From fbfd98ef7732531d52daa0194a7180b666de0909 Mon Sep 17 00:00:00 2001
From: Dominic Masters <dominic@domsplace.com>
Date: Wed, 1 Mar 2023 05:56:20 -0800
Subject: [PATCH] Improved proper handling of state events

---
 src/dawn/state/State.hpp      | 19 ++++++++++++++++++-
 src/dawn/state/StateEvent.hpp | 35 +++++++++++++++++++++--------------
 2 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/src/dawn/state/State.hpp b/src/dawn/state/State.hpp
index 9f9c39f4..adac24cd 100644
--- a/src/dawn/state/State.hpp
+++ b/src/dawn/state/State.hpp
@@ -8,9 +8,26 @@
 #include "StateProperty.hpp"
 
 namespace Dawn {
-  class StateOwner {
+  class StateOwner : public IStateOwner {
     private:
       std::vector<IStateEvent*> eventsSubscribed;
+
+      /**
+       * Called by the state event when it is disposing (before the StateOwner
+       * itself is).
+       * 
+       * @param evt Event that is being disposed.
+       */
+      void _stateEventDisposed(IStateEvent *evt) override {
+        auto it = eventsSubscribed.begin();
+        while(it != eventsSubscribed.end()) {
+          if(*it == evt) {
+            it = eventsSubscribed.erase(it);
+          } else {
+            ++it;
+          }
+        }
+      }
   
     public:
       /**
diff --git a/src/dawn/state/StateEvent.hpp b/src/dawn/state/StateEvent.hpp
index 2e048388..79b5318a 100644
--- a/src/dawn/state/StateEvent.hpp
+++ b/src/dawn/state/StateEvent.hpp
@@ -7,15 +7,19 @@
 #include "assert/assert.hpp"
 
 namespace Dawn {
-  class StateOwner;
-
+  /** Forwarders / Fake Virtuals for other methods. */
   template<typename...A>
   class StateEvent;
+  class IStateEvent;
+  class IStateOwner {
+    public:
+      virtual void _stateEventDisposed(IStateEvent *evt) = 0;
+  };
 
   template<typename...A>
   struct StateEventListener {
     uint32_t id;
-    StateOwner *owner;
+    IStateOwner *owner;
     std::function<void(A...)> listener;
     std::function<void(StateEventListener<A...>)> unsubWithParams;
     std::function<void()> unsub;
@@ -31,7 +35,7 @@ namespace Dawn {
        * 
        * @param owner State owner that is being disposed.
        */
-      virtual void _stateOwnerDestroyed(StateOwner *owner) = 0;
+      virtual void _stateOwnerDestroyed(IStateOwner *owner) = 0;
 
       friend class StateOwner;
   };
@@ -41,7 +45,8 @@ namespace Dawn {
     protected:
       uint32_t stateEventId = 0;
 
-      void _stateOwnerDestroyed(StateOwner *owner) override {
+      /** Refer to IStateEvent::_stateOwnerDestroyed */
+      void _stateOwnerDestroyed(IStateOwner *owner) override {
         auto it = this->_eventListeners.begin();
         while(it != this->_eventListeners.end()) {
           if(it->owner == owner) {
@@ -66,15 +71,17 @@ namespace Dawn {
           it->listener(args...);
           ++it;
         }
-        // auto itListeners = this->_eventListeners.begin();
-        // while(itListeners != this->_eventListeners.end()) {
-        //   auto itLists = itListeners->second.begin();
-        //   while(itLists != itListeners->second.end()) {
-        //     (*itLists)(args...);
-        //     ++itLists;
-        //   }
-        //   ++itListeners;
-        // }
+      }
+
+      /**
+       * Disposal of a state event.
+       */
+      ~StateEvent() {
+        auto it = this->_eventListeners.begin();
+        while(it != this->_eventListeners.end()) {
+          it->owner->_stateEventDisposed(this);
+          ++it;
+        }
       }
 
       friend class StateOwner;