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

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import { is_promise, noop } from '../../../shared/utils.js';
import {
	current_component_context,
	flush_sync,
	set_current_component_context,
	set_current_effect,
	set_current_reaction,
	set_dev_current_component_function
} from '../../runtime.js';
import { block, branch, pause_effect, resume_effect } from '../../reactivity/effects.js';
import { DEV } from 'esm-env';
import { queue_micro_task } from '../task.js';
import { hydrating } from '../hydration.js';
import { set, source } from '../../reactivity/sources.js';
 
const PENDING = 0;
const THEN = 1;
const CATCH = 2;
 
/**
 * @template V
 * @param {Comment} anchor
 * @param {(() => Promise<V>)} get_input
 * @param {null | ((anchor: Node) => void)} pending_fn
 * @param {null | ((anchor: Node, value: import('#client').Source<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) {
	var component_context = current_component_context;
 
	/** @type {any} */
	var component_function = DEV ? component_context?.function : null;
 
	/** @type {V | Promise<V>} */
	var input;
 
	/** @type {import('#client').Effect | null} */
	var pending_effect;
 
	/** @type {import('#client').Effect | null} */
	var then_effect;
 
	/** @type {import('#client').Effect | null} */
	var catch_effect;
 
	var input_source = source(/** @type {V} */ (undefined));
	var error_source = source(undefined);
	var resolved = false;
 
	/**
	 * @param {PENDING | THEN | CATCH} state
	 * @param {boolean} restore
	 */
	function update(state, restore) {
		resolved = true;
 
		if (restore) {
			set_current_effect(effect);
			set_current_reaction(effect); // TODO do we need both?
			set_current_component_context(component_context);
			if (DEV) set_dev_current_component_function(component_function);
		}
 
		if (state === PENDING && pending_fn) {
			if (pending_effect) resume_effect(pending_effect);
			else pending_effect = branch(() => pending_fn(anchor));
		}
 
		if (state === THEN && then_fn) {
			if (then_effect) resume_effect(then_effect);
			else then_effect = branch(() => then_fn(anchor, input_source));
		}
 
		if (state === CATCH && catch_fn) {
			if (catch_effect) resume_effect(catch_effect);
			else catch_effect = branch(() => catch_fn(anchor, error_source));
		}
 
		if (state !== PENDING && pending_effect) {
			pause_effect(pending_effect, () => (pending_effect = null));
		}
 
		if (state !== THEN && then_effect) {
			pause_effect(then_effect, () => (then_effect = null));
		}
 
		if (state !== CATCH && catch_effect) {
			pause_effect(catch_effect, () => (catch_effect = null));
		}
 
		if (restore) {
			if (DEV) set_dev_current_component_function(null);
			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();
		}
	}
 
	var effect = block(() => {
		if (input === (input = get_input())) return;
 
		if (is_promise(input)) {
			var promise = input;
 
			resolved = false;
 
			promise.then(
				(value) => {
					if (promise !== input) return;
					set(input_source, value);
					update(THEN, true);
				},
				(error) => {
					if (promise !== input) return;
					set(error_source, error);
					update(CATCH, true);
				}
			);
 
			if (hydrating) {
				if (pending_fn) {
					pending_effect = branch(() => pending_fn(anchor));
				}
			} else {
				// Wait a microtask before checking if we should show the pending state as
				// the promise might have resolved by the next microtask.
				queue_micro_task(() => {
					if (!resolved) update(PENDING, true);
				});
			}
		} else {
			set(input_source, input);
			update(THEN, false);
		}
 
		// Inert effects are proactively detached from the effect tree. Returning a noop
		// teardown function is an easy way to ensure that this is not discarded
		return noop;
	});
}