kc3-lang/harfbuzz/src/hb-open-type-private.hh

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• Hash : dde64483
  Author :
  Date : 2018-02-11T18:24:22
  

  Another try at fixing multiple-defintion of NullPool
  
  This one might do it...
  

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• src/hb-open-type-private.hh

• /*
   * Copyright © 2007,2008,2009,2010  Red Hat, Inc.
   * Copyright © 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_OPEN_TYPE_PRIVATE_HH
  #define HB_OPEN_TYPE_PRIVATE_HH
  
  #include "hb-private.hh"
  #include "hb-debug.hh"
  #include "hb-face-private.hh"
  
  
  namespace OT {
  
  
  
  /*
   * Casts
   */
  
  /* Cast to struct T, reference to reference */
  template<typename Type, typename TObject>
  static inline const Type& CastR(const TObject &X)
  { return reinterpret_cast<const Type&> (X); }
  template<typename Type, typename TObject>
  static inline Type& CastR(TObject &X)
  { return reinterpret_cast<Type&> (X); }
  
  /* Cast to struct T, pointer to pointer */
  template<typename Type, typename TObject>
  static inline const Type* CastP(const TObject *X)
  { return reinterpret_cast<const Type*> (X); }
  template<typename Type, typename TObject>
  static inline Type* CastP(TObject *X)
  { return reinterpret_cast<Type*> (X); }
  
  /* StructAtOffset<T>(P,Ofs) returns the struct T& that is placed at memory
   * location pointed to by P plus Ofs bytes. */
  template<typename Type>
  static inline const Type& StructAtOffset(const void *P, unsigned int offset)
  { return * reinterpret_cast<const Type*> ((const char *) P + offset); }
  template<typename Type>
  static inline Type& StructAtOffset(void *P, unsigned int offset)
  { return * reinterpret_cast<Type*> ((char *) P + offset); }
  
  /* StructAfter<T>(X) returns the struct T& that is placed after X.
   * Works with X of variable size also.  X must implement get_size() */
  template<typename Type, typename TObject>
  static inline const Type& StructAfter(const TObject &X)
  { return StructAtOffset<Type>(&X, X.get_size()); }
  template<typename Type, typename TObject>
  static inline Type& StructAfter(TObject &X)
  { return StructAtOffset<Type>(&X, X.get_size()); }
  
  
  
  /*
   * Size checking
   */
  
  /* Check _assertion in a method environment */
  #define _DEFINE_INSTANCE_ASSERTION1(_line, _assertion) \
    inline void _instance_assertion_on_line_##_line (void) const \
    { \
      static_assert ((_assertion), ""); \
      ASSERT_INSTANCE_POD (*this); /* Make sure it's POD. */ \
    }
  # define _DEFINE_INSTANCE_ASSERTION0(_line, _assertion) _DEFINE_INSTANCE_ASSERTION1 (_line, _assertion)
  # define DEFINE_INSTANCE_ASSERTION(_assertion) _DEFINE_INSTANCE_ASSERTION0 (__LINE__, _assertion)
  
  /* Check that _code compiles in a method environment */
  #define _DEFINE_COMPILES_ASSERTION1(_line, _code) \
    inline void _compiles_assertion_on_line_##_line (void) const \
    { _code; }
  # define _DEFINE_COMPILES_ASSERTION0(_line, _code) _DEFINE_COMPILES_ASSERTION1 (_line, _code)
  # define DEFINE_COMPILES_ASSERTION(_code) _DEFINE_COMPILES_ASSERTION0 (__LINE__, _code)
  
  
  #define DEFINE_SIZE_STATIC(size) \
    DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size)); \
    static const unsigned int static_size = (size); \
    static const unsigned int min_size = (size); \
    inline unsigned int get_size (void) const { return (size); }
  
  #define DEFINE_SIZE_UNION(size, _member) \
    DEFINE_INSTANCE_ASSERTION (0*sizeof(this->u._member.static_size) + sizeof(this->u._member) == (size)); \
    static const unsigned int min_size = (size)
  
  #define DEFINE_SIZE_MIN(size) \
    DEFINE_INSTANCE_ASSERTION (sizeof (*this) >= (size)); \
    static const unsigned int min_size = (size)
  
  #define DEFINE_SIZE_ARRAY(size, array) \
    DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + sizeof (array[0])); \
    DEFINE_COMPILES_ASSERTION ((void) array[0].static_size) \
    static const unsigned int min_size = (size)
  
  #define DEFINE_SIZE_ARRAY2(size, array1, array2) \
    DEFINE_INSTANCE_ASSERTION (sizeof (*this) == (size) + sizeof (this->array1[0]) + sizeof (this->array2[0])); \
    DEFINE_COMPILES_ASSERTION ((void) array1[0].static_size; (void) array2[0].static_size) \
    static const unsigned int min_size = (size)
  
  
  
  /*
   * Null objects
   */
  
  /* Global nul-content Null pool.  Enlarge as necessary. */
  
  #define HB_NULL_POOL_SIZE 264
  static_assert (HB_NULL_POOL_SIZE % sizeof (void *) == 0, "Align HB_NULL_POOL_SIZE.");
  
  #ifdef HB_NO_VISIBILITY
  static
  #else
  extern HB_INTERNAL
  #endif
  const void * const _hb_NullPool[HB_NULL_POOL_SIZE / sizeof (void *)]
  #ifdef HB_NO_VISIBILITY
  = {}
  #endif
  ;
  
  /* Generic nul-content Null objects. */
  template <typename Type>
  static inline const Type& Null (void) {
    static_assert (sizeof (Type) <= HB_NULL_POOL_SIZE, "Increase HB_NULL_POOL_SIZE.");
    return *CastP<Type> (_hb_NullPool);
  }
  
  /* Specializaiton for arbitrary-content arbitrary-sized Null objects. */
  #define DEFINE_NULL_DATA(Type, data) \
  static const char _Null##Type[sizeof (Type) + 1] = data; /* +1 is for nul-termination in data */ \
  template <> \
  /*static*/ inline const Type& Null<Type> (void) { \
    return *CastP<Type> (_Null##Type); \
  } /* The following line really exists such that we end in a place needing semicolon */ \
  static_assert (Type::min_size + 1 <= sizeof (_Null##Type), "Null pool too small.  Enlarge.")
  
  /* Accessor macro. */
  #define Null(Type) Null<Type>()
  
  
  /*
   * Dispatch
   */
  
  template <typename Context, typename Return, unsigned int MaxDebugDepth>
  struct hb_dispatch_context_t
  {
    static const unsigned int max_debug_depth = MaxDebugDepth;
    typedef Return return_t;
    template <typename T, typename F>
    inline bool may_dispatch (const T *obj, const F *format) { return true; }
    static return_t no_dispatch_return_value (void) { return Context::default_return_value (); }
  };
  
  
  /*
   * Sanitize
   */
  
  /* This limits sanitizing time on really broken fonts. */
  #ifndef HB_SANITIZE_MAX_EDITS
  #define HB_SANITIZE_MAX_EDITS 32
  #endif
  
  struct hb_sanitize_context_t :
         hb_dispatch_context_t<hb_sanitize_context_t, bool, HB_DEBUG_SANITIZE>
  {
    inline hb_sanitize_context_t (void) :
  	debug_depth (0),
  	start (nullptr), end (nullptr),
  	writable (false), edit_count (0),
  	blob (nullptr),
  	num_glyphs (0) {}
  
    inline const char *get_name (void) { return "SANITIZE"; }
    template <typename T, typename F>
    inline bool may_dispatch (const T *obj, const F *format)
    { return format->sanitize (this); }
    template <typename T>
    inline return_t dispatch (const T &obj) { return obj.sanitize (this); }
    static return_t default_return_value (void) { return true; }
    static return_t no_dispatch_return_value (void) { return false; }
    bool stop_sublookup_iteration (const return_t r) const { return !r; }
  
    inline void init (hb_blob_t *b)
    {
      this->blob = hb_blob_reference (b);
      this->writable = false;
    }
  
    inline void start_processing (void)
    {
      this->start = hb_blob_get_data (this->blob, nullptr);
      this->end = this->start + hb_blob_get_length (this->blob);
      assert (this->start <= this->end); /* Must not overflow. */
      this->edit_count = 0;
      this->debug_depth = 0;
  
      DEBUG_MSG_LEVEL (SANITIZE, start, 0, +1,
  		     "start [%p..%p] (%lu bytes)",
  		     this->start, this->end,
  		     (unsigned long) (this->end - this->start));
    }
  
    inline void end_processing (void)
    {
      DEBUG_MSG_LEVEL (SANITIZE, this->start, 0, -1,
  		     "end [%p..%p] %u edit requests",
  		     this->start, this->end, this->edit_count);
  
      hb_blob_destroy (this->blob);
      this->blob = nullptr;
      this->start = this->end = nullptr;
    }
  
    inline bool check_range (const void *base, unsigned int len) const
    {
      const char *p = (const char *) base;
      bool ok = this->start <= p && p <= this->end && (unsigned int) (this->end - p) >= len;
  
      DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0,
         "check_range [%p..%p] (%d bytes) in [%p..%p] -> %s",
         p, p + len, len,
         this->start, this->end,
         ok ? "OK" : "OUT-OF-RANGE");
  
      return likely (ok);
    }
  
    inline bool check_array (const void *base, unsigned int record_size, unsigned int len) const
    {
      const char *p = (const char *) base;
      bool overflows = _hb_unsigned_int_mul_overflows (len, record_size);
      unsigned int array_size = record_size * len;
      bool ok = !overflows && this->check_range (base, array_size);
  
      DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0,
         "check_array [%p..%p] (%d*%d=%d bytes) in [%p..%p] -> %s",
         p, p + (record_size * len), record_size, len, (unsigned int) array_size,
         this->start, this->end,
         overflows ? "OVERFLOWS" : ok ? "OK" : "OUT-OF-RANGE");
  
      return likely (ok);
    }
  
    template <typename Type>
    inline bool check_struct (const Type *obj) const
    {
      return likely (this->check_range (obj, obj->min_size));
    }
  
    inline bool may_edit (const void *base HB_UNUSED, unsigned int len HB_UNUSED)
    {
      if (this->edit_count >= HB_SANITIZE_MAX_EDITS)
        return false;
  
      const char *p = (const char *) base;
      this->edit_count++;
  
      DEBUG_MSG_LEVEL (SANITIZE, p, this->debug_depth+1, 0,
         "may_edit(%u) [%p..%p] (%d bytes) in [%p..%p] -> %s",
         this->edit_count,
         p, p + len, len,
         this->start, this->end,
         this->writable ? "GRANTED" : "DENIED");
  
      return this->writable;
    }
  
    template <typename Type, typename ValueType>
    inline bool try_set (const Type *obj, const ValueType &v) {
      if (this->may_edit (obj, obj->static_size)) {
        const_cast<Type *> (obj)->set (v);
        return true;
      }
      return false;
    }
  
    mutable unsigned int debug_depth;
    const char *start, *end;
    bool writable;
    unsigned int edit_count;
    hb_blob_t *blob;
    unsigned int num_glyphs;
  };
  
  
  
  /* Template to sanitize an object. */
  template <typename Type>
  struct Sanitizer
  {
    inline Sanitizer (void) {}
  
    inline hb_blob_t *sanitize (hb_blob_t *blob) {
      bool sane;
  
      /* TODO is_sane() stuff */
  
      c->init (blob);
  
    retry:
      DEBUG_MSG_FUNC (SANITIZE, c->start, "start");
  
      c->start_processing ();
  
      if (unlikely (!c->start)) {
        c->end_processing ();
        return blob;
      }
  
      Type *t = CastP<Type> (const_cast<char *> (c->start));
  
      sane = t->sanitize (c);
      if (sane) {
        if (c->edit_count) {
  	DEBUG_MSG_FUNC (SANITIZE, c->start, "passed first round with %d edits; going for second round", c->edit_count);
  
          /* sanitize again to ensure no toe-stepping */
          c->edit_count = 0;
  	sane = t->sanitize (c);
  	if (c->edit_count) {
  	  DEBUG_MSG_FUNC (SANITIZE, c->start, "requested %d edits in second round; FAILLING", c->edit_count);
  	  sane = false;
  	}
        }
      } else {
        unsigned int edit_count = c->edit_count;
        if (edit_count && !c->writable) {
          c->start = hb_blob_get_data_writable (blob, nullptr);
  	c->end = c->start + hb_blob_get_length (blob);
  
  	if (c->start) {
  	  c->writable = true;
  	  /* ok, we made it writable by relocating.  try again */
  	  DEBUG_MSG_FUNC (SANITIZE, c->start, "retry");
  	  goto retry;
  	}
        }
      }
  
      c->end_processing ();
  
      DEBUG_MSG_FUNC (SANITIZE, c->start, sane ? "PASSED" : "FAILED");
      if (sane)
        return blob;
      else {
        hb_blob_destroy (blob);
        return hb_blob_get_empty ();
      }
    }
  
    static const Type* lock_instance (hb_blob_t *blob) {
      hb_blob_make_immutable (blob);
      const char *base = hb_blob_get_data (blob, nullptr);
      return unlikely (!base) ? &Null(Type) : CastP<Type> (base);
    }
  
    inline void set_num_glyphs (unsigned int num_glyphs) { c->num_glyphs = num_glyphs; }
  
    private:
    hb_sanitize_context_t c[1];
  };
  
  
  
  /*
   * Serialize
   */
  
  
  struct hb_serialize_context_t
  {
    inline hb_serialize_context_t (void *start_, unsigned int size)
    {
      this->start = (char *) start_;
      this->end = this->start + size;
  
      this->ran_out_of_room = false;
      this->head = this->start;
      this->debug_depth = 0;
    }
  
    template <typename Type>
    inline Type *start_serialize (void)
    {
      DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, +1,
  		     "start [%p..%p] (%lu bytes)",
  		     this->start, this->end,
  		     (unsigned long) (this->end - this->start));
  
      return start_embed<Type> ();
    }
  
    inline void end_serialize (void)
    {
      DEBUG_MSG_LEVEL (SERIALIZE, this->start, 0, -1,
  		     "end [%p..%p] serialized %d bytes; %s",
  		     this->start, this->end,
  		     (int) (this->head - this->start),
  		     this->ran_out_of_room ? "RAN OUT OF ROOM" : "did not ran out of room");
  
