From a94a806f69586e08a30fff0cdb3e52b0ce7acfa5 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Fri, 5 Apr 2019 00:11:36 +0800
Subject: Refactor event.

---
 include/cru/common/event.hpp | 127 +++++++++++++++++++++++++++++--------------
 1 file changed, 86 insertions(+), 41 deletions(-)

(limited to 'include/cru/common/event.hpp')

diff --git a/include/cru/common/event.hpp b/include/cru/common/event.hpp
index 6228d867..987bcdd6 100644
--- a/include/cru/common/event.hpp
+++ b/include/cru/common/event.hpp
@@ -2,73 +2,102 @@
 #include "base.hpp"
 
 #include <functional>
+#include <list>
 #include <map>
 #include <memory>
 #include <utility>
 
 namespace cru {
-using EventHandlerRevoker = std::function<void()>;
+class EventRevoker;
+
+namespace details {
+class EventBase {
+  friend EventRevoker;
+
+ protected:
+  using EventHandlerToken = long;
+
+  EventBase() : resolve_ptr_(new std::reference_wrapper(*this)) {}
+
+  EventBase(const EventBase& other) = delete;
+  EventBase(EventBase&& other) = delete;
+  EventBase& operator=(const EventBase& other) = delete;
+  EventBase& operator=(EventBase&& other) = delete;
+  virtual ~EventBase() = default;
+
+  virtual void RemoveHandler(EventHandlerToken token) = 0;
+
+  inline EventRevoker CreateRevoker(EventHandlerToken token);
+
+ private:
+  std::shared_ptr<std::reference_wrapper<EventBase>> resolve_ptr_;
+};
+}  // namespace details
+
+class EventRevoker {
+  friend class ::cru::details::EventBase;
 
-// A non-copyable non-movable Event class.
-// It stores a list of event handlers.
-template <typename... TArgs>
-class Event {
  private:
-  using EventResolver = std::function<Event*()>;
-  class EventHandlerRevokerImpl {
-   public:
-    EventHandlerRevokerImpl(const std::shared_ptr<EventResolver>& resolver,
-                            long token)
-        : resolver_(resolver), token_(token) {}
-    EventHandlerRevokerImpl(const EventHandlerRevokerImpl& other) = default;
-    EventHandlerRevokerImpl(EventHandlerRevokerImpl&& other) = default;
-    EventHandlerRevokerImpl& operator=(const EventHandlerRevokerImpl& other) =
-        default;
-    EventHandlerRevokerImpl& operator=(EventHandlerRevokerImpl&& other) =
-        default;
-    ~EventHandlerRevokerImpl() = default;
-
-    void operator()() {
-      const auto true_resolver = resolver_.lock();
-      if (true_resolver) {
-        (*true_resolver)()->RemoveHandler(token_);
-      }
+  EventRevoker(const std::shared_ptr<
+                   std::reference_wrapper<details::EventBase>>& resolve_ptr,
+               details::EventBase::EventHandlerToken token)
+      : weak_ptr_(resolve_ptr), token_(token) {}
+
+ public:
+  EventRevoker(const EventRevoker& other) = default;
+  EventRevoker(EventRevoker&& other) = default;
+  EventRevoker& operator=(const EventRevoker& other) = default;
+  EventRevoker& operator=(EventRevoker&& other) = default;
+  ~EventRevoker() = default;
+
+  void operator()() const {
+    const auto true_resolver = weak_ptr_.lock();
+    if (true_resolver) {
+      (*true_resolver).get().RemoveHandler(token_);
     }
+  }
+
+ private:
+  std::weak_ptr<std::reference_wrapper<details::EventBase>> weak_ptr_;
+  details::EventBase::EventHandlerToken token_;
+};
 
-   private:
-    std::weak_ptr<EventResolver> resolver_;
-    long token_;
-  };
+inline EventRevoker details::EventBase::CreateRevoker(EventHandlerToken token) {
+  return EventRevoker(resolve_ptr_, token);
+}
 
+// A non-copyable non-movable Event class.
+// It stores a list of event handlers.
+template <typename... TArgs>
+class Event : public details::EventBase {
  public:
   using EventHandler = std::function<void(TArgs...)>;
 
-  Event()
-      : event_resolver_(new std::function<Event*()>([this] { return this; })) {}
+  Event() = default;
   Event(const Event&) = delete;
   Event& operator=(const Event&) = delete;
   Event(Event&&) = delete;
   Event& operator=(Event&&) = delete;
   ~Event() = default;
 
-  EventHandlerRevoker AddHandler(const EventHandler& handler) {
+  EventRevoker AddHandler(const EventHandler& handler) {
     const auto token = current_token_++;
     handlers_.emplace(token, handler);
-    return EventHandlerRevoker(EventHandlerRevokerImpl(event_resolver_, token));
+    return CreateRevoker(token);
   }
 
-  EventHandlerRevoker AddHandler(EventHandler&& handler) {
+  EventRevoker AddHandler(EventHandler&& handler) {
     const auto token = current_token_++;
     handlers_.emplace(token, std::move(handler));
-    return EventHandlerRevoker(EventHandlerRevokerImpl(event_resolver_, token));
+    return CreateRevoker(token);
   }
 
   template <typename Arg>
-  EventHandlerRevoker AddHandler(Arg&& handler) {
+  EventRevoker AddHandler(Arg&& handler) {
     static_assert(std::is_invocable_v<Arg, TArgs...>, "Handler not invocable.");
     const auto token = current_token_++;
     handlers_.emplace(token, EventHandler(std::forward<Arg>(handler)));
-    return EventHandlerRevoker(EventHandlerRevokerImpl(event_resolver_, token));
+    return CreateRevoker(token);
   }
 
   template <typename... Args>
@@ -77,15 +106,31 @@ class Event {
       (handler.second)(std::forward<Args>(args)...);
   }
 
- private:
-  void RemoveHandler(const long token) {
+ protected:
+  void RemoveHandler(EventHandlerToken token) override {
     auto find_result = handlers_.find(token);
     if (find_result != handlers_.cend()) handlers_.erase(find_result);
   }
 
  private:
-  std::map<long, EventHandler> handlers_{};
-  long current_token_ = 0;
-  std::shared_ptr<EventResolver> event_resolver_;
+  std::map<EventHandlerToken, EventHandler> handlers_{};
+  EventHandlerToken current_token_ = 0;
+};
+
+class EventRevokerGuard {
+ public:
+  EventRevokerGuard() = default;
+  EventRevokerGuard(const EventRevokerGuard& other) = delete;
+  EventRevokerGuard(EventRevokerGuard&& other) = delete;
+  EventRevokerGuard& operator=(const EventRevokerGuard& other) = delete;
+  EventRevokerGuard& operator=(EventRevokerGuard&& other) = delete;
+  ~EventRevokerGuard() {
+    for (const auto revoker : revokers_) revoker();
+  }
+
+  void Add(EventRevoker revoker) { revokers_.push_back(std::move(revoker)); }
+
+ private:
+  std::list<EventRevoker> revokers_;
 };
 }  // namespace cru
-- 
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