text: //
  // buffer.hpp
  // ~~~~~~~~~~
  //
  // Copyright (c) 2003-2011 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_BUFFER_HPP
  #define BOOST_ASIO_BUFFER_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 <cstring>
  #include <string>
  #include <vector>
  #include <boost/detail/workaround.hpp>
  #include <boost/asio/detail/array_fwd.hpp>
  
  #if defined(BOOST_MSVC)
  # if defined(_HAS_ITERATOR_DEBUGGING) && (_HAS_ITERATOR_DEBUGGING != 0)
  #  if !defined(BOOST_ASIO_DISABLE_BUFFER_DEBUGGING)
  #   define BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
  #  endif // !defined(BOOST_ASIO_DISABLE_BUFFER_DEBUGGING)
  # endif // defined(_HAS_ITERATOR_DEBUGGING)
  #endif // defined(BOOST_MSVC)
  
  #if defined(__GNUC__)
  # if defined(_GLIBCXX_DEBUG)
  #  if !defined(BOOST_ASIO_DISABLE_BUFFER_DEBUGGING)
  #   define BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
  #  endif // !defined(BOOST_ASIO_DISABLE_BUFFER_DEBUGGING)
  # endif // defined(_GLIBCXX_DEBUG)
  #endif // defined(__GNUC__)
  
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
  # include <boost/function.hpp>
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
  
  #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582)) \
    || BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x590))
  # include <boost/type_traits/is_const.hpp>
  #endif // BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582))
         // || BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x590))
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  
  class mutable_buffer;
  class const_buffer;
  
  namespace detail {
  void* buffer_cast_helper(const mutable_buffer&);
  const void* buffer_cast_helper(const const_buffer&);
  std::size_t buffer_size_helper(const mutable_buffer&);
  std::size_t buffer_size_helper(const const_buffer&);
  } // namespace detail
  
  /// Holds a buffer that can be modified.
  /**
   * The mutable_buffer class provides a safe representation of a buffer that can
   * be modified. It does not own the underlying data, and so is cheap to copy or
   * assign.
   *
   * @par Accessing Buffer Contents
   *
   * The contents of a buffer may be accessed using the @ref buffer_size
   * and @ref buffer_cast functions:
   *
   * @code boost::asio::mutable_buffer b1 = ...;
   * std::size_t s1 = boost::asio::buffer_size(b1);
   * unsigned char* p1 = boost::asio::buffer_cast<unsigned char*>(b1);
   * @endcode
   *
   * The boost::asio::buffer_cast function permits violations of type safety, so
   * uses of it in application code should be carefully considered.
   */
  class mutable_buffer
  {
  public:
    /// Construct an empty buffer.
    mutable_buffer()
      : data_(0),
        size_(0)
    {
    }
  
    /// Construct a buffer to represent a given memory range.
    mutable_buffer(void* data, std::size_t size)
      : data_(data),
        size_(size)
    {
    }
  
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
    mutable_buffer(void* data, std::size_t size,
        boost::function<void()> debug_check)
      : data_(data),
        size_(size),
        debug_check_(debug_check)
    {
    }
  
    const boost::function<void()>& get_debug_check() const
    {
      return debug_check_;
    }
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
  
  private:
    friend void* boost::asio::detail::buffer_cast_helper(
        const mutable_buffer& b);
    friend std::size_t boost::asio::detail::buffer_size_helper(
        const mutable_buffer& b);
  
    void* data_;
    std::size_t size_;
  
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
    boost::function<void()> debug_check_;
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
  };
  
  namespace detail {
  
  inline void* buffer_cast_helper(const mutable_buffer& b)
  {
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
    if (b.size_ && b.debug_check_)
      b.debug_check_();
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
    return b.data_;
  }
  
  inline std::size_t buffer_size_helper(const mutable_buffer& b)
  {
    return b.size_;
  }
  
  } // namespace detail
  
  /// Adapts a single modifiable buffer so that it meets the requirements of the
  /// MutableBufferSequence concept.
  class mutable_buffers_1
    : public mutable_buffer
  {
  public:
    /// The type for each element in the list of buffers.
    typedef mutable_buffer value_type;
  
    /// A random-access iterator type that may be used to read elements.
    typedef const mutable_buffer* const_iterator;
  
    /// Construct to represent a given memory range.
    mutable_buffers_1(void* data, std::size_t size)
      : mutable_buffer(data, size)
    {
    }
  
    /// Construct to represent a single modifiable buffer.
    explicit mutable_buffers_1(const mutable_buffer& b)
      : mutable_buffer(b)
    {
    }
  
    /// Get a random-access iterator to the first element.
    const_iterator begin() const
    {
      return this;
    }
  
    /// Get a random-access iterator for one past the last element.
    const_iterator end() const
    {
      return begin() + 1;
    }
  };
  
  /// Holds a buffer that cannot be modified.
  /**
   * The const_buffer class provides a safe representation of a buffer that cannot
   * be modified. It does not own the underlying data, and so is cheap to copy or
   * assign.
   *
   * @par Accessing Buffer Contents
   *
   * The contents of a buffer may be accessed using the @ref buffer_size
   * and @ref buffer_cast functions:
   *
   * @code boost::asio::const_buffer b1 = ...;
   * std::size_t s1 = boost::asio::buffer_size(b1);
   * const unsigned char* p1 = boost::asio::buffer_cast<const unsigned char*>(b1);
   * @endcode
   *
   * The boost::asio::buffer_cast function permits violations of type safety, so
   * uses of it in application code should be carefully considered.
   */
  class const_buffer
  {
  public:
    /// Construct an empty buffer.
    const_buffer()
      : data_(0),
        size_(0)
    {
    }
  
