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Viewing changes to portable/libtorrent/include/libtorrent/asio/detail/const_buffers_iterator.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/const_buffers_iterator.hpp
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//
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// const_buffers_iterator.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_CONST_BUFFERS_ITERATOR_HPP
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#define ASIO_DETAIL_CONST_BUFFERS_ITERATOR_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 <cstddef>
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#include <boost/config.hpp>
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#include <boost/iterator/iterator_facade.hpp>
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#include "asio/detail/pop_options.hpp"
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#include "asio/buffer.hpp"
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namespace asio {
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namespace detail {
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// A proxy iterator for a sub-range in a list of buffers.
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template <typename ConstBufferSequence>
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class const_buffers_iterator
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  : public boost::iterator_facade<const_buffers_iterator<ConstBufferSequence>,
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        const char, boost::bidirectional_traversal_tag>
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{
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public:
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  // Default constructor creates an iterator in an undefined state.
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  const_buffers_iterator()
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  {
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  }
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  // Create an iterator for the specified position.
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  const_buffers_iterator(const ConstBufferSequence& buffers,
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      std::size_t position)
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    : begin_(buffers.begin()),
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      current_(buffers.begin()),
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      end_(buffers.end()),
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      position_(0)
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  {
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    while (current_ != end_)
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    {
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      current_buffer_ = *current_;
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      std::size_t buffer_size = asio::buffer_size(current_buffer_);
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      if (position - position_ < buffer_size)
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      {
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        current_buffer_position_ = position - position_;
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        position_ = position;
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        return;
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      }
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      position_ += buffer_size;
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      ++current_;
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    }
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    current_buffer_ = asio::const_buffer();
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    current_buffer_position_ = 0;
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  }
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  std::size_t position() const
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  {
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    return position_;
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  }
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private:
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  friend class boost::iterator_core_access;
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  void increment()
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  {
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    if (current_ == end_)
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      return;
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    ++position_;
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    ++current_buffer_position_;
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    if (current_buffer_position_ != asio::buffer_size(current_buffer_))
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      return;
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    ++current_;
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    current_buffer_position_ = 0;
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    while (current_ != end_)
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    {
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      current_buffer_ = *current_;
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      if (asio::buffer_size(current_buffer_) > 0)
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        return;
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      ++current_;
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    }
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  }
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  void decrement()
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  {
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    if (position_ == 0)
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      return;
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    --position_;
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    if (current_buffer_position_ != 0)
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    {
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      --current_buffer_position_;
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      return;
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    }
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    typename ConstBufferSequence::const_iterator iter = current_;
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    while (iter != begin_)
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    {
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      --iter;
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      asio::const_buffer buffer = *iter;
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      std::size_t buffer_size = asio::buffer_size(buffer);
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      if (buffer_size > 0)
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      {
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        current_ = iter;
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        current_buffer_ = buffer;
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        current_buffer_position_ = buffer_size - 1;
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        return;
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      }
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    }
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  }
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  bool equal(const const_buffers_iterator& other) const
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  {
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    return position_ == other.position_;
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  }
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  const char& dereference() const
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  {
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    return asio::buffer_cast<const char*>(
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        current_buffer_)[current_buffer_position_];
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  }
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  asio::const_buffer current_buffer_;
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  std::size_t current_buffer_position_;
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  typename ConstBufferSequence::const_iterator begin_;
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  typename ConstBufferSequence::const_iterator current_;
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  typename ConstBufferSequence::const_iterator end_;
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  std::size_t position_;
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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_CONST_BUFFERS_ITERATOR_HPP