1), varIdx);
   return v;
 }

 void operator() (hb_array_t<float> out, uint32_t varIdx, unsigned short offset = 0) const
 {
   if (coords && varIdx != VarIdx::NO_VARIATION)
   {
     varIdx += offset;
     if (varIdxMap)
varIdx = varIdxMap->map (varIdx);
     varStore->get_delta (varIdx, coords, out, cache);
   }
   else
     for (unsigned i = 0; i < out.length; i++)
       out.arrayZ[i] = 0.f;
 }

 const MultiItemVariationStore *varStore;
 const DeltaSetIndexMap *varIdxMap;
 hb_array_t<const int> coords;
 hb_scalar_cache_t *cache;
};


/*
* Feature Variations
*/
enum Cond_with_Var_flag_t
{
 KEEP_COND_WITH_VAR = 0,
 KEEP_RECORD_WITH_VAR = 1,
 DROP_COND_WITH_VAR = 2,
 DROP_RECORD_WITH_VAR = 3,
};

struct Condition;

template <typename Instancer>
static bool
_hb_recurse_condition_evaluate (const struct Condition &condition,
			const int *coords,
			unsigned int coord_len,
			Instancer *instancer);

struct ConditionAxisRange
{
 friend struct Condition;

 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->embed (this);
   if (unlikely (!out)) return_trace (false);

   const hb_map_t *index_map = &c->plan->axes_index_map;
   if (index_map->is_empty ()) return_trace (true);

   const hb_map_t& axes_old_index_tag_map = c->plan->axes_old_index_tag_map;
   hb_codepoint_t *axis_tag;
   if (!axes_old_index_tag_map.has (axisIndex, &axis_tag) ||
       !index_map->has (axisIndex))
     return_trace (false);

   const hb_hashmap_t<hb_tag_t, Triple>& normalized_axes_location = c->plan->axes_location;
   Triple axis_limit{-1.0, 0.0, 1.0};
   Triple *normalized_limit;
   if (normalized_axes_location.has (*axis_tag, &normalized_limit))
     axis_limit = *normalized_limit;

   const hb_hashmap_t<hb_tag_t, TripleDistances>& axes_triple_distances = c->plan->axes_triple_distances;
   TripleDistances axis_triple_distances{1.0, 1.0};
   TripleDistances *triple_dists;
   if (axes_triple_distances.has (*axis_tag, &triple_dists))
     axis_triple_distances = *triple_dists;

   float normalized_min = renormalizeValue ((double) filterRangeMinValue.to_float (), axis_limit, axis_triple_distances, false);
   float normalized_max = renormalizeValue ((double) filterRangeMaxValue.to_float (), axis_limit, axis_triple_distances, false);
   out->filterRangeMinValue.set_float (normalized_min);
   out->filterRangeMaxValue.set_float (normalized_max);

   return_trace (c->serializer->check_assign (out->axisIndex, index_map->get (axisIndex),
                                              HB_SERIALIZE_ERROR_INT_OVERFLOW));
 }

 private:
 Cond_with_Var_flag_t keep_with_variations (hb_collect_feature_substitutes_with_var_context_t *c,
                                            hb_map_t *condition_map /* OUT */) const
 {
   //invalid axis index, drop the entire record
   if (!c->axes_index_tag_map->has (axisIndex))
     return DROP_RECORD_WITH_VAR;

   hb_tag_t axis_tag = c->axes_index_tag_map->get (axisIndex);

   Triple axis_range (-1.0, 0.0, 1.0);
   Triple *axis_limit;
   bool axis_set_by_user = false;
   if (c->axes_location->has (axis_tag, &axis_limit))
   {
     axis_range = *axis_limit;
     axis_set_by_user = true;
   }

   float axis_min_val = axis_range.minimum;
   float axis_default_val = axis_range.middle;
   float axis_max_val = axis_range.maximum;

   float filter_min_val = filterRangeMinValue.to_float ();
   float filter_max_val = filterRangeMaxValue.to_float ();

   if (axis_default_val < filter_min_val ||
       axis_default_val > filter_max_val)
     c->apply = false;

   //condition not met, drop the entire record
   if (axis_min_val > filter_max_val || axis_max_val < filter_min_val ||
       filter_min_val > filter_max_val)
     return DROP_RECORD_WITH_VAR;

