1 // Copyright (c) 2009-2016 Vladimir Batov. 2 // Use, modification and distribution are subject to the Boost Software License, 3 // Version 1.0. See http://www.boost.org/LICENSE_1_0.txt. 4 5 #ifndef BOOST_CONVERT_IS_FUNCTION_HPP 6 #define BOOST_CONVERT_IS_FUNCTION_HPP 7 8 #include <boost/convert/detail/config.hpp> 9 #include <boost/convert/detail/has_member.hpp> 10 #include <boost/utility/enable_if.hpp> 11 #include <boost/type_traits.hpp> 12 #include <boost/function_types/is_function_pointer.hpp> 13 #include <boost/function_types/function_arity.hpp> 14 #include <boost/function_types/result_type.hpp> 15 16 namespace boost { namespace cnv 17 { 18 typedef ::boost::type_traits::yes_type yes_type; 19 typedef ::boost::type_traits:: no_type no_type; 20 21 template <bool has_operator, typename Functor, typename TypeOut> 22 struct check_functor { BOOST_STATIC_CONSTANT(bool, value = false); }; 23 24 template<typename Func, typename TypeOut, class Enable =void> 25 struct is_fun { BOOST_STATIC_CONSTANT(bool, value = false); }; 26 27 template <typename Functor, typename TypeOut> 28 struct check_functor<true, Functor, TypeOut> 29 { 30 static yes_type test (TypeOut const&); 31 static no_type test (...); 32 33 static const bool value = sizeof(yes_type) == sizeof(test(((Functor*) 0)->operator()())); 34 }; 35 36 template<typename Functor, typename TypeOut> 37 struct is_fun<Functor, TypeOut, 38 typename enable_if_c<is_class<Functor>::value && !is_convertible<Functor, TypeOut>::value, void>::type> 39 { 40 BOOST_DECLARE_HAS_MEMBER(has_funop, operator()); 41 42 BOOST_STATIC_CONSTANT(bool, value = (check_functor<has_funop<Functor>::value, Functor, TypeOut>::value)); 43 }; 44 45 template<typename Function, typename TypeOut> 46 struct is_fun<Function, TypeOut, 47 typename enable_if_c< 48 function_types::is_function_pointer<Function>::value && 49 function_types::function_arity<Function>::value == 0 && 50 !is_same<Function, TypeOut>::value, 51 void>::type> 52 { 53 typedef TypeOut out_type; 54 typedef typename function_types::result_type<Function>::type func_out_type; 55 56 BOOST_STATIC_CONSTANT(bool, value = (is_convertible<func_out_type, out_type>::value)); 57 }; 58 }} 59 60 #endif // BOOST_CONVERT_IS_FUNCTION_HPP 61 62