store.js — svelte Source File

Source Code

/** @import { StoreReferencesContainer } from '#client' */
/** @import { Store } from '#shared' */
import { subscribe_to_store } from '../../../store/utils.js';
import { get as get_store } from '../../../store/shared/index.js';
import { define_property, noop } from '../../shared/utils.js';
import { get } from '../runtime.js';
import { teardown } from './effects.js';
import { mutable_source, set } from './sources.js';
import { DEV } from 'esm-env';

/**
 * Whether or not the prop currently being read is a store binding, as in
 * `<Child bind:x={$y} />`. If it is, we treat the prop as mutable even in
 * runes mode, and skip `binding_property_non_reactive` validation
 */
let is_store_binding = false;

let IS_UNMOUNTED = Symbol();

/**
 * Gets the current value of a store. If the store isn't subscribed to yet, it will create a proxy
 * signal that will be updated when the store is. The store references container is needed to
 * track reassignments to stores and to track the correct component context.
 * @template V
 * @param {Store<V> | null | undefined} store
 * @param {string} store_name
 * @param {StoreReferencesContainer} stores
 * @returns {V}
 */
export function store_get(store, store_name, stores) {
	const entry = (stores[store_name] ??= {
		store: null,
		source: mutable_source(undefined),
		unsubscribe: noop
	});

	if (DEV) {
		entry.source.label = store_name;
	}

	// if the component that setup this is already unmounted we don't want to register a subscription
	if (entry.store !== store && !(IS_UNMOUNTED in stores)) {
		entry.unsubscribe();
		entry.store = store ?? null;

		if (store == null) {
			entry.source.v = undefined; // see synchronous callback comment below
			entry.unsubscribe = noop;
		} else {
			var is_synchronous_callback = true;

			entry.unsubscribe = subscribe_to_store(store, (v) => {
				if (is_synchronous_callback) {
					// If the first updates to the store value (possibly multiple of them) are synchronously
					// inside a derived, we will hit the `state_unsafe_mutation` error if we `set` the value
					entry.source.v = v;
				} else {
					set(entry.source, v);
				}
			});
// ... (144 more lines)