35 lines
773 B
TypeScript
35 lines
773 B
TypeScript
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import DerivationFromSource from './derivations/DerivationFromSource'
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import type {IDerivation} from './derivations/IDerivation'
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import Emitter from './utils/Emitter'
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export interface IBox<V> {
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set(v: V): void
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get(): V
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derivation: IDerivation<V>
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}
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export default class Box<V> implements IBox<V> {
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private _publicDerivation: IDerivation<V>
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private _emitter = new Emitter<V>()
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constructor(protected _value: V) {
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this._publicDerivation = new DerivationFromSource(
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(listener) => this._emitter.tappable.tap(listener),
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this.get.bind(this),
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)
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}
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set(v: V) {
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if (v === this._value) return
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this._value = v
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this._emitter.emit(v)
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}
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get() {
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return this._value
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}
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get derivation() {
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return this._publicDerivation
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}
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}
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