408 lines
12 KiB
C++
408 lines
12 KiB
C++
//
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// buffered_read_stream.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2007 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_BUFFERED_READ_STREAM_HPP
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#define ASIO_BUFFERED_READ_STREAM_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 <cstring>
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#include <boost/config.hpp>
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#include <boost/type_traits.hpp>
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#include "asio/detail/pop_options.hpp"
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#include "asio/buffered_read_stream_fwd.hpp"
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#include "asio/buffer.hpp"
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#include "asio/error.hpp"
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#include "asio/io_service.hpp"
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#include "asio/detail/bind_handler.hpp"
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#include "asio/detail/buffer_resize_guard.hpp"
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#include "asio/detail/buffered_stream_storage.hpp"
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#include "asio/detail/noncopyable.hpp"
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namespace asio {
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/// Adds buffering to the read-related operations of a stream.
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/**
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* The buffered_read_stream class template can be used to add buffering to the
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* synchronous and asynchronous read operations of a stream.
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*
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* @par Thread Safety
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* @e Distinct @e objects: Safe.@n
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* @e Shared @e objects: Unsafe.
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*
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* @par Concepts:
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* AsyncReadStream, AsyncWriteStream, Stream, Sync_Read_Stream, SyncWriteStream.
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*/
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template <typename Stream>
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class buffered_read_stream
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: private noncopyable
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{
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public:
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/// The type of the next layer.
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typedef typename boost::remove_reference<Stream>::type next_layer_type;
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/// The type of the lowest layer.
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typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
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#if defined(GENERATING_DOCUMENTATION)
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/// The default buffer size.
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static const std::size_t default_buffer_size = implementation_defined;
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#else
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BOOST_STATIC_CONSTANT(std::size_t, default_buffer_size = 1024);
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#endif
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/// Construct, passing the specified argument to initialise the next layer.
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template <typename Arg>
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explicit buffered_read_stream(Arg& a)
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: next_layer_(a),
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storage_(default_buffer_size)
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{
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}
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/// Construct, passing the specified argument to initialise the next layer.
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template <typename Arg>
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buffered_read_stream(Arg& a, std::size_t buffer_size)
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: next_layer_(a),
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storage_(buffer_size)
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{
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}
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/// Get a reference to the next layer.
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next_layer_type& next_layer()
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{
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return next_layer_;
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}
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/// Get a reference to the lowest layer.
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lowest_layer_type& lowest_layer()
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{
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return next_layer_.lowest_layer();
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}
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/// Get the io_service associated with the object.
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asio::io_service& io_service()
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{
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return next_layer_.io_service();
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}
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/// Close the stream.
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void close()
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{
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next_layer_.close();
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}
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/// Close the stream.
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asio::error_code close(asio::error_code& ec)
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{
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return next_layer_.close(ec);
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}
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/// Write the given data to the stream. Returns the number of bytes written.
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/// Throws an exception on failure.
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template <typename ConstBufferSequence>
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std::size_t write_some(const ConstBufferSequence& buffers)
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{
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return next_layer_.write_some(buffers);
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}
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/// Write the given data to the stream. Returns the number of bytes written,
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/// or 0 if an error occurred.
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template <typename ConstBufferSequence>
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std::size_t write_some(const ConstBufferSequence& buffers,
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asio::error_code& ec)
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{
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return next_layer_.write_some(buffers, ec);
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}
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/// Start an asynchronous write. The data being written must be valid for the
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/// lifetime of the asynchronous operation.
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template <typename ConstBufferSequence, typename WriteHandler>
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void async_write_some(const ConstBufferSequence& buffers,
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WriteHandler handler)
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{
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next_layer_.async_write_some(buffers, handler);
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}
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/// Fill the buffer with some data. Returns the number of bytes placed in the
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/// buffer as a result of the operation. Throws an exception on failure.
