[Complex Text Layouts] Add third-party TextServer dependencies (ICU, HarfBuzz, Graphite).

1 files changed, 3178 insertions, 0 deletions

diff --git a/thirdparty/harfbuzz/src/hb-ot-layout-common.hh b/thirdparty/harfbuzz/src/hb-ot-layout-common.hh
new file mode 100644
index 0000000000..3140dd6328
--- /dev/null
+++ b/thirdparty/harfbuzz/src/hb-ot-layout-common.hh
@@ -0,0 +1,3178 @@
+/*
+ * 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"
+
+
+#ifndef HB_MAX_NESTING_LEVEL
+#define HB_MAX_NESTING_LEVEL	6
+#endif
+#ifndef HB_MAX_CONTEXT_LENGTH
+#define HB_MAX_CONTEXT_LENGTH	64
+#endif
+#ifndef HB_CLOSURE_MAX_STAGES
+/*
+ * The maximum number of times a lookup can be applied during shaping.
+ * Used to limit the number of iterations of the closure algorithm.
+ * This must be larger than the number of times add_pause() is
+ * called in a collect_features call of any shaper.
+ */
+#define HB_CLOSURE_MAX_STAGES	32
+#endif
+
+#ifndef HB_MAX_SCRIPTS
+#define HB_MAX_SCRIPTS	500
+#endif
+
+#ifndef HB_MAX_LANGSYS
+#define HB_MAX_LANGSYS	2000
+#endif
+
+#ifndef HB_MAX_FEATURES
+#define HB_MAX_FEATURES 750
+#endif
+
+#ifndef HB_MAX_FEATURE_INDICES
+#define HB_MAX_FEATURE_INDICES	1500
+#endif
+
+#ifndef HB_MAX_LOOKUP_INDICES
+#define HB_MAX_LOOKUP_INDICES	20000
+#endif
+
+
+namespace OT {
+
+
+#define NOT_COVERED		((unsigned int) -1)
+
+
+template<typename Iterator>
+static inline void Coverage_serialize (hb_serialize_context_t *c,
+				       Iterator it);
+
+template<typename Iterator>
+static inline void ClassDef_serialize (hb_serialize_context_t *c,
+				       Iterator it);
+
+static void ClassDef_remap_and_serialize (hb_serialize_context_t *c,
+					  const hb_set_t &glyphset,
+					  const hb_map_t &gid_klass_map,
+					  hb_sorted_vector_t<HBGlyphID> &glyphs,
+					  const hb_set_t &klasses,
+					  hb_map_t *klass_map /*INOUT*/);
+
+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_INDICES;
+  }
+
+  hb_subset_context_t *subset_context;
+  const hb_tag_t table_tag;
+  const hb_map_t *lookup_index_map;
+  const hb_map_t *feature_index_map;
+
+  hb_subset_layout_context_t (hb_subset_context_t *c_,
+			      hb_tag_t tag_,
+			      hb_map_t *lookup_map_,
+			      hb_map_t *feature_map_) :
+				subset_context (c_),
+				table_tag (tag_),
+				lookup_index_map (lookup_map_),
+				feature_index_map (feature_map_),
+				script_count (0),
+				langsys_count (0),
+				feature_index_count (0),
+				lookup_index_count (0)
+  {}
+
+  private:
+  unsigned script_count;
+  unsigned langsys_count;
+  unsigned feature_index_count;
+  unsigned lookup_index_count;
+};
+
+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 *o = out.serialize_append (subset_context->serializer);
+    if (unlikely (!o)) return false;
+    auto snap = subset_context->serializer->snapshot ();
+    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 *o = out.serialize_append (subset_context->serializer);
+    if (unlikely (!o)) return false;
+    auto snap = subset_context->serializer->snapshot ();
+    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;
+};
+
+/*
+ * 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); }
+}
+HB_FUNCOBJ (subset_record_array);
+
+/*
+ *
+ * OpenType Layout Common Table Formats
+ *
+ */
+
+
+/*
+ * Script, ScriptList, LangSys, Feature, FeatureList, Lookup, LookupList
+ */
+
+struct Record_sanitize_closure_t {
+  hb_tag_t tag;
+  const void *list_base;
+};
+
+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
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->subset_context->serializer->embed (this);
+    if (unlikely (!out)) return_trace (false);
+    bool ret = out->offset.serialize_subset (c->subset_context, offset, base, c, &tag);
+    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 */
+  OffsetTo<Type>
+		offset;		/* Offset from beginning of object holding
+				 * the Record */
+  public:
+  DEFINE_SIZE_STATIC (6);
+};
+
+template <typename Type>
+struct RecordArrayOf : SortedArrayOf<Record<Type>>
+{
+  const OffsetTo<Type>& get_offset (unsigned int i) const
+  { return (*this)[i].offset; }
+  OffsetTo<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->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_BFIND_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 Feature;
+
+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 (!out || !c->serializer->extend_min (out))) return_trace (false);
+
+    unsigned count = this->len;
+    + hb_zip (*this, hb_range (count))
+    | hb_filter (l->feature_index_map, hb_second)
+    | hb_map (hb_first)
+    | hb_apply (subset_record_array (l, out, this))
+    ;
+    return_trace (true);
+  }
+};
+
+struct RangeRecord
+{
+  int cmp (hb_codepoint_t g) const
+  { return g < first ? -1 : g <= last ? 0 : +1; }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this));
+  }
+
+  bool intersects (const hb_set_t *glyphs) const
+  { return glyphs->intersects (first, last); }
+
+  template <typename set_t>
+  bool collect_coverage (set_t *glyphs) const
+  { return glyphs->add_range (first, last); }
+
+  HBGlyphID	first;		/* First GlyphID in the range */
+  HBGlyphID	last;		/* Last GlyphID in the range */
+  HBUINT16	value;		/* Value */
+  public:
+  DEFINE_SIZE_STATIC (6);
+};
+DECLARE_NULL_NAMESPACE_BYTES (OT, RangeRecord);
+
+
+struct IndexArray : ArrayOf<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->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 (arrayZ, len);
+  }
+};
+
+
+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 operator == (const LangSys& o) const
+  {
+    if (featureIndex.len != o.featureIndex.len ||
+	reqFeatureIndex != o.reqFeatureIndex)
+      return false;
+
+    for (const auto _ : + hb_zip (featureIndex, o.featureIndex))
+      if (_.first != _.second) return false;
+
+    return true;
+  }
+
+  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 (!out || !c->serializer->extend_min (out))) return_trace (false);
+
+    out->reqFeatureIndex = l->feature_index_map->has (reqFeatureIndex) ? l->feature_index_map->get (reqFeatureIndex) : 0xFFFFu;
+
+    if (!l->visitFeatureIndex (featureIndex.len))
+      return_trace (false);
+
+    auto it =
+    + hb_iter (featureIndex)
+    | hb_filter (l->feature_index_map)
+    | hb_map (l->feature_index_map)
+    ;
+
+    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; }
+
+  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);
+
+    auto *out = c->serializer->start_embed (*this);
+    if (unlikely (!out || !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;
+      }
+    }
+
+    + langSys.iter ()
+    | hb_filter ([=] (const Record<LangSys>& record) {return l->visitLangSys (); })
+    | hb_filter ([&] (const Record<LangSys>& record)
+		 {
+		   const LangSys& d = this+defaultLangSys;
+		   const LangSys& l = this+record.offset;
+		   return !(l == d);
+		 })
+    | 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:
+  OffsetTo<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);
+};
+
+typedef RecordListOf<Script> ScriptList;
+
+
+/* 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);
+
+    /* This subtable has some "history", if you will.  Some earlier versions of
+     * Adobe tools calculated the offset of the FeatureParams sutable 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);
+  }
+
+  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));
+  }
+
+  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.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; }
+
+  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.) */
+  ArrayOf<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);
+  }
+
+  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 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); }
+
+  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 (!out || !c->serializer->extend_min (out))) return_trace (false);
+
+    bool subset_featureParams = 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);
+    return_trace (bool (it) || subset_featureParams
+		  || (tag && *tag == HB_TAG ('p', 'r', 'e', 'f')));
+  }
+
+  bool sanitize (hb_sanitize_context_t *c,
+		 const Record_sanitize_closure_t *closure = nullptr) const
+  {
+    TRACE_SANITIZE (this);
+    if (unlikely (!(c->check_struct (this) && lookupIndex.sanitize (c))))
+      return_trace (false);
+
+    /* Some earlier versions of Adobe tools calculated the offset of the
+     * FeatureParams subtable from the beginning of the FeatureList table!
