mirror of
https://gitlab.com/veilid/veilidchat.git
synced 2024-12-14 02:24:27 -05:00
81 lines
2.3 KiB
Dart
81 lines
2.3 KiB
Dart
import 'dart:async';
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import 'dart:convert';
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import 'package:shared_preferences/shared_preferences.dart';
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abstract mixin class SharedPreferencesBacked<T> {
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SharedPreferences get _sharedPreferences;
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String keyName();
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T valueFromJson(Object? obj);
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Object? valueToJson(T val);
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/// Load things from storage
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Future<T> load() async {
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final valueJsonStr = _sharedPreferences.getString(keyName());
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final Object? valueJsonObj =
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valueJsonStr != null ? jsonDecode(valueJsonStr) : null;
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return valueFromJson(valueJsonObj);
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}
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/// Store things to storage
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Future<T> store(T obj) async {
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final valueJsonObj = valueToJson(obj);
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if (valueJsonObj == null) {
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await _sharedPreferences.remove(keyName());
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} else {
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await _sharedPreferences.setString(keyName(), jsonEncode(valueJsonObj));
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}
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return obj;
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}
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}
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class SharedPreferencesValue<T> extends SharedPreferencesBacked<T> {
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SharedPreferencesValue({
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required SharedPreferences sharedPreferences,
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required String keyName,
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required T Function(Object? obj) valueFromJson,
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required Object? Function(T obj) valueToJson,
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}) : _sharedPreferencesInstance = sharedPreferences,
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_valueFromJson = valueFromJson,
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_valueToJson = valueToJson,
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_keyName = keyName,
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_streamController = StreamController<T>.broadcast();
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@override
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SharedPreferences get _sharedPreferences => _sharedPreferencesInstance;
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T? get value => _value;
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T get requireValue => _value!;
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Stream<T> get stream => _streamController.stream;
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Future<T> get() async {
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final val = _value;
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if (val != null) {
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return val;
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}
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final loadedValue = await load();
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return _value = loadedValue;
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}
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Future<void> set(T newVal) async {
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_value = await store(newVal);
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_streamController.add(newVal);
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}
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T? _value;
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final SharedPreferences _sharedPreferencesInstance;
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final String _keyName;
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final T Function(Object? obj) _valueFromJson;
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final Object? Function(T obj) _valueToJson;
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final StreamController<T> _streamController;
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//////////////////////////////////////////////////////////////
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/// SharedPreferencesBacked
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@override
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String keyName() => _keyName;
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@override
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T valueFromJson(Object? obj) => _valueFromJson(obj);
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@override
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Object? valueToJson(T val) => _valueToJson(val);
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}
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