text: //
  // read.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_READ_HPP
  #define BOOST_ASIO_READ_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include <boost/asio/detail/config.hpp>
  #include <cstddef>
  #include <boost/asio/basic_streambuf_fwd.hpp>
  #include <boost/asio/error.hpp>
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  
  /**
   * @defgroup read boost::asio::read
   *
   * @brief Attempt to read a certain amount of data from a stream before
   * returning.
   */
  /*@{*/
  
  /// 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 zero 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 boost::system::system_error Thrown on failure.
   *
   * @par Example
   * To read into a single data buffer use the @ref buffer function as follows:
   * @code boost::asio::read(s, boost::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 boost::asio::read(
   *     s, buffers,
   *     boost::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 0.
   *
   * This operation is implemented in terms of zero 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 std::size_t completion_condition(
   *   // Result of latest read_some operation.
   *   const boost::system::error_code& error,
   *
   *   // Number of bytes transferred so far.
   *   std::size_t bytes_transferred
   * ); @endcode
   * A return value of 0 indicates that the read operation is complete. A non-zero
   * return value indicates the maximum number of bytes to be read on the next
   * call to the stream's read_some function.
   *
   * @returns The number of bytes transferred.
   *
   * @throws boost::system::system_error Thrown on failure.
   *
   * @par Example
   * To read into a single data buffer use the @ref buffer function as follows:
   * @code boost::asio::read(s, boost::asio::buffer(data, size),
   *     boost::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 0.
   *
   * This operation is implemented in terms of zero 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 std::size_t completion_condition(
   *   // Result of latest read_some operation.
   *   const boost::system::error_code& error,
   *
   *   // Number of bytes transferred so far.
   *   std::size_t bytes_transferred
   * ); @endcode
   * A return value of 0 indicates that the read operation is complete. A non-zero
   * return value indicates the maximum number of bytes to be read on the next
   * call to the stream's read_some function.
   *
   * @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, boost::system::error_code& ec);
  
  #if !defined(BOOST_NO_IOSTREAM)
  
  /// 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 zero 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 boost::system::system_error Thrown on failure.
   *
   * @note This overload is equivalent to calling:
   * @code boost::asio::read(
   *     s, b,
   *     boost::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 0.
   *
   * This operation is implemented in terms of zero 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 std::size_t completion_condition(
   *   // Result of latest read_some operation.
   *   const boost::system::error_code& error,
   *
   *   // Number of bytes transferred so far.
   *   std::size_t bytes_transferred
   * ); @endcode
   * A return value of 0 indicates that the read operation is complete. A non-zero
   * return value indicates the maximum number of bytes to be read on the next
   * call to the stream's read_some function.
   *
   * @returns The number of bytes transferred.
   *
   * @throws boost::system::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 0.
   *
   * This operation is implemented in terms of zero 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 std::size_t completion_condition(
   *   // Result of latest read_some operation.
   *   const boost::system::error_code& error,
   *
   *   // Number of bytes transferred so far.
   *   std::size_t bytes_transferred
   * ); @endcode
   * A return value of 0 indicates that the read operation is complete. A non-zero
   * return value indicates the maximum number of bytes to be read on the next
   * call to the stream's read_some function.
   *
   * @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 Allocator,
      typename CompletionCondition>
  std::size_t read(SyncReadStream& s, basic_streambuf<Allocator>& b,
      CompletionCondition completion_condition, boost::system::error_code& ec);
  
  #endif // !defined(BOOST_NO_IOSTREAM)
  
  /*@}*/
  /**
   * @defgroup async_read boost::asio::async_read
   *
   * @brief Start an asynchronous operation to read a certain amount of data from
   * a stream.
   */
  /*@{*/
  
