Update boost to 1.71 and add asio

boost/asio/impl/co_spawn.hpp

@@ -0,0 +1,140 @@
+//
+// impl/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 BOOST_ASIO_IMPL_CO_SPAWN_HPP
+#define BOOST_ASIO_IMPL_CO_SPAWN_HPP
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1200)
+# pragma once
+#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
+
+#include <boost/asio/detail/config.hpp>
+#include <boost/asio/awaitable.hpp>
+#include <boost/asio/dispatch.hpp>
+#include <boost/asio/post.hpp>
+#include <boost/asio/use_awaitable.hpp>
+
+#include <boost/asio/detail/push_options.hpp>
+
+namespace boost {
+namespace asio {
+namespace detail {
+
+template <typename T, typename Executor, typename F, typename Handler>
+awaitable<void, Executor> co_spawn_entry_point(
+    awaitable<T, Executor>*, Executor ex, F f, Handler handler)
+{
+  auto spawn_work = make_work_guard(ex);
+  auto handler_work = make_work_guard(handler, ex);
+
+  (void) co_await (post)(spawn_work.get_executor(),
+      use_awaitable_t<Executor>{});
+
+  bool done = false;
+  try
+  {
+    T t = co_await f();
+
+    done = true;
+
+    (dispatch)(handler_work.get_executor(),
+        [handler = std::move(handler), t = std::move(t)]() mutable
+        {
+          handler(std::exception_ptr(), std::move(t));
+        });
+  }
+  catch (...)
+  {
+    if (done)
+      throw;
+
+    (dispatch)(handler_work.get_executor(),
+        [handler = std::move(handler), e = std::current_exception()]() mutable
+        {
+          handler(e, T());
+        });
+  }
+}
+
+template <typename Executor, typename F, typename Handler>
+awaitable<void, Executor> co_spawn_entry_point(
+    awaitable<void, Executor>*, Executor ex, F f, Handler handler)
+{
+  auto spawn_work = make_work_guard(ex);
+  auto handler_work = make_work_guard(handler, ex);
+
+  (void) co_await (post)(spawn_work.get_executor(),
+      use_awaitable_t<Executor>{});
+
+  std::exception_ptr e = nullptr;
+  try
+  {
+    co_await f();
+  }
+  catch (...)
+  {
+    e = std::current_exception();
+  }
+
+  (dispatch)(handler_work.get_executor(),
+      [handler = std::move(handler), e]() mutable
+      {
+        handler(e);
+      });
+}
+
+struct initiate_co_spawn
+{
+  template <typename Handler, typename Executor, typename F>
+  void operator()(Handler&& handler, const Executor& ex, F&& f) const
+  {
+    typedef typename result_of<F()>::type awaitable_type;
+    typedef typename awaitable_type::executor_type executor_type;
+
+    executor_type ex2(ex);
+    auto a = (co_spawn_entry_point)(static_cast<awaitable_type*>(nullptr),
+        ex2, std::forward<F>(f), std::forward<Handler>(handler));
+    awaitable_handler<executor_type, void>(std::move(a), ex2).launch();
+  }
+};
+
+} // namespace detail
+
+template <typename Executor, typename F, typename CompletionToken>
+inline BOOST_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*)
+{
+  return async_initiate<CompletionToken,
+    typename detail::awaitable_signature<typename result_of<F()>::type>>(
+      detail::initiate_co_spawn(), token, ex, std::forward<F>(f));
+}
+
+template <typename ExecutionContext, typename F, typename CompletionToken>
+inline BOOST_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*)
+{
+  return (co_spawn)(ctx.get_executor(), std::forward<F>(f),
+      std::forward<CompletionToken>(token));
+}
+
+} // namespace asio
+} // namespace boost
+
+#include <boost/asio/detail/pop_options.hpp>
+
+#endif // BOOST_ASIO_IMPL_CO_SPAWN_HPP