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#include <boost/config.hpp>
15
16namespace boost {
17 template<typename T>
18 struct last_value {
19 typedef T result_type;
20
21 template<typename InputIterator>
22 T operator()(InputIterator first, InputIterator last) const
23 {
24 assert(first != last);
25 T value = *first++;
26 while (first != last)
27 value = *first++;
28 return value;
29 }
30 };
31
32 template<>
33 struct last_value<void> {
34#ifdef BOOST_NO_VOID_RETURNS
35 struct unusable {};
36
37 public:
38 typedef unusable result_type;
39#else
40 public:
41 typedef void result_type;
42#endif // BOOST_NO_VOID_RETURNS
43
44 template<typename InputIterator>
45 result_type
46 operator()(InputIterator first, InputIterator last) const
47 {
48 while (first != last)
49 *first++;
50 return result_type();
51 }
52 };
53}
54#endif // BOOST_SIGNALS_LAST_VALUE_HPP
55

source code of boost/boost/last_value.hpp