type_traits

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  template<typename _Tp>
    struct has_trivial_destructor
    : public integral_constant<bool, is_pod<_Tp>::value> { };

  template<typename _Tp>
    struct has_nothrow_constructor
    : public integral_constant<bool, is_pod<_Tp>::value> { };

  template<typename _Tp>
    struct has_nothrow_copy
    : public integral_constant<bool, is_pod<_Tp>::value> { };

  template<typename _Tp>
    struct has_nothrow_assign
    : public integral_constant<bool, is_pod<_Tp>::value> { };

  template<typename>
    struct has_virtual_destructor
    : public false_type { };

  template<typename>
    struct is_signed
    : public false_type { };
  _DEFINE_SPEC(0, is_signed, signed char, true)
  _DEFINE_SPEC(0, is_signed, short, true)
  _DEFINE_SPEC(0, is_signed, int, true)
  _DEFINE_SPEC(0, is_signed, long, true)
  _DEFINE_SPEC(0, is_signed, long long, true)

  template<typename>
    struct is_unsigned
    : public false_type { };
  _DEFINE_SPEC(0, is_unsigned, unsigned char, true)
  _DEFINE_SPEC(0, is_unsigned, unsigned short, true)
  _DEFINE_SPEC(0, is_unsigned, unsigned int, true)
  _DEFINE_SPEC(0, is_unsigned, unsigned long, true)
  _DEFINE_SPEC(0, is_unsigned, unsigned long long, true)

  template<typename _Tp>
    struct alignment_of
    : public integral_constant<std::size_t, __alignof__(_Tp)> { };
  
  template<typename>
    struct rank
    : public integral_constant<std::size_t, 0> { };
   
  template<typename _Tp, std::size_t _Size>
    struct rank<_Tp[_Size]>
    : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };

  template<typename _Tp>
    struct rank<_Tp[]>
    : public integral_constant<std::size_t, 1 + rank<_Tp>::value> { };
   
  template<typename, unsigned>
    struct extent
    : public integral_constant<std::size_t, 0> { };
  
  template<typename _Tp, unsigned _Uint, std::size_t _Size>
    struct extent<_Tp[_Size], _Uint>
    : public integral_constant<std::size_t,
			       _Uint == 0 ? _Size : extent<_Tp,
							   _Uint - 1>::value>
    { };

  template<typename _Tp, unsigned _Uint>
    struct extent<_Tp[], _Uint>
    : public integral_constant<std::size_t,
			       _Uint == 0 ? 0 : extent<_Tp,
						       _Uint - 1>::value>
    { };
  
  /// @brief  relationships between types [4.6].
  template<typename, typename>
    struct is_same
    : public false_type { };

  template<typename _Tp>
    struct is_same<_Tp, _Tp>
    : public true_type { };

  // See Daveed Vandevoorde explanation in http://tinyurl.com/502f.
  // Also see Rani Sharoni in http://tinyurl.com/6jvyq.
  template<typename _Base, typename _Derived,
	   bool = (!__is_union_or_class<_Base>::value
		   || !__is_union_or_class<_Derived>::value
		   || is_same<_Base, _Derived>::value)>
    struct __is_base_of_helper
    : public __sfinae_types
    {
    private:
      typedef typename remove_cv<_Base>::type     _NoCv_Base;      
      typedef typename remove_cv<_Derived>::type  _NoCv_Derived;
      
      template<typename _Up>
        static __one __test(_NoCv_Derived&, _Up);
      static __two __test(_NoCv_Base&, int);
   
      struct _Conv
      {
	operator _NoCv_Derived&();
	operator _NoCv_Base&() const;
      };
   
    public:
      static const bool __value = sizeof(__test(_Conv(), 0)) == 1;
    };

  template<typename _Base, typename _Derived>
    struct __is_base_of_helper<_Base, _Derived, true>
    { static const bool __value = is_same<_Base, _Derived>::value; };

  template<typename _Base, typename _Derived>
    struct is_base_of
    : public integral_constant<bool,
			       __is_base_of_helper<_Base, _Derived>::__value>
    { };

  template<typename _From, typename _To>
    struct __is_convertible_simple
    : public __sfinae_types
    {
    private:
      static __one __test(_To);
      static __two __test(...);
      static _From __makeFrom();
    
    public:
      static const bool __value = sizeof(__test(__makeFrom())) == 1;
    };

  template<typename _Tp>
    struct __is_int_or_cref
    {
      typedef typename remove_reference<_Tp>::type __rr_Tp;
      static const bool __value = (is_integral<_Tp>::value
				   || (is_integral<__rr_Tp>::value
				       && is_const<__rr_Tp>::value
				       && !is_volatile<__rr_Tp>::value));
    };

  template<typename _From, typename _To,
	   bool = (is_void<_From>::value || is_void<_To>::value
		   || is_function<_To>::value || is_array<_To>::value
		   // This special case is here only to avoid warnings.		   
		   || (is_floating_point<typename
		       remove_reference<_From>::type>::value
		       && __is_int_or_cref<_To>::__value))>
    struct __is_convertible_helper
    {
      // "An imaginary lvalue of type From...".
      static const bool __value = (__is_convertible_simple<typename
				   add_reference<_From>::type, _To>::__value);
    };

  template<typename _From, typename _To>
    struct __is_convertible_helper<_From, _To, true>
    { static const bool __value = (is_void<_To>::value
				   || (__is_int_or_cref<_To>::__value
				       && !is_void<_From>::value)); };

  template<typename _From, typename _To>
    struct is_convertible
    : public integral_constant<bool,
			       __is_convertible_helper<_From, _To>::__value>
    { };

