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106 lines
2.9 KiB
106 lines
2.9 KiB
// Copyright David Abrahams 2005. Distributed under the Boost |
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// Software License, Version 1.0. (See accompanying |
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
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#ifndef BOOST_PARAMETER_BINDING_DWA200558_HPP |
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# define BOOST_PARAMETER_BINDING_DWA200558_HPP |
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# include <boost/mpl/apply.hpp> |
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# include <boost/mpl/assert.hpp> |
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# include <boost/mpl/and.hpp> |
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# include <boost/parameter/aux_/result_of0.hpp> |
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# include <boost/parameter/aux_/void.hpp> |
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# include <boost/type_traits/is_same.hpp> |
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# if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
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# include <boost/mpl/eval_if.hpp> |
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# endif |
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namespace boost { namespace parameter { |
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// A metafunction that, given an argument pack, returns the type of |
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// the parameter identified by the given keyword. If no such |
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// parameter has been specified, returns Default |
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# if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) \ |
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|| BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) |
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template <class Parameters, class Keyword, class Default> |
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struct binding0 |
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{ |
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typedef typename mpl::apply_wrap3< |
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typename Parameters::binding,Keyword,Default,mpl::true_ |
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>::type type; |
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BOOST_MPL_ASSERT_NOT(( |
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mpl::and_< |
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is_same<Default, void_> |
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, is_same<type, void_> |
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> |
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)); |
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}; |
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# endif |
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template <class Parameters, class Keyword, class Default = void_> |
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# if !BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
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struct binding |
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# else |
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struct binding_eti |
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# endif |
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{ |
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# if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) \ |
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|| BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) |
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typedef typename mpl::eval_if< |
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mpl::is_placeholder<Parameters> |
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, mpl::identity<int> |
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, binding0<Parameters,Keyword,Default> |
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>::type type; |
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# else |
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typedef typename mpl::apply_wrap3< |
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typename Parameters::binding,Keyword,Default,mpl::true_ |
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>::type type; |
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BOOST_MPL_ASSERT_NOT(( |
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mpl::and_< |
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is_same<Default, void_> |
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, is_same<type, void_> |
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> |
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)); |
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# endif |
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# if !BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
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BOOST_MPL_AUX_LAMBDA_SUPPORT(3,binding,(Parameters,Keyword,Default)) |
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# endif |
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}; |
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# if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
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template <class Parameters, class Keyword, class Default = void_> |
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struct binding |
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{ |
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typedef typename mpl::eval_if< |
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is_same<Parameters, int> |
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, mpl::identity<int> |
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, binding_eti<Parameters, Keyword, Default> |
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>::type type; |
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BOOST_MPL_AUX_LAMBDA_SUPPORT(3,binding,(Parameters,Keyword,Default)) |
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}; |
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# endif |
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// A metafunction that, given an argument pack, returns the type of |
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// the parameter identified by the given keyword. If no such |
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// parameter has been specified, returns the type returned by invoking |
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// DefaultFn |
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template <class Parameters, class Keyword, class DefaultFn> |
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struct lazy_binding |
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{ |
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typedef typename mpl::apply_wrap3< |
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typename Parameters::binding |
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, Keyword |
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, typename aux::result_of0<DefaultFn>::type |
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, mpl::true_ |
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>::type type; |
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}; |
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}} // namespace boost::parameter |
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#endif // BOOST_PARAMETER_BINDING_DWA200558_HPP
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