Context object the represents the currently executing coroutine. More...

#include <spawn.hpp>

Collaboration diagram for boost::asio::basic_yield_context< Handler >:

Public Types
typedef boost::coroutines::coroutine < void()>	callee_type
	The coroutine callee type, used by the implementation. More...

typedef boost::coroutines::coroutine < void()>::caller_type	caller_type
	The coroutine caller type, used by the implementation. More...

Public Member Functions
	basic_yield_context (const detail::weak_ptr< callee_type > &coro, caller_type &ca, Handler &handler)
	Construct a yield context to represent the specified coroutine. More...

basic_yield_context	operator[] (boost::system::error_code &ec) const
	Return a yield context that sets the specified error_code. More...

Public Attributes
detail::weak_ptr< callee_type >	coro_

caller_type &	ca_

Handler &	handler_

boost::system::error_code *	ec_

Detailed Description

template<typename Handler>
class boost::asio::basic_yield_context< Handler >

Context object the represents the currently executing coroutine.

The basic_yield_context class is used to represent the currently executing stackful coroutine. A basic_yield_context may be passed as a handler to an asynchronous operation. For example:

 template <typename Handler>
void my_coroutine(basic_yield_context<Handler> yield)
{
  ...
  std::size_t n = my_socket.async_read_some(buffer, yield);
  ...
} 

The initiating function (async_read_some in the above example) suspends the current coroutine. The coroutine is resumed when the asynchronous operation completes, and the result of the operation is returned.

Member Typedef Documentation

template<typename Handler>

typedef boost::coroutines::coroutine<void()> boost::asio::basic_yield_context< Handler >::callee_type

The coroutine callee type, used by the implementation.

When using Boost.Coroutine v1, this type is:

typename coroutine<void()>

When using Boost.Coroutine v2 (unidirectional coroutines), this type is:

push_coroutine<void>

template<typename Handler>

typedef boost::coroutines::coroutine<void()>::caller_type boost::asio::basic_yield_context< Handler >::caller_type

The coroutine caller type, used by the implementation.

When using Boost.Coroutine v1, this type is:

typename coroutine<void()>::caller_type

When using Boost.Coroutine v2 (unidirectional coroutines), this type is:

pull_coroutine<void>

Constructor & Destructor Documentation

template<typename Handler>

boost::asio::basic_yield_context< Handler >::basic_yield_context	(	const detail::weak_ptr< callee_type > &	coro,
		caller_type &	ca,
		Handler &	handler
	)

inline

Construct a yield context to represent the specified coroutine.

Most applications do not need to use this constructor. Instead, the spawn() function passes a yield context as an argument to the coroutine function.

Member Function Documentation

template<typename Handler>

basic_yield_context boost::asio::basic_yield_context< Handler >::operator[] ( boost::system::error_code & ec ) const

inline

Return a yield context that sets the specified error_code.

By default, when a yield context is used with an asynchronous operation, a non-success error_code is converted to system_error and thrown. This operator may be used to specify an error_code object that should instead be set with the asynchronous operation's result. For example:

 template <typename Handler>
void my_coroutine(basic_yield_context<Handler> yield)
{
  ...
  std::size_t n = my_socket.async_read_some(buffer, yield[ec]);
  if (ec)
  {
    // An error occurred.
  }
  ...
} 