asio/include/asio/co_spawn.hpp

//
// co_spawn.hpp
// ~~~~~~~~~~~~
//
// Copyright (c) 2003-2019 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_CO_SPAWN_HPP
#define ASIO_CO_SPAWN_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/config.hpp"

#if defined(ASIO_HAS_CO_AWAIT) || defined(GENERATING_DOCUMENTATION)

#include "asio/awaitable.hpp"
#include "asio/execution_context.hpp"
#include "asio/is_executor.hpp"

#include "asio/detail/push_options.hpp"

namespace asio {
namespace detail {

template <typename T>
struct awaitable_signature;

template <typename T, typename Executor>
struct awaitable_signature<awaitable<T, Executor>>
{
  typedef void type(std::exception_ptr, T);
};

template <typename Executor>
struct awaitable_signature<awaitable<void, Executor>>
{
  typedef void type(std::exception_ptr);
};

} // namespace detail

/// Spawn a new thread of execution.
/**
 * The entry point function object @c f must have the signature:
 *
 * @code awaitable<void, E> f(); @endcode
 *
 * where @c E is convertible from @c Executor.
 */
template <typename Executor, typename F, typename CompletionToken>
ASIO_INITFN_RESULT_TYPE(CompletionToken,
    typename detail::awaitable_signature<typename result_of<F()>::type>::type)
co_spawn(const Executor& ex, F&& f, CompletionToken&& token,
    typename enable_if<
      is_executor<Executor>::value
    >::type* = 0);

/// Spawn a new thread of execution.
/**
 * The entry point function object @c f must have the signature:
 *
 * @code awaitable<void, E> f(); @endcode
 *
 * where @c E is convertible from @c ExecutionContext::executor_type.
 */
template <typename ExecutionContext, typename F, typename CompletionToken>
ASIO_INITFN_RESULT_TYPE(CompletionToken,
    typename detail::awaitable_signature<typename result_of<F()>::type>::type)
co_spawn(ExecutionContext& ctx, F&& f, CompletionToken&& token,
    typename enable_if<
      is_convertible<ExecutionContext&, execution_context&>::value
    >::type* = 0);

} // namespace asio

#include "asio/detail/pop_options.hpp"

#include "asio/impl/co_spawn.hpp"

#endif // defined(ASIO_HAS_CO_AWAIT) || defined(GENERATING_DOCUMENTATION)

#endif // ASIO_CO_SPAWN_HPP