| // declval.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_DECLVAL_HPP_INCLUDED |
| #define BOOST_TYPE_TRAITS_DECLVAL_HPP_INCLUDED |
| |
| #include <boost/config.hpp> |
| |
| //----------------------------------------------------------------------------// |
| |
| #include <boost/type_traits/add_rvalue_reference.hpp> |
| |
| //----------------------------------------------------------------------------// |
| // // |
| // C++03 implementation of // |
| // 20.2.4 Function template declval [declval] // |
| // Written by Vicente J. Botet Escriba // |
| // // |
| // 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 participates in overloading |
| // if the type From can be explicitly converted to type To. For another example |
| // see class template common_type (20.9.7.6). -end example ] |
| //----------------------------------------------------------------------------// |
| |
| namespace boost { |
| |
| template <typename T> |
| typename add_rvalue_reference<T>::type declval() BOOST_NOEXCEPT; // as unevaluated operand |
| |
| } // namespace boost |
| |
| #endif // BOOST_TYPE_TRAITS_DECLVAL_HPP_INCLUDED |
