Do not crash when a monitor is removed

src/modules/hyprland/backend.cpp

@@ -95,15 +95,37 @@ void IPC::parseIPC(const std::string& ev) {
 
   for (auto& [eventname, handler] : callbacks) {
     if (eventname == request) {
-      handler(ev);
+      handler->onEvent(ev);
     }
   }
 }
 
-void IPC::registerForIPC(const std::string& ev, std::function<void(const std::string&)> fn) {
+void IPC::registerForIPC(const std::string& ev, EventHandler* ev_handler) {
+  if (!ev_handler) {
+    return;
+  }
   callbackMutex.lock();
 
-  callbacks.emplace_back(std::make_pair(ev, fn));
+  callbacks.emplace_back(std::make_pair(ev, ev_handler));
+
+  callbackMutex.unlock();
+}
+
+void IPC::unregisterForIPC(EventHandler* ev_handler) {
+    if (!ev_handler) {
+    return;
+  }
+
+  callbackMutex.lock();
+
+  for(auto it = callbacks.begin(); it != callbacks.end(); ) {
+    auto it_current = it;
+    it++;
+    auto& [eventname, handler] = *it_current;
+    if (handler == ev_handler) {
+      callbacks.erase(it_current);
+    }
+  }
 
   callbackMutex.unlock();
 }
@@ -168,4 +190,4 @@ std::string IPC::getSocket1Reply(const std::string& rq) {
   return std::string(buffer);
 }
 
-}  // namespace waybar::modules::hyprland
+}  // namespace waybar::modules::hyprland

src/modules/hyprland/language.cpp

@@ -25,7 +25,13 @@ Language::Language(const std::string& id, const Bar& bar, const Json::Value& con
   AButton::update();
 
   // register for hyprland ipc
-  gIPC->registerForIPC("activelayout", [&](const std::string& ev) { this->onEvent(ev); });
+  gIPC->registerForIPC("activelayout", this);
+}
+
+Language::~Language() {
+  gIPC->unregisterForIPC(this);
+  // wait for possible event handler to finish
+  std::lock_guard<std::mutex> lg(mutex_);
 }
 
 auto Language::update() -> void {

src/modules/hyprland/window.cpp

@@ -25,7 +25,13 @@ Window::Window(const std::string& id, const Bar& bar, const Json::Value& config)
   ALabel::update();
 
   // register for hyprland ipc
-  gIPC->registerForIPC("activewindow", [&](const std::string& ev) { this->onEvent(ev); });
+  gIPC->registerForIPC("activewindow", this);
+}
+
+Window::~Window() {
+  gIPC->unregisterForIPC(this);
+  // wait for possible event handler to finish
+  std::lock_guard<std::mutex> lg(mutex_);
 }
 
 auto Window::update() -> void {
@@ -50,7 +56,9 @@ uint Window::getActiveWorkspaceID(std::string monitorName) {
   assert(json.isArray());
   auto monitor = std::find_if(json.begin(), json.end(),
                               [&](Json::Value monitor) { return monitor["name"] == monitorName; });
-  assert(monitor != std::end(json));
+  if(monitor == std::end(json)) {
+    return 0;
+  }
   return (*monitor)["activeWorkspace"]["id"].as<uint>();
 }
 
@@ -89,4 +97,4 @@ void Window::onEvent(const std::string& ev) {
 
   dp.emit();
 }
-}  // namespace waybar::modules::hyprland
+}  // namespace waybar::modules::hyprland