    /// Construct a buffer to represent a given memory range.
    const_buffer(const void* data, std::size_t size)
      : data_(data),
        size_(size)
    {
    }
  
    /// Construct a non-modifiable buffer from a modifiable one.
    const_buffer(const mutable_buffer& b)
      : data_(boost::asio::detail::buffer_cast_helper(b)),
        size_(boost::asio::detail::buffer_size_helper(b))
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
        , debug_check_(b.get_debug_check())
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
    {
    }
  
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
    const_buffer(const void* data, std::size_t size,
        boost::function<void()> debug_check)
      : data_(data),
        size_(size),
        debug_check_(debug_check)
    {
    }
  
    const boost::function<void()>& get_debug_check() const
    {
      return debug_check_;
    }
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
  
  private:
    friend const void* boost::asio::detail::buffer_cast_helper(
        const const_buffer& b);
    friend std::size_t boost::asio::detail::buffer_size_helper(
        const const_buffer& b);
  
    const void* data_;
    std::size_t size_;
  
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
    boost::function<void()> debug_check_;
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
  };
  
  namespace detail {
  
  inline const void* buffer_cast_helper(const const_buffer& b)
  {
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
    if (b.size_ && b.debug_check_)
      b.debug_check_();
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
    return b.data_;
  }
  
  inline std::size_t buffer_size_helper(const const_buffer& b)
  {
    return b.size_;
  }
  
  } // namespace detail
  
  /// Adapts a single non-modifiable buffer so that it meets the requirements of
  /// the ConstBufferSequence concept.
  class const_buffers_1
    : public const_buffer
  {
  public:
    /// The type for each element in the list of buffers.
    typedef const_buffer value_type;
  
    /// A random-access iterator type that may be used to read elements.
    typedef const const_buffer* const_iterator;
  
    /// Construct to represent a given memory range.
    const_buffers_1(const void* data, std::size_t size)
      : const_buffer(data, size)
    {
    }
  
    /// Construct to represent a single non-modifiable buffer.
    explicit const_buffers_1(const const_buffer& b)
      : const_buffer(b)
    {
    }
  
    /// Get a random-access iterator to the first element.
    const_iterator begin() const
    {
      return this;
    }
  
    /// Get a random-access iterator for one past the last element.
    const_iterator end() const
    {
      return begin() + 1;
    }
  };
  
  /// An implementation of both the ConstBufferSequence and MutableBufferSequence
  /// concepts to represent a null buffer sequence.
  class null_buffers
  {
  public:
    /// The type for each element in the list of buffers.
    typedef mutable_buffer value_type;
  
    /// A random-access iterator type that may be used to read elements.
    typedef const mutable_buffer* const_iterator;
  
    /// Get a random-access iterator to the first element.
    const_iterator begin() const
    {
      return &buf_;
    }
  
    /// Get a random-access iterator for one past the last element.
    const_iterator end() const
    {
      return &buf_;
    }
  
  private:
    mutable_buffer buf_;
  };
  
  /** @defgroup buffer_size boost::asio::buffer_size
   *
   * @brief The boost::asio::buffer_size function determines the total number of
   * bytes in a buffer or buffer sequence.
   */
  /*@{*/
  
  /// Get the number of bytes in a modifiable buffer.
  inline std::size_t buffer_size(const mutable_buffer& b)
  {
    return detail::buffer_size_helper(b);
  }
  
  /// Get the number of bytes in a modifiable buffer.
  inline std::size_t buffer_size(const mutable_buffers_1& b)
  {
    return detail::buffer_size_helper(b);
  }
  
  /// Get the number of bytes in a non-modifiable buffer.
  inline std::size_t buffer_size(const const_buffer& b)
  {
    return detail::buffer_size_helper(b);
  }
  
  /// Get the number of bytes in a non-modifiable buffer.
  inline std::size_t buffer_size(const const_buffers_1& b)
  {
    return detail::buffer_size_helper(b);
  }
  
  /// Get the total number of bytes in a buffer sequence.
  /** 
   * The @c BufferSequence template parameter may meet either of the @c
   * ConstBufferSequence or @c MutableBufferSequence type requirements.
   */
  template <typename BufferSequence>
  inline std::size_t buffer_size(const BufferSequence& b)
  {
    std::size_t total_buffer_size = 0;
  
    typename BufferSequence::const_iterator iter = b.begin();
    typename BufferSequence::const_iterator end = b.end();
    for (; iter != end; ++iter)
      total_buffer_size += detail::buffer_size_helper(*iter);
  
    return total_buffer_size;
  }
  
  /*@}*/
  
  /** @defgroup buffer_cast boost::asio::buffer_cast
   *
   * @brief The boost::asio::buffer_cast function is used to obtain a pointer to
   * the underlying memory region associated with a buffer.
   *
   * @par Examples:
   *
   * To access the memory of a non-modifiable buffer, use:
   * @code boost::asio::const_buffer b1 = ...;
   * const unsigned char* p1 = boost::asio::buffer_cast<const unsigned char*>(b1);
   * @endcode
   *
   * To access the memory of a modifiable buffer, use:
   * @code boost::asio::mutable_buffer b2 = ...;
   * unsigned char* p2 = boost::asio::buffer_cast<unsigned char*>(b2);
   * @endcode
   *
   * The boost::asio::buffer_cast function permits violations of type safety, so
   * uses of it in application code should be carefully considered.
   */
  /*@{*/
  
  /// Cast a non-modifiable buffer to a specified pointer to POD type.
  template <typename PointerToPodType>
  inline PointerToPodType buffer_cast(const mutable_buffer& b)
  {
    return static_cast<PointerToPodType>(detail::buffer_cast_helper(b));
  }
  
