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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_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_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_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_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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