| // common_type.hpp ---------------------------------------------------------// | |
| // Copyright 2010 Vicente J. Botet Escriba | |
| // Distributed under the Boost Software License, Version 1.0. | |
| // See http://www.boost.org/LICENSE_1_0.txt | |
| #ifndef BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP | |
| #define BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP | |
| #include <boost/config.hpp> | |
| //----------------------------------------------------------------------------// | |
| #include <boost/type_traits/add_rvalue_reference.hpp> | |
| //----------------------------------------------------------------------------// | |
| // // | |
| // C++03 implementation of // | |
| // Written by Vicente J. Botet Escriba // | |
| //~ 20.3.4 Function template declval [declval] | |
| //~ 1 The library provides the function template declval to simplify the definition of expressions which occur as | |
| //~ unevaluated operands. | |
| //~ 2 Remarks: If this function is used, the program is ill-formed. | |
| //~ 3 Remarks: The template parameter T of declval may be an incomplete type. | |
| //~ [ Example: | |
| //~ template <class To, class From> | |
| //~ decltype(static_cast<To>(declval<From>())) convert(From&&); | |
| //~ declares a function template convert which only participats in overloading if the type From can be | |
| //~ explicitly converted to type To. For another example see class template common_type (20.7.6.6). —end | |
| //~ example ] | |
| // // | |
| //----------------------------------------------------------------------------// | |
| namespace boost { | |
| template <typename T> | |
| typename add_rvalue_reference<T>::type declval(); //noexcept; // as unevaluated operand | |
| } // namespace boost | |
| #endif // BOOST_TYPE_TRAITS_EXT_DECLVAL__HPP |