2 files changed, 79 insertions, 5 deletions

diff --git a/include/cru/common/base.hpp b/include/cru/common/base.hpp
index 4264142d..d4f164bf 100644
--- a/include/cru/common/base.hpp
+++ b/include/cru/common/base.hpp
@@ -2,6 +2,7 @@
 #include "pre_config.hpp"
 
 #include <stdexcept>
+#include <type_traits>
 
 #define CRU_UNUSED(entity) static_cast<void>(entity);
 
@@ -40,4 +41,70 @@ struct Interface {
 [[noreturn]] inline void UnreachableCode() {
   throw std::runtime_error("Unreachable code.");
 }
+
 }  // namespace cru
+
+template <typename Enum>
+struct enable_bitmask_operators : std::false_type {};
+
+#define CRU_ENABLE_BITMASK_OPERATORS(enumname) \
+  template <>                                  \
+  struct enable_bitmask_operators<enumname> : std::true_type {};
+
+template <typename Enum>
+auto operator|(Enum lhs, Enum rhs)
+    -> std::enable_if_t<enable_bitmask_operators<Enum>::value, Enum> {
+  using underlying = typename std::underlying_type<Enum>::type;
+  return static_cast<Enum>(static_cast<underlying>(lhs) |
+                           static_cast<underlying>(rhs));
+}
+
+template <typename Enum>
+auto operator&(Enum lhs, Enum rhs)
+    -> std::enable_if_t<enable_bitmask_operators<Enum>::value, Enum> {
+  using underlying = typename std::underlying_type<Enum>::type;
+  return static_cast<Enum>(static_cast<underlying>(lhs) &
+                           static_cast<underlying>(rhs));
+}
+
+template <typename Enum>
+auto operator^(Enum lhs, Enum rhs)
+    -> std::enable_if_t<enable_bitmask_operators<Enum>::value, Enum> {
+  using underlying = typename std::underlying_type<Enum>::type;
+  return static_cast<Enum>(static_cast<underlying>(lhs) ^
+                           static_cast<underlying>(rhs));
+}
+
+template <typename Enum>
+auto operator~(Enum rhs)
+    -> std::enable_if_t<enable_bitmask_operators<Enum>::value, Enum> {
+  using underlying = typename std::underlying_type<Enum>::type;
+  return static_cast<Enum>(~static_cast<underlying>(rhs));
+}
+
+template <typename Enum>
+auto operator|=(Enum& lhs, Enum rhs)
+    -> std::enable_if_t<enable_bitmask_operators<Enum>::value, Enum&> {
+  using underlying = typename std::underlying_type<Enum>::type;
+  lhs = static_cast<Enum>(static_cast<underlying>(lhs) |
+                          static_cast<underlying>(rhs));
+  return lhs;
+}
+
+template <typename Enum>
+auto operator&=(Enum& lhs, Enum rhs)
+    -> std::enable_if_t<enable_bitmask_operators<Enum>::value, Enum&> {
+  using underlying = typename std::underlying_type<Enum>::type;
+  lhs = static_cast<Enum>(static_cast<underlying>(lhs) &
+                          static_cast<underlying>(rhs));
+  return lhs;
+}
+
+template <typename Enum>
+auto operator^=(Enum& lhs, Enum rhs)
+    -> std::enable_if_t<enable_bitmask_operators<Enum>::value, Enum&> {
+  using underlying = typename std::underlying_type<Enum>::type;
+  lhs = static_cast<Enum>(static_cast<underlying>(lhs) ^
+                          static_cast<underlying>(rhs));
+  return lhs;
+}
diff --git a/include/cru/common/event.hpp b/include/cru/common/event.hpp
index 33b2e3f6..55a00d7e 100644
--- a/include/cru/common/event.hpp
+++ b/include/cru/common/event.hpp
@@ -3,6 +3,7 @@
 
 #include "self_resolvable.hpp"
 
+#include <cassert>
 #include <forward_list>
 #include <functional>
 #include <memory>
@@ -99,7 +100,8 @@ struct IEvent {
   IEvent(IEvent&& other) = delete;
   IEvent& operator=(const IEvent& other) = delete;
   IEvent& operator=(IEvent&& other) = delete;
-  ~IEvent() = default;
+  ~IEvent() = default;  // Note that user can't destroy a Event via IEvent. So
+                        // destructor should be protected.
 
  public:
   virtual EventRevoker AddHandler(const EventHandler& handler) = 0;
@@ -130,14 +132,16 @@ class Event : public details::EventBase, public IEvent<TEventArgs> {
 
   EventRevoker AddHandler(const EventHandler& handler) override {
     const auto token = current_token_++;
-    this->handler_data_list_.emplace_after(this->last_handler_iterator_ ,token, handler);
+    this->handler_data_list_.emplace_after(this->last_handler_iterator_, token,
+                                           handler);
     ++(this->last_handler_iterator_);
     return CreateRevoker(token);
   }
 
   EventRevoker AddHandler(EventHandler&& handler) override {
     const auto token = current_token_++;
-    this->handler_data_list_.emplace_after(this->last_handler_iterator_ ,token, std::move(handler));
+    this->handler_data_list_.emplace_after(this->last_handler_iterator_, token,
+                                           std::move(handler));
     ++(this->last_handler_iterator_);
     return CreateRevoker(token);
   }
@@ -163,12 +167,15 @@ class Event : public details::EventBase, public IEvent<TEventArgs> {
  protected:
   void RemoveHandler(EventHandlerToken token) override {
     this->handler_data_list_.remove_if(
-				       [token](const HandlerData& data) { return data.token == token; });
+        [token](const HandlerData& data) { return data.token == token; });
   }
 
  private:
   std::forward_list<HandlerData> handler_data_list_{};
-  typename std::forward_list<HandlerData>::const_iterator last_handler_iterator_ = this->handler_data_list_.cbefore_begin(); // remember the last handler to make push back O(1)
+  typename std::forward_list<
+      HandlerData>::const_iterator last_handler_iterator_ =
+      this->handler_data_list_
+          .cbefore_begin();  // remember the last handler to make push back O(1)
   EventHandlerToken current_token_ = 0;
 };