| // 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 |