| // |
| // detail/buffer_resize_guard.hpp |
| // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| // |
| // Copyright (c) 2003-2010 Christopher M. Kohlhoff (chris at kohlhoff dot com) |
| // |
| // Distributed under 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) |
| // |
| |
| #ifndef BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP |
| #define BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP |
| |
| #if defined(_MSC_VER) && (_MSC_VER >= 1200) |
| # pragma once |
| #endif // defined(_MSC_VER) && (_MSC_VER >= 1200) |
| |
| #include <boost/asio/detail/config.hpp> |
| #include <boost/limits.hpp> |
| |
| #include <boost/asio/detail/push_options.hpp> |
| |
| namespace boost { |
| namespace asio { |
| namespace detail { |
| |
| // Helper class to manage buffer resizing in an exception safe way. |
| template <typename Buffer> |
| class buffer_resize_guard |
| { |
| public: |
| // Constructor. |
| buffer_resize_guard(Buffer& buffer) |
| : buffer_(buffer), |
| old_size_(buffer.size()) |
| { |
| } |
| |
| // Destructor rolls back the buffer resize unless commit was called. |
| ~buffer_resize_guard() |
| { |
| if (old_size_ |
| != std::numeric_limits<size_t>::max BOOST_PREVENT_MACRO_SUBSTITUTION()) |
| { |
| buffer_.resize(old_size_); |
| } |
| } |
| |
| // Commit the resize transaction. |
| void commit() |
| { |
| old_size_ |
| = std::numeric_limits<size_t>::max BOOST_PREVENT_MACRO_SUBSTITUTION(); |
| } |
| |
| private: |
| // The buffer being managed. |
| Buffer& buffer_; |
| |
| // The size of the buffer at the time the guard was constructed. |
| size_t old_size_; |
| }; |
| |
| } // namespace detail |
| } // namespace asio |
| } // namespace boost |
| |
| #include <boost/asio/detail/pop_options.hpp> |
| |
| #endif // BOOST_ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP |