Created
March 16, 2020 11:20
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| class Prop { | |
| constructor(writer, listeners) { | |
| this.writer = writer; | |
| this.listeners = listeners; | |
| } | |
| } | |
| class PropReader { | |
| constructor(name, changeListener, props) { | |
| this._name = name; | |
| this._changeListener = changeListener; | |
| this._props = props; | |
| this._registered = true; | |
| } | |
| get name() { | |
| return this._name; | |
| } | |
| get registered() { | |
| return this._registered; | |
| } | |
| /** | |
| * Will return undefined until value is set. This method should | |
| * not be frequently called | |
| */ | |
| get() { | |
| const prop = this._props._map.get(this._name); | |
| if (prop && (writer = prop.writer)) return writer._value; | |
| return undefined; | |
| } | |
| register() { | |
| if (this._registered) return false; | |
| this._props._registerChangeListener(_this.name, this._changeListener); | |
| this._registered = true; | |
| return true; | |
| } | |
| unregister() { | |
| if (!this._registered) return false; | |
| const prop = this._props._map.get(this._name); | |
| if (prop) { | |
| prop.listeners.delete(this._changeListener); | |
| } | |
| this.registered = false; | |
| return true; | |
| } | |
| } | |
| class PropWriter { | |
| constructor(name, listeners, props) { | |
| this._name = name; | |
| this._registered = true; | |
| this._listeners = listeners; | |
| this._props = props; | |
| } | |
| get name() { | |
| return this._name; | |
| } | |
| get registered() { | |
| return this._registered; | |
| } | |
| set(newValue) { | |
| for (let l of this._listeners) { | |
| l(newValue, this._value) | |
| } | |
| this._value = newValue; | |
| } | |
| unregister() { | |
| if (!this._registered) return false; | |
| const prop = this._props._map.get(this._name); | |
| delete prop.writer; | |
| this._registered = false; | |
| return true; | |
| } | |
| } | |
| export class Props { | |
| constructor() { | |
| this._map = new Map(); | |
| } | |
| reader(name, changeListener) { | |
| const reader = new PropReader(name, changeListener, this); | |
| this._registerChangeListener(name, changeListener); | |
| return reader; | |
| } | |
| _registerChangeListener(name, changeListener) { | |
| let prop = this._map.get(name); | |
| if (prop) { | |
| prop.listeners.add(changeListener); | |
| } else { | |
| prop = new Prop(null, new Set().add(changeListener)); | |
| this._map.set(name, prop); | |
| } | |
| } | |
| writer(name) { | |
| let prop = this._map.get(name); | |
| if (prop) { | |
| if (prop.writer) throw 'Writer already exists for ' + name; | |
| const w = new PropWriter(name, prop.listeners, this); | |
| prop.writer = w; | |
| return w; | |
| } | |
| const listeners = new Set(); | |
| const w = new PropWriter(name, listeners, this); | |
| prop = new Prop(w, listeners); | |
| this._map.set(name, prop); | |
| return w; | |
| } | |
| } | |
| export const props = new Props(); |
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