  /// Cast a non-modifiable buffer to a specified pointer to POD type.
  template <typename PointerToPodType>
  inline PointerToPodType buffer_cast(const const_buffer& b)
  {
    return static_cast<PointerToPodType>(detail::buffer_cast_helper(b));
  }
  
  /*@}*/
  
  /// Create a new modifiable buffer that is offset from the start of another.
  /**
   * @relates mutable_buffer
   */
  inline mutable_buffer operator+(const mutable_buffer& b, std::size_t start)
  {
    if (start > buffer_size(b))
      return mutable_buffer();
    char* new_data = buffer_cast<char*>(b) + start;
    std::size_t new_size = buffer_size(b) - start;
    return mutable_buffer(new_data, new_size
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
        , b.get_debug_check()
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
        );
  }
  
  /// Create a new modifiable buffer that is offset from the start of another.
  /**
   * @relates mutable_buffer
   */
  inline mutable_buffer operator+(std::size_t start, const mutable_buffer& b)
  {
    if (start > buffer_size(b))
      return mutable_buffer();
    char* new_data = buffer_cast<char*>(b) + start;
    std::size_t new_size = buffer_size(b) - start;
    return mutable_buffer(new_data, new_size
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
        , b.get_debug_check()
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
        );
  }
  
  /// Create a new non-modifiable buffer that is offset from the start of another.
  /**
   * @relates const_buffer
   */
  inline const_buffer operator+(const const_buffer& b, std::size_t start)
  {
    if (start > buffer_size(b))
      return const_buffer();
    const char* new_data = buffer_cast<const char*>(b) + start;
    std::size_t new_size = buffer_size(b) - start;
    return const_buffer(new_data, new_size
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
        , b.get_debug_check()
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
        );
  }
  
  /// Create a new non-modifiable buffer that is offset from the start of another.
  /**
   * @relates const_buffer
   */
  inline const_buffer operator+(std::size_t start, const const_buffer& b)
  {
    if (start > buffer_size(b))
      return const_buffer();
    const char* new_data = buffer_cast<const char*>(b) + start;
    std::size_t new_size = buffer_size(b) - start;
    return const_buffer(new_data, new_size
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
        , b.get_debug_check()
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
        );
  }
  
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
  namespace detail {
  
  template <typename Iterator>
  class buffer_debug_check
  {
  public:
    buffer_debug_check(Iterator iter)
      : iter_(iter)
    {
    }
  
    ~buffer_debug_check()
    {
  #if BOOST_WORKAROUND(BOOST_MSVC, == 1400)
      // MSVC 8's string iterator checking may crash in a std::string::iterator
      // object's destructor when the iterator points to an already-destroyed
      // std::string object, unless the iterator is cleared first.
      iter_ = Iterator();
  #endif // BOOST_WORKAROUND(BOOST_MSVC, == 1400)
    }
  
    void operator()()
    {
      *iter_;
    }
  
  private:
    Iterator iter_;
  };
  