   //condition met and axis pinned, drop the condition
   if (axis_set_by_user && axis_range.is_point ())
     return DROP_COND_WITH_VAR;

   if (filter_max_val != axis_max_val || filter_min_val != axis_min_val)
   {
     // add axisIndex->value into the hashmap so we can check if the record is
     // unique with variations
     uint16_t int_filter_max_val = (uint16_t) filterRangeMaxValue.to_int ();
     uint16_t int_filter_min_val = (uint16_t) filterRangeMinValue.to_int ();
     hb_codepoint_t val = (int_filter_max_val << 16) + int_filter_min_val;

     condition_map->set (axisIndex, val);
     return KEEP_COND_WITH_VAR;
   }
   return KEEP_RECORD_WITH_VAR;
 }

 template <typename Instancer>
 bool evaluate (const int *coords, unsigned int coord_len,
	 Instancer *instancer HB_UNUSED) const
 {
   int coord = axisIndex < coord_len ? coords[axisIndex] : 0;
   return filterRangeMinValue.to_int () <= coord && coord <= filterRangeMaxValue.to_int ();
 }

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

 protected:
 HBUINT16	format;		/* Format identifier--format = 1 */
 HBUINT16	axisIndex;
 F2DOT14	filterRangeMinValue;
 F2DOT14	filterRangeMaxValue;
 public:
 DEFINE_SIZE_STATIC (8);
};

struct ConditionValue
{
 friend struct Condition;

 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   // TODO(subset)
   return_trace (false);
 }

 private:
 template <typename Instancer>
 bool evaluate (const int *coords, unsigned int coord_len,
	 Instancer *instancer) const
 {
   signed value = defaultValue;
   value += (*instancer)[varIdx];
   return value > 0;
 }

 bool subset (hb_subset_context_t *c,
              hb_subset_layout_context_t *l,
              bool insert_catch_all) const
 {
   TRACE_SUBSET (this);
   // TODO(subset)
   return_trace (false);
 }

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

 protected:
 HBUINT16	format;		/* Format identifier--format = 2 */
 HBINT16	defaultValue;   /* Value at default instance. */
 VarIdx	varIdx;		/* Variation index */
 public:
 DEFINE_SIZE_STATIC (8);
};

struct ConditionAnd
{
 friend struct Condition;

 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   // TODO(subset)
   return_trace (false);
 }

 private:
 template <typename Instancer>
 bool evaluate (const int *coords, unsigned int coord_len,
	 Instancer *instancer) const
 {
   unsigned int count = conditions.len;
   for (unsigned int i = 0; i < count; i++)
     if (!_hb_recurse_condition_evaluate (this+conditions.arrayZ[i],
				   coords, coord_len,
				   instancer))
return false;
   return true;
 }

 bool subset (hb_subset_context_t *c,
              hb_subset_layout_context_t *l,
              bool insert_catch_all) const
 {
   TRACE_SUBSET (this);
   // TODO(subset)
   return_trace (false);
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (conditions.sanitize (c, this));
 }

 protected:
 HBUINT16	format;		/* Format identifier--format = 3 */
 Array8OfOffset24To<struct Condition>	conditions;
 public:
 DEFINE_SIZE_ARRAY (3, conditions);
};

struct ConditionOr
{
 friend struct Condition;

 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   // TODO(subset)
   return_trace (false);
 }

 private:
 template <typename Instancer>
 bool evaluate (const int *coords, unsigned int coord_len,
	 Instancer *instancer) const
 {
   unsigned int count = conditions.len;
   for (unsigned int i = 0; i < count; i++)
     if (_hb_recurse_condition_evaluate (this+conditions.arrayZ[i],
				  coords, coord_len,
				  instancer))
return true;
   return false;
 }

 bool subset (hb_subset_context_t *c,
              hb_subset_layout_context_t *l,
              bool insert_catch_all) const
 {
   TRACE_SUBSET (this);
   // TODO(subset)
   return_trace (false);
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (conditions.sanitize (c, this));
 }

 protected:
 HBUINT16	format;		/* Format identifier--format = 4 */
 Array8OfOffset24To<struct Condition>	conditions;
 public:
 DEFINE_SIZE_ARRAY (3, conditions);
};

struct ConditionNegate
{
 friend struct Condition;

 bool subset (hb_subset_context_t *c) const
 {
   TRACE_SUBSET (this);
   // TODO(subset)
   return_trace (false);
 }

 private:
 template <typename Instancer>
 bool evaluate (const int *coords, unsigned int coord_len,
	 Instancer *instancer) const
 {
   return !_hb_recurse_condition_evaluate (this+condition,
				    coords, coord_len,
				    instancer);
 }

