multi_index/detail/is_transparent.hpp

0001 /* Copyright 2003-2022 Joaquin M Lopez Munoz.
0002  * Distributed under the Boost Software License, Version 1.0.
0003  * (See accompanying file LICENSE_1_0.txt or copy at
0004  * http://www.boost.org/LICENSE_1_0.txt)
0005  *
0006  * See http://www.boost.org/libs/multi_index for library home page.
0007  */
0008
0009 #ifndef BOOST_MULTI_INDEX_DETAIL_IS_TRANSPARENT_HPP
0010 #define BOOST_MULTI_INDEX_DETAIL_IS_TRANSPARENT_HPP
0011
0012 #if defined(_MSC_VER)
0013 #pragma once
0014 #endif
0015
0016 #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
0017 #include <boost/mpl/bool.hpp>
0018 #include <boost/type_traits/intrinsics.hpp>
0019
0020 namespace boost{
0021
0022 namespace multi_index{
0023
0024 namespace detail{
0025
0026 /* Metafunction that checks if f(arg,arg2) executes without argument type
0027  * conversion. By default (i.e. when it cannot be determined) it evaluates to
0028  * true.
0029  */
0030
0031 template<typename F,typename Arg1,typename Arg2,typename=void>
0032 struct is_transparent:mpl::true_{};
0033
0034 } /* namespace multi_index::detail */
0035
0036 } /* namespace multi_index */
0037
0038 } /* namespace boost */
0039
0040 #if !defined(BOOST_NO_SFINAE)&&!defined(BOOST_NO_SFINAE_EXPR)&& \
0041     !defined(BOOST_NO_CXX11_DECLTYPE)&& \
0042     (defined(BOOST_NO_CXX11_FINAL)||defined(BOOST_IS_FINAL))
0043
0044 #include <boost/core/enable_if.hpp>
0045 #include <boost/mpl/and.hpp>
0046 #include <boost/mpl/not.hpp>
0047 #include <boost/mpl/or.hpp>
0048 #include <boost/type_traits/declval.hpp>
0049 #include <boost/type_traits/function_traits.hpp>
0050 #include <boost/type_traits/is_class.hpp>
0051 #include <boost/type_traits/is_final.hpp>
0052 #include <boost/type_traits/is_function.hpp>
0053 #include <boost/type_traits/is_same.hpp>
0054 #include <boost/type_traits/remove_pointer.hpp>
0055
0056 namespace boost{
0057
0058 namespace multi_index{
0059
0060 namespace detail{
0061
0062 struct not_is_transparent_result_type{};
0063
0064 template<typename F,typename Arg1,typename Arg2>
0065 struct is_transparent_class_helper:F
0066 {
0067   using F::operator();
0068   template<typename T,typename Q>
0069   not_is_transparent_result_type operator()(const T&,const Q&)const;
0070 };
0071
0072 template<typename F,typename Arg1,typename Arg2,typename=void>
0073 struct is_transparent_class:mpl::true_{};
0074
0075 template<typename F,typename Arg1,typename Arg2>
0076 struct is_transparent_class<
0077   F,Arg1,Arg2,
0078   typename enable_if<
0079     is_same<
0080       decltype(
0081         declval<const is_transparent_class_helper<F,Arg1,Arg2> >()(
0082           declval<const Arg1&>(),declval<const Arg2&>())
0083       ),
0084       not_is_transparent_result_type
0085     >
0086   >::type
0087 >:mpl::false_{};
0088
0089 template<typename F,typename Arg1,typename Arg2>
0090 struct is_transparent<
0091   F,Arg1,Arg2,
0092   typename enable_if<
0093     mpl::and_<
0094       is_class<F>,
0095       mpl::not_<is_final<F> > /* is_transparent_class_helper derives from F */
0096     >
0097   >::type
0098 >:is_transparent_class<F,Arg1,Arg2>{};
0099
0100 template<typename F,typename Arg1,typename Arg2,typename=void>
0101 struct is_transparent_function:mpl::true_{};
0102
0103 template<typename F,typename Arg1,typename Arg2>
0104 struct is_transparent_function<
0105   F,Arg1,Arg2,
0106   typename enable_if<
0107     mpl::or_<
0108       mpl::not_<mpl::or_<
0109         is_same<typename function_traits<F>::arg1_type,const Arg1&>,
0110         is_same<typename function_traits<F>::arg1_type,Arg1>
0111       > >,
0112       mpl::not_<mpl::or_<
0113         is_same<typename function_traits<F>::arg2_type,const Arg2&>,
0114         is_same<typename function_traits<F>::arg2_type,Arg2>
0115       > >
0116     >
0117   >::type
0118 >:mpl::false_{};
0119
0120 template<typename F,typename Arg1,typename Arg2>
0121 struct is_transparent<
0122   F,Arg1,Arg2,
0123   typename enable_if<
0124     is_function<typename remove_pointer<F>::type>
0125   >::type
0126 >:is_transparent_function<typename remove_pointer<F>::type,Arg1,Arg2>{};
0127
0128 } /* namespace multi_index::detail */
0129
0130 } /* namespace multi_index */
0131
0132 } /* namespace boost */
0133
0134 #endif
0135 #endif