  } // namespace detail
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
  
  /** @defgroup buffer boost::asio::buffer
   *
   * @brief The boost::asio::buffer function is used to create a buffer object to
   * represent raw memory, an array of POD elements, a vector of POD elements,
   * or a std::string.
   *
   * A buffer object represents a contiguous region of memory as a 2-tuple
   * consisting of a pointer and size in bytes. A tuple of the form <tt>{void*,
   * size_t}</tt> specifies a mutable (modifiable) region of memory. Similarly, a
   * tuple of the form <tt>{const void*, size_t}</tt> specifies a const
   * (non-modifiable) region of memory. These two forms correspond to the classes
   * mutable_buffer and const_buffer, respectively. To mirror C++'s conversion
   * rules, a mutable_buffer is implicitly convertible to a const_buffer, and the
   * opposite conversion is not permitted.
   *
   * The simplest use case involves reading or writing a single buffer of a
   * specified size:
   *
   * @code sock.send(boost::asio::buffer(data, size)); @endcode
   *
   * In the above example, the return value of boost::asio::buffer meets the
   * requirements of the ConstBufferSequence concept so that it may be directly
   * passed to the socket's write function. A buffer created for modifiable
   * memory also meets the requirements of the MutableBufferSequence concept.
   *
   * An individual buffer may be created from a builtin array, std::vector,
   * std::array or boost::array of POD elements. This helps prevent buffer
   * overruns by automatically determining the size of the buffer:
   *
   * @code char d1[128];
   * size_t bytes_transferred = sock.receive(boost::asio::buffer(d1));
   *
   * std::vector<char> d2(128);
   * bytes_transferred = sock.receive(boost::asio::buffer(d2));
   *
   * std::array<char, 128> d3;
   * bytes_transferred = sock.receive(boost::asio::buffer(d3));
   *
   * boost::array<char, 128> d4;
   * bytes_transferred = sock.receive(boost::asio::buffer(d4)); @endcode
   *
   * In all three cases above, the buffers created are exactly 128 bytes long.
   * Note that a vector is @e never automatically resized when creating or using
   * a buffer. The buffer size is determined using the vector's <tt>size()</tt>
   * member function, and not its capacity.
   *
   * @par Accessing Buffer Contents
   *
   * The contents of a buffer may be accessed using the @ref buffer_size and
   * @ref buffer_cast functions:
   *
   * @code boost::asio::mutable_buffer b1 = ...;
   * std::size_t s1 = boost::asio::buffer_size(b1);
   * unsigned char* p1 = boost::asio::buffer_cast<unsigned char*>(b1);
   *
   * boost::asio::const_buffer b2 = ...;
   * std::size_t s2 = boost::asio::buffer_size(b2);
   * const void* p2 = boost::asio::buffer_cast<const void*>(b2); @endcode
   *
   * The boost::asio::buffer_cast function permits violations of type safety, so
   * uses of it in application code should be carefully considered.
   *
   * For convenience, the @ref buffer_size function also works on buffer
   * sequences (that is, types meeting the ConstBufferSequence or
   * MutableBufferSequence type requirements). In this case, the function returns
   * the total size of all buffers in the sequence.
   *
   * @par Buffer Copying
   *
   * The @ref buffer_copy function may be used to copy raw bytes between
   * individual buffers and buffer sequences.
   *
   * In particular, when used with the @ref buffer_size, the @ref buffer_copy
   * function can be used to linearise a sequence of buffers. For example:
   *
   * @code vector<const_buffer> buffers = ...;
   *
   * vector<unsigned char> data(boost::asio::buffer_size(buffers));
   * boost::asio::buffer_copy(boost::asio::buffer(data), buffers); @endcode
   *
   * @par Buffer Invalidation
   *
   * A buffer object does not have any ownership of the memory it refers to. It
   * is the responsibility of the application to ensure the memory region remains
   * valid until it is no longer required for an I/O operation. When the memory
   * is no longer available, the buffer is said to have been invalidated.
   *
   * For the boost::asio::buffer overloads that accept an argument of type
   * std::vector, the buffer objects returned are invalidated by any vector
   * operation that also invalidates all references, pointers and iterators
   * referring to the elements in the sequence (C++ Std, 23.2.4)
   *
   * For the boost::asio::buffer overloads that accept an argument of type
   * std::basic_string, the buffer objects returned are invalidated according to
   * the rules defined for invalidation of references, pointers and iterators
   * referring to elements of the sequence (C++ Std, 21.3).
   *
   * @par Buffer Arithmetic
   *
   * Buffer objects may be manipulated using simple arithmetic in a safe way
   * which helps prevent buffer overruns. Consider an array initialised as
   * follows:
   *
   * @code boost::array<char, 6> a = { 'a', 'b', 'c', 'd', 'e' }; @endcode
   *
   * A buffer object @c b1 created using:
   *
   * @code b1 = boost::asio::buffer(a); @endcode
   *
   * represents the entire array, <tt>{ 'a', 'b', 'c', 'd', 'e' }</tt>. An
   * optional second argument to the boost::asio::buffer function may be used to
   * limit the size, in bytes, of the buffer:
   *
   * @code b2 = boost::asio::buffer(a, 3); @endcode
   *
   * such that @c b2 represents the data <tt>{ 'a', 'b', 'c' }</tt>. Even if the
   * size argument exceeds the actual size of the array, the size of the buffer
   * object created will be limited to the array size.
   *
   * An offset may be applied to an existing buffer to create a new one:
   *
   * @code b3 = b1 + 2; @endcode
   *
   * where @c b3 will set to represent <tt>{ 'c', 'd', 'e' }</tt>. If the offset
   * exceeds the size of the existing buffer, the newly created buffer will be
   * empty.
   *
   * Both an offset and size may be specified to create a buffer that corresponds
   * to a specific range of bytes within an existing buffer:
   *
   * @code b4 = boost::asio::buffer(b1 + 1, 3); @endcode
   *
   * so that @c b4 will refer to the bytes <tt>{ 'b', 'c', 'd' }</tt>.
   *
   * @par Buffers and Scatter-Gather I/O
   *
   * To read or write using multiple buffers (i.e. scatter-gather I/O), multiple
   * buffer objects may be assigned into a container that supports the
   * MutableBufferSequence (for read) or ConstBufferSequence (for write) concepts:
   *
   * @code
   * char d1[128];
   * std::vector<char> d2(128);
   * boost::array<char, 128> d3;
   *
   * boost::array<mutable_buffer, 3> bufs1 = {
   *   boost::asio::buffer(d1),
   *   boost::asio::buffer(d2),
   *   boost::asio::buffer(d3) };
   * bytes_transferred = sock.receive(bufs1);
   *
   * std::vector<const_buffer> bufs2;
   * bufs2.push_back(boost::asio::buffer(d1));
   * bufs2.push_back(boost::asio::buffer(d2));
   * bufs2.push_back(boost::asio::buffer(d3));
   * bytes_transferred = sock.send(bufs2); @endcode
   */
  /*@{*/
  
  /// Create a new modifiable buffer from an existing buffer.
  /**
   * @returns <tt>mutable_buffers_1(b)</tt>.
   */
  inline mutable_buffers_1 buffer(const mutable_buffer& b)
  {
    return mutable_buffers_1(b);
  }
  
  /// Create a new modifiable buffer from an existing buffer.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     buffer_cast<void*>(b),
   *     min(buffer_size(b), max_size_in_bytes)); @endcode
   */
  inline mutable_buffers_1 buffer(const mutable_buffer& b,
      std::size_t max_size_in_bytes)
  {
    return mutable_buffers_1(
        mutable_buffer(buffer_cast<void*>(b),
          buffer_size(b) < max_size_in_bytes
          ? buffer_size(b) : max_size_in_bytes
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
          , b.get_debug_check()
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
          ));
  }
  
  /// Create a new non-modifiable buffer from an existing buffer.
  /**
   * @returns <tt>const_buffers_1(b)</tt>.
   */
  inline const_buffers_1 buffer(const const_buffer& b)
  {
    return const_buffers_1(b);
  }
  
  /// Create a new non-modifiable buffer from an existing buffer.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     buffer_cast<const void*>(b),
   *     min(buffer_size(b), max_size_in_bytes)); @endcode
   */
  inline const_buffers_1 buffer(const const_buffer& b,
      std::size_t max_size_in_bytes)
  {
    return const_buffers_1(
        const_buffer(buffer_cast<const void*>(b),
          buffer_size(b) < max_size_in_bytes
          ? buffer_size(b) : max_size_in_bytes
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
          , b.get_debug_check()
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
          ));
  }
  
