type_inspection.hpp

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/*
    Copyright 2008 Adobe Systems Incorporated
    Distributed under the Boost Software License - Version 1.0 (see the accompanying file LICENSE
    or a copy at https://stlab.github.io/adobe_source_libraries/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];
};
} // namespace detail

#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 {};
} // namespace detail
 
#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 adobe
 
#endif // include guard