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@letsar
Last active January 23, 2021 12:16
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ChangeNotifier with List and queuing
typedef VoidCallback = void Function();
class ChangeNotifier {
List<VoidCallback> _listeners = List<VoidCallback>();
List<int> _toRemove = List<int>();
bool _notifying = false;
bool get hasListeners {
return _listeners.isNotEmpty;
}
void addListener(VoidCallback listener) {
_listeners.add(listener);
}
void removeListener(VoidCallback listener) {
for (int i = 0; i < _listeners.length; i++) {
if (_listeners[i] == listener) {
if (_notifying) {
_toRemove.add(i);
} else {
_listeners.removeAt(i);
}
break;
}
}
}
void dispose() {
_listeners = null;
}
void notifyListeners() {
_notifying = true;
if (_listeners != null) {
final int start = _listeners.length - 1;
for (int i = start; i >= 0; i--) {
try {
_listeners[i]();
} catch (exception, stack) {
print('error');
}
}
for (int i = _toRemove.length - 1; i >= 0; i--) {
_listeners.removeAt(_toRemove[i]);
}
_toRemove.clear();
}
_notifying = false;
}
}
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