  /// Create a new modifiable buffer that represents the given memory range.
  /**
   * @returns <tt>mutable_buffers_1(data, size_in_bytes)</tt>.
   */
  inline mutable_buffers_1 buffer(void* data, std::size_t size_in_bytes)
  {
    return mutable_buffers_1(mutable_buffer(data, size_in_bytes));
  }
  
  /// Create a new non-modifiable buffer that represents the given memory range.
  /**
   * @returns <tt>const_buffers_1(data, size_in_bytes)</tt>.
   */
  inline const_buffers_1 buffer(const void* data,
      std::size_t size_in_bytes)
  {
    return const_buffers_1(const_buffer(data, size_in_bytes));
  }
  
  /// Create a new modifiable buffer that represents the given POD array.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     static_cast<void*>(data),
   *     N * sizeof(PodType)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline mutable_buffers_1 buffer(PodType (&data)[N])
  {
    return mutable_buffers_1(mutable_buffer(data, N * sizeof(PodType)));
  }
   
  /// Create a new modifiable buffer that represents the given POD array.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     static_cast<void*>(data),
   *     min(N * sizeof(PodType), max_size_in_bytes)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline mutable_buffers_1 buffer(PodType (&data)[N],
      std::size_t max_size_in_bytes)
  {
    return mutable_buffers_1(
        mutable_buffer(data,
          N * sizeof(PodType) < max_size_in_bytes
          ? N * sizeof(PodType) : max_size_in_bytes));
  }
   
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     static_cast<const void*>(data),
   *     N * sizeof(PodType)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(const PodType (&data)[N])
  {
    return const_buffers_1(const_buffer(data, N * sizeof(PodType)));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     static_cast<const void*>(data),
   *     min(N * sizeof(PodType), max_size_in_bytes)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(const PodType (&data)[N],
      std::size_t max_size_in_bytes)
  {
    return const_buffers_1(
        const_buffer(data,
          N * sizeof(PodType) < max_size_in_bytes
          ? N * sizeof(PodType) : max_size_in_bytes));
  }
  
  #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582)) \
    || BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x590))
  
  // Borland C++ and Sun Studio think the overloads:
  //
  //   unspecified buffer(boost::array<PodType, N>& array ...);
  //
  // and
  //
  //   unspecified buffer(boost::array<const PodType, N>& array ...);
  //
  // are ambiguous. This will be worked around by using a buffer_types traits
  // class that contains typedefs for the appropriate buffer and container
  // classes, based on whether PodType is const or non-const.
  
  namespace detail {
  
  template <bool IsConst>
  struct buffer_types_base;
  
  template <>
  struct buffer_types_base<false>
  {
    typedef mutable_buffer buffer_type;
    typedef mutable_buffers_1 container_type;
  };
  
  template <>
  struct buffer_types_base<true>
  {
    typedef const_buffer buffer_type;
    typedef const_buffers_1 container_type;
  };
  
  template <typename PodType>
  struct buffer_types
    : public buffer_types_base<boost::is_const<PodType>::value>
  {
  };
  
  } // namespace detail
  
  template <typename PodType, std::size_t N>
  inline typename detail::buffer_types<PodType>::container_type
  buffer(boost::array<PodType, N>& data)
  {
    typedef typename boost::asio::detail::buffer_types<PodType>::buffer_type
      buffer_type;
    typedef typename boost::asio::detail::buffer_types<PodType>::container_type
      container_type;
    return container_type(
        buffer_type(data.c_array(), data.size() * sizeof(PodType)));
  }
  
  template <typename PodType, std::size_t N>
  inline typename detail::buffer_types<PodType>::container_type
  buffer(boost::array<PodType, N>& data, std::size_t max_size_in_bytes)
  {
    typedef typename boost::asio::detail::buffer_types<PodType>::buffer_type
      buffer_type;
    typedef typename boost::asio::detail::buffer_types<PodType>::container_type
      container_type;
    return container_type(
        buffer_type(data.c_array(),
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes));
  }
  
  #else // BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582))
        // || BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x590))
  
  /// Create a new modifiable buffer that represents the given POD array.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     data.data(),
   *     data.size() * sizeof(PodType)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline mutable_buffers_1 buffer(boost::array<PodType, N>& data)
  {
    return mutable_buffers_1(
        mutable_buffer(data.c_array(), data.size() * sizeof(PodType)));
  }
  
  /// Create a new modifiable buffer that represents the given POD array.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     data.data(),
   *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline mutable_buffers_1 buffer(boost::array<PodType, N>& data,
      std::size_t max_size_in_bytes)
  {
    return mutable_buffers_1(
        mutable_buffer(data.c_array(),
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     data.size() * sizeof(PodType)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(boost::array<const PodType, N>& data)
  {
    return const_buffers_1(
        const_buffer(data.data(), data.size() * sizeof(PodType)));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(boost::array<const PodType, N>& data,
      std::size_t max_size_in_bytes)
  {
    return const_buffers_1(
        const_buffer(data.data(),
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes));
  }
  
  #endif // BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x582))
         // || BOOST_WORKAROUND(__SUNPRO_CC, BOOST_TESTED_AT(0x590))
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     data.size() * sizeof(PodType)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(const boost::array<PodType, N>& data)
  {
    return const_buffers_1(
        const_buffer(data.data(), data.size() * sizeof(PodType)));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(const boost::array<PodType, N>& data,
      std::size_t max_size_in_bytes)
  {
    return const_buffers_1(
        const_buffer(data.data(),
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes));
  }
  
  #if defined(BOOST_ASIO_HAS_STD_ARRAY) || defined(GENERATING_DOCUMENTATION)
  
