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- /*=============================================================================
- Copyright (c) 2001-2011 Joel de Guzman
- 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)
- ==============================================================================*/
- #if !defined(FUSION_REPLACE_08182005_0841)
- #define FUSION_REPLACE_08182005_0841
- #include <boost/fusion/support/config.hpp>
- #include <boost/type_traits/is_convertible.hpp>
- #include <boost/mpl/if.hpp>
- #include <boost/type_traits/remove_reference.hpp>
- namespace boost { namespace fusion { namespace detail
- {
- template <bool is_convertible>
- struct replacer_helper;
- template <>
- struct replacer_helper<false>
- {
- template <typename U, typename T>
- BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
- static U&
- call(U& x, T const&, T const&)
- {
- return x;
- }
- };
- template <>
- struct replacer_helper<true>
- {
- template <typename U, typename T>
- BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
- static U
- call(U& x, T const& old_value, T const& new_value)
- {
- return (x == old_value) ? new_value : x;
- }
- };
- template <typename T>
- struct replacer
- {
- BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
- replacer(T const& in_old_value, T const& in_new_value)
- : old_value(in_old_value), new_value(in_new_value) {}
- template<typename Sig>
- struct result;
- template <typename U1, typename U2>
- struct result<replacer<U1>(U2)>
- {
- typedef typename remove_reference<U2>::type value;
- typedef typename
- mpl::if_<is_convertible<T, value>, value, value const&>::type
- type;
- };
- template <typename U>
- BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
- typename result<replacer(U)>::type
- operator()(U const& x) const
- {
- return replacer_helper<is_convertible<T, U>::value>::
- call(x, old_value, new_value);
- }
- T old_value;
- T new_value;
- };
- }}}
- #endif
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