  /// Start an asynchronous operation to read a certain amount of data from a
  /// stream.
  /**
   * This function is used to asynchronously read a certain number of bytes of
   * data from a stream. The function call always returns immediately. The
   * asynchronous operation will continue 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 zero or more calls to the stream's
   * async_read_some function, and is known as a <em>composed operation</em>. The
   * program must ensure that the stream performs no other read operations (such
   * as async_read, the stream's async_read_some function, or any other composed
   * operations that perform reads) until this operation completes.
   *
   * @param s The stream from which the data is to be read. The type must support
   * the AsyncReadStream 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. Although the buffers object may be copied as necessary, ownership of
   * the underlying memory blocks is retained by the caller, which must guarantee
   * that they remain valid until the handler is called.
   *
   * @param handler The handler to be called when the read operation completes.
   * Copies will be made of the handler as required. The function signature of the
   * handler must be:
   * @code void handler(
   *   const boost::system::error_code& error, // Result of operation.
   *
   *   std::size_t bytes_transferred           // Number of bytes copied into the
   *                                           // buffers. If an error occurred,
   *                                           // this will be the  number of
   *                                           // bytes successfully transferred
   *                                           // prior to the error.
   * ); @endcode
   * Regardless of whether the asynchronous operation completes immediately or
   * not, the handler will not be invoked from within this function. Invocation of
   * the handler will be performed in a manner equivalent to using
   * boost::asio::io_service::post().
   *
   * @par Example
   * To read into a single data buffer use the @ref buffer function as follows:
   * @code
   * boost::asio::async_read(s, boost::asio::buffer(data, size), handler);
   * @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 boost::asio::async_read(
   *     s, buffers,
   *     boost::asio::transfer_all(),
   *     handler); @endcode
   */
  template <typename AsyncReadStream, typename MutableBufferSequence,
      typename ReadHandler>
  void async_read(AsyncReadStream& s, const MutableBufferSequence& buffers,
      ReadHandler handler);
  
  /// Start an asynchronous operation to read a certain amount of data from a
  /// stream.
  /**
   * This function is used to asynchronously read a certain number of bytes of
   * data from a stream. The function call always returns immediately. The
   * asynchronous operation will continue 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 0.
   *
   * @param s The stream from which the data is to be read. The type must support
   * the AsyncReadStream 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. Although the buffers object may be copied as necessary, ownership of
   * the underlying memory blocks is retained by the caller, which must guarantee
   * that they remain valid until the handler is called.
   *
   * @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 std::size_t completion_condition(
   *   // Result of latest async_read_some operation.
   *   const boost::system::error_code& error,
   *
   *   // Number of bytes transferred so far.
   *   std::size_t bytes_transferred
   * ); @endcode
   * A return value of 0 indicates that the read operation is complete. A non-zero
   * return value indicates the maximum number of bytes to be read on the next
   * call to the stream's async_read_some function.
   *
   * @param handler The handler to be called when the read operation completes.
   * Copies will be made of the handler as required. The function signature of the
   * handler must be:
   * @code void handler(
   *   const boost::system::error_code& error, // Result of operation.
   *
   *   std::size_t bytes_transferred           // Number of bytes copied into the
   *                                           // buffers. If an error occurred,
   *                                           // this will be the  number of
   *                                           // bytes successfully transferred
   *                                           // prior to the error.
   * ); @endcode
   * Regardless of whether the asynchronous operation completes immediately or
   * not, the handler will not be invoked from within this function. Invocation of
   * the handler will be performed in a manner equivalent to using
   * boost::asio::io_service::post().
   *
   * @par Example
   * To read into a single data buffer use the @ref buffer function as follows:
   * @code boost::asio::async_read(s,
   *     boost::asio::buffer(data, size),
   *     boost::asio::transfer_at_least(32),
   *     handler); @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 AsyncReadStream, typename MutableBufferSequence,
      typename CompletionCondition, typename ReadHandler>
  void async_read(AsyncReadStream& s, const MutableBufferSequence& buffers,
      CompletionCondition completion_condition, ReadHandler handler);
  
  #if !defined(BOOST_NO_IOSTREAM)
  
