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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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