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1 | // |
2 | // detail/buffer_resize_guard.hpp | |
3 | // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
4 | // | |
5 | // Copyright (c) 2003-2016 Christopher M. Kohlhoff (chris at kohlhoff dot com) | |
6 | // | |
7 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | |
8 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | |
9 | // | |
10 | ||
11 | #ifndef BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP | |
12 | #define BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP | |
13 | ||
14 | #if defined(_MSC_VER) && (_MSC_VER >= 1200) | |
15 | # pragma once | |
16 | #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) | |
17 | ||
18 | #include <boost/asio/detail/config.hpp> | |
19 | #include <boost/asio/detail/limits.hpp> | |
20 | ||
21 | #include <boost/asio/detail/push_options.hpp> | |
22 | ||
23 | namespace boost { | |
24 | namespace asio { | |
25 | namespace detail { | |
26 | ||
27 | // Helper class to manage buffer resizing in an exception safe way. | |
28 | template <typename Buffer> | |
29 | class buffer_resize_guard | |
30 | { | |
31 | public: | |
32 | // Constructor. | |
33 | buffer_resize_guard(Buffer& buffer) | |
34 | : buffer_(buffer), | |
35 | old_size_(buffer.size()) | |
36 | { | |
37 | } | |
38 | ||
39 | // Destructor rolls back the buffer resize unless commit was called. | |
40 | ~buffer_resize_guard() | |
41 | { | |
42 | if (old_size_ != (std::numeric_limits<size_t>::max)()) | |
43 | { | |
44 | buffer_.resize(old_size_); | |
45 | } | |
46 | } | |
47 | ||
48 | // Commit the resize transaction. | |
49 | void commit() | |
50 | { | |
51 | old_size_ = (std::numeric_limits<size_t>::max)(); | |
52 | } | |
53 | ||
54 | private: | |
55 | // The buffer being managed. | |
56 | Buffer& buffer_; | |
57 | ||
58 | // The size of the buffer at the time the guard was constructed. | |
59 | size_t old_size_; | |
60 | }; | |
61 | ||
62 | } // namespace detail | |
63 | } // namespace asio | |
64 | } // namespace boost | |
65 | ||
66 | #include <boost/asio/detail/pop_options.hpp> | |
67 | ||
68 | #endif // BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP |