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63 lines
1.6 KiB
Dart
63 lines
1.6 KiB
Dart
// Copyright 2016 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'dart:async';
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final AppContext _defaultContext = new AppContext();
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/// A singleton for application functionality. This singleton can be different
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/// on a per-Zone basis.
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AppContext get context {
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AppContext currentContext = Zone.current['context'];
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return currentContext == null ? _defaultContext : currentContext;
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}
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class AppContext {
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Map<Type, dynamic> _instances = <Type, dynamic>{};
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bool isSet(Type type) {
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if (_instances.containsKey(type))
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return true;
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AppContext parent = _calcParent(Zone.current);
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return parent != null ? parent.isSet(type) : false;
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}
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dynamic getVariable(Type type) {
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if (_instances.containsKey(type))
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return _instances[type];
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AppContext parent = _calcParent(Zone.current);
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return parent?.getVariable(type);
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}
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void setVariable(Type type, dynamic instance) {
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_instances[type] = instance;
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}
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dynamic operator[](Type type) => getVariable(type);
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void operator[]=(Type type, dynamic instance) => setVariable(type, instance);
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AppContext _calcParent(Zone zone) {
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if (this == _defaultContext)
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return null;
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Zone parentZone = zone.parent;
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if (parentZone == null)
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return _defaultContext;
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AppContext deps = parentZone['context'];
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if (deps == this) {
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return _calcParent(parentZone);
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} else {
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return deps != null ? deps : _defaultContext;
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}
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}
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dynamic runInZone(dynamic method()) {
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return runZoned(method, zoneValues: {'context': this});
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}
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}
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