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Viewing changes to portable/libtorrent/include/libtorrent/asio/detail/buffer_resize_guard.hpp

  • Committer: Daniel Hahler
  • Date: 2010-04-13 18:51:35 UTC
  • mfrom: (1.2.10 upstream)
  • Revision ID: ubuntu-launchpad@thequod.de-20100413185135-xi24v1diqg8w406x
Merging shared upstream rev into target branch.

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portable/libtorrent/include/libtorrent/asio/detail/buffer_resize_guard.hpp
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//
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// buffer_resize_guard.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP
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#define ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include "asio/detail/push_options.hpp"
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#include "asio/detail/push_options.hpp"
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#include <limits>
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#include <boost/config.hpp>
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#include "asio/detail/pop_options.hpp"
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namespace asio {
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namespace detail {
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// Helper class to manage buffer resizing in an exception safe way.
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template <typename Buffer>
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class buffer_resize_guard
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{
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public:
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  // Constructor.
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  buffer_resize_guard(Buffer& buffer)
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    : buffer_(buffer),
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      old_size_(buffer.size())
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  {
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  }
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  // Destructor rolls back the buffer resize unless commit was called.
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  ~buffer_resize_guard()
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  {
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    if (old_size_
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        != std::numeric_limits<size_t>::max BOOST_PREVENT_MACRO_SUBSTITUTION())
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    {
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      buffer_.resize(old_size_);
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    }
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  }
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  // Commit the resize transaction.
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  void commit()
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  {
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    old_size_
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      = std::numeric_limits<size_t>::max BOOST_PREVENT_MACRO_SUBSTITUTION();
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  }
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private:
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  // The buffer being managed.
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  Buffer& buffer_;
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  // The size of the buffer at the time the guard was constructed.
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  size_t old_size_;
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};
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} // namespace detail
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} // namespace asio
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#include "asio/detail/pop_options.hpp"
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#endif // ASIO_DETAIL_BUFFER_RESIZE_GUARD_HPP