    }
  
    template <typename Type>
    inline Type *copy (void)
    {
      assert (!this->ran_out_of_room);
      unsigned int len = this->head - this->start;
      void *p = malloc (len);
      if (p)
        memcpy (p, this->start, len);
      return reinterpret_cast<Type *> (p);
    }
  
    template <typename Type>
    inline Type *allocate_size (unsigned int size)
    {
      if (unlikely (this->ran_out_of_room || this->end - this->head < ptrdiff_t (size))) {
        this->ran_out_of_room = true;
        return nullptr;
      }
      memset (this->head, 0, size);
      char *ret = this->head;
      this->head += size;
      return reinterpret_cast<Type *> (ret);
    }
  
    template <typename Type>
    inline Type *allocate_min (void)
    {
      return this->allocate_size<Type> (Type::min_size);
    }
  
    template <typename Type>
    inline Type *start_embed (void)
    {
      Type *ret = reinterpret_cast<Type *> (this->head);
      return ret;
    }
  
    template <typename Type>
    inline Type *embed (const Type &obj)
    {
      unsigned int size = obj.get_size ();
      Type *ret = this->allocate_size<Type> (size);
      if (unlikely (!ret)) return nullptr;
      memcpy (ret, obj, size);
      return ret;
    }
  
    template <typename Type>
    inline Type *extend_min (Type &obj)
    {
      unsigned int size = obj.min_size;
      assert (this->start <= (char *) &obj && (char *) &obj <= this->head && (char *) &obj + size >= this->head);
      if (unlikely (!this->allocate_size<Type> (((char *) &obj) + size - this->head))) return nullptr;
      return reinterpret_cast<Type *> (&obj);
    }
  
    template <typename Type>
    inline Type *extend (Type &obj)
    {
      unsigned int size = obj.get_size ();
      assert (this->start < (char *) &obj && (char *) &obj <= this->head && (char *) &obj + size >= this->head);
      if (unlikely (!this->allocate_size<Type> (((char *) &obj) + size - this->head))) return nullptr;
      return reinterpret_cast<Type *> (&obj);
    }
  
    inline void truncate (void *new_head)
    {
      assert (this->start < new_head && new_head <= this->head);
      this->head = (char *) new_head;
    }
  
    unsigned int debug_depth;
    char *start, *end, *head;
    bool ran_out_of_room;
  };
  
  template <typename Type>
  struct Supplier
  {
    inline Supplier (const Type *array, unsigned int len_, unsigned int stride_=sizeof(Type))
    {
      head = array;
      len = len_;
      stride = stride_;
    }
    inline const Type operator [] (unsigned int i) const
    {
      if (unlikely (i >= len)) return Type ();
      return * (const Type *) (const void *) ((const char *) head + stride * i);
    }
  
    inline Supplier<Type> & operator += (unsigned int count)
    {
      if (unlikely (count > len))
        count = len;
      len -= count;
      head = (const Type *) (const void *) ((const char *) head + stride * count);
      return *this;
    }
  
    private:
    inline Supplier (const Supplier<Type> &); /* Disallow copy */
    inline Supplier<Type>& operator= (const Supplier<Type> &); /* Disallow copy */
  
    unsigned int len;
    unsigned int stride;
    const Type *head;
  };
  
  
  /*
   *
   * The OpenType Font File: Data Types
   */
  
  
  /* "The following data types are used in the OpenType font file.
   *  All OpenType fonts use Motorola-style byte ordering (Big Endian):" */
  
  /*
   * Int types
   */
  
  
  template <typename Type, int Bytes> struct BEInt;
  
  template <typename Type>
  struct BEInt<Type, 1>
  {
    public:
    inline void set (Type V)
    {
      v = V;
    }
    inline operator Type (void) const
    {
      return v;
    }
    private: uint8_t v;
  };
  template <typename Type>
  struct BEInt<Type, 2>
  {
    public:
    inline void set (Type V)
    {
      v[0] = (V >>  8) & 0xFF;
      v[1] = (V      ) & 0xFF;
    }
    inline operator Type (void) const
    {
      return (v[0] <<  8)
           + (v[1]      );
    }
    private: uint8_t v[2];
  };
  template <typename Type>
  struct BEInt<Type, 3>
  {
    public:
    inline void set (Type V)
    {
      v[0] = (V >> 16) & 0xFF;
      v[1] = (V >>  8) & 0xFF;
      v[2] = (V      ) & 0xFF;
    }
    inline operator Type (void) const
    {
      return (v[0] << 16)
           + (v[1] <<  8)
           + (v[2]      );
    }
    private: uint8_t v[3];
  };
  template <typename Type>
  struct BEInt<Type, 4>
  {
    public:
    inline void set (Type V)
    {
      v[0] = (V >> 24) & 0xFF;
      v[1] = (V >> 16) & 0xFF;
      v[2] = (V >>  8) & 0xFF;
      v[3] = (V      ) & 0xFF;
    }
    inline operator Type (void) const
    {
      return (v[0] << 24)
           + (v[1] << 16)
           + (v[2] <<  8)
           + (v[3]      );
    }
    private: uint8_t v[4];
  };
  