+     *
+     * If sanitizing "failed" for the FeatureParams subtable, try it with the
+     * alternative location.  We would know sanitize "failed" if old value
+     * of the offset was non-zero, but it's zeroed now.
+     *
+     * Only do this for the 'size' feature, since at the time of the faulty
+     * Adobe tools, only the 'size' feature had FeatureParams defined.
+     */
+
+    if (likely (featureParams.is_null ()))
+      return_trace (true);
+
+    unsigned int orig_offset = featureParams;
+    if (unlikely (!featureParams.sanitize (c, this, closure ? closure->tag : HB_TAG_NONE)))
+      return_trace (false);
+
+    if (featureParams == 0 && closure &&
+	closure->tag == HB_TAG ('s','i','z','e') &&
+	closure->list_base && closure->list_base < this)
+    {
+      unsigned int new_offset_int = orig_offset -
+				    (((char *) this) - ((char *) closure->list_base));
+
+      OffsetTo<FeatureParams> new_offset;
+      /* Check that it would not overflow. */
+      new_offset = new_offset_int;
+      if (new_offset == new_offset_int &&
+	  c->try_set (&featureParams, new_offset_int) &&
+	  !featureParams.sanitize (c, this, closure ? closure->tag : HB_TAG_NONE))
+	return_trace (false);
+    }
+
+    return_trace (true);
+  }
+
+  OffsetTo<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);
+};
+
+typedef RecordListOf<Feature> FeatureList;
+
+
+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 OffsetArrayOf<TSubTable>& get_subtables () const
+  { return reinterpret_cast<const OffsetArrayOf<TSubTable> &> (subTable); }
+  template <typename TSubTable>
+  OffsetArrayOf<TSubTable>& get_subtables ()
+  { return reinterpret_cast<OffsetArrayOf<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, hb_forward<Ts> (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 (!out || !c->serializer->extend_min (out))) return_trace (false);
+    out->lookupType = lookupType;
+    out->lookupFlag = lookupFlag;
+
+    const hb_set_t *glyphset = c->plan->glyphset ();
+    unsigned int lookup_type = get_type ();
+    + hb_iter (get_subtables <TSubTable> ())
+    | hb_filter ([this, glyphset, lookup_type] (const OffsetTo<TSubTable> &_) { return (this+_).intersects (glyphset, lookup_type); })
+    | hb_apply (subset_offset_array (c, out->get_subtables<TSubTable> (), this, lookup_type))
+    ;
+
+    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);
+
+    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 && !c->get_edit_count ()))
+    {
+      /* 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!
+       *
+       * We only do this if sanitizer edit_count is zero.  Otherwise,
+       * some of the subtables might have become insane after they
+       * were sanity-checked by the edits of subsequent subtables.
+       * https://bugs.chromium.org/p/chromium/issues/detail?id=960331
+       */
+      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);
+  }
+
+  private:
+  HBUINT16	lookupType;		/* Different enumerations for GSUB and GPOS */
+  HBUINT16	lookupFlag;		/* Lookup qualifiers */
+  ArrayOf<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);
+};
+
+typedef OffsetListOf<Lookup> LookupList;
+
+template <typename TLookup>
+struct LookupOffsetList : OffsetListOf<TLookup>
+{
+  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);
+
+    unsigned count = this->len;
+    + hb_zip (*this, hb_range (count))
+    | hb_filter (l->lookup_index_map, hb_second)
+    | hb_map (hb_first)
+    | hb_apply (subset_offset_array (c, *out, this))
+    ;
+    return_trace (true);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (OffsetListOf<TLookup>::sanitize (c, this));
+  }
+};
+
+
+/*
+ * Coverage Table
+ */
+
+struct CoverageFormat1
+{
+  friend struct Coverage;
+
+  private:
+  unsigned int get_coverage (hb_codepoint_t glyph_id) const
+  {
+    unsigned int i;
+    glyphArray.bfind (glyph_id, &i, HB_BFIND_NOT_FOUND_STORE, NOT_COVERED);
+    return i;
+  }
+
+  template <typename Iterator,
+      hb_requires (hb_is_sorted_source_of (Iterator, hb_codepoint_t))>
+  bool serialize (hb_serialize_context_t *c, Iterator glyphs)
+  {
+    TRACE_SERIALIZE (this);
+    return_trace (glyphArray.serialize (c, glyphs));
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (glyphArray.sanitize (c));
+  }
+
+  bool intersects (const hb_set_t *glyphs) const
+  {
+    /* TODO Speed up, using hb_set_next() and bsearch()? */
+    unsigned int count = glyphArray.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (glyphs->has (glyphArray[i]))
+	return true;
+    return false;
+  }
+  bool intersects_coverage (const hb_set_t *glyphs, unsigned int index) const
+  { return glyphs->has (glyphArray[index]); }
+
+  template <typename set_t>
+  bool collect_coverage (set_t *glyphs) const
+  { return glyphs->add_sorted_array (glyphArray.arrayZ, glyphArray.len); }
+
+  public:
+  /* Older compilers need this to be public. */
+  struct iter_t
+  {
+    void init (const struct CoverageFormat1 &c_) { c = &c_; i = 0; }
+    void fini () {}
+    bool more () const { return i < c->glyphArray.len; }
+    void next () { i++; }
+    hb_codepoint_t get_glyph () const { return c->glyphArray[i]; }
+    bool operator != (const iter_t& o) const
+    { return i != o.i || c != o.c; }
+
+    private:
+    const struct CoverageFormat1 *c;
+    unsigned int i;
+  };
+  private:
+
+  protected:
+  HBUINT16	coverageFormat;	/* Format identifier--format = 1 */
+  SortedArrayOf<HBGlyphID>
+		glyphArray;	/* Array of GlyphIDs--in numerical order */
+  public:
+  DEFINE_SIZE_ARRAY (4, glyphArray);
+};
+
+struct CoverageFormat2
+{
+  friend struct Coverage;
+
+  private:
+  unsigned int get_coverage (hb_codepoint_t glyph_id) const
+  {
+    const RangeRecord &range = rangeRecord.bsearch (glyph_id);
+    return likely (range.first <= range.last)
+	 ? (unsigned int) range.value + (glyph_id - range.first)
+	 : NOT_COVERED;
+  }
+
+  template <typename Iterator,
+      hb_requires (hb_is_sorted_source_of (Iterator, hb_codepoint_t))>
+  bool serialize (hb_serialize_context_t *c, Iterator glyphs)
+  {
+    TRACE_SERIALIZE (this);
+    if (unlikely (!c->extend_min (*this))) return_trace (false);
+
+    if (unlikely (!glyphs))
+    {
+      rangeRecord.len = 0;
