SvelteSet Class — svelte Architecture

Source Code

packages/svelte/src/reactivity/set.js lines 47–213

export class SvelteSet extends Set {
	/** @type {Map<T, Source<boolean>>} */
	#sources = new Map();
	#version = state(0);
	#size = state(0);
	#update_version = update_version || -1;

	/**
	 * @param {Iterable<T> | null | undefined} [value]
	 */
	constructor(value) {
		super();

		if (DEV) {
			// If the value is invalid then the native exception will fire here
			value = new Set(value);

			tag(this.#version, 'SvelteSet version');
			tag(this.#size, 'SvelteSet.size');
		}

		if (value) {
			for (var element of value) {
				super.add(element);
			}
			this.#size.v = super.size;
		}

		if (!inited) this.#init();
	}

	/**
	 * If the source is being created inside the same reaction as the SvelteSet instance,
	 * we use `state` so that it will not be a dependency of the reaction. Otherwise we
	 * use `source` so it will be.
	 *
	 * @template T
	 * @param {T} value
	 * @returns {Source<T>}
	 */
	#source(value) {
		return update_version === this.#update_version ? state(value) : source(value);
	}

	// We init as part of the first instance so that we can treeshake this class
	#init() {
		inited = true;

		var proto = SvelteSet.prototype;
		var set_proto = Set.prototype;

		for (const method of read_methods) {
			// @ts-ignore
			proto[method] = function (...v) {
				get(this.#version);
				// @ts-ignore
				return set_proto[method].apply(this, v);
			};
		}

		for (const method of set_like_methods) {
			// @ts-ignore
			proto[method] = function (...v) {
				get(this.#version);
				// @ts-ignore
				var set = /** @type {Set<T>} */ (set_proto[method].apply(this, v));
				return new SvelteSet(set);
			};
		}
	}

	/** @param {T} value */
	has(value) {
		var has = super.has(value);
		var sources = this.#sources;
		var s = sources.get(value);

		if (s === undefined) {
			if (!has) {
				// If the value doesn't exist, track the version in case it's added later
				// but don't create sources willy-nilly to track all possible values