All files / src/internal/client/dom/blocks await.js

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import { is_promise } from '../../../shared/utils.js';
import {
	current_component_context,
	flush_sync,
	set_current_component_context,
	set_current_effect,
	set_current_reaction
} from '../../runtime.js';
import { block, branch, destroy_effect, pause_effect } from '../../reactivity/effects.js';
import { INERT } from '../../constants.js';
 
/**
 * @template V
 * @param {Comment} anchor
 * @param {(() => Promise<V>)} get_input
 * @param {null | ((anchor: Node) => void)} pending_fn
 * @param {null | ((anchor: Node, value: V) => void)} then_fn
 * @param {null | ((anchor: Node, error: unknown) => void)} catch_fn
 * @returns {void}
 */
export function await_block(anchor, get_input, pending_fn, then_fn, catch_fn) {
	const component_context = current_component_context;
 
	/** @type {any} */
	let input;
 
	/** @type {import('#client').Effect | null} */
	let pending_effect;
 
	/** @type {import('#client').Effect | null} */
	let then_effect;
 
	/** @type {import('#client').Effect | null} */
	let catch_effect;
 
	/**
	 * @param {(anchor: Comment, value: any) => void} fn
	 * @param {any} value
	 */
	function create_effect(fn, value) {
		set_current_effect(effect);
		set_current_reaction(effect); // TODO do we need both?
		set_current_component_context(component_context);
		var e = branch(() => fn(anchor, value));
		set_current_component_context(null);
		set_current_reaction(null);
		set_current_effect(null);
 
		// without this, the DOM does not update until two ticks after the promise,
		// resolves which is unexpected behaviour (and somewhat irksome to test)
		flush_sync();
 
		return e;
	}
 
	const effect = block(() => {
		if (input === (input = get_input())) return;
 
		if (is_promise(input)) {
			const promise = /** @type {Promise<any>} */ (input);
 
			if (pending_fn) {
				if (pending_effect && (pending_effect.f & INERT) === 0) {
					destroy_effect(pending_effect);
				}
 
				pending_effect = branch(() => pending_fn(anchor));
			}
 
			if (then_effect) pause_effect(then_effect);
			if (catch_effect) pause_effect(catch_effect);
 
			promise.then(
				(value) => {
					if (promise !== input) return;
					if (pending_effect) pause_effect(pending_effect);
 
					if (then_fn) {
						then_effect = create_effect(then_fn, value);
					}
				},
				(error) => {
					if (promise !== input) return;
					if (pending_effect) pause_effect(pending_effect);
 
					if (catch_fn) {
						catch_effect = create_effect(catch_fn, error);
					}
				}
			);
		} else {
			if (pending_effect) pause_effect(pending_effect);
			if (catch_effect) pause_effect(catch_effect);
 
			if (then_fn) {
				if (then_effect) {
					destroy_effect(then_effect);
				}
 
				then_effect = branch(() => then_fn(anchor, input));
			}
		}
	});
}