feat: Create ListenerManager to safely unregister listeners

Author: mrousavy

package/cpp/Choreographer.cpp

@@ -3,6 +3,7 @@
 //
 
 #include "Choreographer.h"
+#include "ListenerManager.h"
 
 namespace margelo {
 
@@ -13,15 +14,13 @@ void Choreographer::loadHybridMethods() {
 }
 
 std::shared_ptr<Listener> Choreographer::addOnFrameListener(Choreographer::OnFrameCallback onFrameCallback) {
-  _callbacks.push_back(std::move(onFrameCallback));
-  return std::make_shared<Listener>([]() {
-    // TODO: Find a safe way to remove this listener from the vector.
-  });
+  auto listener = _listeners.add(std::move(onFrameCallback));
+  return std::make_shared<Listener>(std::move(listener));
 }
 
 void Choreographer::onFrame(double timestamp) {
-  for (const auto& callback : _callbacks) {
-    callback(timestamp);
+  for (const auto& listener : _listeners.getListeners()) {
+    listener(timestamp);
   }
 }
 

package/cpp/Choreographer.h

@@ -5,6 +5,7 @@
 #pragma once
 
 #include "Listener.h"
+#include "ListenerManager.h"
 #include "jsi/HybridObject.h"
 #include <functional>
 
@@ -25,7 +26,7 @@ class Choreographer : public HybridObject {
   void loadHybridMethods() override;
 
 private:
-  std::vector<OnFrameCallback> _callbacks;
+  ListenerManager<OnFrameCallback> _listeners;
 };
 
 } // namespace margelo

package/cpp/ListenerManager.h

@@ -0,0 +1,30 @@
+//
+// Created by Marc Rousavy on 24.02.24.
+//
+
+#pragma once
+
+#include "Listener.h"
+#include <algorithm>
+#include <functional>
+#include <list>
+
+namespace margelo {
+
+template <typename Callback> class ListenerManager {
+private:
+  std::list<Callback> _listeners;
+
+public:
+  Listener add(Callback listener) {
+    _listeners.push_back(std::move(listener));
+    auto id = --_listeners.end();
+    return Listener([id, this]() { _listeners.erase(id); });
+  }
+
+  const std::list<Callback>& getListeners() {
+    return _listeners;
+  }
+};
+
+} // namespace margelo

package/cpp/SurfaceProvider.cpp

@@ -10,32 +10,29 @@ void SurfaceProvider::loadHybridMethods() {
   registerHybridMethod("getSurface", &SurfaceProvider::getSurfaceOrNull, this);
 }
 
-Listener SurfaceProvider::addOnSurfaceChangedListener(margelo::SurfaceProvider::Callback callback) {
+Listener SurfaceProvider::addOnSurfaceChangedListener(SurfaceProvider::Callback callback) {
   std::unique_lock lock(_mutex);
 
-  _callbacks.push_back(std::move(callback));
-  return Listener([]() {
-    // TODO: Find a safe way to remove this listener from the vector.
-  });
+  return _listeners.add(std::move(callback));
 }
 
 void SurfaceProvider::onSurfaceCreated(std::shared_ptr<Surface> surface) {
   std::unique_lock lock(_mutex);
-  for (const auto& listener : _callbacks) {
+  for (const auto& listener : _listeners.getListeners()) {
     listener.onSurfaceCreated(surface);
   }
 }
 
 void SurfaceProvider::onSurfaceChanged(std::shared_ptr<Surface> surface, int width, int height) {
   std::unique_lock lock(_mutex);
-  for (const auto& listener : _callbacks) {
+  for (const auto& listener : _listeners.getListeners()) {
     listener.onSurfaceSizeChanged(surface, width, height);
   }
 }
 
 void SurfaceProvider::onSurfaceDestroyed(std::shared_ptr<Surface> surface) {
   std::unique_lock lock(_mutex);
-  for (const auto& listener : _callbacks) {
+  for (const auto& listener : _listeners.getListeners()) {
     listener.onSurfaceDestroyed(surface);
   }
 }

package/cpp/SurfaceProvider.h

@@ -5,6 +5,7 @@
 #pragma once
 
 #include "Listener.h"
+#include "ListenerManager.h"
 #include "Surface.h"
 #include "jsi/HybridObject.h"
 #include <functional>
@@ -39,7 +40,7 @@ class SurfaceProvider : public HybridObject {
   void onSurfaceDestroyed(std::shared_ptr<Surface> surface);
 
 private:
-  std::vector<Callback> _callbacks;
+  ListenerManager<Callback> _listeners;
   std::mutex _mutex;
 };