/*

 * 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-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 \

  { \

    ASSERT_STATIC (_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. */

/* TODO This really should be a extern HB_INTERNAL and defined somewhere... */

static const void *_NullPool[(256+8) / sizeof (void *)];

/* Generic nul-content Null objects. */

template <typename Type>

static inline const Type& Null (void) {

  ASSERT_STATIC (sizeof (Type) <= sizeof (_NullPool));

  return *CastP<Type> (_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 */ \

ASSERT_STATIC (Type::min_size + 1 <= sizeof (_Null##Type))

/* 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

 */

#ifndef HB_DEBUG_SANITIZE

#define HB_DEBUG_SANITIZE (HB_DEBUG+0)

#endif

#define TRACE_SANITIZE(this) \

	hb_auto_trace_t<HB_DEBUG_SANITIZE, bool> trace \

	(&c->debug_depth, c->get_name (), this, HB_FUNC, \

	 "");

/* 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 (NULL), end (NULL),

	writable (false), edit_count (0),

	blob (NULL) {}

  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, NULL);

    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 = NULL;

    this->start = this->end = NULL;

  }

  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;

};

/* Template to sanitize an object. */

template <typename Type>

struct Sanitizer

{

  static hb_blob_t *sanitize (hb_blob_t *blob) {

    hb_sanitize_context_t c[1];

    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, NULL);

	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, NULL);

    return unlikely (!base) ? &Null(Type) : CastP<Type> (base);

  }

};

/*

 * Serialize

 */

#ifndef HB_DEBUG_SERIALIZE

#define HB_DEBUG_SERIALIZE (HB_DEBUG+0)

#endif

#define TRACE_SERIALIZE(this) \

	hb_auto_trace_t<HB_DEBUG_SERIALIZE, bool> trace \

	(&c->debug_depth, "SERIALIZE", c, HB_FUNC, \

	 "");

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 NULL;

    }

    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 NULL;

    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 NULL;

    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 NULL;

    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_)

  {

    head = array;

    len = len_;

  }

  inline const Type operator [] (unsigned int i) const

  {

    if (unlikely (i >= len)) return Type ();

    return head[i];

  }

  inline void advance (unsigned int count)

  {

    if (unlikely (count > len))

      count = len;

    len -= count;

    head += count;

  }

  private:

  inline Supplier (const Supplier<Type> &); /* Disallow copy */

  inline Supplier<Type>& operator= (const Supplier<Type> &); /* Disallow copy */

  unsigned int len;

  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); }

  inline int cmp (Type a) const

  {

    Type b = v;

    if (sizeof (Type) < 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<int8_t	, 1> CHAR;	/* 8-bit signed integer. */

typedef	IntType<uint8_t	, 1> BYTE;	/* 8-bit unsigned integer. */

typedef	IntType<int8_t	, 1> INT8;	/* 8-bit signed integer. */

typedef IntType<uint16_t, 2> USHORT;	/* 16-bit unsigned integer. */

typedef IntType<int16_t,  2> SHORT;	/* 16-bit signed integer. */

typedef IntType<uint32_t, 4> ULONG;	/* 32-bit unsigned integer. */

typedef IntType<int32_t,  4> LONG;	/* 32-bit signed integer. */

typedef IntType<uint32_t, 3> UINT24;	/* 24-bit unsigned integer. */

/* 16-bit signed integer (SHORT) that describes a quantity in FUnits. */

typedef SHORT FWORD;

/* 16-bit unsigned integer (USHORT) that describes a quantity in FUnits. */

typedef USHORT UFWORD;

/* 16-bit signed fixed number with the low 14 bits of fraction (2.14). */

struct F2DOT14 : SHORT

{

  //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: LONG

{

  //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:

  LONG major;

  ULONG 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 : ULONG

{

  /* 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) */

struct GlyphID : USHORT {

  static inline int cmp (const GlyphID *a, const GlyphID *b) { return b->USHORT::cmp (*a); }

  inline int cmp (hb_codepoint_t a) const { return (int) a - (int) *this; }

};

/* Script/language-system/feature index */

struct Index : USHORT {

  static const unsigned int NOT_FOUND_INDEX = 0xFFFFu;

};

DEFINE_NULL_DATA (Index, "\xff\xff");

/* Offset, Null offset = 0 */

template <typename Type=USHORT>

struct Offset : Type

{

  inline bool is_null (void) const { return 0 == *this; }

  public:

  DEFINE_SIZE_STATIC (sizeof(Type));

};

/* CheckSum */

struct CheckSum : ULONG

{

  /* This is reference implementation from the spec. */

  static inline uint32_t CalcTableChecksum (const ULONG *Table, uint32_t Length)

  {

    uint32_t Sum = 0L;

    const ULONG *EndPtr = Table+((Length+3) & ~3) / ULONG::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 ULONG *) data, length)); }

  public:

  DEFINE_SIZE_STATIC (4);

};

/*

 * Version Numbers

 */

template <typename FixedType=USHORT>

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=USHORT>

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)

  {

    Type *t = c->start_embed<Type> ();

    this->set ((char *) t - (char *) base); /* TODO(serialize) Overflow? */

    return *t;

  }

  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, ULONG> {};

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=USHORT>

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);

  }