Class basic_streambuf

3rd/asio-1.24.0/include/asio/basic_streambuf.hpp:110–360

template <typename Allocator>
#endif
class basic_streambuf
  : public std::streambuf,
    private noncopyable
{
public:
#if defined(GENERATING_DOCUMENTATION)
  /// The type used to represent the input sequence as a list of buffers.
  typedef implementation_defined const_buffers_type;

  /// The type used to represent the output sequence as a list of buffers.
  typedef implementation_defined mutable_buffers_type;
#else
  typedef ASIO_CONST_BUFFER const_buffers_type;
  typedef ASIO_MUTABLE_BUFFER mutable_buffers_type;
#endif

  /// Construct a basic_streambuf object.
  /**
   * Constructs a streambuf with the specified maximum size. The initial size
   * of the streambuf's input sequence is 0.
   */
  explicit basic_streambuf(
      std::size_t maximum_size = (std::numeric_limits<std::size_t>::max)(),
      const Allocator& allocator = Allocator())
    : max_size_(maximum_size),
      buffer_(allocator)
  {
    std::size_t pend = (std::min<std::size_t>)(max_size_, buffer_delta);
    buffer_.resize((std::max<std::size_t>)(pend, 1));
    setg(&buffer_[0], &buffer_[0], &buffer_[0]);
    setp(&buffer_[0], &buffer_[0] + pend);
  }

  /// Get the size of the input sequence.
  /**
   * @returns The size of the input sequence. The value is equal to that
   * calculated for @c s in the following code:
   * @code
   * size_t s = 0;
   * const_buffers_type bufs = data();
   * const_buffers_type::const_iterator i = bufs.begin();
   * while (i != bufs.end())
   * {
   *   const_buffer buf(*i++);
   *   s += buf.size();
   * }
   * @endcode
   */
  std::size_t size() const ASIO_NOEXCEPT
  {
    return pptr() - gptr();
  }

  /// Get the maximum size of the basic_streambuf.
  /**
   * @returns The allowed maximum of the sum of the sizes of the input sequence
   * and output sequence.
   */