seitu/dist/core/computed/index.mjs

import { createReadableSubscription, createSubscription } from "../subscription/index.mjs";
//#region src/core/computed/index.ts
function createComputed(source, transform) {
	const sources = Array.isArray(source) ? source : [source];
	const isSingle = !Array.isArray(source);
	const { subscribe, notify } = createSubscription({ onFirstSubscribe() {
		const unsubscribes = sources.map((s) => s.subscribe(() => notify()));
		return () => unsubscribes.forEach((u) => u());
	} });
	const evaluate = (values) => transform(isSingle ? values[0] : values);
	let lastInputs;
	let lastOutput;
	const get = () => {
		const inputs = sources.map((s) => s.get());
		if (!lastInputs || lastInputs.some((v, i) => v !== inputs[i])) {
			lastOutput = evaluate(inputs);
			lastInputs = inputs;
		}
		return lastOutput;
	};
	const getServer = sources.every((s) => s.getServer) ? () => evaluate(sources.map((s) => s.getServer())) : void 0;
	return createReadableSubscription(get, subscribe, notify, getServer);
}
//#endregion
export { createComputed };