boost/parameter/aux_/is_tagged_argument.hpp
// Copyright Daniel Wallin, David Abrahams 2005.
// Copyright Cromwell D. Enage 2017.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_PARAMETER_IS_TAGGED_ARGUMENT_HPP
#define BOOST_PARAMETER_IS_TAGGED_ARGUMENT_HPP
namespace boost { namespace parameter { namespace aux {
struct tagged_argument_base
{
};
}}} // namespace boost::parameter::aux
#include <boost/parameter/config.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/if.hpp>
#if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING) || \
(0 < BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY)
#include <boost/type_traits/is_base_of.hpp>
#include <boost/type_traits/remove_const.hpp>
#include <boost/type_traits/remove_reference.hpp>
namespace boost { namespace parameter { namespace aux {
// This metafunction identifies tagged_argument specializations
// and their derived classes.
template <typename T>
struct is_tagged_argument
: ::boost::mpl::if_<
// Cannot use is_convertible<> to check if T is derived from
// tagged_argument_base. -- Cromwell D. Enage
::boost::is_base_of<
::boost::parameter::aux::tagged_argument_base
, typename ::boost::remove_const<
typename ::boost::remove_reference<T>::type
>::type
>
, ::boost::mpl::true_
, ::boost::mpl::false_
>::type
{
};
}}} // namespace boost::parameter::aux
#else // no perfect forwarding support and no exponential overloads
#include <boost/type_traits/is_convertible.hpp>
#include <boost/type_traits/is_lvalue_reference.hpp>
namespace boost { namespace parameter { namespace aux {
template <typename T>
struct is_tagged_argument_aux
: ::boost::is_convertible<
T*
, ::boost::parameter::aux::tagged_argument_base const*
>
{
};
// This metafunction identifies tagged_argument specializations
// and their derived classes.
template <typename T>
struct is_tagged_argument
: ::boost::mpl::if_<
::boost::is_lvalue_reference<T>
, ::boost::mpl::false_
, ::boost::parameter::aux::is_tagged_argument_aux<T>
>::type
{
};
}}} // namespace boost::parameter::aux
#endif // perfect forwarding support, or exponential overloads
#if defined(BOOST_PARAMETER_CAN_USE_MP11)
#include <type_traits>
namespace boost { namespace parameter { namespace aux {
template <typename T>
using is_tagged_argument_mp11 = ::std::is_base_of<
::boost::parameter::aux::tagged_argument_base
, typename ::std::remove_const<
typename ::std::remove_reference<T>::type
>::type
>;
}}} // namespace boost::parameter::aux
#endif // BOOST_PARAMETER_CAN_USE_MP11
#endif // include guard