+      return_trace (true);
+    }
+
+    /* TODO(iter) Write more efficiently? */
+
+    unsigned num_ranges = 0;
+    hb_codepoint_t last = (hb_codepoint_t) -2;
+    for (auto g: glyphs)
+    {
+      if (last + 1 != g)
+	num_ranges++;
+      last = g;
+    }
+
+    if (unlikely (!rangeRecord.serialize (c, num_ranges))) return_trace (false);
+
+    unsigned count = 0;
+    unsigned range = (unsigned) -1;
+    last = (hb_codepoint_t) -2;
+    for (auto g: glyphs)
+    {
+      if (last + 1 != g)
+      {
+	range++;
+	rangeRecord[range].first = g;
+	rangeRecord[range].value = count;
+      }
+      rangeRecord[range].last = g;
+      last = g;
+      count++;
+    }
+
+    return_trace (true);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (rangeRecord.sanitize (c));
+  }
+
+  bool intersects (const hb_set_t *glyphs) const
+  {
+    /* TODO Speed up, using hb_set_next() and bsearch()? */
+    unsigned int count = rangeRecord.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (rangeRecord[i].intersects (glyphs))
+	return true;
+    return false;
+  }
+  bool intersects_coverage (const hb_set_t *glyphs, unsigned int index) const
+  {
+    unsigned int i;
+    unsigned int count = rangeRecord.len;
+    for (i = 0; i < count; i++) {
+      const RangeRecord &range = rangeRecord[i];
+      if (range.value <= index &&
+	  index < (unsigned int) range.value + (range.last - range.first) &&
+	  range.intersects (glyphs))
+	return true;
+      else if (index < range.value)
+	return false;
+    }
+    return false;
+  }
+
+  template <typename set_t>
+  bool collect_coverage (set_t *glyphs) const
+  {
+    unsigned int count = rangeRecord.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (unlikely (!rangeRecord[i].collect_coverage (glyphs)))
+	return false;
+    return true;
+  }
+
+  public:
+  /* Older compilers need this to be public. */
+  struct iter_t
+  {
+    void init (const CoverageFormat2 &c_)
+    {
+      c = &c_;
+      coverage = 0;
+      i = 0;
+      j = c->rangeRecord.len ? c->rangeRecord[0].first : 0;
+      if (unlikely (c->rangeRecord[0].first > c->rangeRecord[0].last))
+      {
+	/* Broken table. Skip. */
+	i = c->rangeRecord.len;
+      }
+    }
+    void fini () {}
+    bool more () const { return i < c->rangeRecord.len; }
+    void next ()
+    {
+      if (j >= c->rangeRecord[i].last)
+      {
+	i++;
+	if (more ())
+	{
+	  unsigned int old = coverage;
+	  j = c->rangeRecord[i].first;
+	  coverage = c->rangeRecord[i].value;
+	  if (unlikely (coverage != old + 1))
+	  {
+	    /* Broken table. Skip. Important to avoid DoS.
+	     * Also, our callers depend on coverage being
+	     * consecutive and monotonically increasing,
+	     * ie. iota(). */
+	   i = c->rangeRecord.len;
+	   return;
+	  }
+	}
+	return;
+      }
+      coverage++;
+      j++;
+    }
+    hb_codepoint_t get_glyph () const { return j; }
+    bool operator != (const iter_t& o) const
+    { return i != o.i || j != o.j || c != o.c; }
+
+    private:
+    const struct CoverageFormat2 *c;
+    unsigned int i, coverage;
+    hb_codepoint_t j;
+  };
+  private:
+
+  protected:
+  HBUINT16	coverageFormat;	/* Format identifier--format = 2 */
+  SortedArrayOf<RangeRecord>
+		rangeRecord;	/* Array of glyph ranges--ordered by
+				 * Start GlyphID. rangeCount entries
+				 * long */
+  public:
+  DEFINE_SIZE_ARRAY (4, rangeRecord);
+};
+
+struct Coverage
+{
+  /* Has interface. */
+  static constexpr unsigned SENTINEL = NOT_COVERED;
+  typedef unsigned int value_t;
+  value_t operator [] (hb_codepoint_t k) const { return get (k); }
+  bool has (hb_codepoint_t k) const { return (*this)[k] != SENTINEL; }
+  /* Predicate. */
+  bool operator () (hb_codepoint_t k) const { return has (k); }
+
+  unsigned int get (hb_codepoint_t k) const { return get_coverage (k); }
+  unsigned int get_coverage (hb_codepoint_t glyph_id) const
+  {
+    switch (u.format) {
+    case 1: return u.format1.get_coverage (glyph_id);
+    case 2: return u.format2.get_coverage (glyph_id);
+    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 glyphs)
+  {
+    TRACE_SERIALIZE (this);
+    if (unlikely (!c->extend_min (*this))) return_trace (false);
+
+    unsigned count = 0;
+    unsigned num_ranges = 0;
+    hb_codepoint_t last = (hb_codepoint_t) -2;
+    for (auto g: glyphs)
+    {
+      if (last + 1 != g)
+	num_ranges++;
+      last = g;
+      count++;
+    }
+    u.format = count <= num_ranges * 3 ? 1 : 2;
+
+    switch (u.format)
+    {
+    case 1: return_trace (u.format1.serialize (c, glyphs));
+    case 2: return_trace (u.format2.serialize (c, glyphs));
+    default:return_trace (false);
+    }
+  }
+
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->glyphset ();
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    auto it =
+    + iter ()
+    | hb_filter (glyphset)
+    | hb_map_retains_sorting (glyph_map)
+    ;
+
+    bool ret = bool (it);
+    Coverage_serialize (c->serializer, it);
+    return_trace (ret);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    if (!u.format.sanitize (c)) return_trace (false);
+    switch (u.format)
+    {
+    case 1: return_trace (u.format1.sanitize (c));
+    case 2: return_trace (u.format2.sanitize (c));
+    default:return_trace (true);
+    }
+  }
+
+  bool intersects (const hb_set_t *glyphs) const
+  {
+    switch (u.format)
+    {
+    case 1: return u.format1.intersects (glyphs);
+    case 2: return u.format2.intersects (glyphs);
+    default:return false;
+    }
+  }
+  bool intersects_coverage (const hb_set_t *glyphs, unsigned int index) const
+  {
+    switch (u.format)
+    {
+    case 1: return u.format1.intersects_coverage (glyphs, index);
+    case 2: return u.format2.intersects_coverage (glyphs, index);
+    default:return false;
+    }
+  }
+
+  /* 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)
+    {
+    case 1: return u.format1.collect_coverage (glyphs);
+    case 2: return u.format2.collect_coverage (glyphs);
+    default:return false;
+    }
+  }
+
+  struct iter_t : hb_iter_with_fallback_t<iter_t, hb_codepoint_t>
+  {
+    static constexpr bool is_sorted_iterator = true;
+    iter_t (const Coverage &c_ = Null (Coverage))
+    {
+      memset (this, 0, sizeof (*this));
+      format = c_.u.format;