  /// Create a new modifiable buffer that represents the given POD array.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     data.data(),
   *     data.size() * sizeof(PodType)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline mutable_buffers_1 buffer(std::array<PodType, N>& data)
  {
    return mutable_buffers_1(
        mutable_buffer(data.data(), data.size() * sizeof(PodType)));
  }
  
  /// Create a new modifiable buffer that represents the given POD array.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     data.data(),
   *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline mutable_buffers_1 buffer(std::array<PodType, N>& data,
      std::size_t max_size_in_bytes)
  {
    return mutable_buffers_1(
        mutable_buffer(data.data(),
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     data.size() * sizeof(PodType)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(std::array<const PodType, N>& data)
  {
    return const_buffers_1(
        const_buffer(data.data(), data.size() * sizeof(PodType)));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(std::array<const PodType, N>& data,
      std::size_t max_size_in_bytes)
  {
    return const_buffers_1(
        const_buffer(data.data(),
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     data.size() * sizeof(PodType)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(const std::array<PodType, N>& data)
  {
    return const_buffers_1(
        const_buffer(data.data(), data.size() * sizeof(PodType)));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD array.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
   */
  template <typename PodType, std::size_t N>
  inline const_buffers_1 buffer(const std::array<PodType, N>& data,
      std::size_t max_size_in_bytes)
  {
    return const_buffers_1(
        const_buffer(data.data(),
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes));
  }
  
  #endif // defined(BOOST_ASIO_HAS_STD_ARRAY) || defined(GENERATING_DOCUMENTATION)
  
  /// Create a new modifiable buffer that represents the given POD vector.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     data.size() ? &data[0] : 0,
   *     data.size() * sizeof(PodType)); @endcode
   *
   * @note The buffer is invalidated by any vector operation that would also
   * invalidate iterators.
   */
  template <typename PodType, typename Allocator>
  inline mutable_buffers_1 buffer(std::vector<PodType, Allocator>& data)
  {
    return mutable_buffers_1(
        mutable_buffer(data.size() ? &data[0] : 0, data.size() * sizeof(PodType)
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
          , detail::buffer_debug_check<
              typename std::vector<PodType, Allocator>::iterator
            >(data.begin())
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
          ));
  }
  
  /// Create a new modifiable buffer that represents the given POD vector.
  /**
   * @returns A mutable_buffers_1 value equivalent to:
   * @code mutable_buffers_1(
   *     data.size() ? &data[0] : 0,
   *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
   *
   * @note The buffer is invalidated by any vector operation that would also
   * invalidate iterators.
   */
  template <typename PodType, typename Allocator>
  inline mutable_buffers_1 buffer(std::vector<PodType, Allocator>& data,
      std::size_t max_size_in_bytes)
  {
    return mutable_buffers_1(
        mutable_buffer(data.size() ? &data[0] : 0,
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
          , detail::buffer_debug_check<
              typename std::vector<PodType, Allocator>::iterator
            >(data.begin())
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
          ));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD vector.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.size() ? &data[0] : 0,
   *     data.size() * sizeof(PodType)); @endcode
   *
   * @note The buffer is invalidated by any vector operation that would also
   * invalidate iterators.
   */
  template <typename PodType, typename Allocator>
  inline const_buffers_1 buffer(
      const std::vector<PodType, Allocator>& data)
  {
    return const_buffers_1(
        const_buffer(data.size() ? &data[0] : 0, data.size() * sizeof(PodType)
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
          , detail::buffer_debug_check<
              typename std::vector<PodType, Allocator>::const_iterator
            >(data.begin())
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
          ));
  }
  
  /// Create a new non-modifiable buffer that represents the given POD vector.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.size() ? &data[0] : 0,
   *     min(data.size() * sizeof(PodType), max_size_in_bytes)); @endcode
   *
   * @note The buffer is invalidated by any vector operation that would also
   * invalidate iterators.
   */
  template <typename PodType, typename Allocator>
  inline const_buffers_1 buffer(
      const std::vector<PodType, Allocator>& data, std::size_t max_size_in_bytes)
  {
    return const_buffers_1(
        const_buffer(data.size() ? &data[0] : 0,
          data.size() * sizeof(PodType) < max_size_in_bytes
          ? data.size() * sizeof(PodType) : max_size_in_bytes
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
          , detail::buffer_debug_check<
              typename std::vector<PodType, Allocator>::const_iterator
            >(data.begin())
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
          ));
  }
  
  /// Create a new non-modifiable buffer that represents the given string.
  /**
   * @returns <tt>const_buffers_1(data.data(), data.size() * sizeof(Elem))</tt>.
   *
   * @note The buffer is invalidated by any non-const operation called on the
   * given string object.
   */
  template <typename Elem, typename Traits, typename Allocator>
  inline const_buffers_1 buffer(
      const std::basic_string<Elem, Traits, Allocator>& data)
  {
    return const_buffers_1(const_buffer(data.data(), data.size() * sizeof(Elem)
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
          , detail::buffer_debug_check<
              typename std::basic_string<Elem, Traits, Allocator>::const_iterator
            >(data.begin())
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
          ));
  }
  