  /// Start an asynchronous operation to read a certain amount of data from a
  /// stream.
  /**
   * This function is used to asynchronously read a certain number of bytes of
   * data from a stream. The function call always returns immediately. The
   * asynchronous operation will continue until one of the following conditions is
   * true:
   *
   * @li An error occurred.
   *
   * This operation is implemented in terms of zero or more calls to the stream's
   * async_read_some function, and is known as a <em>composed operation</em>. The
   * program must ensure that the stream performs no other read operations (such
   * as async_read, the stream's async_read_some function, or any other composed
   * operations that perform reads) until this operation completes.
   *
   * @param s The stream from which the data is to be read. The type must support
   * the AsyncReadStream concept.
   *
   * @param b A basic_streambuf object into which the data will be read. Ownership
   * of the streambuf is retained by the caller, which must guarantee that it
   * remains valid until the handler is called.
   *
   * @param handler The handler to be called when the read operation completes.
   * Copies will be made of the handler as required. The function signature of the
   * handler must be:
   * @code void handler(
   *   const boost::system::error_code& error, // Result of operation.
   *
   *   std::size_t bytes_transferred           // Number of bytes copied into the
   *                                           // buffers. If an error occurred,
   *                                           // this will be the  number of
   *                                           // bytes successfully transferred
   *                                           // prior to the error.
   * ); @endcode
   * Regardless of whether the asynchronous operation completes immediately or
   * not, the handler will not be invoked from within this function. Invocation of
   * the handler will be performed in a manner equivalent to using
   * boost::asio::io_service::post().
   *
   * @note This overload is equivalent to calling:
   * @code boost::asio::async_read(
   *     s, b,
   *     boost::asio::transfer_all(),
   *     handler); @endcode
   */
  template <typename AsyncReadStream, typename Allocator, typename ReadHandler>
  void async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b,
      ReadHandler handler);
  
  /// Start an asynchronous operation to read a certain amount of data from a
  /// stream.
  /**
   * This function is used to asynchronously read a certain number of bytes of
   * data from a stream. The function call always returns immediately. The
   * asynchronous operation will continue until one of the following conditions is
   * true:
   *
   * @li The completion_condition function object returns 0.
   *
   * This operation is implemented in terms of zero or more calls to the stream's
   * async_read_some function, and is known as a <em>composed operation</em>. The
   * program must ensure that the stream performs no other read operations (such
   * as async_read, the stream's async_read_some function, or any other composed
   * operations that perform reads) until this operation completes.
   *
   * @param s The stream from which the data is to be read. The type must support
   * the AsyncReadStream concept.
   *
   * @param b A basic_streambuf object into which the data will be read. Ownership
   * of the streambuf is retained by the caller, which must guarantee that it
   * remains valid until the handler is called.
   *
   * @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 std::size_t completion_condition(
   *   // Result of latest async_read_some operation.
   *   const boost::system::error_code& error,
   *
   *   // Number of bytes transferred so far.
   *   std::size_t bytes_transferred
   * ); @endcode
   * A return value of 0 indicates that the read operation is complete. A non-zero
   * return value indicates the maximum number of bytes to be read on the next
   * call to the stream's async_read_some function.
   *
   * @param handler The handler to be called when the read operation completes.
   * Copies will be made of the handler as required. The function signature of the
   * handler must be:
   * @code void handler(
   *   const boost::system::error_code& error, // Result of operation.
   *
   *   std::size_t bytes_transferred           // Number of bytes copied into the
   *                                           // buffers. If an error occurred,
   *                                           // this will be the  number of
   *                                           // bytes successfully transferred
   *                                           // prior to the error.
   * ); @endcode
   * Regardless of whether the asynchronous operation completes immediately or
   * not, the handler will not be invoked from within this function. Invocation of
   * the handler will be performed in a manner equivalent to using
   * boost::asio::io_service::post().
   */
  template <typename AsyncReadStream, typename Allocator,
      typename CompletionCondition, typename ReadHandler>
  void async_read(AsyncReadStream& s, basic_streambuf<Allocator>& b,
      CompletionCondition completion_condition, ReadHandler handler);
  
  #endif // !defined(BOOST_NO_IOSTREAM)
  
  /*@}*/
  
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #include <boost/asio/impl/read.hpp>
  
  #endif // BOOST_ASIO_READ_HPP
  