+      switch (format)
+      {
+      case 1: u.format1.init (c_.u.format1); return;
+      case 2: u.format2.init (c_.u.format2); return;
+      default:				     return;
+      }
+    }
+    bool __more__ () const
+    {
+      switch (format)
+      {
+      case 1: return u.format1.more ();
+      case 2: return u.format2.more ();
+      default:return false;
+      }
+    }
+    void __next__ ()
+    {
+      switch (format)
+      {
+      case 1: u.format1.next (); break;
+      case 2: u.format2.next (); break;
+      default:			 break;
+      }
+    }
+    typedef hb_codepoint_t __item_t__;
+    __item_t__ __item__ () const { return get_glyph (); }
+
+    hb_codepoint_t get_glyph () const
+    {
+      switch (format)
+      {
+      case 1: return u.format1.get_glyph ();
+      case 2: return u.format2.get_glyph ();
+      default:return 0;
+      }
+    }
+    bool operator != (const iter_t& o) const
+    {
+      if (format != o.format) return true;
+      switch (format)
+      {
+      case 1: return u.format1 != o.u.format1;
+      case 2: return u.format2 != o.u.format2;
+      default:return false;
+      }
+    }
+
+    private:
+    unsigned int format;
+    union {
+    CoverageFormat2::iter_t	format2; /* Put this one first since it's larger; helps shut up compiler. */
+    CoverageFormat1::iter_t	format1;
+    } u;
+  };
+  iter_t iter () const { return iter_t (*this); }
+
+  protected:
+  union {
+  HBUINT16		format;		/* Format identifier */
+  CoverageFormat1	format1;
+  CoverageFormat2	format2;
+  } u;
+  public:
+  DEFINE_SIZE_UNION (2, format);
+};
+
+template<typename Iterator>
+static inline void
+Coverage_serialize (hb_serialize_context_t *c,
+		    Iterator it)
+{ c->start_embed<Coverage> ()->serialize (c, it); }
+
+static void ClassDef_remap_and_serialize (hb_serialize_context_t *c,
+					  const hb_set_t &glyphset,
+					  const hb_map_t &gid_klass_map,
+					  hb_sorted_vector_t<HBGlyphID> &glyphs,
+					  const hb_set_t &klasses,
+					  hb_map_t *klass_map /*INOUT*/)
+{
+  if (!klass_map)
+  {
+    ClassDef_serialize (c, hb_zip (glyphs.iter (), + glyphs.iter ()
+						   | hb_map (gid_klass_map)));
+    return;
+  }
+
+  /* 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 (glyphset.get_population () > gid_klass_map.get_population ())
+    klass_map->set (0, 0);
+
+  unsigned idx = klass_map->has (0) ? 1 : 0;
+  for (const unsigned k: klasses.iter ())
+  {
+    if (klass_map->has (k)) continue;
+    klass_map->set (k, idx);
+    idx++;
+  }
+
+  auto it =
+  + glyphs.iter ()
+  | hb_map_retains_sorting ([&] (const HBGlyphID& gid) -> hb_pair_t<hb_codepoint_t, unsigned>
+			    {
+			      unsigned new_klass = klass_map->get (gid_klass_map[gid]);
+			      return hb_pair ((hb_codepoint_t)gid, new_klass);
+			    })
+  ;
+
+  c->propagate_error (glyphs, klasses);
+  ClassDef_serialize (c, it);
+}
+
+/*
+ * Class Definition Table
+ */
+
+struct ClassDefFormat1
+{
+  friend struct ClassDef;
+
+  private:
+  unsigned int get_class (hb_codepoint_t glyph_id) const
+  {
+    return classValue[(unsigned int) (glyph_id - startGlyph)];
+  }
+
+  template<typename Iterator,
+	   hb_requires (hb_is_iterator (Iterator))>
+  bool serialize (hb_serialize_context_t *c,
+		  Iterator it)
+  {
+    TRACE_SERIALIZE (this);
+    if (unlikely (!c->extend_min (*this))) return_trace (false);
+
+    if (unlikely (!it))
+    {
+      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, unsigned> 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*/) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->_glyphset_gsub;
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    hb_sorted_vector_t<HBGlyphID> glyphs;
+    hb_set_t orig_klasses;
+    hb_map_t gid_org_klass_map;
+
+    hb_codepoint_t start = startGlyph;
+    hb_codepoint_t end   = start + classValue.len;
+    for (const hb_codepoint_t gid : + hb_range (start, end)
+				    | hb_filter (glyphset))
+    {
+      unsigned klass = classValue[gid - start];
+      if (!klass) continue;
+
+      glyphs.push (glyph_map[gid]);
+      gid_org_klass_map.set (glyph_map[gid], klass);
+      orig_klasses.add (klass);
+    }
+
+    ClassDef_remap_and_serialize (c->serializer, glyphset, gid_org_klass_map,
+				  glyphs, orig_klasses, klass_map);
+    return_trace ((bool) glyphs);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) && classValue.sanitize (c));
+  }
+
+  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 int 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
+  {
+    /* TODO Speed up, using hb_set_next()? */
+    hb_codepoint_t start = startGlyph;
+    hb_codepoint_t end = startGlyph + classValue.len;
+    for (hb_codepoint_t iter = startGlyph - 1;
+	 hb_set_next (glyphs, &iter) && iter < end;)
+      if (classValue[iter - start]) return true;
+    return false;
+  }
+  bool intersects_class (const hb_set_t *glyphs, unsigned int 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 (!hb_set_next (glyphs, &g)) return false;
+      if (g < startGlyph) return true;
+      g = startGlyph + count - 1;
+      if (hb_set_next (glyphs, &g)) return true;
+      /* Fall through. */
+    }
+    for (unsigned int i = 0; i < count; i++)
+      if (classValue[i] == klass && glyphs->has (startGlyph + i))
+	return true;
+    return false;
+  }
+
+  protected:
+  HBUINT16	classFormat;	/* Format identifier--format = 1 */
+  HBGlyphID	startGlyph;	/* First GlyphID of the classValueArray */
+  ArrayOf<HBUINT16>
+		classValue;	/* Array of Class Values--one per GlyphID */
+  public:
+  DEFINE_SIZE_ARRAY (6, classValue);
+};
+
+struct ClassDefFormat2
+{
+  friend struct ClassDef;
+
+  private:
+  unsigned int get_class (hb_codepoint_t glyph_id) const
+  {
+    return rangeRecord.bsearch (glyph_id).value;
+  }
+
+  template<typename Iterator,
+	   hb_requires (hb_is_iterator (Iterator))>
+  bool serialize (hb_serialize_context_t *c,
+		  Iterator it)
+  {
+    TRACE_SERIALIZE (this);
+    if (unlikely (!c->extend_min (*this))) return_trace (false);
+
+    if (unlikely (!it))
+    {
+      rangeRecord.len = 0;
+      return_trace (true);
+    }
+
+    unsigned num_ranges = 1;
+    hb_codepoint_t prev_gid = (*it).first;
+    unsigned prev_klass = (*it).second;
