// Boost.Signals2 library
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// Copyright Douglas Gregor 2001-2004.
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// Copyright Frank Mori Hess 2007. Use, modification and
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// distribution is subject to the Boost Software License, Version
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// 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// For more information, see http://www.boost.org
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#ifndef BOOST_SIGNALS2_RESULT_TYPE_WRAPPER_HPP
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#define BOOST_SIGNALS2_RESULT_TYPE_WRAPPER_HPP
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#include <boost/config.hpp>
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namespace boost {
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namespace signals2 {
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namespace detail {
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// A placeholder for void on compilers that don't support void returns
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struct void_type {};
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// Replaces void with void_type
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template<typename R>
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struct nonvoid {
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typedef R type;
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};
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template<>
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struct nonvoid<void> {
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typedef void_type type;
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};
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// Replaces void with void_type only if compiler doesn't support void returns
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template<typename R>
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struct result_type_wrapper {
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typedef R type;
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};
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#ifdef BOOST_NO_VOID_RETURNS
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template<>
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struct result_type_wrapper<void> {
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typedef void_type type;
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};
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#endif
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// specialization deals with possible void return from combiners
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template<typename R> class combiner_invoker
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{
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public:
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typedef R result_type;
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template<typename Combiner, typename InputIterator>
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result_type operator()(Combiner &combiner,
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InputIterator first, InputIterator last) const
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{
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return combiner(first, last);
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}
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};
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template<> class combiner_invoker<void>
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{
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public:
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typedef result_type_wrapper<void>::type result_type;
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template<typename Combiner, typename InputIterator>
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result_type operator()(Combiner &combiner,
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InputIterator first, InputIterator last) const
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{
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combiner(first, last);
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return result_type();
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}
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};
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} // end namespace detail
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} // end namespace signals2
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} // end namespace boost
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#endif // BOOST_SIGNALS2_RESULT_TYPE_WRAPPER_HPP
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