 bool subset (hb_subset_context_t *c,
              hb_subset_layout_context_t *l,
              bool insert_catch_all) const
 {
   TRACE_SUBSET (this);
   // TODO(subset)
   return_trace (false);
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (condition.sanitize (c, this));
 }

 protected:
 HBUINT16	format;		/* Format identifier--format = 5 */
 Offset24To<struct Condition>	condition;
 public:
 DEFINE_SIZE_STATIC (5);
};

struct Condition
{
 template <typename Instancer>
 bool evaluate (const int *coords, unsigned int coord_len,
	 Instancer *instancer) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.evaluate (coords, coord_len, instancer);
   case 2: hb_barrier (); return u.format2.evaluate (coords, coord_len, instancer);
   case 3: hb_barrier (); return u.format3.evaluate (coords, coord_len, instancer);
   case 4: hb_barrier (); return u.format4.evaluate (coords, coord_len, instancer);
   case 5: hb_barrier (); return u.format5.evaluate (coords, coord_len, instancer);
   default:return false;
   }
 }

 Cond_with_Var_flag_t keep_with_variations (hb_collect_feature_substitutes_with_var_context_t *c,
                                            hb_map_t *condition_map /* OUT */) const
 {
   switch (u.format.v) {
   case 1: hb_barrier (); return u.format1.keep_with_variations (c, condition_map);
   // TODO(subset)
   default: c->apply = false; return KEEP_COND_WITH_VAR;
   }
 }

 template <typename context_t, typename ...Ts>
 typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const
 {
   if (unlikely (!c->may_dispatch (this, &u.format.v))) return c->no_dispatch_return_value ();
   TRACE_DISPATCH (this, u.format.v);
   switch (u.format.v) {
   case 1: hb_barrier (); return_trace (c->dispatch (u.format1, std::forward<Ts> (ds)...));
   case 2: hb_barrier (); return_trace (c->dispatch (u.format2, std::forward<Ts> (ds)...));
   case 3: hb_barrier (); return_trace (c->dispatch (u.format3, std::forward<Ts> (ds)...));
   case 4: hb_barrier (); return_trace (c->dispatch (u.format4, std::forward<Ts> (ds)...));
   case 5: hb_barrier (); return_trace (c->dispatch (u.format5, std::forward<Ts> (ds)...));
   default:return_trace (c->default_return_value ());
   }
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   if (!u.format.v.sanitize (c)) return_trace (false);
   hb_barrier ();
   switch (u.format.v) {
   case 1: hb_barrier (); return_trace (u.format1.sanitize (c));
   case 2: hb_barrier (); return_trace (u.format2.sanitize (c));
   case 3: hb_barrier (); return_trace (u.format3.sanitize (c));
   case 4: hb_barrier (); return_trace (u.format4.sanitize (c));
   case 5: hb_barrier (); return_trace (u.format5.sanitize (c));
   default:return_trace (true);
   }
 }

 protected:
 union {
 struct { HBUINT16 v; }	format;		/* Format identifier */
 ConditionAxisRange	format1;
 ConditionValue	format2;
 ConditionAnd		format3;
 ConditionOr		format4;
 ConditionNegate	format5;
 } u;
 public:
 DEFINE_SIZE_UNION (2, format.v);
};

template <typename Instancer>
bool
_hb_recurse_condition_evaluate (const struct Condition &condition,
			const int *coords,
			unsigned int coord_len,
			Instancer *instancer)
{
 return condition.evaluate (coords, coord_len, instancer);
}

struct ConditionList
{
 const Condition& operator[] (unsigned i) const
 { return this+conditions[i]; }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (conditions.sanitize (c, this));
 }

 protected:
 Array32OfOffset32To<Condition> conditions;
 public:
 DEFINE_SIZE_ARRAY (4, conditions);
};

struct ConditionSet
{
 bool evaluate (const int *coords, unsigned int coord_len,
	 ItemVarStoreInstancer *instancer) const
 {
   unsigned int count = conditions.len;
   for (unsigned int i = 0; i < count; i++)
     if (!(this+conditions.arrayZ[i]).evaluate (coords, coord_len, instancer))
return false;
   return true;
 }

 void keep_with_variations (hb_collect_feature_substitutes_with_var_context_t *c) const
 {
   hb_map_t *condition_map = hb_map_create ();
   if (unlikely (!condition_map)) return;
   hb::shared_ptr<hb_map_t> p {condition_map};