  /// Create a new non-modifiable buffer that represents the given string.
  /**
   * @returns A const_buffers_1 value equivalent to:
   * @code const_buffers_1(
   *     data.data(),
   *     min(data.size() * sizeof(Elem), max_size_in_bytes)); @endcode
   *
   * @note The buffer is invalidated by any non-const operation called on the
   * given string object.
   */
  template <typename Elem, typename Traits, typename Allocator>
  inline const_buffers_1 buffer(
      const std::basic_string<Elem, Traits, Allocator>& data,
      std::size_t max_size_in_bytes)
  {
    return const_buffers_1(
        const_buffer(data.data(),
          data.size() * sizeof(Elem) < max_size_in_bytes
          ? data.size() * sizeof(Elem) : max_size_in_bytes
  #if defined(BOOST_ASIO_ENABLE_BUFFER_DEBUGGING)
          , detail::buffer_debug_check<
              typename std::basic_string<Elem, Traits, Allocator>::const_iterator
            >(data.begin())
  #endif // BOOST_ASIO_ENABLE_BUFFER_DEBUGGING
          ));
  }
  
  /*@}*/
  
  /** @defgroup buffer_copy boost::asio::buffer_copy
   *
   * @brief The boost::asio::buffer_copy function is used to copy bytes from a
   * source buffer (or buffer sequence) to a target buffer (or buffer sequence).
   *
   * The @c buffer_copy function is available in two forms:
   *
   * @li A 2-argument form: @c buffer_copy(target, source)
   *
   * @li A 3-argument form: @c buffer_copy(target, source, max_bytes_to_copy)
  
   * Both forms return the number of bytes actually copied. The number of bytes
   * copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c If specified, @c max_bytes_to_copy.
   *
   * This prevents buffer overflow, regardless of the buffer sizes used in the
   * copy operation.
   */
  /*@{*/
  
  /// Copies bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const const_buffer& source)
  {
    using namespace std; // For memcpy.
    std::size_t target_size = buffer_size(target);
    std::size_t source_size = buffer_size(source);
    std::size_t n = target_size < source_size ? target_size : source_size;
    memcpy(buffer_cast<void*>(target), buffer_cast<const void*>(source), n);
    return n;
  }
  
  /// Copies bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const const_buffers_1& source)
  {
    return buffer_copy(target, static_cast<const const_buffer&>(source));
  }
  
  /// Copies bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const mutable_buffer& source)
  {
    return buffer_copy(target, const_buffer(source));
  }
  
  /// Copies bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const mutable_buffers_1& source)
  {
    return buffer_copy(target, const_buffer(source));
  }
  
  /// Copies bytes from a source buffer sequence to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer sequence representing the memory
   * regions from which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  template <typename ConstBufferSequence>
  std::size_t buffer_copy(const mutable_buffer& target,
      const ConstBufferSequence& source)
  {
    std::size_t total_bytes_copied = 0;
  
    typename ConstBufferSequence::const_iterator source_iter = source.begin();
    typename ConstBufferSequence::const_iterator source_end = source.end();
  
    for (mutable_buffer target_buffer(target);
        buffer_size(target_buffer) && source_iter != source_end; ++source_iter)
    {
      const_buffer source_buffer(*source_iter);
      std::size_t bytes_copied = buffer_copy(target_buffer, source_buffer);
      total_bytes_copied += bytes_copied;
      target_buffer = target_buffer + bytes_copied;
    }
  
    return total_bytes_copied;
  }
  
  /// Copies bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const const_buffer& source)
  {
    return buffer_copy(static_cast<const mutable_buffer&>(target), source);
  }
  
  /// Copies bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const const_buffers_1& source)
  {
    return buffer_copy(static_cast<const mutable_buffer&>(target),
        static_cast<const const_buffer&>(source));
  }
  
  /// Copies bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const mutable_buffer& source)
  {
    return buffer_copy(static_cast<const mutable_buffer&>(target),
        const_buffer(source));
  }
  
  /// Copies bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const mutable_buffers_1& source)
  {
    return buffer_copy(static_cast<const mutable_buffer&>(target),
        const_buffer(source));
  }
  
  /// Copies bytes from a source buffer sequence to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer sequence representing the memory
   * regions from which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  template <typename ConstBufferSequence>
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const ConstBufferSequence& source)
  {
    return buffer_copy(static_cast<const mutable_buffer&>(target), source);
  }
  
  /// Copies bytes from a source buffer to a target buffer sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  template <typename MutableBufferSequence>
  std::size_t buffer_copy(const MutableBufferSequence& target,
      const const_buffer& source)
  {
    std::size_t total_bytes_copied = 0;
  
    typename MutableBufferSequence::const_iterator target_iter = target.begin();
    typename MutableBufferSequence::const_iterator target_end = target.end();
  
    for (const_buffer source_buffer(source);
        buffer_size(source_buffer) && target_iter != target_end; ++target_iter)
    {
      mutable_buffer target_buffer(*target_iter);
      std::size_t bytes_copied = buffer_copy(target_buffer, source_buffer);
      total_bytes_copied += bytes_copied;
      source_buffer = source_buffer + bytes_copied;
    }
  
    return total_bytes_copied;
  }
  
  /// Copies bytes from a source buffer to a target buffer sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  template <typename MutableBufferSequence>
  inline std::size_t buffer_copy(const MutableBufferSequence& target,
      const const_buffers_1& source)
  {
    return buffer_copy(target, static_cast<const const_buffer&>(source));
  }
  
  /// Copies bytes from a source buffer to a target buffer sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  template <typename MutableBufferSequence>
  inline std::size_t buffer_copy(const MutableBufferSequence& target,
      const mutable_buffer& source)
  {
    return buffer_copy(target, const_buffer(source));
  }
  
  /// Copies bytes from a source buffer to a target buffer sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  template <typename MutableBufferSequence>
  inline std::size_t buffer_copy(const MutableBufferSequence& target,
      const mutable_buffers_1& source)
  {
    return buffer_copy(target, const_buffer(source));
  }
  
