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/*=============================================================================
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Copyright (c) 2001-2006 Joel de Guzman
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Distributed under the Boost 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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==============================================================================*/
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#if !defined(FUSION_REPLACE_08182005_0841)
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#define FUSION_REPLACE_08182005_0841
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#include <boost/type_traits/is_convertible.hpp>
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#include <boost/mpl/if.hpp>
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#include <boost/type_traits/remove_reference.hpp>
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namespace boost { namespace fusion { namespace detail
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template <bool is_convertible>
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struct replacer_helper;
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struct replacer_helper<false>
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template <typename U, typename T>
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call(U& x, T const&, T const&)
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struct replacer_helper<true>
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template <typename U, typename T>
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call(U& x, T const& old_value, T const& new_value)
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return (x == old_value) ? new_value : x;
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replacer(T const& old_value, T const& new_value)
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: old_value(old_value), new_value(new_value) {}
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template<typename Sig>
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template <typename U1, typename U2>
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struct result<replacer<U1>(U2)>
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typedef typename remove_reference<U2>::type value;
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mpl::if_<is_convertible<T, value>, value, value const&>::type
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typename result<replacer(U)>::type
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operator()(U const& x) const
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return replacer_helper<is_convertible<T, U>::value>::
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call(x, old_value, new_value);