   hb_set_t *cond_set = hb_set_create ();
   if (unlikely (!cond_set)) return;
   hb::shared_ptr<hb_set_t> s {cond_set};

   c->apply = true;
   bool should_keep = false;
   unsigned num_kept_cond = 0, cond_idx = 0;
   for (const auto& offset : conditions)
   {
     Cond_with_Var_flag_t ret = (this+offset).keep_with_variations (c, condition_map);
     // condition is not met or condition out of range, drop the entire record
     if (ret == DROP_RECORD_WITH_VAR)
       return;

     if (ret == KEEP_COND_WITH_VAR)
     {
       should_keep = true;
       cond_set->add (cond_idx);
       num_kept_cond++;
     }

     if (ret == KEEP_RECORD_WITH_VAR)
       should_keep = true;

     cond_idx++;
   }

   if (!should_keep) return;

   //check if condition_set is unique with variations
   if (c->conditionset_map->has (p))
     //duplicate found, drop the entire record
     return;

   c->conditionset_map->set (p, 1);
   c->record_cond_idx_map->set (c->cur_record_idx, s);
   if (should_keep && num_kept_cond == 0)
     c->universal = true;
 }

 bool subset (hb_subset_context_t *c,
              hb_subset_layout_context_t *l,
              bool insert_catch_all) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (this);
   if (unlikely (!out || !c->serializer->extend_min (out))) return_trace (false);

   if (insert_catch_all) return_trace (true);

   hb_set_t *retained_cond_set = nullptr;
   if (l->feature_record_cond_idx_map != nullptr)
     retained_cond_set = l->feature_record_cond_idx_map->get (l->cur_feature_var_record_idx);

   unsigned int count = conditions.len;
   for (unsigned int i = 0; i < count; i++)
   {
     if (retained_cond_set != nullptr && !retained_cond_set->has (i))
       continue;
     subset_offset_array (c, out->conditions, this) (conditions[i]);
   }

   return_trace (bool (out->conditions));
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (conditions.sanitize (c, this));
 }

 protected:
 Array16OfOffset32To<Condition>	conditions;
 public:
 DEFINE_SIZE_ARRAY (2, conditions);
};

struct FeatureTableSubstitutionRecord
{
 friend struct FeatureTableSubstitution;

 void collect_lookups (const void *base, hb_set_t *lookup_indexes /* OUT */) const
 {
   return (base+feature).add_lookup_indexes_to (lookup_indexes);
 }

 void closure_features (const void *base,
		 const hb_map_t *lookup_indexes,
		 hb_set_t       *feature_indexes /* OUT */) const
 {
   if ((base+feature).intersects_lookup_indexes (lookup_indexes))
     feature_indexes->add (featureIndex);
 }

 void collect_feature_substitutes_with_variations (hb_hashmap_t<unsigned, const Feature*> *feature_substitutes_map,
                                                   hb_set_t& catch_all_record_feature_idxes,
                                                   const hb_set_t *feature_indices,
                                                   const void *base) const
 {
   if (feature_indices->has (featureIndex))
   {
     feature_substitutes_map->set (featureIndex, &(base+feature));
     catch_all_record_feature_idxes.add (featureIndex);
   }
 }

 bool serialize (hb_subset_layout_context_t *c,
                 unsigned feature_index,
                 const Feature *f, const Tag *tag)
 {
   TRACE_SERIALIZE (this);
   hb_serialize_context_t *s = c->subset_context->serializer;
   if (unlikely (!s->extend_min (this))) return_trace (false);

   uint32_t *new_feature_idx;
   if (!c->feature_map_w_duplicates->has (feature_index, &new_feature_idx))
     return_trace (false);

   if (!s->check_assign (featureIndex, *new_feature_idx, HB_SERIALIZE_ERROR_INT_OVERFLOW))
     return_trace (false);

   s->push ();
   bool ret = f->subset (c->subset_context, c, tag);
   if (ret) s->add_link (feature, s->pop_pack ());
   else s->pop_discard ();

   return_trace (ret);
 }

 bool subset (hb_subset_layout_context_t *c, const void *base) const
 {
   TRACE_SUBSET (this);
   uint32_t *new_feature_index;
   if (!c->feature_map_w_duplicates->has (featureIndex, &new_feature_index))
     return_trace (false);

   auto *out = c->subset_context->serializer->embed (this);
   if (unlikely (!out)) return_trace (false);

   out->featureIndex = *new_feature_index;
   return_trace (out->feature.serialize_subset (c->subset_context, feature, base, c));
 }

