[/
 / Copyright (c) 2003-2022 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)
 /]

[section:BufferedHandshakeToken SSL buffered handshake token requirements]

A buffered_handshake token is a [link boost_asio.overview.model.completion_tokens
completion token] for completion signature `void(error_code, size_t)`.

[heading Examples]

A free function as a buffered_handshake token:

  void buffered_handshake_handler(
      const boost::system::error_code& ec,
      std::size_t bytes_transferred)
  {
    ...
  }

A buffered_handshake token function object:

  struct buffered_handshake_handler
  {
    ...
    void operator()(
        const boost::system::error_code& ec,
        std::size_t bytes_transferred)
    {
      ...
    }
    ...
  };

A lambda as a buffered_handshake token:

  ssl_stream.async_handshake(...,
      [](const boost::system::error_code& ec,
        std::size_t bytes_transferred)
      {
        ...
      });

A non-static class member function adapted to a buffered_handshake token using
`std::bind()`:

  void my_class::buffered_handshake_handler(
      const boost::system::error_code& ec,
      std::size_t bytes_transferred)
  {
    ...
  }
  ...
  ssl_stream.async_handshake(...,
      std::bind(&my_class::buffered_handshake_handler,
        this, std::placeholders::_1,
        std::placeholders::_2));

A non-static class member function adapted to a buffered_handshake token using
`boost::bind()`:

  void my_class::buffered_handshake_handler(
      const boost::system::error_code& ec,
      std::size_t bytes_transferred)
  {
    ...
  }
  ...
  ssl_stream.async_handshake(...,
      boost::bind(&my_class::buffered_handshake_handler,
        this, boost::asio::placeholders::error,
        boost::asio::placeholders::bytes_transferred));

Using [link boost_asio.reference.use_future use_future] as a buffered handshake token:

  std::future<std::size_t> f =
    ssl_stream.async_handshake(..., boost::asio::use_future);
  ...
  try
  {
    std::size_t n = f.get();
    ...
  }
  catch (const system_error& e)
  {
    ...
  }

Using [link boost_asio.reference.use_awaitable use_awaitable] as a buffered handshake
token:

  boost::asio::awaitable<void> my_coroutine()
  {
    try
    {
      ...
      std::size_t n =
        co_await ssl_stream.async_handshake(
            ..., boost::asio::use_awaitable);
      ...
    }
    catch (const system_error& e)
    {
      ...
    }
  }

[endsect]