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std::size_t fill()
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{
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detail::buffer_resize_guard<detail::buffered_stream_storage>
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resize_guard(storage_);
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std::size_t previous_size = storage_.size();
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storage_.resize(storage_.capacity());
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storage_.resize(previous_size + next_layer_.read_some(buffer(
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storage_.data() + previous_size,
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storage_.size() - previous_size)));
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resize_guard.commit();
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return storage_.size() - previous_size;
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}
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/// Fill the buffer with some data. Returns the number of bytes placed in the
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/// buffer as a result of the operation, or 0 if an error occurred.
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std::size_t fill(asio::error_code& ec)
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{
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detail::buffer_resize_guard<detail::buffered_stream_storage>
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resize_guard(storage_);
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std::size_t previous_size = storage_.size();
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storage_.resize(storage_.capacity());
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storage_.resize(previous_size + next_layer_.read_some(buffer(
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storage_.data() + previous_size,
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storage_.size() - previous_size),
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ec));
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resize_guard.commit();
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return storage_.size() - previous_size;
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}
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template <typename ReadHandler>
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class fill_handler
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{
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public:
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fill_handler(asio::io_service& io_service,
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detail::buffered_stream_storage& storage,
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std::size_t previous_size, ReadHandler handler)
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: io_service_(io_service),
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storage_(storage),
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previous_size_(previous_size),
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handler_(handler)
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{
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}
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void operator()(const asio::error_code& ec,
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std::size_t bytes_transferred)
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{
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storage_.resize(previous_size_ + bytes_transferred);
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io_service_.dispatch(detail::bind_handler(
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handler_, ec, bytes_transferred));
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}
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private:
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asio::io_service& io_service_;
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detail::buffered_stream_storage& storage_;
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std::size_t previous_size_;
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ReadHandler handler_;
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};
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/// Start an asynchronous fill.
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template <typename ReadHandler>
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void async_fill(ReadHandler handler)
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{
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std::size_t previous_size = storage_.size();
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storage_.resize(storage_.capacity());
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next_layer_.async_read_some(
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buffer(
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storage_.data() + previous_size,
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storage_.size() - previous_size),
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fill_handler<ReadHandler>(io_service(),
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storage_, previous_size, handler));
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}
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/// Read some data from the stream. Returns the number of bytes read. Throws
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/// an exception on failure.
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template <typename MutableBufferSequence>
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std::size_t read_some(const MutableBufferSequence& buffers)
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{
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if (storage_.empty())
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fill();
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return copy(buffers);
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}
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/// Read some data from the stream. Returns the number of bytes read or 0 if
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/// an error occurred.
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template <typename MutableBufferSequence>
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std::size_t read_some(const MutableBufferSequence& buffers,
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asio::error_code& ec)
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{
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ec = asio::error_code();
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if (storage_.empty() && !fill(ec))
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return 0;
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return copy(buffers);
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}
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template <typename MutableBufferSequence, typename ReadHandler>
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class read_some_handler
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{
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public:
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read_some_handler(asio::io_service& io_service,
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detail::buffered_stream_storage& storage,
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const MutableBufferSequence& buffers, ReadHandler handler)
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: io_service_(io_service),
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storage_(storage),
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buffers_(buffers),
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handler_(handler)
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{
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}
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void operator()(const asio::error_code& ec, std::size_t)
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{
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if (ec || storage_.empty())
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{
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std::size_t length = 0;
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io_service_.dispatch(detail::bind_handler(handler_, ec, length));
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}
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else
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{
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using namespace std; // For memcpy.
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std::size_t bytes_avail = storage_.size();
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std::size_t bytes_copied = 0;
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typename MutableBufferSequence::const_iterator iter = buffers_.begin();
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typename MutableBufferSequence::const_iterator end = buffers_.end();
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for (; iter != end && bytes_avail > 0; ++iter)
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{
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std::size_t max_length = buffer_size(*iter);
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std::size_t length = (max_length < bytes_avail)
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? max_length : bytes_avail;
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memcpy(buffer_cast<void*>(*iter),
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storage_.data() + bytes_copied, length);
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bytes_copied += length;
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bytes_avail -= length;
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}
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storage_.consume(bytes_copied);
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io_service_.dispatch(detail::bind_handler(handler_, ec, bytes_copied));
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}
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}
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private:
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asio::io_service& io_service_;
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detail::buffered_stream_storage& storage_;
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MutableBufferSequence buffers_;
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ReadHandler handler_;
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};
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/// Start an asynchronous read. The buffer into which the data will be read
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/// must be valid for the lifetime of the asynchronous operation.