 bool sanitize (hb_sanitize_context_t *c, const void *base) const
 {
   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) && feature.sanitize (c, base));
 }

 protected:
 HBUINT16		featureIndex;
 Offset32To<Feature>	feature;
 public:
 DEFINE_SIZE_STATIC (6);
};

struct FeatureTableSubstitution
{
 const Feature *find_substitute (unsigned int feature_index) const
 {
   unsigned int count = substitutions.len;
   for (unsigned int i = 0; i < count; i++)
   {
     const FeatureTableSubstitutionRecord &record = substitutions.arrayZ[i];
     if (record.featureIndex == feature_index)
return &(this+record.feature);
   }
   return nullptr;
 }

 void collect_lookups (const hb_set_t *feature_indexes,
		hb_set_t       *lookup_indexes /* OUT */) const
 {
   + hb_iter (substitutions)
   | hb_filter (feature_indexes, &FeatureTableSubstitutionRecord::featureIndex)
   | hb_apply ([this, lookup_indexes] (const FeatureTableSubstitutionRecord& r)
	{ r.collect_lookups (this, lookup_indexes); })
   ;
 }

 void closure_features (const hb_map_t *lookup_indexes,
		 hb_set_t       *feature_indexes /* OUT */) const
 {
   for (const FeatureTableSubstitutionRecord& record : substitutions)
     record.closure_features (this, lookup_indexes, feature_indexes);
 }

 bool intersects_features (const hb_map_t *feature_index_map) const
 {
   for (const FeatureTableSubstitutionRecord& record : substitutions)
   {
     if (feature_index_map->has (record.featureIndex)) return true;
   }
   return false;
 }

 void collect_feature_substitutes_with_variations (hb_collect_feature_substitutes_with_var_context_t *c) const
 {
   for (const FeatureTableSubstitutionRecord& record : substitutions)
     record.collect_feature_substitutes_with_variations (c->feature_substitutes_map,
                                                         c->catch_all_record_feature_idxes,
                                                         c->feature_indices, this);
 }

 bool subset (hb_subset_context_t        *c,
       hb_subset_layout_context_t *l,
              bool insert_catch_all) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!out || !c->serializer->extend_min (out))) return_trace (false);

   out->version.major = version.major;
   out->version.minor = version.minor;

   if (insert_catch_all)
   {
     for (unsigned feature_index : *(l->catch_all_record_feature_idxes))
     {
       hb_pair_t<const void*, const void*> *p;
       if (!l->feature_idx_tag_map->has (feature_index, &p))
         return_trace (false);
       auto *o = out->substitutions.serialize_append (c->serializer);
       if (!o->serialize (l, feature_index,
                          reinterpret_cast<const Feature*> (p->first),
                          reinterpret_cast<const Tag*> (p->second)))
         return_trace (false);
     }
     return_trace (true);
   }

   + substitutions.iter ()
   | hb_apply (subset_record_array (l, &(out->substitutions), this))
   ;

   return_trace (bool (out->substitutions));
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (version.sanitize (c) &&
	  hb_barrier () &&
	  likely (version.major == 1) &&
	  substitutions.sanitize (c, this));
 }

 protected:
 FixedVersion<>	version;	/* Version--0x00010000u */
 Array16Of<FeatureTableSubstitutionRecord>
		substitutions;
 public:
 DEFINE_SIZE_ARRAY (6, substitutions);
};

struct FeatureVariationRecord
{
 friend struct FeatureVariations;

 void collect_lookups (const void     *base,
		const hb_set_t *feature_indexes,
		hb_set_t       *lookup_indexes /* OUT */) const
 {
   return (base+substitutions).collect_lookups (feature_indexes, lookup_indexes);
 }

 void closure_features (const void     *base,
		 const hb_map_t *lookup_indexes,
		 hb_set_t       *feature_indexes /* OUT */) const
 {
   (base+substitutions).closure_features (lookup_indexes, feature_indexes);
 }

 bool intersects_features (const void *base, const hb_map_t *feature_index_map) const
 {
   return (base+substitutions).intersects_features (feature_index_map);
 }

 void collect_feature_substitutes_with_variations (hb_collect_feature_substitutes_with_var_context_t *c,
                                                   const void *base) const
 {
   (base+conditions).keep_with_variations (c);
   if (c->apply && !c->variation_applied)
   {
     (base+substitutions).collect_feature_substitutes_with_variations (c);
     c->variation_applied = true; // set variations only once
   }
 }