  /* Integer types in big-endian order and no alignment requirement */
  template <typename Type, unsigned int Size>
  struct IntType
  {
    inline void set (Type i) { v.set (i); }
    inline operator Type(void) const { return v; }
    inline bool operator == (const IntType<Type,Size> &o) const { return (Type) v == (Type) o.v; }
    inline bool operator != (const IntType<Type,Size> &o) const { return !(*this == o); }
    static inline int cmp (const IntType<Type,Size> *a, const IntType<Type,Size> *b) { return b->cmp (*a); }
    template <typename Type2>
    inline int cmp (Type2 a) const
    {
      Type b = v;
      if (sizeof (Type) < sizeof (int) && sizeof (Type2) < sizeof (int))
        return (int) a - (int) b;
      else
        return a < b ? -1 : a == b ? 0 : +1;
    }
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (likely (c->check_struct (this)));
    }
    protected:
    BEInt<Type, Size> v;
    public:
    DEFINE_SIZE_STATIC (Size);
  };
  
  typedef IntType<uint8_t,  1> HBUINT8;	/* 8-bit unsigned integer. */
  typedef IntType<int8_t,   1> HBINT8;	/* 8-bit signed integer. */
  typedef IntType<uint16_t, 2> HBUINT16;	/* 16-bit unsigned integer. */
  typedef IntType<int16_t,  2> HBINT16;	/* 16-bit signed integer. */
  typedef IntType<uint32_t, 4> HBUINT32;	/* 32-bit unsigned integer. */
  typedef IntType<int32_t,  4> HBINT32;	/* 32-bit signed integer. */
  typedef IntType<uint32_t, 3> UINT24;	/* 24-bit unsigned integer. */
  
  /* 16-bit signed integer (HBINT16) that describes a quantity in FUnits. */
  typedef HBINT16 FWORD;
  
  /* 16-bit unsigned integer (HBUINT16) that describes a quantity in FUnits. */
  typedef HBUINT16 UFWORD;
  
  /* 16-bit signed fixed number with the low 14 bits of fraction (2.14). */
  struct F2DOT14 : HBINT16
  {
    //inline float to_float (void) const { return ???; }
    //inline void set_float (float f) { v.set (f * ???); }
    public:
    DEFINE_SIZE_STATIC (2);
  };
  
  /* 32-bit signed fixed-point number (16.16). */
  struct Fixed: HBINT32
  {
    //inline float to_float (void) const { return ???; }
    //inline void set_float (float f) { v.set (f * ???); }
    public:
    DEFINE_SIZE_STATIC (4);
  };
  
  /* Date represented in number of seconds since 12:00 midnight, January 1,
   * 1904. The value is represented as a signed 64-bit integer. */
  struct LONGDATETIME
  {
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (likely (c->check_struct (this)));
    }
    protected:
    HBINT32 major;
    HBUINT32 minor;
    public:
    DEFINE_SIZE_STATIC (8);
  };
  
  /* Array of four uint8s (length = 32 bits) used to identify a script, language
   * system, feature, or baseline */
  struct Tag : HBUINT32
  {
    /* What the char* converters return is NOT nul-terminated.  Print using "%.4s" */
    inline operator const char* (void) const { return reinterpret_cast<const char *> (&this->v); }
    inline operator char* (void) { return reinterpret_cast<char *> (&this->v); }
    public:
    DEFINE_SIZE_STATIC (4);
  };
  DEFINE_NULL_DATA (Tag, "    ");
  
  /* Glyph index number, same as uint16 (length = 16 bits) */
  typedef HBUINT16 GlyphID;
  
  /* Script/language-system/feature index */
  struct Index : HBUINT16 {
    static const unsigned int NOT_FOUND_INDEX = 0xFFFFu;
  };
  DEFINE_NULL_DATA (Index, "\xff\xff");
  
