Chris@16: // optional_last_value function object (documented as part of Boost.Signals2)
Chris@16: 
Chris@16: // Copyright Frank Mori Hess 2007-2008.
Chris@16: // Copyright Douglas Gregor 2001-2003.
Chris@16: // Distributed under the Boost Software License, Version
Chris@16: // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: // See http://www.boost.org/libs/signals2 for library home page.
Chris@16: 
Chris@16: #ifndef BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP
Chris@16: #define BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP
Chris@16: 
Chris@16: #include <boost/optional.hpp>
Chris@16: #include <boost/signals2/expired_slot.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16:   namespace signals2 {
Chris@16: 
Chris@16:     template<typename T>
Chris@16:       class optional_last_value
Chris@16:     {
Chris@16:     public:
Chris@16:       typedef optional<T> result_type;
Chris@16: 
Chris@16:       template<typename InputIterator>
Chris@16:         optional<T> operator()(InputIterator first, InputIterator last) const
Chris@16:       {
Chris@16:         optional<T> value;
Chris@16:         while (first != last)
Chris@16:         {
Chris@16:           try
Chris@16:           {
Chris@16:             value = *first;
Chris@16:           }
Chris@16:           catch(const expired_slot &) {}
Chris@16:           ++first;
Chris@16:         }
Chris@16:         return value;
Chris@16:       }
Chris@16:     };
Chris@16: 
Chris@16:     template<>
Chris@16:       class optional_last_value<void>
Chris@16:     {
Chris@16:     public:
Chris@16:       typedef void result_type;
Chris@16:       template<typename InputIterator>
Chris@16:         result_type operator()(InputIterator first, InputIterator last) const
Chris@16:       {
Chris@16:         while (first != last)
Chris@16:         {
Chris@16:           try
Chris@16:           {
Chris@16:             *first;
Chris@16:           }
Chris@16:           catch(const expired_slot &) {}
Chris@16:           ++first;
Chris@16:         }
Chris@16:         return;
Chris@16:       }
Chris@16:     };
Chris@16:   } // namespace signals2
Chris@16: } // namespace boost
Chris@16: #endif // BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP