boost/signals2/optional_last_value.hpp

0001 // optional_last_value function object (documented as part of Boost.Signals2)
0002
0003 // Copyright Frank Mori Hess 2007-2008.
0004 // Copyright Douglas Gregor 2001-2003.
0005 // Distributed under the Boost Software License, Version
0006 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0007 // http://www.boost.org/LICENSE_1_0.txt)
0008
0009 // See http://www.boost.org/libs/signals2 for library home page.
0010
0011 #ifndef BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP
0012 #define BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP
0013
0014 #include <boost/core/no_exceptions_support.hpp>
0015 #include <boost/move/utility_core.hpp>
0016 #include <boost/optional.hpp>
0017 #include <boost/signals2/expired_slot.hpp>
0018
0019 namespace boost {
0020   namespace signals2 {
0021
0022     template<typename T>
0023       class optional_last_value
0024     {
0025     public:
0026       typedef optional<T> result_type;
0027
0028       template<typename InputIterator>
0029         optional<T> operator()(InputIterator first, InputIterator last) const
0030       {
0031         optional<T> value;
0032         while (first != last)
0033         {
0034           BOOST_TRY
0035           {
0036             value = boost::move_if_not_lvalue_reference<T>(*first);
0037           }
0038           BOOST_CATCH(const expired_slot &) {}
0039           BOOST_CATCH_END
0040           ++first;
0041         }
0042         return value;
0043       }
0044     };
0045
0046     template<>
0047       class optional_last_value<void>
0048     {
0049     public:
0050       typedef void result_type;
0051       template<typename InputIterator>
0052         result_type operator()(InputIterator first, InputIterator last) const
0053       {
0054         while (first != last)
0055         {
0056           BOOST_TRY
0057           {
0058             *first;
0059           }
0060           BOOST_CATCH(const expired_slot &) {}
0061           BOOST_CATCH_END
0062           ++first;
0063         }
0064         return;
0065       }
0066     };
0067   } // namespace signals2
0068 } // namespace boost
0069 #endif // BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP