type_inspection.hpp

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/*
    Copyright 2008 Adobe Systems Incorporated
    Distributed under the MIT License (see accompanying file LICENSE_1_0_0.txt
    or a copy at http://stlab.adobe.com/licenses.html)
*/

/*************************************************************************************************/


#ifndef ADOBE_TYPE_INSPECTION_HPP
#define ADOBE_TYPE_INSPECTION_HPP



namespace adobe
{


namespace detail
{
    struct yes_struct {char a;};
    struct no_struct  { yes_struct a[2];};
}

#define ADOBE_HAS_TYPE_IMPL(TypeInQuestion) \
template< \
    typename C##TypeInQuestion> \
struct has_type##TypeInQuestion \
{ \
    template <typename T##TypeInQuestion> \
    static adobe::detail::yes_struct SFINAE(typename T##TypeInQuestion::TypeInQuestion*); \
    template <typename> \
    static adobe::detail::no_struct SFINAE(...); \
    static const bool value = sizeof(SFINAE<C##TypeInQuestion>(0)) == sizeof(adobe::detail::yes_struct); \
}

#define ADOBE_HAS_TYPE(C, TypeInQuestion) \
has_type##TypeInQuestion<C>::value


// one of the most important types to look for is 'type', so let's just implement that one here
template <typename T>
struct has_type_type
{
    ADOBE_HAS_TYPE_IMPL(type);

    static const bool value = ADOBE_HAS_TYPE(T, type);
};

template <typename T, typename Default>
struct type_or_default
{
    template <bool condition, typename IFtype, typename ELSEtype>
    struct if_has_type
    {
        typedef typename IFtype::type type;
    };
    template <typename IFtype, typename ELSEtype>
    struct if_has_type<false, IFtype, ELSEtype>
    {
        typedef ELSEtype type;
    };
    typedef typename if_has_type<has_type_type<T>::value, T, Default>::type type;
};


#if _MSC_VER <= 1400
#define ADOBE_HAS_MEMBER_IMPL(Member) \
template <class Class> \
struct has_member##Member \
{ \
    __if_exists(Class::Member) \
    { \
        static const bool value = true; \
    } \
    __if_not_exists(Class::Member) \
    { \
        static const bool value = false; \
    } \
}
#else

namespace detail
{
    template<size_t>
    struct member_test_helper
    {
    };
}

#define ADOBE_HAS_MEMBER_IMPL(MemberInQuestion) \
template <class Class> \
struct has_member##MemberInQuestion \
{ \
    template <class T##MemberInQuestion> \
    static adobe::detail::yes_struct SFINAE( adobe::detail::member_test_helper<sizeof(&T##MemberInQuestion::MemberInQuestion)> * ); \
    template<class> \
    static adobe::detail::no_struct SFINAE(...); \
    static const bool value = sizeof(SFINAE<Class>(0)) == sizeof(adobe::detail::yes_struct); \
}
#endif

#define ADOBE_HAS_MEMBER(C, MemberInQuestion) \
has_member##MemberInQuestion<C>::value


#define ADOBE_HAS_TEMPLATE1_IMPL(TemplateInQuestion) \
template< \
    typename C##TemplateInQuestion> \
struct has_template1##TemplateInQuestion \
{ \
    template <typename T##TemplateInQuestion> \
    static adobe::detail::yes_struct SFINAE(typename T##TemplateInQuestion::template TemplateInQuestion<int>*); \
    template <typename> \
    static adobe::detail::no_struct SFINAE(...); \
    static const bool value = sizeof(SFINAE<C##TemplateInQuestion>(0)) == sizeof(adobe::detail::yes_struct); \
}

#define ADOBE_HAS_TEMPLATE1(C, TemplateInQuestion) \
has_template1##TemplateInQuestion<C>::value


// 2 Arg case
//
#define ADOBE_HAS_TEMPLATE2_IMPL(TemplateInQuestion) \
template< \
    typename C##TemplateInQuestion> \
struct has_template2##TemplateInQuestion \
{ \
    template <typename T##TemplateInQuestion> \
    static adobe::detail::yes_struct SFINAE(typename T##TemplateInQuestion::template TemplateInQuestion<int, int>*); \
    template <typename> \
    static adobe::detail::no_struct SFINAE(...); \
    static const bool value = sizeof(SFINAE<C##TemplateInQuestion>(0)) == sizeof(adobe::detail::yes_struct); \
}

#define ADOBE_HAS_TEMPLATE2(C, TemplateInQuestion) \
has_template2##TemplateInQuestion<C>::value

#define ADOBE_HAS_TEMPLATE3_IMPL(TemplateInQuestion) \
template< \
    typename C##TemplateInQuestion> \
struct has_template3##TemplateInQuestion \
{ \
    template <typename T##TemplateInQuestion> \
    static adobe::detail::yes_struct SFINAE(typename T##TemplateInQuestion::template TemplateInQuestion<int, int, int>*); \
    template <typename> \
    static adobe::detail::no_struct SFINAE(...); \
    static const bool value = sizeof(SFINAE<C##TemplateInQuestion>(0)) == sizeof(adobe::detail::yes_struct); \
}

#define ADOBE_HAS_TEMPLATE3(C, TemplateInQuestion) \
has_template3##TemplateInQuestion<C>::value


} // namespace

#endif // include guard