Added thirdparty: boost library

thirdparty/include/boost/cobalt/wait_group.hpp

@@ -0,0 +1,104 @@
+// Copyright (c) 2022 Klemens D. Morgenstern
+//
+// 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_WAIT_GROUP_HPP
+#define BOOST_COBALT_WAIT_GROUP_HPP
+
+#include <boost/cobalt/detail/wait_group.hpp>
+
+namespace boost::cobalt
+{
+// tag::outline[]
+struct wait_group
+{
+    // create a wait_group
+    explicit
+    wait_group(asio::cancellation_type normal_cancel = asio::cancellation_type::none,
+               asio::cancellation_type exception_cancel = asio::cancellation_type::all);
+
+    // insert a task into the group
+    void push_back(promise<void> p);
+
+    // the number of tasks in the group
+    std::size_t size() const;
+    // remove completed tasks without waiting (i.e. zombie tasks)
+    std::size_t reap();
+    // cancel all tasks
+    void cancel(asio::cancellation_type ct = asio::cancellation_type::all);
+    // end::outline[]
+
+    /* tag::outline[]
+    // wait for one task to complete.
+    __wait_one_op__ wait_one();
+    // wait for all tasks to complete
+    __wait_op__ wait();
+    // wait for all tasks to complete
+    __wait_op__ operator co_await ();
+    // when used with `with` , this will receive the exception
+    // and wait for the completion
+    // if `ep` is set, this will use the `exception_cancel` level,
+    // otherwise the `normal_cancel` to cancel all promises.
+    __wait_op__ await_exit(std::exception_ptr ep);
+     end::outline[] */
+
+    auto wait_one() -> detail::race_wrapper
+    {
+        return  detail::race_wrapper(waitables_);
+    }
+
+    detail::gather_wrapper wait()
+    {
+        return detail::gather_wrapper(waitables_);
+
+    }
+    detail::gather_wrapper::awaitable_type operator co_await ()
+    {
+      return detail::gather_wrapper(waitables_).operator co_await();
+    }
+    // swallow the exception here.
+    detail::gather_wrapper await_exit(std::exception_ptr ep)
+    {
+        auto ct = ep ? ct_except_ : ct_normal_;
+        if (ct != asio::cancellation_type::none)
+            for (auto & w : waitables_)
+                w.cancel(ct);
+        return detail::gather_wrapper(waitables_);
+    }
+
+
+  private:
+    std::list<promise<void>> waitables_;
+    asio::cancellation_type ct_normal_, ct_except_;
+  // tag::outline[]
+};
+// end::outline[]
+
+inline wait_group::wait_group(
+    asio::cancellation_type normal_cancel,
+    asio::cancellation_type exception_cancel)
+: ct_normal_(normal_cancel), ct_except_(exception_cancel) {}
+
+inline
+std::size_t wait_group::size() const {return waitables_.size();}
+
+inline
+std::size_t wait_group::reap()
+{
+  return erase_if(waitables_, [](promise<void> & p) { return p.ready() && p;});
+}
+
+inline
+void wait_group::cancel(asio::cancellation_type ct)
+{
+  for (auto & w : waitables_)
+    w.cancel(ct);
+}
+
+inline
+void wait_group::push_back(promise<void> p) { waitables_.push_back(std::move(p));}
+
+
+}
+
+#endif //BOOST_COBALT_WAIT_GROUP_HPP