// Copyright Daniel Wallin 2006.
|
// 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_TEMPLATE_KEYWORD_HPP
|
#define BOOST_PARAMETER_TEMPLATE_KEYWORD_HPP
|
|
#include <boost/parameter/aux_/template_keyword.hpp>
|
#include <boost/parameter/config.hpp>
|
|
#if defined(BOOST_PARAMETER_CAN_USE_MP11)
|
#include <boost/mp11/integral.hpp>
|
#include <boost/mp11/utility.hpp>
|
#include <type_traits>
|
#else
|
#include <boost/mpl/bool.hpp>
|
#include <boost/mpl/if.hpp>
|
#include <boost/mpl/eval_if.hpp>
|
#include <boost/mpl/identity.hpp>
|
#include <boost/type_traits/add_lvalue_reference.hpp>
|
#include <boost/type_traits/is_function.hpp>
|
#include <boost/type_traits/is_array.hpp>
|
#endif
|
|
namespace boost { namespace parameter {
|
|
template <typename Tag, typename T>
|
struct template_keyword : ::boost::parameter::aux::template_keyword_base
|
{
|
typedef Tag key_type;
|
typedef T value_type;
|
|
// reference is needed for two reasons:
|
//
|
// 1. It is used in the body of arg_list<...>
|
//
|
// 2. It is the result of binding<...>, which we mistakenly told
|
// people to use instead of value_type<...> to access named
|
// template parameters
|
//
|
// It used to be that reference == value_type, but that broke when
|
// the argument was a function or array type, because various
|
// arg_list functions return reference.
|
//
|
// Simply making reference == value_type& would break all the
|
// legacy code that uses binding<...> to access named template
|
// parameters. -- David Abrahams
|
#if defined(BOOST_PARAMETER_CAN_USE_MP11)
|
using reference = typename ::boost::mp11::mp_eval_if<
|
::boost::mp11::mp_if<
|
::std::is_function<value_type>
|
, ::boost::mp11::mp_true
|
, ::std::is_array<value_type>
|
>
|
, ::std::add_lvalue_reference<value_type>
|
, ::boost::mp11::mp_identity
|
, value_type
|
>::type;
|
#else
|
typedef typename ::boost::mpl::eval_if<
|
typename ::boost::mpl::if_<
|
::boost::is_function<value_type>
|
, ::boost::mpl::true_
|
, ::boost::is_array<value_type>
|
>::type
|
, ::boost::add_lvalue_reference<value_type>
|
, ::boost::mpl::identity<value_type>
|
>::type reference;
|
#endif // BOOST_PARAMETER_CAN_USE_MP11
|
};
|
}} // namespace boost::parameter
|
|
#define BOOST_PARAMETER_TEMPLATE_KEYWORD(name) \
|
namespace tag \
|
{ \
|
struct name; \
|
} \
|
template <typename T> \
|
struct name : ::boost::parameter::template_keyword<tag::name,T> \
|
{ \
|
};
|
/**/
|
|
#endif // include guard
|
