apps.apple.com/node_modules/svelte/src/runtime/internal/utils.js

/** @returns {void} */
export function noop() {}

export const identity = (x) => x;

/**
 * @template T
 * @template S
 * @param {T} tar
 * @param {S} src
 * @returns {T & S}
 */
export function assign(tar, src) {
	// @ts-ignore
	for (const k in src) tar[k] = src[k];
	return /** @type {T & S} */ (tar);
}

// Adapted from https://github.com/then/is-promise/blob/master/index.js
// Distributed under MIT License https://github.com/then/is-promise/blob/master/LICENSE
/**
 * @param {any} value
 * @returns {value is PromiseLike<any>}
 */
export function is_promise(value) {
	return (
		!!value &&
		(typeof value === 'object' || typeof value === 'function') &&
		typeof (/** @type {any} */ (value).then) === 'function'
	);
}

/** @returns {void} */
export function add_location(element, file, line, column, char) {
	element.__svelte_meta = {
		loc: { file, line, column, char }
	};
}

export function run(fn) {
	return fn();
}

export function blank_object() {
	return Object.create(null);
}

/**
 * @param {Function[]} fns
 * @returns {void}
 */
export function run_all(fns) {
	fns.forEach(run);
}

/**
 * @param {any} thing
 * @returns {thing is Function}
 */
export function is_function(thing) {
	return typeof thing === 'function';
}

/** @returns {boolean} */
export function safe_not_equal(a, b) {
	return a != a ? b == b : a !== b || (a && typeof a === 'object') || typeof a === 'function';
}

let src_url_equal_anchor;

/**
 * @param {string} element_src
 * @param {string} url
 * @returns {boolean}
 */
export function src_url_equal(element_src, url) {
	if (element_src === url) return true;
	if (!src_url_equal_anchor) {
		src_url_equal_anchor = document.createElement('a');
	}
	// This is actually faster than doing URL(..).href
	src_url_equal_anchor.href = url;
	return element_src === src_url_equal_anchor.href;
}

/** @param {string} srcset */
function split_srcset(srcset) {
	return srcset.split(',').map((src) => src.trim().split(' ').filter(Boolean));
}

/**
 * @param {HTMLSourceElement | HTMLImageElement} element_srcset
 * @param {string | undefined | null} srcset
 * @returns {boolean}
 */
export function srcset_url_equal(element_srcset, srcset) {
	const element_urls = split_srcset(element_srcset.srcset);
	const urls = split_srcset(srcset || '');

	return (
		urls.length === element_urls.length &&
		urls.every(
			([url, width], i) =>
				width === element_urls[i][1] &&
				// We need to test both ways because Vite will create an a full URL with
				// `new URL(asset, import.meta.url).href` for the client when `base: './'`, and the
				// relative URLs inside srcset are not automatically resolved to absolute URLs by
				// browsers (in contrast to img.src). This means both SSR and DOM code could
				// contain relative or absolute URLs.
				(src_url_equal(element_urls[i][0], url) || src_url_equal(url, element_urls[i][0]))
		)
	);
}

/** @returns {boolean} */
export function not_equal(a, b) {
	return a != a ? b == b : a !== b;
}

/** @returns {boolean} */
export function is_empty(obj) {
	return Object.keys(obj).length === 0;
}

/** @returns {void} */
export function validate_store(store, name) {
	if (store != null && typeof store.subscribe !== 'function') {
		throw new Error(`'${name}' is not a store with a 'subscribe' method`);
	}
}

export function subscribe(store, ...callbacks) {
	if (store == null) {
		for (const callback of callbacks) {
			callback(undefined);
		}
		return noop;
	}
	const unsub = store.subscribe(...callbacks);
	return unsub.unsubscribe ? () => unsub.unsubscribe() : unsub;
}

/**
 * Get the current value from a store by subscribing and immediately unsubscribing.
 *
 * https://svelte.dev/docs/svelte-store#get
 * @template T
 * @param {import('../store/public.js').Readable<T>} store
 * @returns {T}
 */
export function get_store_value(store) {
	let value;
	subscribe(store, (_) => (value = _))();
	return value;
}

