defer.h

#pragma once
#include <asyncpp/detail/concepts.h>
#include <asyncpp/detail/std_import.h>
#include <utility>
 
namespace asyncpp {
    template<Dispatcher TDispatcher>
    struct defer {
        TDispatcher* target_dispatcher;
 
        explicit constexpr defer(TDispatcher* target) noexcept : target_dispatcher(target) {}
 
        explicit constexpr defer(TDispatcher& target) noexcept : target_dispatcher(&target) {}
 
        [[nodiscard]] constexpr bool await_ready() const noexcept { return target_dispatcher == nullptr; }
        void await_suspend(coroutine_handle<> hndl) const
            noexcept(noexcept(target_dispatcher->push(std::declval<std::function<void()>>()))) {
            target_dispatcher->push([hndl]() mutable { hndl.resume(); });
        }
        constexpr void await_resume() const noexcept {}
    };
} // namespace asyncpp