read.hpp

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//
// read.hpp
// ~~~~~~~~
//
// Copyright (c) 2003-2007 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 ASIO_READ_HPP
#define ASIO_READ_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/push_options.hpp"

#include "asio/detail/push_options.hpp"
#include <cstddef>
#include <boost/config.hpp>
#include "asio/detail/pop_options.hpp"

#include "asio/basic_streambuf.hpp"
#include "asio/error.hpp"

namespace asio {

/**
 * @defgroup read asio::read
 */
/*@{*/

/// Attempt to read a certain amount of data from a stream before returning.
/**
 * This function is used to read a certain number of bytes of data from a
 * stream. The call will block until one of the following conditions is true:
 *
 * @li The supplied buffers are full. That is, the bytes transferred is equal to
 * the sum of the buffer sizes.
 *
 * @li An error occurred.
 *
 * This operation is implemented in terms of one or more calls to the stream's
 * read_some function.
 *
 * @param s The stream from which the data is to be read. The type must support
 * the SyncReadStream concept.
 *
 * @param buffers One or more buffers into which the data will be read. The sum
 * of the buffer sizes indicates the maximum number of bytes to read from the
 * stream.
 *
 * @returns The number of bytes transferred.
 *
 * @throws asio::system_error Thrown on failure.
 *
 * @par Example
 * To read into a single data buffer use the @ref buffer function as follows:
 * @code asio::read(s, asio::buffer(data, size)); @endcode
 * See the @ref buffer documentation for information on reading into multiple
 * buffers in one go, and how to use it with arrays, boost::array or
 * std::vector.
 *
 * @note This overload is equivalent to calling:
 * @code asio::read(
 *     s, buffers,
 *     asio::transfer_all()); @endcode
 */
template <typename SyncReadStream, typename MutableBufferSequence>
std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers);

/// Attempt to read a certain amount of data from a stream before returning.
/**
 * This function is used to read a certain number of bytes of data from a
 * stream. The call will block until one of the following conditions is true:
 *
 * @li The supplied buffers are full. That is, the bytes transferred is equal to
 * the sum of the buffer sizes.
 *
 * @li The completion_condition function object returns true.
 *
 * This operation is implemented in terms of one or more calls to the stream's
 * read_some function.
 *
 * @param s The stream from which the data is to be read. The type must support
 * the SyncReadStream concept.
 *
 * @param buffers One or more buffers into which the data will be read. The sum
 * of the buffer sizes indicates the maximum number of bytes to read from the
 * stream.
 *
 * @param completion_condition The function object to be called to determine
 * whether the read operation is complete. The signature of the function object
 * must be:
 * @code bool completion_condition(
 *   const asio::error_code& error, // Result of latest read_some
 *                                           // operation.
 *
 *   std::size_t bytes_transferred           // Number of bytes transferred
 *                                           // so far.
 * ); @endcode
 * A return value of true indicates that the read operation is complete. False
 * indicates that further calls to the stream's read_some function are required.
 *
 * @returns The number of bytes transferred.
 *
 * @throws asio::system_error Thrown on failure.
 *
 * @par Example
 * To read into a single data buffer use the @ref buffer function as follows:
 * @code asio::read(s, asio::buffer(data, size),
 *     asio::transfer_at_least(32)); @endcode
 * See the @ref buffer documentation for information on reading into multiple
 * buffers in one go, and how to use it with arrays, boost::array or
 * std::vector.
 */
template <typename SyncReadStream, typename MutableBufferSequence,
  typename CompletionCondition>
std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
    CompletionCondition completion_condition);

