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