138 lines
4.0 KiB
Plaintext
138 lines
4.0 KiB
Plaintext
///////////////////////////////////////////////////////////////////////////////
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/// \file utility.hpp
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/// Proto callables for things found in the std \<utility\> header
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//
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// Copyright 2010 Eric Niebler. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_PROTO_FUNCTIONAL_STD_UTILITY_HPP_EAN_11_27_2010
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#define BOOST_PROTO_FUNCTIONAL_STD_UTILITY_HPP_EAN_11_27_2010
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#include <utility>
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#include <boost/type_traits/remove_const.hpp>
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#include <boost/type_traits/remove_reference.hpp>
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#include <boost/proto/proto_fwd.hpp>
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namespace boost { namespace proto { namespace functional
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{
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/// \brief A PolymorphicFunctionObject type that invokes the
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/// \c std::make_pair() algorithm on its arguments.
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///
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/// A PolymorphicFunctionObject type that invokes the
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/// \c std::make_pair() algorithm on its arguments.
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struct make_pair
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename First, typename Second>
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struct result<This(First, Second)>
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{
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typedef
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std::pair<
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typename remove_const<typename remove_reference<First>::type>::type
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, typename remove_const<typename remove_reference<Second>::type>::type
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>
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type;
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};
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template<typename First, typename Second>
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std::pair<First, Second> operator()(First const &first, Second const &second) const
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{
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return std::make_pair(first, second);
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}
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};
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/// \brief A PolymorphicFunctionObject type that returns
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/// the first element of a std::pair.
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///
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/// A PolymorphicFunctionObject type that returns
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/// the first element of a std::pair..
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struct first
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename Pair>
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struct result<This(Pair)>
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{
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typedef typename Pair::first_type type;
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};
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template<typename This, typename Pair>
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struct result<This(Pair &)>
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{
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typedef typename Pair::first_type &type;
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};
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template<typename This, typename Pair>
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struct result<This(Pair const &)>
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{
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typedef typename Pair::first_type const &type;
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};
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template<typename Pair>
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typename Pair::first_type &operator()(Pair &pair) const
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{
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return pair.first;
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}
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template<typename Pair>
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typename Pair::first_type const &operator()(Pair const &pair) const
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{
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return pair.first;
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}
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};
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/// \brief A PolymorphicFunctionObject type that returns
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/// the second element of a std::pair.
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///
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/// A PolymorphicFunctionObject type that returns
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/// the second element of a std::pair..
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struct second
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{
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BOOST_PROTO_CALLABLE()
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template<typename Sig>
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struct result;
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template<typename This, typename Pair>
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struct result<This(Pair)>
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{
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typedef typename Pair::second_type type;
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};
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template<typename This, typename Pair>
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struct result<This(Pair &)>
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{
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typedef typename Pair::second_type &type;
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};
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template<typename This, typename Pair>
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struct result<This(Pair const &)>
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{
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typedef typename Pair::second_type const &type;
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};
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template<typename Pair>
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typename Pair::second_type &operator()(Pair &pair) const
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{
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return pair.second;
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}
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template<typename Pair>
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typename Pair::second_type const &operator()(Pair const &pair) const
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{
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return pair.second;
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}
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};
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}}}
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#endif
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