  /* Offset, Null offset = 0 */
  template <typename Type>
  struct Offset : Type
  {
    inline bool is_null (void) const { return 0 == *this; }
    public:
    DEFINE_SIZE_STATIC (sizeof(Type));
  
    inline void *serialize (hb_serialize_context_t *c, const void *base)
    {
      void *t = c->start_embed<void> ();
      this->set ((char *) t - (char *) base); /* TODO(serialize) Overflow? */
      return t;
    }
  };
  
  typedef Offset<HBUINT16> Offset16;
  typedef Offset<HBUINT32> Offset32;
  
  
  /* CheckSum */
  struct CheckSum : HBUINT32
  {
    /* This is reference implementation from the spec. */
    static inline uint32_t CalcTableChecksum (const HBUINT32 *Table, uint32_t Length)
    {
      uint32_t Sum = 0L;
      const HBUINT32 *EndPtr = Table+((Length+3) & ~3) / HBUINT32::static_size;
  
      while (Table < EndPtr)
        Sum += *Table++;
      return Sum;
    }
  
    /* Note: data should be 4byte aligned and have 4byte padding at the end. */
    inline void set_for_data (const void *data, unsigned int length)
    { set (CalcTableChecksum ((const HBUINT32 *) data, length)); }
  
    public:
    DEFINE_SIZE_STATIC (4);
  };
  
  
  /*
   * Version Numbers
   */
  
  template <typename FixedType=HBUINT16>
  struct FixedVersion
  {
    inline uint32_t to_int (void) const { return (major << (sizeof(FixedType) * 8)) + minor; }
  
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (c->check_struct (this));
    }
  
    FixedType major;
    FixedType minor;
    public:
    DEFINE_SIZE_STATIC (2 * sizeof(FixedType));
  };
  
  
  
  /*
   * Template subclasses of Offset that do the dereferencing.
   * Use: (base+offset)
   */
  
  template <typename Type, typename OffsetType=HBUINT16>
  struct OffsetTo : Offset<OffsetType>
  {
    inline const Type& operator () (const void *base) const
    {
      unsigned int offset = *this;
      if (unlikely (!offset)) return Null(Type);
      return StructAtOffset<Type> (base, offset);
    }
  
    inline Type& serialize (hb_serialize_context_t *c, const void *base)
    {
      return * (Type *) Offset<OffsetType>::serialize (c, base);
    }
  
    inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
    {
      TRACE_SANITIZE (this);
      if (unlikely (!c->check_struct (this))) return_trace (false);
      unsigned int offset = *this;
      if (unlikely (!offset)) return_trace (true);
      if (unlikely (!c->check_range (base, offset))) return_trace (false);
      const Type &obj = StructAtOffset<Type> (base, offset);
      return_trace (likely (obj.sanitize (c)) || neuter (c));
    }
    template <typename T>
    inline bool sanitize (hb_sanitize_context_t *c, const void *base, T user_data) const
    {
      TRACE_SANITIZE (this);
      if (unlikely (!c->check_struct (this))) return_trace (false);
      unsigned int offset = *this;
      if (unlikely (!offset)) return_trace (true);
      if (unlikely (!c->check_range (base, offset))) return_trace (false);
      const Type &obj = StructAtOffset<Type> (base, offset);
      return_trace (likely (obj.sanitize (c, user_data)) || neuter (c));
    }
  
    /* Set the offset to Null */
    inline bool neuter (hb_sanitize_context_t *c) const {
      return c->try_set (this, 0);
    }
    DEFINE_SIZE_STATIC (sizeof(OffsetType));
  };
  template <typename Type> struct LOffsetTo : OffsetTo<Type, HBUINT32> {};
  template <typename Base, typename OffsetType, typename Type>
  static inline const Type& operator + (const Base &base, const OffsetTo<Type, OffsetType> &offset) { return offset (base); }
  template <typename Base, typename OffsetType, typename Type>
  static inline Type& operator + (Base &base, OffsetTo<Type, OffsetType> &offset) { return offset (base); }
  
  
  /*
   * Array Types
   */
  
  /* An array with a number of elements. */
  template <typename Type, typename LenType=HBUINT16>
  struct ArrayOf
  {
    const Type *sub_array (unsigned int start_offset, unsigned int *pcount /* IN/OUT */) const
    {
      unsigned int count = len;
      if (unlikely (start_offset > count))
        count = 0;
      else
        count -= start_offset;
      count = MIN (count, *pcount);
      *pcount = count;
      return array + start_offset;
    }
  
    inline const Type& operator [] (unsigned int i) const
    {
      if (unlikely (i >= len)) return Null(Type);
      return array[i];
    }
    inline Type& operator [] (unsigned int i)
    {
      return array[i];
    }
    inline unsigned int get_size (void) const
    { return len.static_size + len * Type::static_size; }
  
    inline bool serialize (hb_serialize_context_t *c,
  			 unsigned int items_len)
    {
      TRACE_SERIALIZE (this);
      if (unlikely (!c->extend_min (*this))) return_trace (false);
      len.set (items_len); /* TODO(serialize) Overflow? */
      if (unlikely (!c->extend (*this))) return_trace (false);
      return_trace (true);
    }
  
    inline bool serialize (hb_serialize_context_t *c,
  			 Supplier<Type> &items,
  			 unsigned int items_len)
    {
      TRACE_SERIALIZE (this);
      if (unlikely (!serialize (c, items_len))) return_trace (false);
      for (unsigned int i = 0; i < items_len; i++)
        array[i] = items[i];
      items += items_len;
      return_trace (true);
    }
  