 bool subset (hb_subset_layout_context_t *c, const void *base,
              bool insert_catch_all = false) const
 {
   TRACE_SUBSET (this);
   auto *out = c->subset_context->serializer->embed (this);
   if (unlikely (!out)) return_trace (false);

   out->conditions.serialize_subset (c->subset_context, conditions, base, c, insert_catch_all);
   out->substitutions.serialize_subset (c->subset_context, substitutions, base, c, insert_catch_all);

   return_trace (true);
 }

 bool sanitize (hb_sanitize_context_t *c, const void *base) const
 {
   TRACE_SANITIZE (this);
   return_trace (conditions.sanitize (c, base) &&
	  substitutions.sanitize (c, base));
 }

 protected:
 Offset32To<ConditionSet>
		conditions;
 Offset32To<FeatureTableSubstitution>
		substitutions;
 public:
 DEFINE_SIZE_STATIC (8);
};

struct FeatureVariations
{
 static constexpr unsigned NOT_FOUND_INDEX = 0xFFFFFFFFu;

 bool find_index (const int *coords, unsigned int coord_len,
	   unsigned int *index,
	   ItemVarStoreInstancer *instancer) const
 {
   unsigned int count = varRecords.len;
   for (unsigned int i = 0; i < count; i++)
   {
     const FeatureVariationRecord &record = varRecords.arrayZ[i];
     if ((this+record.conditions).evaluate (coords, coord_len, instancer))
     {
*index = i;
return true;
     }
   }
   *index = NOT_FOUND_INDEX;
   return false;
 }

 const Feature *find_substitute (unsigned int variations_index,
			  unsigned int feature_index) const
 {
   const FeatureVariationRecord &record = varRecords[variations_index];
   return (this+record.substitutions).find_substitute (feature_index);
 }

 void collect_feature_substitutes_with_variations (hb_collect_feature_substitutes_with_var_context_t *c) const
 {
   unsigned int count = varRecords.len;
   for (unsigned int i = 0; i < count; i++)
   {
     c->cur_record_idx = i;
     varRecords[i].collect_feature_substitutes_with_variations (c, this);
     if (c->universal)
       break;
   }
   if (c->universal || c->record_cond_idx_map->is_empty ())
     c->catch_all_record_feature_idxes.reset ();
 }

 FeatureVariations* copy (hb_serialize_context_t *c) const
 {
   TRACE_SERIALIZE (this);
   return_trace (c->embed (*this));
 }

 void collect_lookups (const hb_set_t *feature_indexes,
		const hb_hashmap_t<unsigned, hb::shared_ptr<hb_set_t>> *feature_record_cond_idx_map,
		hb_set_t       *lookup_indexes /* OUT */) const
 {
   unsigned count = varRecords.len;
   for (unsigned int i = 0; i < count; i++)
   {
     if (feature_record_cond_idx_map &&
         !feature_record_cond_idx_map->has (i))
       continue;
     varRecords[i].collect_lookups (this, feature_indexes, lookup_indexes);
   }
 }

 void closure_features (const hb_map_t *lookup_indexes,
		 const hb_hashmap_t<unsigned, hb::shared_ptr<hb_set_t>> *feature_record_cond_idx_map,
		 hb_set_t       *feature_indexes /* OUT */) const
 {
   unsigned int count = varRecords.len;
   for (unsigned int i = 0; i < count; i++)
   {
     if (feature_record_cond_idx_map != nullptr &&
         !feature_record_cond_idx_map->has (i))
       continue;
     varRecords[i].closure_features (this, lookup_indexes, feature_indexes);
   }
 }

 bool subset (hb_subset_context_t *c,
       hb_subset_layout_context_t *l) const
 {
   TRACE_SUBSET (this);
   auto *out = c->serializer->start_embed (*this);
   if (unlikely (!out || !c->serializer->extend_min (out))) return_trace (false);

   out->version.major = version.major;
   out->version.minor = version.minor;

   int keep_up_to = -1;
   for (int i = varRecords.len - 1; i >= 0; i--) {
     if (varRecords[i].intersects_features (this, l->feature_map_w_duplicates)) {
       keep_up_to = i;
       break;
     }
   }

   unsigned count = (unsigned) (keep_up_to + 1);
   for (unsigned i = 0; i < count; i++)
   {
     if (l->feature_record_cond_idx_map != nullptr &&
         !l->feature_record_cond_idx_map->has (i))
       continue;

