// last_value function object (documented as part of Boost.Signals)

 // Copyright Douglas Gregor 2001-2003. 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/libs/signals

 #ifndef BOOST_LAST_VALUE_HPP

 #define BOOST_LAST_VALUE_HPP

 #include <cassert>

 namespace boost {

   template<typename T>

   struct last_value {

     typedef T result_type;

     template<typename InputIterator>

     T operator()(InputIterator first, InputIterator last) const

     {

       assert(first != last);

       T value = *first++;

       while (first != last)

         value = *first++;

       return value;

     }

   };

   template<>

   struct last_value<void> {

     struct unusable {};

   public:

     typedef unusable result_type;

     template<typename InputIterator>

     result_type

     operator()(InputIterator first, InputIterator last) const

     {

       while (first != last)

         *first++;

       return result_type();

     }

   };

 }

 #endif // BOOST_SIGNALS_LAST_VALUE_HPP