Function await_block

packages/svelte/src/internal/client/dom/blocks/await.js:36–153

(node, get_input, pending_fn, then_fn, catch_fn)

 * @returns {void}
 */
export function await_block(node, get_input, pending_fn, then_fn, catch_fn) {
	if (hydrating) {
		hydrate_next();
	}

	var runes = is_runes();

	var v = /** @type {V} */ (UNINITIALIZED);
	var value = runes ? source(v) : mutable_source(v, false, false);
	var error = runes ? source(v) : mutable_source(v, false, false);

	if (DEV) {
		value.label = '{#await ...} value';
		error.label = '{#await ...} error';
	}

	var branches = new BranchManager(node);

	block(() => {
		var batch = /** @type {Batch} */ (current_batch);
		var input = get_input();

		var destroyed = false;

		/** Whether or not there was a hydration mismatch. Needs to be a `let` or else it isn't treeshaken out */
		// @ts-ignore coercing `node` to a `Comment` causes TypeScript and Prettier to fight
		let mismatch = hydrating && is_promise(input) === (node.data === HYDRATION_START_ELSE);

		if (mismatch) {
			// Hydration mismatch: remove everything inside the anchor and start fresh
			set_hydrate_node(skip_nodes());
			set_hydrating(false);
		}

		if (is_promise(input)) {
			var restore = capture();
			var resolved = false;

			/**
			 * @param {() => void} fn
			 */
			const resolve = (fn) => {
				if (destroyed) return;

				resolved = true;
				// We don't want to restore the previous batch here; {#await} blocks don't follow the async logic
				// we have elsewhere, instead pending/resolve/fail states are each their own batch so to speak.
				restore(false);
				// ...but it might still be set here. That means a `save(...)` has restored it — but that batch will
				// likely already have been committed by the time it resolves, and this resolve should be processed
				// in a separate batch. We're not using batch.deactivate()/activate() above because get_input()
				// could write to sources, which would then incorrectly create a new batch or could mess with
				// async_derived expecting a current_batch to exist.
				if (current_batch === batch) {
					batch.deactivate();
				}
				// Make sure we have a batch, since the branch manager expects one to exist
				Batch.ensure();