/// Attempt to read a certain amount of data from a stream before returning.
/**
 * This function is used to read a certain number of bytes of data from a
 * stream. The call will block until one of the following conditions is true:
 *
 * @li The supplied buffers are full. That is, the bytes transferred is equal to
 * the sum of the buffer sizes.
 *
 * @li The completion_condition function object returns true.
 *
 * This operation is implemented in terms of one or more calls to the stream's
 * read_some function.
 *
 * @param s The stream from which the data is to be read. The type must support
 * the SyncReadStream concept.
 *
 * @param buffers One or more buffers into which the data will be read. The sum
 * of the buffer sizes indicates the maximum number of bytes to read from the
 * stream.
 *
 * @param completion_condition The function object to be called to determine
 * whether the read operation is complete. The signature of the function object
 * must be:
 * @code bool completion_condition(
 *   const asio::error_code& error, // Result of latest read_some
 *                                           // operation.
 *
 *   std::size_t bytes_transferred           // Number of bytes transferred
 *                                           // so far.
 * ); @endcode
 * A return value of true indicates that the read operation is complete. False
 * indicates that further calls to the stream's read_some function are required.
 *
 * @param ec Set to indicate what error occurred, if any.
 *
 * @returns The number of bytes read. If an error occurs, returns the total
 * number of bytes successfully transferred prior to the error.
 */
template <typename SyncReadStream, typename MutableBufferSequence,
    typename CompletionCondition>
std::size_t read(SyncReadStream& s, const MutableBufferSequence& buffers,
    CompletionCondition completion_condition, asio::error_code& ec);

/// Attempt to read a certain amount of data from a stream before returning.
/**
 * This function is used to read a certain number of bytes of data from a
 * stream. The call will block until one of the following conditions is true:
 *
 * @li An error occurred.
 *
 * This operation is implemented in terms of one or more calls to the stream's
 * read_some function.
 *
 * @param s The stream from which the data is to be read. The type must support
 * the SyncReadStream concept.
 *
 * @param b The basic_streambuf object into which the data will be read.
 *
 * @returns The number of bytes transferred.
 *
 * @throws asio::system_error Thrown on failure.
 *
 * @note This overload is equivalent to calling:
 * @code asio::read(
 *     s, b,
 *     asio::transfer_all()); @endcode
 */
template <typename SyncReadStream, typename Allocator>
std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b);

/// Attempt to read a certain amount of data from a stream before returning.
/**
 * This function is used to read a certain number of bytes of data from a
 * stream. The call will block until one of the following conditions is true:
 *
 * @li The completion_condition function object returns true.
 *
 * This operation is implemented in terms of one or more calls to the stream's
 * read_some function.
 *
 * @param s The stream from which the data is to be read. The type must support
 * the SyncReadStream concept.
 *
 * @param b The basic_streambuf object into which the data will be read.
 *
 * @param completion_condition The function object to be called to determine
 * whether the read operation is complete. The signature of the function object
 * must be:
 * @code bool completion_condition(
 *   const asio::error_code& error, // Result of latest read_some
 *                                           // operation.
 *
 *   std::size_t bytes_transferred           // Number of bytes transferred
 *                                           // so far.
 * ); @endcode
 * A return value of true indicates that the read operation is complete. False
 * indicates that further calls to the stream's read_some function are required.
 *
 * @returns The number of bytes transferred.
 *
 * @throws asio::system_error Thrown on failure.
 */
template <typename SyncReadStream, typename Allocator,
    typename CompletionCondition>
std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b,
    CompletionCondition completion_condition);

/// Attempt to read a certain amount of data from a stream before returning.
/**
 * This function is used to read a certain number of bytes of data from a
 * stream. The call will block until one of the following conditions is true:
 *
 * @li The completion_condition function object returns true.
 *
 * This operation is implemented in terms of one or more calls to the stream's
 * read_some function.
 *
 * @param s The stream from which the data is to be read. The type must support
 * the SyncReadStream concept.
 *
 * @param b The basic_streambuf object into which the data will be read.
 *
 * @param completion_condition The function object to be called to determine
 * whether the read operation is complete. The signature of the function object
 * must be:
 * @code bool completion_condition(
 *   const asio::error_code& error, // Result of latest read_some
 *                                           // operation.
 *
 *   std::size_t bytes_transferred           // Number of bytes transferred
 *                                           // so far.
 * ); @endcode
 * A return value of true indicates that the read operation is complete. False
 * indicates that further calls to the stream's read_some function are required.
 *
 * @param ec Set to indicate what error occurred, if any.