+
+    RangeRecord range_rec;
+    range_rec.first = prev_gid;
+    range_rec.last = prev_gid;
+    range_rec.value = prev_klass;
+
+    RangeRecord *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 (!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 (likely (record)) record->last = prev_gid;
+    rangeRecord.len = num_ranges;
+    return_trace (true);
+  }
+
+  bool subset (hb_subset_context_t *c,
+	       hb_map_t *klass_map = nullptr /*OUT*/) const
+  {
+    TRACE_SUBSET (this);
+    const hb_set_t &glyphset = *c->plan->_glyphset_gsub;
+    const hb_map_t &glyph_map = *c->plan->glyph_map;
+
+    hb_sorted_vector_t<HBGlyphID> glyphs;
+    hb_set_t orig_klasses;
+    hb_map_t gid_org_klass_map;
+
+    unsigned count = rangeRecord.len;
+    for (unsigned i = 0; i < count; i++)
+    {
+      unsigned klass = rangeRecord[i].value;
+      if (!klass) continue;
+      hb_codepoint_t start = rangeRecord[i].first;
+      hb_codepoint_t end   = rangeRecord[i].last + 1;
+      for (hb_codepoint_t g = start; g < end; g++)
+      {
+	if (!glyphset.has (g)) continue;
+	glyphs.push (glyph_map[g]);
+	gid_org_klass_map.set (glyph_map[g], klass);
+	orig_klasses.add (klass);
+      }
+    }
+
+    ClassDef_remap_and_serialize (c->serializer, glyphset, gid_org_klass_map,
+				  glyphs, orig_klasses, klass_map);
+    return_trace ((bool) glyphs);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (rangeRecord.sanitize (c));
+  }
+
+  template <typename set_t>
+  bool collect_coverage (set_t *glyphs) const
+  {
+    unsigned int count = rangeRecord.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (rangeRecord[i].value)
+	if (unlikely (!rangeRecord[i].collect_coverage (glyphs)))
+	  return false;
+    return true;
+  }
+
+  template <typename set_t>
+  bool collect_class (set_t *glyphs, unsigned int klass) const
+  {
+    unsigned int count = rangeRecord.len;
+    for (unsigned int i = 0; i < count; i++)
+    {
+      if (rangeRecord[i].value == klass)
+	if (unlikely (!rangeRecord[i].collect_coverage (glyphs)))
+	  return false;
+    }
+    return true;
+  }
+
+  bool intersects (const hb_set_t *glyphs) const
+  {
+    /* TODO Speed up, using hb_set_next() and bsearch()? */
+    unsigned int count = rangeRecord.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (rangeRecord[i].intersects (glyphs))
+	return true;
+    return false;
+  }
+  bool intersects_class (const hb_set_t *glyphs, unsigned int klass) const
+  {
+    unsigned int count = rangeRecord.len;
+    if (klass == 0)
+    {
+      /* Match if there's any glyph that is not listed! */
+      hb_codepoint_t g = HB_SET_VALUE_INVALID;
+      for (unsigned int i = 0; i < count; i++)
+      {
+	if (!hb_set_next (glyphs, &g))
+	  break;
+	if (g < rangeRecord[i].first)
+	  return true;
+	g = rangeRecord[i].last;
+      }
+      if (g != HB_SET_VALUE_INVALID && hb_set_next (glyphs, &g))
+	return true;
+      /* Fall through. */
+    }
+    for (unsigned int i = 0; i < count; i++)
+      if (rangeRecord[i].value == klass && rangeRecord[i].intersects (glyphs))
+	return true;
+    return false;
+  }
+
+  protected:
+  HBUINT16	classFormat;	/* Format identifier--format = 2 */
+  SortedArrayOf<RangeRecord>
+		rangeRecord;	/* Array of glyph ranges--ordered by
+				 * Start GlyphID */
+  public:
+  DEFINE_SIZE_ARRAY (4, rangeRecord);
+};
+
+struct ClassDef
+{
+  /* Has interface. */
+  static constexpr unsigned SENTINEL = 0;
+  typedef unsigned int value_t;
+  value_t operator [] (hb_codepoint_t k) const { return get (k); }
+  bool has (hb_codepoint_t k) const { return (*this)[k] != SENTINEL; }
+  /* 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) {
+    case 1: return u.format1.get_class (glyph_id);
+    case 2: return u.format2.get_class (glyph_id);
+    default:return 0;
+    }
+  }
+
+  template<typename Iterator,
+	   hb_requires (hb_is_iterator (Iterator))>
+  bool serialize (hb_serialize_context_t *c, Iterator it)
+  {
+    TRACE_SERIALIZE (this);
+    if (unlikely (!c->extend_min (*this))) return_trace (false);
+
+    unsigned format = 2;
+    if (likely (it))
+    {
+      hb_codepoint_t glyph_min = (*it).first;
+      hb_codepoint_t glyph_max = + it
+				 | hb_map (hb_first)
+				 | hb_reduce (hb_max, 0u);
+
+      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;
+	if (cur_gid == glyph_min || !cur_klass) continue;
+	if (cur_gid != prev_gid + 1 ||
+	    cur_klass != prev_klass)
+	  num_ranges++;
+
+	prev_gid = cur_gid;
+	prev_klass = cur_klass;
+      }
+
+      if (1 + (glyph_max - glyph_min + 1) <= num_ranges * 3)
+	format = 1;
+    }
+    u.format = format;
+
+    switch (u.format)
+    {
+    case 1: return_trace (u.format1.serialize (c, it));
+    case 2: return_trace (u.format2.serialize (c, it));
+    default:return_trace (false);
+    }
+  }
+
+  bool subset (hb_subset_context_t *c,
+	       hb_map_t *klass_map = nullptr /*OUT*/) const
+  {
+    TRACE_SUBSET (this);
+    switch (u.format) {
+    case 1: return_trace (u.format1.subset (c, klass_map));
+    case 2: return_trace (u.format2.subset (c, klass_map));
+    default:return_trace (false);
+    }
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    if (!u.format.sanitize (c)) return_trace (false);
+    switch (u.format) {
+    case 1: return_trace (u.format1.sanitize (c));
+    case 2: return_trace (u.format2.sanitize (c));
+    default:return_trace (true);
+    }
+  }
+
+  /* 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) {
+    case 1: return u.format1.collect_coverage (glyphs);
+    case 2: return u.format2.collect_coverage (glyphs);
+    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) {
+    case 1: return u.format1.collect_class (glyphs, klass);
+    case 2: return u.format2.collect_class (glyphs, klass);
+    default:return false;
+    }
+  }
+
+  bool intersects (const hb_set_t *glyphs) const
+  {
+    switch (u.format) {
+    case 1: return u.format1.intersects (glyphs);
+    case 2: return u.format2.intersects (glyphs);
+    default:return false;
+    }
+  }
+  bool intersects_class (const hb_set_t *glyphs, unsigned int klass) const
+  {
+    switch (u.format) {
+    case 1: return u.format1.intersects_class (glyphs, klass);
+    case 2: return u.format2.intersects_class (glyphs, klass);
