@trpc/server/dist/observable-kpFFzvou.mjs

The tRPC server library

//#region src/observable/observable.ts
/**
* Whether a value is an observable: an object with `subscribe`.
* @public
*/
function isObservable(x) {
	return typeof x === "object" && x !== null && "subscribe" in x;
}
/**
* Creates an observable. `subscribe` runs for each subscriber, and can
* return a function that cleans up when it unsubscribes.
* @example
* ```ts
* const ticks = observable<number>((observer) => {
*   const timer = setInterval(() => observer.next(Date.now()), 1000);
*   return () => clearInterval(timer);
* });
* ```
* @see https://trpc.io/docs/client/links#creating-a-custom-link
* @public
*/
function observable(subscribe) {
	const self = {
		subscribe(observer) {
			let teardownRef = null;
			let isDone = false;
			let unsubscribed = false;
			let teardownImmediately = false;
			let subscribing = true;
			let thrownWhileSubscribing = null;
			function end(notify) {
				try {
					notify();
				} catch (cause) {
					var _thrownWhileSubscribi;
					if (!subscribing) throw cause;
					(_thrownWhileSubscribi = thrownWhileSubscribing) !== null && _thrownWhileSubscribi !== void 0 || (thrownWhileSubscribing = { cause });
				} finally {
					unsubscribe();
				}
			}
			function unsubscribe() {
				if (teardownRef === null) {
					teardownImmediately = true;
					return;
				}
				if (unsubscribed) return;
				unsubscribed = true;
				if (typeof teardownRef === "function") teardownRef();
				else if (teardownRef) teardownRef.unsubscribe();
			}
			teardownRef = subscribe({
				next(value) {
					var _observer$next;
					if (isDone) return;
					(_observer$next = observer.next) === null || _observer$next === void 0 || _observer$next.call(observer, value);
				},
				error(err) {
					if (isDone) return;
					isDone = true;
					end(() => {
						var _observer$error;
						return (_observer$error = observer.error) === null || _observer$error === void 0 ? void 0 : _observer$error.call(observer, err);
					});
				},
				complete() {
					if (isDone) return;
					isDone = true;
					end(() => {
						var _observer$complete;
						return (_observer$complete = observer.complete) === null || _observer$complete === void 0 ? void 0 : _observer$complete.call(observer);
					});
				}
			});
			subscribing = false;
			if (teardownImmediately) unsubscribe();
			if (thrownWhileSubscribing) throw thrownWhileSubscribing.cause;
			return { unsubscribe };
		},
		pipe(...operations) {
			return operations.reduce(pipeReducer, self);
		}
	};
	return self;
}
function pipeReducer(prev, fn) {
	return fn(prev);
}
/**
* Resolves with an observable's first value. Rejects if it errors or
* completes first. It doesn't unsubscribe after the first value.
* @internal
*/
function observableToPromise(observable) {
	const ac = new AbortController();
	return new Promise((resolve, reject) => {
		let isDone = false;
		function onDone() {
			if (isDone) return;
			isDone = true;
			obs$.unsubscribe();
		}
		ac.signal.addEventListener("abort", () => {
			reject(ac.signal.reason);
		});
		const obs$ = observable.subscribe({
			next(data) {
				isDone = true;
				resolve(data);
				onDone();
			},
			error(data) {
				reject(data);
			},
			complete() {
				ac.abort();
				onDone();
			}
		});
	});
}
/**
* Turns an observable into an async iterable, like Node's `events.on()`.
* Values wait in a queue until `next()` reads them. An error rejects the
* `next()` after the queued values, once. Completion, `return()` and aborting
* `signal` unsubscribe and end every pending `next()` with `{ done: true }`;
* anything the observable sends after that is ignored.
*
* If unsubscribing throws, `return()` rejects with the error, and completion
* or an error from the observable rethrows it. On abort, it rejects the
* `next()` after the queued values instead, as an error would.
* @internal
*/
function observableToAsyncIterable(observable, signal) {
	const values = [];
	const pending = [];
	let error = null;
	let finished = false;
	let subscription = null;
	/** Unsubscribes once, and returns what the teardown threw. */
	function unsubscribe() {
		if (finished) return null;
		finished = true;
		signal.removeEventListener("abort", abort);
		try {
			subscription === null || subscription === void 0 || subscription.unsubscribe();
			return null;
		} catch (cause) {
			return { cause };
		}
	}
	/** Settles every pending `next()`: the first with `error` if there is one. */
	function settle() {
		const first = error ? pending.shift() : void 0;
		if (error && first) {
			const { cause } = error;
			error = null;
			first.reject(cause);
		}
		for (const promise of pending.splice(0)) promise.resolve({
			value: void 0,
			done: true
		});
	}
	function finish() {
		const failure = unsubscribe();
		settle();
		if (failure) throw failure.cause;
	}
	function abort() {
		const failure = unsubscribe();
		if (failure) error = failure;
		settle();
	}
	subscription = observable.subscribe({
		next(value) {
			if (finished) return;
			const promise = pending.shift();
			if (promise) promise.resolve({
				value,
				done: false
			});
			else values.push(value);
		},
		error(cause) {
			if (finished) return;
			error = { cause };
			finish();
		},
		complete: finish
	});
	if (finished) subscription.unsubscribe();
	else if (signal.aborted) abort();
	else signal.addEventListener("abort", abort, { once: true });
	const iterator = {
		[Symbol.asyncIterator]() {
			return iterator;
		},
		async next() {
			if (values.length > 0) return {
				value: values.shift(),
				done: false
			};
			if (error) {
				const { cause } = error;
				error = null;
				throw cause;
			}
			if (finished) return {
				value: void 0,
				done: true
			};
			return new Promise((resolve, reject) => {
				pending.push({
					resolve,
					reject
				});
			});
		},
		async return() {
			values.length = 0;
			error = null;
			finish();
			return {
				value: void 0,
				done: true
			};
		}
	};
	return iterator;
}
//#endregion
export { observableToPromise as i, observable as n, observableToAsyncIterable as r, isObservable as t };


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