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// Boost.Signals2 library
// Copyright Douglas Gregor 2001-2004.
// Copyright Frank Mori Hess 2007. Use, modification and
// distribution is subject to 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)
// For more information, see http://www.boost.org
#ifndef BOOST_SIGNALS2_RESULT_TYPE_WRAPPER_HPP
#define BOOST_SIGNALS2_RESULT_TYPE_WRAPPER_HPP
#include <boost/config.hpp>
namespace boost {
namespace signals2 {
namespace detail {
// A placeholder for void on compilers that don't support void returns
struct void_type {};
// Replaces void with void_type
template<typename R>
struct nonvoid {
typedef R type;
};
template<>
struct nonvoid<void> {
typedef void_type type;
};
// Replaces void with void_type only if compiler doesn't support void returns
template<typename R>
struct result_type_wrapper {
typedef R type;
};
#ifdef BOOST_NO_VOID_RETURNS
template<>
struct result_type_wrapper<void> {
typedef void_type type;
};
#endif
// specialization deals with possible void return from combiners
template<typename R> class combiner_invoker
{
public:
typedef R result_type;
template<typename Combiner, typename InputIterator>
result_type operator()(Combiner &combiner,
InputIterator first, InputIterator last) const
{
return combiner(first, last);
}
};
template<> class combiner_invoker<void>
{
public:
typedef result_type_wrapper<void>::type result_type;
template<typename Combiner, typename InputIterator>
result_type operator()(Combiner &combiner,
InputIterator first, InputIterator last) const
{
combiner(first, last);
return result_type();
}
};
} // end namespace detail
} // end namespace signals2
} // end namespace boost
#endif // BOOST_SIGNALS2_RESULT_TYPE_WRAPPER_HPP
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