+    default:return false;
+    }
+  }
+
+  protected:
+  union {
+  HBUINT16		format;		/* Format identifier */
+  ClassDefFormat1	format1;
+  ClassDefFormat2	format2;
+  } u;
+  public:
+  DEFINE_SIZE_UNION (2, format);
+};
+
+template<typename Iterator>
+static inline void ClassDef_serialize (hb_serialize_context_t *c,
+				       Iterator it)
+{ c->start_embed<ClassDef> ()->serialize (c, it); }
+
+
+/*
+ * Item Variation Store
+ */
+
+struct VarRegionAxis
+{
+  float evaluate (int coord) const
+  {
+    int start = startCoord, peak = peakCoord, end = endCoord;
+
+    /* TODO Move these to sanitize(). */
+    if (unlikely (start > peak || peak > end))
+      return 1.;
+    if (unlikely (start < 0 && end > 0 && peak != 0))
+      return 1.;
+
+    if (peak == 0 || coord == peak)
+      return 1.;
+
+    if (coord <= start || end <= coord)
+      return 0.;
+
+    /* 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));
+    /* TODO Handle invalid start/peak/end configs, so we don't
+     * have to do that at runtime. */
+  }
+
+  public:
+  F2DOT14	startCoord;
+  F2DOT14	peakCoord;
+  F2DOT14	endCoord;
+  public:
+  DEFINE_SIZE_STATIC (6);
+};
+
+struct VarRegionList
+{
+  float evaluate (unsigned int region_index,
+		  const int *coords, unsigned int coord_len) const
+  {
+    if (unlikely (region_index >= regionCount))
+      return 0.;
+
+    const VarRegionAxis *axes = axesZ.arrayZ + (region_index * axisCount);
+
+    float v = 1.;
+    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)
+	return 0.;
+      v *= factor;
+    }
+    return v;
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) &&
+		  axesZ.sanitize (c, (unsigned int) axisCount * (unsigned int) regionCount));
+  }
+
+  bool serialize (hb_serialize_context_t *c, const VarRegionList *src, const hb_bimap_t &region_map)
+  {
+    TRACE_SERIALIZE (this);
+    VarRegionList *out = c->allocate_min<VarRegionList> ();
+    if (unlikely (!out)) return_trace (false);
+    axisCount = src->axisCount;
+    regionCount = region_map.get_population ();
+    if (unlikely (!c->allocate_size<VarRegionList> (get_size () - min_size))) return_trace (false);
+    unsigned int region_count = src->get_region_count ();
+    for (unsigned int r = 0; r < regionCount; r++)
+    {
+      unsigned int backward = region_map.backward (r);
+      if (backward >= region_count) return_trace (false);
+      memcpy (&axesZ[axisCount * r], &src->axesZ[axisCount * backward], VarRegionAxis::static_size * axisCount);
+    }
+
+    return_trace (true);
+  }
+
+  unsigned int get_size () const { return min_size + VarRegionAxis::static_size * axisCount * regionCount; }
+  unsigned int get_region_count () const { return regionCount; }
+
+  protected:
+  HBUINT16	axisCount;
+  HBUINT16	regionCount;
+  UnsizedArrayOf<VarRegionAxis>
+		axesZ;
+  public:
+  DEFINE_SIZE_ARRAY (4, axesZ);
+};
+
+struct VarData
+{
+  unsigned int get_region_index_count () const
+  { return regionIndices.len; }
+
+  unsigned int get_row_size () const
+  { return shortCount + regionIndices.len; }
+
+  unsigned int get_size () const
+  { return itemCount * get_row_size (); }
+
+  float get_delta (unsigned int inner,
+		   const int *coords, unsigned int coord_count,
+		   const VarRegionList &regions) const
+  {
+    if (unlikely (inner >= itemCount))
+      return 0.;
+
+   unsigned int count = regionIndices.len;
+   unsigned int scount = shortCount;
+
+   const HBUINT8 *bytes = get_delta_bytes ();
+   const HBUINT8 *row = bytes + inner * (scount + count);
+
+   float delta = 0.;
+   unsigned int i = 0;
+
+   const HBINT16 *scursor = reinterpret_cast<const HBINT16 *> (row);
+   for (; i < scount; i++)
+   {
+     float scalar = regions.evaluate (regionIndices.arrayZ[i], coords, coord_count);
+     delta += scalar * *scursor++;
+   }
+   const HBINT8 *bcursor = reinterpret_cast<const HBINT8 *> (scursor);
+   for (; i < count; i++)
+   {
+     float scalar = regions.evaluate (regionIndices.arrayZ[i], coords, coord_count);
+     delta += scalar * *bcursor++;
+   }
+
+   return delta;
+  }
+
+  void get_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) &&
+		  shortCount <= regionIndices.len &&
+		  c->check_range (get_delta_bytes (),
+				  itemCount,
+				  get_row_size ()));
+  }
+
+  bool serialize (hb_serialize_context_t *c,
+		  const VarData *src,
+		  const hb_inc_bimap_t &inner_map,
+		  const hb_bimap_t &region_map)
+  {
+    TRACE_SERIALIZE (this);
+    if (unlikely (!c->extend_min (*this))) return_trace (false);
+    itemCount = inner_map.get_next_value ();
+
+    /* Optimize short count */
+    unsigned short ri_count = src->regionIndices.len;
+    enum delta_size_t { kZero=0, kByte, kShort };
+    hb_vector_t<delta_size_t> delta_sz;
+    hb_vector_t<unsigned int> ri_map;	/* maps old index to new index */
+    delta_sz.resize (ri_count);
+    ri_map.resize (ri_count);
+    unsigned int new_short_count = 0;
+    unsigned int r;
+    for (r = 0; r < ri_count; r++)
+    {
+      delta_sz[r] = kZero;
+      for (unsigned int i = 0; i < inner_map.get_next_value (); i++)
+      {
+	unsigned int old = inner_map.backward (i);
+	int16_t delta = src->get_item_delta (old, r);
+	if (delta < -128 || 127 < delta)
+	{
+	  delta_sz[r] = kShort;
+	  new_short_count++;
+	  break;
+	}
+	else if (delta != 0)
+	  delta_sz[r] = kByte;
+      }
+    }
+    unsigned int short_index = 0;
+    unsigned int byte_index = new_short_count;
+    unsigned int new_ri_count = 0;
+    for (r = 0; r < ri_count; r++)
+      if (delta_sz[r])
+      {
+	ri_map[r] = (delta_sz[r] == kShort)? short_index++ : byte_index++;
+	new_ri_count++;
+      }
+
+    shortCount = new_short_count;
+    regionIndices.len = new_ri_count;
+
+    unsigned int size = regionIndices.get_size () - HBUINT16::static_size/*regionIndices.len*/ + (get_row_size () * itemCount);
+    if (unlikely (!c->allocate_size<HBUINT8> (size)))
+      return_trace (false);
+
+    for (r = 0; r < ri_count; r++)
+      if (delta_sz[r]) regionIndices[ri_map[r]] = region_map[src->regionIndices[r]];
+
+    for (unsigned int i = 0; i < itemCount; i++)
+    {
+      unsigned int	old = inner_map.backward (i);
+      for (unsigned int r = 0; r < ri_count; r++)
