Added thirdparty: boost library

thirdparty/include/boost/cobalt/detail/forward_cancellation.hpp

@@ -0,0 +1,57 @@
+//
+// Copyright (c) 2022 Klemens Morgenstern (klemens.morgenstern@gmx.net)
+//
+// 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_COBALT_DETAIL_FORWARD_CANCELLATION_HPP
+#define BOOST_COBALT_DETAIL_FORWARD_CANCELLATION_HPP
+
+#include <boost/cobalt/config.hpp>
+#include <boost/asio/cancellation_signal.hpp>
+#include <boost/asio/dispatch.hpp>
+
+namespace boost::cobalt
+{
+
+// Requests cancellation where a successful cancellation results
+// in no apparent side effects and where the op can re-awaited.
+template<typename Awaitable>
+concept interruptible =
+       ( std::is_rvalue_reference_v<Awaitable> && requires (Awaitable && t) {std::move(t).interrupt_await();})
+    || (!std::is_rvalue_reference_v<Awaitable> && requires (Awaitable t) {t.interrupt_await();});
+
+
+}
+
+namespace boost::cobalt::detail
+{
+
+struct forward_cancellation
+{
+  asio::cancellation_signal &cancel_signal;
+
+  forward_cancellation(asio::cancellation_signal &cancel_signal) : cancel_signal(cancel_signal) {}
+  void operator()(asio::cancellation_type ct) const
+  {
+    cancel_signal.emit(ct);
+  }
+};
+
+struct forward_dispatch_cancellation
+{
+  asio::cancellation_signal &cancel_signal;
+  executor exec;
+
+  forward_dispatch_cancellation(asio::cancellation_signal &cancel_signal,
+                            executor exec) : cancel_signal(cancel_signal), exec(exec) {}
+  void operator()(asio::cancellation_type ct) const
+  {
+    asio::dispatch(exec, [this, ct]{cancel_signal.emit(ct);});
+  }
+};
+
+}
+
+#endif //BOOST_COBALT_DETAIL_FORWARD_CANCELLATION_HPP