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1 | // optional_last_value function object (documented as part of Boost.Signals2) |
2 | ||
3 | // Copyright Frank Mori Hess 2007-2008. | |
4 | // Copyright Douglas Gregor 2001-2003. | |
5 | // Distributed under the Boost Software License, Version | |
6 | // 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
7 | // http://www.boost.org/LICENSE_1_0.txt) | |
8 | ||
9 | // See http://www.boost.org/libs/signals2 for library home page. | |
10 | ||
11 | #ifndef BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP | |
12 | #define BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP | |
13 | ||
14 | #include <boost/core/no_exceptions_support.hpp> | |
15 | #include <boost/optional.hpp> | |
16 | #include <boost/signals2/expired_slot.hpp> | |
17 | ||
18 | namespace boost { | |
19 | namespace signals2 { | |
20 | ||
21 | template<typename T> | |
22 | class optional_last_value | |
23 | { | |
24 | public: | |
25 | typedef optional<T> result_type; | |
26 | ||
27 | template<typename InputIterator> | |
28 | optional<T> operator()(InputIterator first, InputIterator last) const | |
29 | { | |
30 | optional<T> value; | |
31 | while (first != last) | |
32 | { | |
33 | BOOST_TRY | |
34 | { | |
35 | value = *first; | |
36 | } | |
37 | BOOST_CATCH(const expired_slot &) {} | |
38 | BOOST_CATCH_END | |
39 | ++first; | |
40 | } | |
41 | return value; | |
42 | } | |
43 | }; | |
44 | ||
45 | template<> | |
46 | class optional_last_value<void> | |
47 | { | |
48 | public: | |
49 | typedef void result_type; | |
50 | template<typename InputIterator> | |
51 | result_type operator()(InputIterator first, InputIterator last) const | |
52 | { | |
53 | while (first != last) | |
54 | { | |
55 | BOOST_TRY | |
56 | { | |
57 | *first; | |
58 | } | |
59 | BOOST_CATCH(const expired_slot &) {} | |
60 | BOOST_CATCH_END | |
61 | ++first; | |
62 | } | |
63 | return; | |
64 | } | |
65 | }; | |
66 | } // namespace signals2 | |
67 | } // namespace boost | |
68 | #endif // BOOST_SIGNALS2_OPTIONAL_LAST_VALUE_HPP |