seitu/dist/core/subscription/index.mjs

//#region src/core/subscription/index.ts
function createReadableSubscription(get, subscribe, notify, getServer) {
	return {
		get,
		...getServer ? { getServer } : {},
		subscribe(callback, options) {
			return subscribe(() => callback(get()), options);
		},
		"~": {
			output: null,
			notify
		}
	};
}
/**
* Subscribe/notify primitive used by every reactive handle.
*
* - `onFirstSubscribe` attaches on first subscriber and cleans up on last.
* - `notify` calls every subscriber; the first throw is rethrown after the loop.
* - `size` is the subscriber count.
*
* @example
* ```ts twoslash
* import { createSubscription } from 'seitu'
*
* const { subscribe, notify, size } = createSubscription({
*   onFirstSubscribe: () => {
*     const id = setInterval(notify, 1000)
*     return () => clearInterval(id)
*   },
* })
* ```
*/
function createSubscription(options) {
	const subscribers = /* @__PURE__ */ new Set();
	let onEmpty;
	const notify = () => {
		let error;
		for (const cb of [...subscribers]) {
			if (!subscribers.has(cb)) continue;
			try {
				cb();
			} catch (caught) {
				error ??= { caught };
			}
		}
		if (error) throw error.caught;
	};
	return {
		subscribe(callback, opts) {
			if (subscribers.size === 0 && options?.onFirstSubscribe) onEmpty = options.onFirstSubscribe() ?? void 0;
			subscribers.add(callback);
			if (opts?.immediate) callback();
			return () => {
				if (!subscribers.delete(callback)) return;
				if (subscribers.size === 0) {
					onEmpty?.();
					onEmpty = void 0;
				}
			};
		},
		notify,
		get size() {
			return subscribers.size;
		}
	};
}
//#endregion
export { createReadableSubscription, createSubscription };