+	if (delta_sz[r]) set_item_delta (i, ri_map[r], src->get_item_delta (old, r));
+    }
+
+    return_trace (true);
+  }
+
+  void collect_region_refs (hb_inc_bimap_t &region_map, const hb_inc_bimap_t &inner_map) const
+  {
+    for (unsigned int r = 0; r < regionIndices.len; r++)
+    {
+      unsigned int region = regionIndices[r];
+      if (region_map.has (region)) continue;
+      for (unsigned int i = 0; i < inner_map.get_next_value (); i++)
+	if (get_item_delta (inner_map.backward (i), r) != 0)
+	{
+	  region_map.add (region);
+	  break;
+	}
+    }
+  }
+
+  protected:
+  const HBUINT8 *get_delta_bytes () const
+  { return &StructAfter<HBUINT8> (regionIndices); }
+
+  HBUINT8 *get_delta_bytes ()
+  { return &StructAfter<HBUINT8> (regionIndices); }
+
+  int16_t get_item_delta (unsigned int item, unsigned int region) const
+  {
+    if ( item >= itemCount || unlikely (region >= regionIndices.len)) return 0;
+    const HBINT8 *p = (const HBINT8 *)get_delta_bytes () + item * get_row_size ();
+    if (region < shortCount)
+      return ((const HBINT16 *)p)[region];
+    else
+      return (p + HBINT16::static_size * shortCount)[region - shortCount];
+  }
+
+  void set_item_delta (unsigned int item, unsigned int region, int16_t delta)
+  {
+    HBINT8 *p = (HBINT8 *)get_delta_bytes () + item * get_row_size ();
+    if (region < shortCount)
+      ((HBINT16 *)p)[region] = delta;
+    else
+      (p + HBINT16::static_size * shortCount)[region - shortCount] = delta;
+  }
+
+  protected:
+  HBUINT16		itemCount;
+  HBUINT16		shortCount;
+  ArrayOf<HBUINT16>	regionIndices;
+/*UnsizedArrayOf<HBUINT8>bytesX;*/
+  public:
+  DEFINE_SIZE_ARRAY (6, regionIndices);
+};
+
+struct VariationStore
+{
+  float get_delta (unsigned int outer, unsigned int inner,
+		   const int *coords, unsigned int coord_count) 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);
+  }
+
+  float get_delta (unsigned int index,
+		   const int *coords, unsigned int coord_count) const
+  {
+    unsigned int outer = index >> 16;
+    unsigned int inner = index & 0xFFFF;
+    return get_delta (outer, inner, coords, coord_count);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+#ifdef HB_NO_VAR
+    return true;
+#endif
+
+    TRACE_SANITIZE (this);
+    return_trace (c->check_struct (this) &&
+		  format == 1 &&
+		  regions.sanitize (c, this) &&
+		  dataSets.sanitize (c, this));
+  }
+
+  bool serialize (hb_serialize_context_t *c,
+		  const VariationStore *src,
+		  const hb_array_t <hb_inc_bimap_t> &inner_maps)
+  {
+    TRACE_SERIALIZE (this);
+    unsigned int set_count = 0;
+    for (unsigned int i = 0; i < inner_maps.length; i++)
+      if (inner_maps[i].get_population () > 0) set_count++;
+
+    unsigned int size = min_size + HBUINT32::static_size * set_count;
+    if (unlikely (!c->allocate_size<HBUINT32> (size))) return_trace (false);
+    format = 1;
+
+    hb_inc_bimap_t region_map;
+    for (unsigned int i = 0; i < inner_maps.length; i++)
+      (src+src->dataSets[i]).collect_region_refs (region_map, inner_maps[i]);
+    region_map.sort ();
+
+    if (unlikely (!regions.serialize (c, this)
+		  .serialize (c, &(src+src->regions), region_map))) return_trace (false);
+
+    /* TODO: The following code could be simplified when
+     * OffsetListOf::subset () can take a custom param to be passed to VarData::serialize ()
+     */
+    dataSets.len = set_count;
+    unsigned int set_index = 0;
+    for (unsigned int i = 0; i < inner_maps.length; i++)
+    {
+      if (inner_maps[i].get_population () == 0) continue;
+      if (unlikely (!dataSets[set_index++].serialize (c, this)
+		      .serialize (c, &(src+src->dataSets[i]), inner_maps[i], region_map)))
+	return_trace (false);
+    }
+
+    return_trace (true);
+  }
+
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+
+    VariationStore *varstore_prime = c->serializer->start_embed<VariationStore> ();
+    if (unlikely (!varstore_prime)) return_trace (false);
+
+    const hb_set_t *variation_indices = c->plan->layout_variation_indices;
+    if (variation_indices->is_empty ()) return_trace (false);
+
+    hb_vector_t<hb_inc_bimap_t> inner_maps;
+    inner_maps.resize ((unsigned) dataSets.len);
+    for (unsigned i = 0; i < inner_maps.length; i++)
+      inner_maps[i].init ();
+
+    for (unsigned idx : c->plan->layout_variation_indices->iter ())
+    {
+      uint16_t major = idx >> 16;
+      uint16_t minor = idx & 0xFFFF;
+
+      if (major >= inner_maps.length)
+      {
+	for (unsigned i = 0; i < inner_maps.length; i++)
+	  inner_maps[i].fini ();
+	return_trace (false);
+      }
+      inner_maps[major].add (minor);
+    }
+    varstore_prime->serialize (c->serializer, this, inner_maps.as_array ());
+
+    for (unsigned i = 0; i < inner_maps.length; i++)
+      inner_maps[i].fini ();
+    return_trace (bool (varstore_prime->dataSets));
+  }
+
+  unsigned int get_region_index_count (unsigned int ivs) const
+  { return (this+dataSets[ivs]).get_region_index_count (); }
+
+  void get_scalars (unsigned int ivs,
+		    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[ivs]).get_scalars (coords, coord_count, this+regions,
+				      &scalars[0], num_scalars);
+  }
+
+  unsigned int get_sub_table_count () const { return dataSets.len; }
+
+  protected:
+  HBUINT16				format;
+  LOffsetTo<VarRegionList>		regions;
+  LOffsetArrayOf<VarData>		dataSets;
+  public:
+  DEFINE_SIZE_ARRAY (8, dataSets);
+};
+
+/*
+ * Feature Variations
+ */
+
+struct ConditionFormat1
+{
+  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);
+    return_trace (true);
+  }
+
+  private:
+  bool evaluate (const int *coords, unsigned int coord_len) const
+  {
+    int coord = axisIndex < coord_len ? coords[axisIndex] : 0;
+    return filterRangeMinValue <= coord && coord <= filterRangeMaxValue;
+  }
+
+  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 Condition
+{
+  bool evaluate (const int *coords, unsigned int coord_len) const
+  {
+    switch (u.format) {
+    case 1: return u.format1.evaluate (coords, coord_len);
+    default:return false;
+    }
+  }
+
+  template <typename context_t, typename ...Ts>
+  typename context_t::return_t dispatch (context_t *c, Ts&&... ds) const
+  {
+    TRACE_DISPATCH (this, u.format);