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template <typename MutableBufferSequence, typename ReadHandler>
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void async_read_some(const MutableBufferSequence& buffers,
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ReadHandler handler)
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{
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if (storage_.empty())
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{
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async_fill(read_some_handler<MutableBufferSequence, ReadHandler>(
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io_service(), storage_, buffers, handler));
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}
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else
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{
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std::size_t length = copy(buffers);
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io_service().post(detail::bind_handler(
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handler, asio::error_code(), length));
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}
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}
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/// Peek at the incoming data on the stream. Returns the number of bytes read.
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/// Throws an exception on failure.
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template <typename MutableBufferSequence>
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std::size_t peek(const MutableBufferSequence& buffers)
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{
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if (storage_.empty())
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fill();
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return peek_copy(buffers);
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}
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/// Peek at the incoming data on the stream. Returns the number of bytes read,
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/// or 0 if an error occurred.
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template <typename MutableBufferSequence>
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std::size_t peek(const MutableBufferSequence& buffers,
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asio::error_code& ec)
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{
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ec = asio::error_code();
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if (storage_.empty() && !fill(ec))
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return 0;
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return peek_copy(buffers);
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}
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/// Determine the amount of data that may be read without blocking.
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std::size_t in_avail()
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{
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return storage_.size();
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}
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/// Determine the amount of data that may be read without blocking.
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std::size_t in_avail(asio::error_code& ec)
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{
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ec = asio::error_code();
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return storage_.size();
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}
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private:
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/// Copy data out of the internal buffer to the specified target buffer.
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/// Returns the number of bytes copied.
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template <typename MutableBufferSequence>
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std::size_t copy(const MutableBufferSequence& buffers)
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{
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using namespace std; // For memcpy.
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std::size_t bytes_avail = storage_.size();
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std::size_t bytes_copied = 0;
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typename MutableBufferSequence::const_iterator iter = buffers.begin();
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typename MutableBufferSequence::const_iterator end = buffers.end();
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for (; iter != end && bytes_avail > 0; ++iter)
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{
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std::size_t max_length = buffer_size(*iter);
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std::size_t length = (max_length < bytes_avail)
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? max_length : bytes_avail;
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memcpy(buffer_cast<void*>(*iter), storage_.data() + bytes_copied, length);
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bytes_copied += length;
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bytes_avail -= length;
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}
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storage_.consume(bytes_copied);
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return bytes_copied;
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}
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/// Copy data from the internal buffer to the specified target buffer, without
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/// removing the data from the internal buffer. Returns the number of bytes
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/// copied.
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template <typename MutableBufferSequence>
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std::size_t peek_copy(const MutableBufferSequence& buffers)
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{
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using namespace std; // For memcpy.
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std::size_t bytes_avail = storage_.size();
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std::size_t bytes_copied = 0;
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typename MutableBufferSequence::const_iterator iter = buffers.begin();
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typename MutableBufferSequence::const_iterator end = buffers.end();
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for (; iter != end && bytes_avail > 0; ++iter)
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{
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std::size_t max_length = buffer_size(*iter);
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std::size_t length = (max_length < bytes_avail)
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? max_length : bytes_avail;
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memcpy(buffer_cast<void*>(*iter), storage_.data() + bytes_copied, length);
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bytes_copied += length;
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bytes_avail -= length;
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}
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return bytes_copied;
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}
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/// The next layer.
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Stream next_layer_;
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// The data in the buffer.
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detail::buffered_stream_storage storage_;
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};
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} // namespace asio
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#include "asio/detail/pop_options.hpp"
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#endif // ASIO_BUFFERED_READ_STREAM_HPP
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