eewing
26 lines
666 B
JavaScript
26 lines
666 B
JavaScript
/**
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* Holds the previous value of a getter.
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*
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* @see {@link https://runed.dev/docs/utilities/previous}
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*/
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export class Previous {
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#previousCallback = () => undefined;
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#previous = $derived.by(() => this.#previousCallback());
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constructor(getter, initialValue) {
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let actualPrevious = undefined;
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if (initialValue !== undefined)
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actualPrevious = initialValue;
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this.#previousCallback = () => {
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try {
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return actualPrevious;
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}
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finally {
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actualPrevious = getter();
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}
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};
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}
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get current() {
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return this.#previous;
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}
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}
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