72 lines
1.6 KiB
Dart
72 lines
1.6 KiB
Dart
typedef EventHandler<T> = void Function(T args);
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class _MapEntry {
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late dynamic owner;
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late dynamic handler;
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}
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class MessageService {
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static final MessageService _singleton = MessageService._internal();
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final Map<String, Set<_MapEntry>> _callbackMaps = <String, Set<_MapEntry>>{};
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factory MessageService() {
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return _singleton;
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}
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MessageService._internal();
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subscribe<T>(String topic, dynamic owner, EventHandler<T>? handler) {
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var entry = _MapEntry();
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entry.owner = owner;
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entry.handler = handler;
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if (_callbackMaps.containsKey(topic)) {
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_callbackMaps[topic]!.remove(entry);
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_callbackMaps[topic]!.add(entry);
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} else {
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_callbackMaps[topic] = <_MapEntry>{};
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_callbackMaps[topic]!.add(entry);
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}
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}
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unsubscribe<T>(String topic, dynamic owner) {
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if (_callbackMaps.containsKey(topic)) {
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for (var entry in _callbackMaps[topic]!) {
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if (entry.owner == owner) {
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_callbackMaps[topic]!.remove(entry);
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unsubscribe(topic, owner);
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break;
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}
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}
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}
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}
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unsubscribeAll<T>(dynamic owner) {
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for (var callbackMapsEntry in _callbackMaps.entries) {
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for (var entry in callbackMapsEntry.value.toList()) {
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if (entry.owner == owner) {
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_callbackMaps[callbackMapsEntry.key]!.remove(entry);
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unsubscribeAll(owner);
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break;
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}
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}
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}
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}
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publish<T>(String topic, {T? arguments}) {
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var entries = _callbackMaps[topic];
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if (entries != null) {
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for (var entry in entries) {
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entry.handler(arguments);
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}
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}
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}
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}
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