45 lines
1.9 KiB
Plaintext
45 lines
1.9 KiB
Plaintext
// 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
|