91 lines
2.1 KiB
TypeScript
91 lines
2.1 KiB
TypeScript
type Untap = () => void
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type UntapFromSource = () => void
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interface IProps<V> {
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tapToSource: (cb: (payload: V) => void) => UntapFromSource
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}
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type Listener<V> = ((v: V) => void) | (() => void)
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export default class Tappable<V> {
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private _props: IProps<V>
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private _tappers: Map<number, {bivarianceHack(v: V): void}['bivarianceHack']>
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private _untapFromSource: null | UntapFromSource
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private _lastTapperId: number
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private _untapFromSourceTimeout: null | NodeJS.Timer = null
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constructor(props: IProps<V>) {
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this._lastTapperId = 0
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this._untapFromSource = null
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this._props = props
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this._tappers = new Map()
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}
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private _check() {
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if (this._untapFromSource) {
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if (this._tappers.size === 0) {
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this._scheduleToUntapFromSource()
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/*
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* this._untapFromSource()
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* this._untapFromSource = null
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*/
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}
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} else {
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if (this._tappers.size !== 0) {
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this._untapFromSource = this._props.tapToSource(this._cb)
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}
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}
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}
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private _scheduleToUntapFromSource() {
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if (this._untapFromSourceTimeout !== null) return
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this._untapFromSourceTimeout = setTimeout(() => {
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this._untapFromSourceTimeout = null
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if (this._tappers.size === 0) {
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this._untapFromSource!()
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this._untapFromSource = null
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}
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}, 0)
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}
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private _cb: any = (arg: any): void => {
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this._tappers.forEach((cb) => {
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cb(arg)
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})
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}
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tap(cb: Listener<V>): Untap {
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const tapperId = this._lastTapperId++
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this._tappers.set(tapperId, cb)
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this._check()
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return () => {
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this._removeTapperById(tapperId)
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}
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}
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/*
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* tapImmediate(cb: Listener<V>): Untap {
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* const ret = this.tap(cb)
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* return ret
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* }
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*/
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private _removeTapperById(id: number) {
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this._tappers.delete(id)
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this._check()
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}
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// /**
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// * @deprecated
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// */
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// map<T>(transform: {bivarianceHack(v: V): T}['bivarianceHack']): Tappable<T> {
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// return new Tappable({
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// tapToSource: (cb: (v: T) => void) => {
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// return this.tap((v: $IntentionalAny) => {
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// return cb(transform(v))
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// })
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// },
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// })
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// }
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}
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