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      if (unlikely (!sanitize_shallow (c))) return_trace (false);
  
      /* Note: for structs that do not reference other structs,
       * we do not need to call their sanitize() as we already did
       * a bound check on the aggregate array size.  We just include
       * a small unreachable expression to make sure the structs
       * pointed to do have a simple sanitize(), ie. they do not
       * reference other structs via offsets.
       */
      (void) (false && array[0].sanitize (c));
  
      return_trace (true);
    }
    inline bool sanitize (hb_sanitize_context_t *c, const void *base) const
    {
      TRACE_SANITIZE (this);
      if (unlikely (!sanitize_shallow (c))) return_trace (false);
      unsigned int count = len;
      for (unsigned int i = 0; i < count; i++)
        if (unlikely (!array[i].sanitize (c, base)))
          return_trace (false);
      return_trace (true);
    }
    template <typename T>
    inline bool sanitize (hb_sanitize_context_t *c, const void *base, T user_data) const
    {
      TRACE_SANITIZE (this);
      if (unlikely (!sanitize_shallow (c))) return_trace (false);
      unsigned int count = len;
      for (unsigned int i = 0; i < count; i++)
        if (unlikely (!array[i].sanitize (c, base, user_data)))
          return_trace (false);
      return_trace (true);
    }
  
    template <typename SearchType>
    inline int lsearch (const SearchType &x) const
    {
      unsigned int count = len;
      for (unsigned int i = 0; i < count; i++)
        if (!this->array[i].cmp (x))
          return i;
      return -1;
    }
  
    inline void qsort (void)
    {
      ::qsort (array, len, sizeof (Type), Type::cmp);
    }
  
    private:
    inline bool sanitize_shallow (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (len.sanitize (c) && c->check_array (array, Type::static_size, len));
    }
  
    public:
    LenType len;
    Type array[VAR];
    public:
    DEFINE_SIZE_ARRAY (sizeof (LenType), array);
  };
  template <typename Type> struct LArrayOf : ArrayOf<Type, HBUINT32> {};
  
  /* Array of Offset's */
  template <typename Type, typename OffsetType=HBUINT16>
  struct OffsetArrayOf : ArrayOf<OffsetTo<Type, OffsetType> > {};
  
  /* Array of offsets relative to the beginning of the array itself. */
  template <typename Type>
  struct OffsetListOf : OffsetArrayOf<Type>
  {
    inline const Type& operator [] (unsigned int i) const
    {
      if (unlikely (i >= this->len)) return Null(Type);
      return this+this->array[i];
    }
  
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (OffsetArrayOf<Type>::sanitize (c, this));
    }
    template <typename T>
    inline bool sanitize (hb_sanitize_context_t *c, T user_data) const
    {
      TRACE_SANITIZE (this);
      return_trace (OffsetArrayOf<Type>::sanitize (c, this, user_data));
    }
  };
  
  
  /* An array starting at second element. */
  template <typename Type, typename LenType=HBUINT16>
  struct HeadlessArrayOf
  {
    inline const Type& operator [] (unsigned int i) const
    {
      if (unlikely (i >= len || !i)) return Null(Type);
      return array[i-1];
    }
    inline unsigned int get_size (void) const
    { return len.static_size + (len ? len - 1 : 0) * Type::static_size; }
  
    inline bool serialize (hb_serialize_context_t *c,
  			 Supplier<Type> &items,
  			 unsigned int items_len)
    {
      TRACE_SERIALIZE (this);
      if (unlikely (!c->extend_min (*this))) return_trace (false);
      len.set (items_len); /* TODO(serialize) Overflow? */
      if (unlikely (!items_len)) return_trace (true);
      if (unlikely (!c->extend (*this))) return_trace (false);
      for (unsigned int i = 0; i < items_len - 1; i++)
        array[i] = items[i];
      items += items_len - 1;
      return_trace (true);
    }
  
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      if (unlikely (!sanitize_shallow (c))) return_trace (false);
  