/** @returns {void} */
export function component_subscribe(component, store, callback) {
	component.$$.on_destroy.push(subscribe(store, callback));
}

export function create_slot(definition, ctx, $$scope, fn) {
	if (definition) {
		const slot_ctx = get_slot_context(definition, ctx, $$scope, fn);
		return definition[0](slot_ctx);
	}
}

function get_slot_context(definition, ctx, $$scope, fn) {
	return definition[1] && fn ? assign($$scope.ctx.slice(), definition[1](fn(ctx))) : $$scope.ctx;
}

export function get_slot_changes(definition, $$scope, dirty, fn) {
	if (definition[2] && fn) {
		const lets = definition[2](fn(dirty));
		if ($$scope.dirty === undefined) {
			return lets;
		}
		if (typeof lets === 'object') {
			const merged = [];
			const len = Math.max($$scope.dirty.length, lets.length);
			for (let i = 0; i < len; i += 1) {
				merged[i] = $$scope.dirty[i] | lets[i];
			}
			return merged;
		}
		return $$scope.dirty | lets;
	}
	return $$scope.dirty;
}

/** @returns {void} */
export function update_slot_base(
	slot,
	slot_definition,
	ctx,
	$$scope,
	slot_changes,
	get_slot_context_fn
) {
	if (slot_changes) {
		const slot_context = get_slot_context(slot_definition, ctx, $$scope, get_slot_context_fn);
		slot.p(slot_context, slot_changes);
	}
}

/** @returns {void} */
export function update_slot(
	slot,
	slot_definition,
	ctx,
	$$scope,
	dirty,
	get_slot_changes_fn,
	get_slot_context_fn
) {
	const slot_changes = get_slot_changes(slot_definition, $$scope, dirty, get_slot_changes_fn);
	update_slot_base(slot, slot_definition, ctx, $$scope, slot_changes, get_slot_context_fn);
}

/** @returns {any[] | -1} */
export function get_all_dirty_from_scope($$scope) {
	if ($$scope.ctx.length > 32) {
		const dirty = [];
		const length = $$scope.ctx.length / 32;
		for (let i = 0; i < length; i++) {
			dirty[i] = -1;
		}
		return dirty;
	}
	return -1;
}

/** @returns {{}} */
export function exclude_internal_props(props) {
	const result = {};
	for (const k in props) if (k[0] !== '$') result[k] = props[k];
	return result;
}

/** @returns {{}} */
export function compute_rest_props(props, keys) {
	const rest = {};
	keys = new Set(keys);
	for (const k in props) if (!keys.has(k) && k[0] !== '$') rest[k] = props[k];
	return rest;
}

/** @returns {{}} */
export function compute_slots(slots) {
	const result = {};
	for (const key in slots) {
		result[key] = true;
	}
	return result;
}

/** @returns {(this: any, ...args: any[]) => void} */
export function once(fn) {
	let ran = false;
	return function (...args) {
		if (ran) return;
		ran = true;
		fn.call(this, ...args);
	};
}

export function null_to_empty(value) {
	return value == null ? '' : value;
}

export function set_store_value(store, ret, value) {
	store.set(value);
	return ret;
}

export const has_prop = (obj, prop) => Object.prototype.hasOwnProperty.call(obj, prop);

export function action_destroyer(action_result) {
	return action_result && is_function(action_result.destroy) ? action_result.destroy : noop;
}

/** @param {number | string} value
 * @returns {[number, string]}
 */
export function split_css_unit(value) {
	const split = typeof value === 'string' && value.match(/^\s*(-?[\d.]+)([^\s]*)\s*$/);
	return split ? [parseFloat(split[1]), split[2] || 'px'] : [/** @type {number} */ (value), 'px'];
}

export const contenteditable_truthy_values = ['', true, 1, 'true', 'contenteditable'];