     l->cur_feature_var_record_idx = i;
     subset_record_array (l, &(out->varRecords), this) (varRecords[i]);
   }

   if (out->varRecords.len && !l->catch_all_record_feature_idxes->is_empty ())
   {
     bool insert_catch_all_record = true;
     subset_record_array (l, &(out->varRecords), this, insert_catch_all_record) (varRecords[0]);
   }

   return_trace (bool (out->varRecords));
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (version.sanitize (c) &&
	  hb_barrier () &&
	  likely (version.major == 1) &&
	  varRecords.sanitize (c, this));
 }

 protected:
 FixedVersion<>	version;	/* Version--0x00010000u */
 Array32Of<FeatureVariationRecord>
		varRecords;
 public:
 DEFINE_SIZE_ARRAY_SIZED (8, varRecords);
};


/*
* Device Tables
*/

struct HintingDevice
{
 friend struct Device;

 private:

 hb_position_t get_x_delta (hb_font_t *font) const
 { return get_delta (font->x_ppem, font->x_scale); }

 hb_position_t get_y_delta (hb_font_t *font) const
 { return get_delta (font->y_ppem, font->y_scale); }

 public:

 unsigned int get_size () const
 {
   unsigned int f = deltaFormat;
   if (unlikely (f < 1 || f > 3 || startSize > endSize)) return 3 * HBUINT16::static_size;
   return HBUINT16::static_size * (4 + ((endSize - startSize) >> (4 - f)));
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   return_trace (c->check_struct (this) && c->check_range (this, this->get_size ()));
 }

 HintingDevice* copy (hb_serialize_context_t *c) const
 {
   TRACE_SERIALIZE (this);
   return_trace (c->embed<HintingDevice> (this));
 }

 private:

 int get_delta (unsigned int ppem, int scale) const
 {
   if (!ppem) return 0;

   int pixels = get_delta_pixels (ppem);

   if (!pixels) return 0;

   return (int) (pixels * (int64_t) scale / ppem);
 }
 int get_delta_pixels (unsigned int ppem_size) const
 {
   unsigned int f = deltaFormat;
   if (unlikely (f < 1 || f > 3))
     return 0;

   if (ppem_size < startSize || ppem_size > endSize)
     return 0;

   unsigned int s = ppem_size - startSize;

   unsigned int byte = deltaValueZ[s >> (4 - f)];
   unsigned int bits = (byte >> (16 - (((s & ((1 << (4 - f)) - 1)) + 1) << f)));
   unsigned int mask = (0xFFFFu >> (16 - (1 << f)));

   int delta = bits & mask;

   if ((unsigned int) delta >= ((mask + 1) >> 1))
     delta -= mask + 1;

   return delta;
 }

 protected:
 HBUINT16	startSize;		/* Smallest size to correct--in ppem */
 HBUINT16	endSize;		/* Largest size to correct--in ppem */
 HBUINT16	deltaFormat;		/* Format of DeltaValue array data: 1, 2, or 3
				 * 1	Signed 2-bit value, 8 values per uint16
				 * 2	Signed 4-bit value, 4 values per uint16
				 * 3	Signed 8-bit value, 2 values per uint16
				 */
 UnsizedArrayOf<HBUINT16>
	deltaValueZ;		/* Array of compressed data */
 public:
 DEFINE_SIZE_ARRAY (6, deltaValueZ);
};

struct VariationDevice
{
 friend struct Device;

 private:

 hb_position_t get_x_delta (hb_font_t *font,
		     const ItemVariationStore &store,
		     hb_scalar_cache_t *store_cache = nullptr) const
 { return !font->has_nonzero_coords ? 0 : font->em_scalef_x (get_delta (font, store, store_cache)); }

 hb_position_t get_y_delta (hb_font_t *font,
		     const ItemVariationStore &store,
		     hb_scalar_cache_t *store_cache = nullptr) const
 { return !font->has_nonzero_coords ? 0 : font->em_scalef_y (get_delta (font, store, store_cache)); }

 VariationDevice* copy (hb_serialize_context_t *c,
                        const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map) const
 {
   TRACE_SERIALIZE (this);
   if (!layout_variation_idx_delta_map) return_trace (nullptr);

   hb_pair_t<unsigned, int> *v;
   if (!layout_variation_idx_delta_map->has (varIdx, &v))
     return_trace (nullptr);

   c->start_zerocopy (this->static_size);
   auto *out = c->embed (this);
   if (unlikely (!out)) return_trace (nullptr);

   if (!c->check_assign (out->varIdx, hb_first (*v), HB_SERIALIZE_ERROR_INT_OVERFLOW))
     return_trace (nullptr);
   return_trace (out);
 }

 void collect_variation_index (hb_collect_variation_indices_context_t *c) const
 { c->layout_variation_indices->add (varIdx); }

