1 files changed, 46 insertions, 0 deletions
diff --git a/include/cru/common/event.hpp b/include/cru/common/event.hpp
new file mode 100644
index 00000000..ce014fb8
--- /dev/null
+++ b/include/cru/common/event.hpp
@@ -0,0 +1,46 @@
+#pragma once
+#include "base.hpp"
+
+#include <functional>
+#include <map>
+#include <utility>
+
+namespace cru {
+// A non-copyable non-movable Event class.
+// It stores a list of event handlers.
+template <typename... TArgs>
+class Event {
+ public:
+  using EventHandler = std::function<void(TArgs...)>;
+  using EventHandlerToken = long;
+
+  Event() = default;
+  Event(const Event&) = delete;
+  Event& operator=(const Event&) = delete;
+  Event(Event&&) = delete;
+  Event& operator=(Event&&) = delete;
+  ~Event() = default;
+
+  EventHandlerToken AddHandler(const EventHandler& handler) {
+    const auto token = current_token_++;
+    handlers_.emplace(token, handler);
+    return token;
+  }
+
+  void RemoveHandler(const EventHandlerToken token) {
+    auto find_result = handlers_.find(token);
+    if (find_result != handlers_.cend()) handlers_.erase(find_result);
+  }
+
+  template <typename... Args>
+  void Raise(Args&&... args) {
+    for (const auto& handler : handlers_)
+      (handler.second)(std::forward<Args>(args)...);
+  }
+
+ private:
+  std::map<EventHandlerToken, EventHandler> handlers_;
+
+  EventHandlerToken current_token_ = 0;
+};
+}  // namespace cru