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include/asio/buffered_stream.hpp

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+//
+// buffered_stream.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ASIO_BUFFERED_STREAM_HPP
+#define ASIO_BUFFERED_STREAM_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include "asio/detail/config.hpp"
+#include <cstddef>
+#include "asio/async_result.hpp"
+#include "asio/buffered_read_stream.hpp"
+#include "asio/buffered_write_stream.hpp"
+#include "asio/buffered_stream_fwd.hpp"
+#include "asio/detail/noncopyable.hpp"
+#include "asio/error.hpp"
+
+#include "asio/detail/push_options.hpp"
+
+namespace asio {
+
+/// Adds buffering to the read- and write-related operations of a stream.
+/**
+ * The buffered_stream class template can be used to add buffering to the
+ * synchronous and asynchronous read and write operations of a stream.
+ *
+ * @par Thread Safety
+ * @e Distinct @e objects: Safe.@n
+ * @e Shared @e objects: Unsafe.
+ *
+ * @par Concepts:
+ * AsyncReadStream, AsyncWriteStream, Stream, SyncReadStream, SyncWriteStream.
+ */
+template <typename Stream>
+class buffered_stream
+  : private noncopyable
+{
+public:
+  /// The type of the next layer.
+  typedef remove_reference_t<Stream> next_layer_type;
+
+  /// The type of the lowest layer.
+  typedef typename next_layer_type::lowest_layer_type lowest_layer_type;
+
+  /// The type of the executor associated with the object.
+  typedef typename lowest_layer_type::executor_type executor_type;
+
+  /// Construct, passing the specified argument to initialise the next layer.
+  template <typename Arg>
+  explicit buffered_stream(Arg&& a)
+    : inner_stream_impl_(static_cast<Arg&&>(a)),
+      stream_impl_(inner_stream_impl_)
+  {
+  }
+
+  /// Construct, passing the specified argument to initialise the next layer.
+  template <typename Arg>
+  explicit buffered_stream(Arg&& a,
+      std::size_t read_buffer_size, std::size_t write_buffer_size)
+    : inner_stream_impl_(static_cast<Arg&&>(a), write_buffer_size),
+      stream_impl_(inner_stream_impl_, read_buffer_size)
+  {
+  }
+
+  /// Get a reference to the next layer.
+  next_layer_type& next_layer()
+  {
+    return stream_impl_.next_layer().next_layer();
+  }
+
+  /// Get a reference to the lowest layer.
+  lowest_layer_type& lowest_layer()
+  {
+    return stream_impl_.lowest_layer();
+  }
+
+  /// Get a const reference to the lowest layer.
+  const lowest_layer_type& lowest_layer() const
+  {
+    return stream_impl_.lowest_layer();
+  }
+
+  /// Get the executor associated with the object.
+  executor_type get_executor() noexcept
+  {
+    return stream_impl_.lowest_layer().get_executor();
+  }
+
+  /// Close the stream.
+  void close()
+  {
+    stream_impl_.close();
+  }
+
+  /// Close the stream.
+  ASIO_SYNC_OP_VOID close(asio::error_code& ec)
+  {
+    stream_impl_.close(ec);
+    ASIO_SYNC_OP_VOID_RETURN(ec);
+  }
+
+  /// Flush all data from the buffer to the next layer. Returns the number of
+  /// bytes written to the next layer on the last write operation. Throws an
+  /// exception on failure.
+  std::size_t flush()
+  {
+    return stream_impl_.next_layer().flush();
+  }
+
+  /// Flush all data from the buffer to the next layer. Returns the number of
+  /// bytes written to the next layer on the last write operation, or 0 if an
+  /// error occurred.
+  std::size_t flush(asio::error_code& ec)
+  {
+    return stream_impl_.next_layer().flush(ec);
+  }
+
+  /// Start an asynchronous flush.
+  /**
+   * @par Completion Signature
+   * @code void(asio::error_code, std::size_t) @endcode
+   */
+  template <
+      ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code,
+        std::size_t)) WriteHandler = default_completion_token_t<executor_type>>
+  auto async_flush(
+      WriteHandler&& handler = default_completion_token_t<executor_type>())
+    -> decltype(
+      declval<buffered_write_stream<Stream>&>().async_flush(
+        static_cast<WriteHandler&&>(handler)))
+  {
+    return stream_impl_.next_layer().async_flush(
+        static_cast<WriteHandler&&>(handler));
+  }
+
+  /// Write the given data to the stream. Returns the number of bytes written.
+  /// Throws an exception on failure.
+  template <typename ConstBufferSequence>
+  std::size_t write_some(const ConstBufferSequence& buffers)
+  {
+    return stream_impl_.write_some(buffers);
+  }
+
+  /// Write the given data to the stream. Returns the number of bytes written,
+  /// or 0 if an error occurred.