  /// @brief  const-volatile modifications [4.7.1].
  template<typename _Tp>
    struct remove_const
    { typedef _Tp     type; };

  template<typename _Tp>
    struct remove_const<_Tp const>
    { typedef _Tp     type; };
  
  template<typename _Tp>
    struct remove_volatile
    { typedef _Tp     type; };

  template<typename _Tp>
    struct remove_volatile<_Tp volatile>
    { typedef _Tp     type; };
  
  template<typename _Tp>
    struct remove_cv
    {
      typedef typename
      remove_const<typename remove_volatile<_Tp>::type>::type     type;
    };
  
  template<typename _Tp>
    struct add_const
    { typedef _Tp const     type; };
   
  template<typename _Tp>
    struct add_volatile
    { typedef _Tp volatile     type; };
  
  template<typename _Tp>
    struct add_cv
    {
      typedef typename
      add_const<typename add_volatile<_Tp>::type>::type     type;
    };

  /// @brief  reference modifications [4.7.2].
  template<typename _Tp>
    struct remove_reference
    { typedef _Tp     type; };

  template<typename _Tp>
    struct remove_reference<_Tp&>
    { typedef _Tp     type; };
  
  template<typename _Tp>
    struct add_reference
    { typedef _Tp&    type; };

  template<typename _Tp>
    struct add_reference<_Tp&>
    { typedef _Tp&    type; };

  /// @brief  array modififications [4.7.3].
  template<typename _Tp>
    struct remove_extent
    { typedef _Tp     type; };

  template<typename _Tp, std::size_t _Size>
    struct remove_extent<_Tp[_Size]>
    { typedef _Tp     type; };

  template<typename _Tp>
    struct remove_extent<_Tp[]>
    { typedef _Tp     type; };

  template<typename _Tp>
    struct remove_all_extents
    { typedef _Tp     type; };

  template<typename _Tp, std::size_t _Size>
    struct remove_all_extents<_Tp[_Size]>
    { typedef typename remove_all_extents<_Tp>::type     type; };

  template<typename _Tp>
    struct remove_all_extents<_Tp[]>
    { typedef typename remove_all_extents<_Tp>::type     type; };

  /// @brief  pointer modifications [4.7.4].
#undef _DEFINE_SPEC_BODY
#define _DEFINE_SPEC_BODY(_Value)      \
    { typedef _Tp     type; };

  template<typename _Tp>
    struct remove_pointer
    { typedef _Tp     type; };
  _DEFINE_SPEC(1, remove_pointer, _Tp*, false)
  
  template<typename _Tp>
    struct add_pointer
    { typedef typename remove_reference<_Tp>::type*     type; };

  /// @brief  other transformations [4.8].
  
  // Due to c++/19163 and c++/17743, for the time being we cannot use
  // the correct, neat implementation :-(
  // 
  // template<std::size_t _Len, std::size_t _Align>
  //   struct aligned_storage
  //   { typedef char type[_Len] __attribute__((__aligned__(_Align))); }
  //
  // Temporary workaround, useful for Align up to 32:
  template<std::size_t, std::size_t>
    struct aligned_storage { };

  template<std::size_t _Len>
    struct aligned_storage<_Len, 1>
    {
      union type
      {
	unsigned char __data[_Len];
	char __align __attribute__((__aligned__(1)));
      };
    };

  template<std::size_t _Len>
    struct aligned_storage<_Len, 2>
    {
      union type
      {
	unsigned char __data[_Len];
	char __align __attribute__((__aligned__(2)));
      };
    };

  template<std::size_t _Len>
    struct aligned_storage<_Len, 4>
    {
      union type
      {
	unsigned char __data[_Len];
	char __align __attribute__((__aligned__(4)));
      };
    };

  template<std::size_t _Len>
    struct aligned_storage<_Len, 8>
    {
      union type
      {
	unsigned char __data[_Len];
	char __align __attribute__((__aligned__(8)));
      };
    };

  template<std::size_t _Len>
    struct aligned_storage<_Len, 16>
    {
      union type
      {
	unsigned char __data[_Len];
	char __align __attribute__((__aligned__(16)));
      };
    };
  
  template<std::size_t _Len>
    struct aligned_storage<_Len, 32>
    {
      union type
      {
	unsigned char __data[_Len];
	char __align __attribute__((__aligned__(32)));
      };
    };

#undef _DEFINE_SPEC_0_HELPER
#undef _DEFINE_SPEC_1_HELPER
#undef _DEFINE_SPEC_2_HELPER
#undef _DEFINE_SPEC
#undef _DEFINE_SPEC_BODY

}
}

#endif