+    if (unlikely (!c->may_dispatch (this, &u.format))) return_trace (c->no_dispatch_return_value ());
+    switch (u.format) {
+    case 1: return_trace (c->dispatch (u.format1, hb_forward<Ts> (ds)...));
+    default:return_trace (c->default_return_value ());
+    }
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    if (!u.format.sanitize (c)) return_trace (false);
+    switch (u.format) {
+    case 1: return_trace (u.format1.sanitize (c));
+    default:return_trace (true);
+    }
+  }
+
+  protected:
+  union {
+  HBUINT16		format;		/* Format identifier */
+  ConditionFormat1	format1;
+  } u;
+  public:
+  DEFINE_SIZE_UNION (2, format);
+};
+
+struct ConditionSet
+{
+  bool evaluate (const int *coords, unsigned int coord_len) const
+  {
+    unsigned int count = conditions.len;
+    for (unsigned int i = 0; i < count; i++)
+      if (!(this+conditions.arrayZ[i]).evaluate (coords, coord_len))
+	return false;
+    return true;
+  }
+
+  bool subset (hb_subset_context_t *c) const
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->serializer->start_embed (this);
+    if (unlikely (!out || !c->serializer->extend_min (out))) return_trace (false);
+
+    + conditions.iter ()
+    | hb_apply (subset_offset_array (c, out->conditions, this))
+    ;
+    return_trace (true);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (conditions.sanitize (c, this));
+  }
+
+  protected:
+  LOffsetArrayOf<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);
+  }
+
+  bool subset (hb_subset_layout_context_t *c, const void *base) const
+  {
+    TRACE_SUBSET (this);
+    auto *out = c->subset_context->serializer->embed (this);
+    if (unlikely (!out)) return_trace (false);
+
+    out->featureIndex = c->feature_index_map->get (featureIndex);
+    bool ret = out->feature.serialize_subset (c->subset_context, feature, base, c);
+    return_trace (ret);
+  }
+
+  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;
+  LOffsetTo<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 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;
+
+    + substitutions.iter ()
+    | hb_apply (subset_record_array (l, &(out->substitutions), this))
+    ;
+    return_trace (true);
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (version.sanitize (c) &&
+		  likely (version.major == 1) &&
+		  substitutions.sanitize (c, this));
+  }
+
+  protected:
+  FixedVersion<>	version;	/* Version--0x00010000u */
+  ArrayOf<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 subset (hb_subset_layout_context_t *c, const void *base) 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);
+    out->substitutions.serialize_subset (c->subset_context, substitutions, base, c);
+
+    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:
+  LOffsetTo<ConditionSet>
+			conditions;
+  LOffsetTo<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) 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))
+      {
+	*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);
+  }
+
+  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,
+			hb_set_t       *lookup_indexes /* OUT */) const
+  {
+    for (const FeatureVariationRecord& r : varRecords)
+      r.collect_lookups (this, feature_indexes, lookup_indexes);
+  }
+
+  void closure_features (const hb_map_t *lookup_indexes,
+			 hb_set_t       *feature_indexes /* OUT */) const
+  {
+    for (const FeatureVariationRecord& record : varRecords)
+      record.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;
+
+    + varRecords.iter ()
+    | hb_apply (subset_record_array (l, &(out->varRecords), this))
+    ;
+    return_trace (bool (out->varRecords));
+  }
+
+  bool sanitize (hb_sanitize_context_t *c) const
+  {
+    TRACE_SANITIZE (this);
+    return_trace (version.sanitize (c) &&
+		  likely (version.major == 1) &&
+		  varRecords.sanitize (c, this));
+  }
+
+  protected:
+  FixedVersion<>	version;	/* Version--0x00010000u */
+  LArrayOf<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 VariationStore &store) const
+  { return font->em_scalef_x (get_delta (font, store)); }
+
+  hb_position_t get_y_delta (hb_font_t *font, const VariationStore &store) const
+  { return font->em_scalef_y (get_delta (font, store)); }
+
+  VariationDevice* copy (hb_serialize_context_t *c, const hb_map_t *layout_variation_idx_map) const
+  {
+    TRACE_SERIALIZE (this);
+    auto snap = c->snapshot ();
+    auto *out = c->embed (this);
+    if (unlikely (!out)) return_trace (nullptr);
+    if (!layout_variation_idx_map || layout_variation_idx_map->is_empty ()) return_trace (out);
+
+    unsigned org_idx = (outerIndex << 16) + innerIndex;
+    if (!layout_variation_idx_map->has (org_idx))
+    {
+      c->revert (snap);
+      return_trace (nullptr);
+    }
+    unsigned new_idx = layout_variation_idx_map->get (org_idx);
+    out->outerIndex = new_idx >> 16;
+    out->innerIndex = new_idx & 0xFFFF;
+    return_trace (out);
+  }
+
+  void record_variation_index (hb_set_t *layout_variation_indices) const
+  {
+    unsigned var_idx = (outerIndex << 16) + innerIndex;
+    layout_variation_indices->add (var_idx);
+  }
+
+  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 VariationStore &store) const
+  {
+    return store.get_delta (outerIndex, innerIndex, font->coords, font->num_coords);
+  }
+
+  protected:
+  HBUINT16	outerIndex;
+  HBUINT16	innerIndex;
+  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 VariationStore &store=Null (VariationStore)) 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);
+#endif
+    default:
+      return 0;
+    }
+  }
+  hb_position_t get_y_delta (hb_font_t *font, const VariationStore &store=Null (VariationStore)) 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);
+#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_map_t *layout_variation_idx_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_map)));
+#endif
+    default:
+      return_trace (nullptr);
+    }
+  }
+
+  void collect_variation_indices (hb_set_t *layout_variation_indices) 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.record_variation_index (layout_variation_indices);
+      return;
+#endif
+    default:
+      return;
+    }
+  }
+
+  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 */