+  template <typename ConstBufferSequence>
+  std::size_t write_some(const ConstBufferSequence& buffers,
+      asio::error_code& ec)
+  {
+    return stream_impl_.write_some(buffers, ec);
+  }
+
+  /// Start an asynchronous write. The data being written must be valid for the
+  /// lifetime of the asynchronous operation.
+  /**
+   * @par Completion Signature
+   * @code void(asio::error_code, std::size_t) @endcode
+   */
+  template <typename ConstBufferSequence,
+      ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code,
+        std::size_t)) WriteHandler = default_completion_token_t<executor_type>>
+  auto async_write_some(const ConstBufferSequence& buffers,
+      WriteHandler&& handler = default_completion_token_t<executor_type>())
+    -> decltype(
+      declval<Stream&>().async_write_some(buffers,
+        static_cast<WriteHandler&&>(handler)))
+  {
+    return stream_impl_.async_write_some(buffers,
+        static_cast<WriteHandler&&>(handler));
+  }
+
+  /// Fill the buffer with some data. Returns the number of bytes placed in the
+  /// buffer as a result of the operation. Throws an exception on failure.
+  std::size_t fill()
+  {
+    return stream_impl_.fill();
+  }
+
+  /// Fill the buffer with some data. Returns the number of bytes placed in the
+  /// buffer as a result of the operation, or 0 if an error occurred.
+  std::size_t fill(asio::error_code& ec)
+  {
+    return stream_impl_.fill(ec);
+  }
+
+  /// Start an asynchronous fill.
+  /**
+   * @par Completion Signature
+   * @code void(asio::error_code, std::size_t) @endcode
+   */
+  template <
+      ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code,
+        std::size_t)) ReadHandler = default_completion_token_t<executor_type>>
+  auto async_fill(
+      ReadHandler&& handler = default_completion_token_t<executor_type>())
+    -> decltype(
+      declval<buffered_read_stream<
+        buffered_write_stream<Stream>>&>().async_fill(
+          static_cast<ReadHandler&&>(handler)))
+  {
+    return stream_impl_.async_fill(static_cast<ReadHandler&&>(handler));
+  }
+
+  /// Read some data from the stream. Returns the number of bytes read. Throws
+  /// an exception on failure.
+  template <typename MutableBufferSequence>
+  std::size_t read_some(const MutableBufferSequence& buffers)
+  {
+    return stream_impl_.read_some(buffers);
+  }
+
+  /// Read some data from the stream. Returns the number of bytes read or 0 if
+  /// an error occurred.
+  template <typename MutableBufferSequence>
+  std::size_t read_some(const MutableBufferSequence& buffers,
+      asio::error_code& ec)
+  {
+    return stream_impl_.read_some(buffers, ec);
+  }
+
+  /// Start an asynchronous read. The buffer into which the data will be read
+  /// must be valid for the lifetime of the asynchronous operation.
+  /**
+   * @par Completion Signature
+   * @code void(asio::error_code, std::size_t) @endcode
+   */
+  template <typename MutableBufferSequence,
+      ASIO_COMPLETION_TOKEN_FOR(void (asio::error_code,
+        std::size_t)) ReadHandler = default_completion_token_t<executor_type>>
+  auto async_read_some(const MutableBufferSequence& buffers,
+      ReadHandler&& handler = default_completion_token_t<executor_type>())
+    -> decltype(
+      declval<Stream&>().async_read_some(buffers,
+        static_cast<ReadHandler&&>(handler)))
+  {
+    return stream_impl_.async_read_some(buffers,
+        static_cast<ReadHandler&&>(handler));
+  }
+
+  /// Peek at the incoming data on the stream. Returns the number of bytes read.
+  /// Throws an exception on failure.
+  template <typename MutableBufferSequence>
+  std::size_t peek(const MutableBufferSequence& buffers)
+  {
+    return stream_impl_.peek(buffers);
+  }
+
+  /// Peek at the incoming data on the stream. Returns the number of bytes read,
+  /// or 0 if an error occurred.
+  template <typename MutableBufferSequence>
+  std::size_t peek(const MutableBufferSequence& buffers,
+      asio::error_code& ec)
+  {
+    return stream_impl_.peek(buffers, ec);
+  }
+
+  /// Determine the amount of data that may be read without blocking.
+  std::size_t in_avail()
+  {
+    return stream_impl_.in_avail();
+  }
+
+  /// Determine the amount of data that may be read without blocking.
+  std::size_t in_avail(asio::error_code& ec)
+  {
+    return stream_impl_.in_avail(ec);
+  }
+
+private:
+  // The buffered write stream.
+  typedef buffered_write_stream<Stream> write_stream_type;
+  write_stream_type inner_stream_impl_;
+
+  // The buffered read stream.
+  typedef buffered_read_stream<write_stream_type&> read_stream_type;
+  read_stream_type stream_impl_;
+};
+
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // ASIO_BUFFERED_STREAM_HPP