root/MMgc/TypeTraits.h

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#ifndef __TypeTraits__
#define __TypeTraits__

#include "StaticAssert.h"

/*
        This header file implements a small subset of the type traits
        functionality defined in TR1. At present, however, TR1 is not 
        available on all supported systems.
*/

namespace MMgc
{
        template <typename _Type>
        struct remove_const { typedef _Type type; };

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

        template <typename _Type>
        struct remove_volatile { typedef _Type type; };

        template <typename _Type>
        struct remove_volatile<_Type volatile> { typedef _Type type; };

        template <typename _Type>
        struct remove_cv
        {
                typedef typename remove_const<typename remove_volatile<_Type>::type>::type type;
        };

        template <typename _Type>
        struct remove_pointer
        {
                typedef _Type type;
        };

#define _RP_SPECIALIZE(_ModifiedType) \
        template <typename _Type> \
        struct remove_pointer<_ModifiedType> \
        { \
                typedef _Type type; \
        };

        _RP_SPECIALIZE(_Type *)
        _RP_SPECIALIZE(_Type * const)
        _RP_SPECIALIZE(_Type * volatile)
        _RP_SPECIALIZE(_Type * const volatile)

#undef _RP_SPECIALIZE

        template <typename _Type, _Type _Value>
        struct integral_constant
        {
                static const _Type value = _Value;
                typedef _Type value_type;
                typedef integral_constant<_Type, _Value> type;
        };

        typedef integral_constant<bool, true> true_type;
        typedef integral_constant<bool, false> false_type;

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

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

        template <typename _Type>
        struct _is_class_or_union_helper
        {
        private:
                typedef char _one;
                typedef struct { char _c[2]; } _two;

        public:
                template <typename _T>
                        static _one _test (int _T::*);
                template <typename>
                        static _two _test (...);

                static const bool _value = sizeof (_test<_Type>(0)) == sizeof (_one);
        };

        template <typename _Type>
        struct _is_class_or_union : public integral_constant<bool, _is_class_or_union_helper<_Type>::_value>
        {
        };

        template <typename _Base, typename _Derived>
        struct _is_base_of_helper
        {
        private:
                // Disallow incomplete types.
                MMGC_STATIC_ASSERT(sizeof (_Base) != 0);
                MMGC_STATIC_ASSERT(sizeof (_Derived) != 0);

                typedef typename remove_cv<_Base>::type _RCV_Base;
                typedef typename remove_cv<_Derived>::type _RCV_Derived;

                typedef char _one;
                typedef struct { char _c[2]; } _two;

        public:
                template <typename _T>
                        static _one _test (_RCV_Derived &, _T);
                static _two _test (_RCV_Base &, int);

                struct _convert
                {
                        operator _RCV_Base & () const;
                        operator _RCV_Derived & ();
                };

                static const bool _value = (_is_class_or_union<_Base>::value &&
                        _is_class_or_union<_Derived>::value &&
                        (sizeof (_test(_convert(), 0)) == sizeof (_one) ||
                        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>
        {
        };
}

#endif /* __TypeTraits__ */

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