      /* Note: for structs that do not reference other structs,
       * we do not need to call their sanitize() as we already did
       * a bound check on the aggregate array size.  We just include
       * a small unreachable expression to make sure the structs
       * pointed to do have a simple sanitize(), ie. they do not
       * reference other structs via offsets.
       */
      (void) (false && array[0].sanitize (c));
  
      return_trace (true);
    }
  
    private:
    inline bool sanitize_shallow (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (len.sanitize (c) &&
  		  (!len || c->check_array (array, Type::static_size, len - 1)));
    }
  
    public:
    LenType len;
    Type array[VAR];
    public:
    DEFINE_SIZE_ARRAY (sizeof (LenType), array);
  };
  
  
  /*
   * An array with sorted elements.  Supports binary searching.
   */
  template <typename Type, typename LenType=HBUINT16>
  struct SortedArrayOf : ArrayOf<Type, LenType>
  {
    template <typename SearchType>
    inline int bsearch (const SearchType &x) const
    {
      /* Hand-coded bsearch here since this is in the hot inner loop. */
      const Type *arr = this->array;
      int min = 0, max = (int) this->len - 1;
      while (min <= max)
      {
        int mid = (min + max) / 2;
        int c = arr[mid].cmp (x);
        if (c < 0)
          max = mid - 1;
        else if (c > 0)
          min = mid + 1;
        else
          return mid;
      }
      return -1;
    }
  };
  
  /*
   * Binary-search arrays
   */
  
  struct BinSearchHeader
  {
    inline operator uint32_t (void) const { return len; }
  
    inline bool sanitize (hb_sanitize_context_t *c) const
    {
      TRACE_SANITIZE (this);
      return_trace (c->check_struct (this));
    }
  
    inline void set (unsigned int v)
    {
      len.set (v);
      assert (len == v);
      entrySelectorZ.set (MAX (1u, _hb_bit_storage (v)) - 1);
      searchRangeZ.set (16 * (1u << entrySelectorZ));
      rangeShiftZ.set (16 * MAX (0, (int) v - searchRangeZ));
    }
  
    protected:
    HBUINT16	len;
    HBUINT16	searchRangeZ;
    HBUINT16	entrySelectorZ;
    HBUINT16	rangeShiftZ;
  
    public:
    DEFINE_SIZE_STATIC (8);
  };
  
  template <typename Type>
  struct BinSearchArrayOf : SortedArrayOf<Type, BinSearchHeader> {};
  
  
  /* Lazy struct and blob loaders. */
  
  /* Logic is shared between hb_lazy_loader_t and hb_lazy_table_loader_t */
  template <typename T>
  struct hb_lazy_loader_t
  {
    inline void init (hb_face_t *face_)
    {
      face = face_;
      instance = nullptr;
    }
  
    inline void fini (void)
    {
      if (instance && instance != &OT::Null(T))
      {
        instance->fini();
        free (instance);
      }
    }
  
    inline const T* get (void) const
    {
    retry:
      T *p = (T *) hb_atomic_ptr_get (&instance);
      if (unlikely (!p))
      {
        p = (T *) calloc (1, sizeof (T));
        if (unlikely (!p))
          p = const_cast<T *> (&OT::Null(T));
        else
  	p->init (face);
        if (unlikely (!hb_atomic_ptr_cmpexch (const_cast<T **>(&instance), nullptr, p)))
        {
  	if (p != &OT::Null(T))
  	  p->fini ();
  	goto retry;
        }
      }
      return p;
    }
  
    inline const T* operator-> (void) const
    {
      return get ();
    }
  
    private:
    hb_face_t *face;
    T *instance;
  };
  
  /* Logic is shared between hb_lazy_loader_t and hb_lazy_table_loader_t */
  template <typename T>
  struct hb_lazy_table_loader_t
  {
    inline void init (hb_face_t *face_)
    {
      face = face_;
      blob = nullptr;
      instance = nullptr;
    }
  
    inline void fini (void)
    {
      hb_blob_destroy (blob);
    }
  
    inline const T* get (void) const
    {
    retry:
      T *p = (T *) hb_atomic_ptr_get (&instance);
      if (unlikely (!p))
      {
        hb_blob_t *blob_ = OT::Sanitizer<T>().sanitize (face->reference_table (T::tableTag));
        p = const_cast<T *>(OT::Sanitizer<T>::lock_instance (blob_));
        if (!hb_atomic_ptr_cmpexch (const_cast<T **>(&instance), nullptr, p))
        {
  	hb_blob_destroy (blob_);
  	goto retry;
        }
        blob = blob_;
      }
      return p;
    }
  
    inline const T* operator-> (void) const
    {
      return get();
    }
  
    hb_face_t *face;
    mutable hb_blob_t *blob;
    private:
    mutable T *instance;
  };
  
  
  } /* namespace OT */
  
  
  #endif /* HB_OPEN_TYPE_PRIVATE_HH */
  

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