1 files changed, 116 insertions, 0 deletions
diff --git a/include/cru/common/Event2.h b/include/cru/common/Event2.h
new file mode 100644
index 00000000..a8476db3
--- /dev/null
+++ b/include/cru/common/Event2.h
@@ -0,0 +1,116 @@
+#pragma once
+
+#include <cru/common/SelfResolvable.h>
+
+#include <cstddef>
+#include <functional>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+namespace cru {
+template <typename TArgument, typename TResult>
+class EventContext {
+ public:
+  EventContext() : argument_(), result_() {}
+  explicit EventContext(TArgument argument)
+      : argument_(std::move(argument)), result_() {}
+  EventContext(TArgument argument, TResult result)
+      : argument_(std::move(argument)), result_(std::move(result)) {}
+
+  TArgument& GetArgument() { return argument_; }
+  const TArgument& GetArgument() const { return argument_; }
+
+  TResult& GetResult() { return result_; }
+  const TResult& GetResult() const { return result_; }
+  void SetResult(TResult&& result) { result_ = std::forward<TResult>(result); }
+
+  bool GetStopHandling() const { return stop_handling_; }
+  void SetStopHandling(bool stop = true) { stop_handling_ = stop; }
+
+ private:
+  TArgument argument_;
+  TResult result_;
+  bool stop_handling_ = false;
+};
+
+template <typename TArgument, typename TResult>
+class Event2;
+
+template <typename T>
+constexpr bool is_event2_v = false;
+
+template <typename TArgument, typename TResult>
+constexpr bool is_event2_v<Event2<TArgument, TResult>> = true;
+
+template <typename TEvent2>
+class EventHandlerToken {
+  static_assert(is_event2_v<TEvent2>, "TEvent2 must be Event2 class.");
+
+ public:
+  EventHandlerToken(ObjectResolver<TEvent2> event_resolver, int token_value);
+
+  ObjectResolver<TEvent2> GetEventResolver() const { return event_resolver_; }
+  int GetTokenValue() const { return token_value_; }
+  void RevokeHandler() const;
+
+ private:
+  ObjectResolver<TEvent2> event_resolver_;
+  int token_value_;
+};
+
+template <typename TArgument = std::nullptr_t,
+          typename TResult = std::nullptr_t>
+class Event2 : public SelfResolvable<Event2<TArgument, TResult>> {
+ public:
+  using HandlerToken = EventHandlerToken<Event2>;
+  using Context = EventContext<TArgument, TResult>;
+  using Handler = std::function<void(Context&)>;
+  using SpyOnlyHandler = std::function<void()>;
+
+  template <typename TFunc>
+  static std::enable_if_t<std::invocable<TFunc>, Handler> WrapAsHandler(
+      TFunc&& handler) {
+    return Handler([h = std::forward<TFunc>(handler)](Context&) { h(); });
+  }
+
+  template <typename TFunc>
+  static std::enable_if_t<std::invocable<TFunc, Context&>, Handler>
+  WrapAsHandler(TFunc&& handler) {
+    return Handler(std::forward<TFunc>(handler));
+  }
+
+ private:
+  struct HandlerData {
+    int token_value_;
+    Handler handler_;
+  };
+
+ public:
+  Event2(const Event2&) = delete;
+  Event2(Event2&&) = delete;
+  Event2& operator=(const Event2&) = delete;
+  Event2& operator=(Event2&&) = delete;
+  ~Event2() override = default;
+
+ public:
+  
+
+  void RevokeHandler(int token_value);
+  void RevokeHandler(const HandlerToken& token) {
+    return RevokeHandler(token.GetTokenValue());
+  }
+
+ private:
+  int current_token_value_ = 1;
+  std::vector<HandlerData> handlers_;
+};
+
+template <typename TEvent2>
+void EventHandlerToken<TEvent2>::RevokeHandler() const {
+  auto event = this->event_resolver_.Resolve();
+  if (event) {
+    event->RevokeHandler(this->token_value_);
+  }
+}
+}  // namespace cru