  /// Copies bytes from a source buffer sequence to a target buffer sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A non-modifiable buffer sequence representing the memory
   * regions from which the bytes will be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   */
  template <typename MutableBufferSequence, typename ConstBufferSequence>
  std::size_t buffer_copy(const MutableBufferSequence& target,
      const ConstBufferSequence& source)
  {
    std::size_t total_bytes_copied = 0;
  
    typename MutableBufferSequence::const_iterator target_iter = target.begin();
    typename MutableBufferSequence::const_iterator target_end = target.end();
    std::size_t target_buffer_offset = 0;
  
    typename ConstBufferSequence::const_iterator source_iter = source.begin();
    typename ConstBufferSequence::const_iterator source_end = source.end();
    std::size_t source_buffer_offset = 0;
  
    while (target_iter != target_end && source_iter != source_end)
    {
      mutable_buffer target_buffer =
        mutable_buffer(*target_iter) + target_buffer_offset;
  
      const_buffer source_buffer =
        const_buffer(*source_iter) + source_buffer_offset;
  
      std::size_t bytes_copied = buffer_copy(target_buffer, source_buffer);
      total_bytes_copied += bytes_copied;
  
      if (bytes_copied == buffer_size(target_buffer))
      {
        ++target_iter;
        target_buffer_offset = 0;
      }
      else
        target_buffer_offset += bytes_copied;
  
      if (bytes_copied == buffer_size(source_buffer))
      {
        ++source_iter;
        source_buffer_offset = 0;
      }
      else
        source_buffer_offset += bytes_copied;
    }
  
    return total_bytes_copied;
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const const_buffer& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const const_buffers_1& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const mutable_buffer& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const mutable_buffers_1& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer sequence to a target
  /// buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer sequence representing the memory
   * regions from which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  template <typename ConstBufferSequence>
  inline std::size_t buffer_copy(const mutable_buffer& target,
      const ConstBufferSequence& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const const_buffer& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const const_buffers_1& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const mutable_buffer& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const mutable_buffers_1& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer sequence to a target
  /// buffer.
  /**
   * @param target A modifiable buffer representing the memory region to which
   * the bytes will be copied.
   *
   * @param source A non-modifiable buffer sequence representing the memory
   * regions from which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  template <typename ConstBufferSequence>
  inline std::size_t buffer_copy(const mutable_buffers_1& target,
      const ConstBufferSequence& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(buffer(target, max_bytes_to_copy), source);
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer
  /// sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  template <typename MutableBufferSequence>
  inline std::size_t buffer_copy(const MutableBufferSequence& target,
      const const_buffer& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(target, buffer(source, max_bytes_to_copy));
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer
  /// sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A non-modifiable buffer representing the memory region from
   * which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  template <typename MutableBufferSequence>
  inline std::size_t buffer_copy(const MutableBufferSequence& target,
      const const_buffers_1& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(target, buffer(source, max_bytes_to_copy));
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer
  /// sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  template <typename MutableBufferSequence>
  inline std::size_t buffer_copy(const MutableBufferSequence& target,
      const mutable_buffer& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(target, buffer(source, max_bytes_to_copy));
  }
  
  /// Copies a limited number of bytes from a source buffer to a target buffer
  /// sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A modifiable buffer representing the memory region from which
   * the bytes will be copied. The contents of the source buffer will not be
   * modified.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  template <typename MutableBufferSequence>
  inline std::size_t buffer_copy(const MutableBufferSequence& target,
      const mutable_buffers_1& source, std::size_t max_bytes_to_copy)
  {
    return buffer_copy(target, buffer(source, max_bytes_to_copy));
  }
  
  /// Copies a limited number of bytes from a source buffer sequence to a target
  /// buffer sequence.
  /**
   * @param target A modifiable buffer sequence representing the memory regions to
   * which the bytes will be copied.
   *
   * @param source A non-modifiable buffer sequence representing the memory
   * regions from which the bytes will be copied.
   *
   * @param max_bytes_to_copy The maximum number of bytes to be copied.
   *
   * @returns The number of bytes copied.
   *
   * @note The number of bytes copied is the lesser of:
   *
   * @li @c buffer_size(target)
   *
   * @li @c buffer_size(source)
   *
   * @li @c max_bytes_to_copy
   */
  template <typename MutableBufferSequence, typename ConstBufferSequence>
  std::size_t buffer_copy(const MutableBufferSequence& target,
      const ConstBufferSequence& source, std::size_t max_bytes_to_copy)
  {
    std::size_t total_bytes_copied = 0;
  
    typename MutableBufferSequence::const_iterator target_iter = target.begin();
    typename MutableBufferSequence::const_iterator target_end = target.end();
    std::size_t target_buffer_offset = 0;
  
    typename ConstBufferSequence::const_iterator source_iter = source.begin();
    typename ConstBufferSequence::const_iterator source_end = source.end();
    std::size_t source_buffer_offset = 0;
  
    while (total_bytes_copied != max_bytes_to_copy
        && target_iter != target_end && source_iter != source_end)
    {
      mutable_buffer target_buffer =
        mutable_buffer(*target_iter) + target_buffer_offset;
  
      const_buffer source_buffer =
        const_buffer(*source_iter) + source_buffer_offset;
  
      std::size_t bytes_copied = buffer_copy(target_buffer,
          source_buffer, max_bytes_to_copy - total_bytes_copied);
      total_bytes_copied += bytes_copied;
  
      if (bytes_copied == buffer_size(target_buffer))
      {
        ++target_iter;
        target_buffer_offset = 0;
      }
      else
        target_buffer_offset += bytes_copied;
  
      if (bytes_copied == buffer_size(source_buffer))
      {
        ++source_iter;
        source_buffer_offset = 0;
      }
      else
        source_buffer_offset += bytes_copied;
    }
  
    return total_bytes_copied;
  }
  
  /*@}*/
  
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #endif // BOOST_ASIO_BUFFER_HPP
  