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

     2 

     3 // Copyright Douglas Gregor 2001-2003. Use, modification and

     4 // distribution is subject to the Boost Software License, Version

     5 // 1.0. (See accompanying file LICENSE_1_0.txt or copy at

     6 // http://www.boost.org/LICENSE_1_0.txt)

     7 

     8 // For more information, see http://www.boost.org/libs/signals

     9 

    10 #ifndef BOOST_LAST_VALUE_HPP

    11 #define BOOST_LAST_VALUE_HPP

    12 

    13 #include <cassert>

    14 

    15 namespace boost {

    16   template<typename T>

    17   struct last_value {

    18     typedef T result_type;

    19 

    20     template<typename InputIterator>

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

    22     {

    23       assert(first != last);

    24       T value = *first++;

    25       while (first != last)

    26         value = *first++;

    27       return value;

    28     }

    29   };

    30 

    31   template<>

    32   struct last_value<void> {

    33     struct unusable {};

    34 

    35   public:

    36     typedef unusable result_type;

    37 

    38     template<typename InputIterator>

    39     result_type

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

    41     {

    42       while (first != last)

    43         *first++;

    44       return result_type();

    45     }

    46   };

    47 }

    48 #endif // BOOST_SIGNALS_LAST_VALUE_HPP