Initial Commit

cpepetest1/demo_scope.hpp

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+// examples/demo_scope.hpp                                            -*-C++-*-
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#ifndef INCLUDED_EXAMPLES_DEMO_SCOPE
+#define INCLUDED_EXAMPLES_DEMO_SCOPE
+
+#include <beman/net29/net.hpp>
+#include <atomic>
+#include <iostream>
+#include <utility>
+
+// ----------------------------------------------------------------------------
+
+namespace demo
+{
+    namespace ex = ::beman::net29::detail::ex;
+
+    class scope
+    {
+    private:
+        static constexpr bool log_completions{false};
+        struct env
+        {
+            scope* self;
+
+            auto query(ex::get_stop_token_t) const noexcept
+            {
+                return this->self->source.get_token();
+            }
+        };
+
+        struct job_base
+        {
+            virtual ~job_base() = default;
+        };
+
+        struct receiver
+        {
+            using receiver_concept = ex::receiver_t;
+            scope*    self;
+            job_base* state{};
+
+            auto set_error(auto&&) noexcept -> void
+            {
+                ::std::cerr << "ERROR: demo::scope::job in scope completed with error!\n";
+                this->complete();
+            }
+            auto set_value() && noexcept -> void
+            {
+                if (log_completions) std::cout << "demo::scope::set_value()\n";
+                this->complete();
+            }
+            auto set_stopped() && noexcept -> void
+            {
+                if (log_completions) std::cout << "demo::scope::set_stopped()\n";
+                this->complete();
+            }
+            auto complete() -> void
+            {
+                scope* self{this->self};
+                delete this->state;
+                if (0u == --self->count)
+                {
+                    self->complete();
+                }
+            }
+            auto get_env() const noexcept -> env { return {this->self}; }
+        };
+
+        template <typename Sender>
+        struct job
+            : job_base
+        {
+            using state_t = decltype(ex::connect(std::declval<Sender&&>(), std::declval<receiver>()));
+            state_t state;
+            template <typename S>
+            job(scope* self, S&& sender)
+                : state(ex::connect(::std::forward<S>(sender), receiver{self, this}))
+            {
+                ex::start(this->state);
+            }
+        };
+
+        std::atomic<std::size_t> count{};
+        ex::inplace_stop_source  source;
+
+        auto complete() -> void {}
+
+    public:
+        ~scope()
+        {
+            if (0u < this->count)
+                std::cerr << "ERROR: scope destroyed with live jobs: " << this->count << "\n";
+        }
+        template <ex::sender Sender>
+        auto spawn(Sender&& sender)
+        {
+            ++this->count;
+            new job<Sender>(this, std::forward<Sender>(sender));
+        }
+        auto stop()
+        {
+            this->source.request_stop();
+        }
+    };
+}
+
+// ----------------------------------------------------------------------------
+
+#endif