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

 private:

 float get_delta (hb_font_t *font,
	   const ItemVariationStore &store,
	   hb_scalar_cache_t *store_cache = nullptr) const
 {
   return store.get_delta (varIdx, font->coords, font->num_coords, store_cache);
 }

 protected:
 VarIdx	varIdx;		/* Variation index */
 HBUINT16	deltaFormat;	/* Format identifier for this table: 0x0x8000 */
 public:
 DEFINE_SIZE_STATIC (6);
};

struct DeviceHeader
{
 protected:
 HBUINT16		reserved1;
 HBUINT16		reserved2;
 public:
 HBUINT16		format;		/* Format identifier */
 public:
 DEFINE_SIZE_STATIC (6);
};

struct Device
{
 hb_position_t get_x_delta (hb_font_t *font,
		     const ItemVariationStore &store=Null (ItemVariationStore),
		     hb_scalar_cache_t *store_cache = nullptr) const
 {
   switch (u.b.format)
   {
#ifndef HB_NO_HINTING
   case 1: case 2: case 3:
     return u.hinting.get_x_delta (font);
#endif
#ifndef HB_NO_VAR
   case 0x8000:
     return u.variation.get_x_delta (font, store, store_cache);
#endif
   default:
     return 0;
   }
 }
 hb_position_t get_y_delta (hb_font_t *font,
		     const ItemVariationStore &store=Null (ItemVariationStore),
		     hb_scalar_cache_t *store_cache = nullptr) const
 {
   switch (u.b.format)
   {
   case 1: case 2: case 3:
#ifndef HB_NO_HINTING
     return u.hinting.get_y_delta (font);
#endif
#ifndef HB_NO_VAR
   case 0x8000:
     return u.variation.get_y_delta (font, store, store_cache);
#endif
   default:
     return 0;
   }
 }

 bool sanitize (hb_sanitize_context_t *c) const
 {
   TRACE_SANITIZE (this);
   if (!u.b.format.sanitize (c)) return_trace (false);
   switch (u.b.format) {
#ifndef HB_NO_HINTING
   case 1: case 2: case 3:
     return_trace (u.hinting.sanitize (c));
#endif
#ifndef HB_NO_VAR
   case 0x8000:
     return_trace (u.variation.sanitize (c));
#endif
   default:
     return_trace (true);
   }
 }

 Device* copy (hb_serialize_context_t *c,
               const hb_hashmap_t<unsigned, hb_pair_t<unsigned, int>> *layout_variation_idx_delta_map=nullptr) const
 {
   TRACE_SERIALIZE (this);
   switch (u.b.format) {
#ifndef HB_NO_HINTING
   case 1:
   case 2:
   case 3:
     return_trace (reinterpret_cast<Device *> (u.hinting.copy (c)));
#endif
#ifndef HB_NO_VAR
   case 0x8000:
     return_trace (reinterpret_cast<Device *> (u.variation.copy (c, layout_variation_idx_delta_map)));
#endif
   default:
     return_trace (nullptr);
   }
 }

 void collect_variation_indices (hb_collect_variation_indices_context_t *c) const
 {
   switch (u.b.format) {
#ifndef HB_NO_HINTING
   case 1:
   case 2:
   case 3:
     return;
#endif
#ifndef HB_NO_VAR
   case 0x8000:
     u.variation.collect_variation_index (c);
     return;
#endif
   default:
     return;
   }
 }

 unsigned get_variation_index () const
 {
   switch (u.b.format) {
#ifndef HB_NO_VAR
   case 0x8000:
     return u.variation.varIdx;
#endif
   default:
     return HB_OT_LAYOUT_NO_VARIATIONS_INDEX;
   }
 }

 bool is_variation_device () const
 {
   switch (u.b.format) {
#ifndef HB_NO_VAR
   case 0x8000:
     return true;
#endif
   default:
     return false;
   }
 }

 protected:
 union {
 DeviceHeader		b;
 HintingDevice		hinting;
#ifndef HB_NO_VAR
 VariationDevice	variation;
#endif
 } u;
 public:
 DEFINE_SIZE_UNION (6, b);
};


} /* namespace OT */


#endif /* HB_OT_LAYOUT_COMMON_HH */