105 lines
2.9 KiB
JavaScript
105 lines
2.9 KiB
JavaScript
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/**
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @format
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* @flow strict
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*/
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// flowlint unsafe-getters-setters:off
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import type {ArrayLike} from './ArrayLikeUtils';
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import {
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createEntriesIterator,
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createKeyIterator,
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createValueIterator,
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} from './ArrayLikeUtils';
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// IMPORTANT: The Flow type definition for this module is defined in `NodeList.js.flow`
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// because Flow only supports indexers in classes in declaration files.
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// $FlowIssue[prop-missing] Flow doesn't understand [Symbol.iterator]() {} and thinks this class doesn't implement the Iterable<T> interface.
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export default class NodeList<T> implements Iterable<T>, ArrayLike<T> {
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_length: number;
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/**
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* Use `createNodeList` to create instances of this class.
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*
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* @private This is not defined in the declaration file, so users will not see
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* the signature of the constructor.
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*/
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constructor(elements: $ReadOnlyArray<T>) {
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for (let i = 0; i < elements.length; i++) {
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Object.defineProperty(this, i, {
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value: elements[i],
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writable: false,
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});
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}
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this._length = elements.length;
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}
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get length(): number {
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return this._length;
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}
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item(index: number): T | null {
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if (index < 0 || index >= this._length) {
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return null;
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}
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// assigning to the interface allows us to access the indexer property in a
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// type-safe way.
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// eslint-disable-next-line consistent-this
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const arrayLike: ArrayLike<T> = this;
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return arrayLike[index];
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}
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entries(): Iterator<[number, T]> {
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return createEntriesIterator(this);
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}
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forEach<ThisType>(
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callbackFn: (value: T, index: number, array: NodeList<T>) => mixed,
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thisArg?: ThisType,
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): void {
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// assigning to the interface allows us to access the indexer property in a
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// type-safe way.
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// eslint-disable-next-line consistent-this
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const arrayLike: ArrayLike<T> = this;
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for (let index = 0; index < this._length; index++) {
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if (thisArg == null) {
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callbackFn(arrayLike[index], index, this);
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} else {
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callbackFn.call(thisArg, arrayLike[index], index, this);
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}
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}
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}
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keys(): Iterator<number> {
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return createKeyIterator(this);
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}
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values(): Iterator<T> {
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return createValueIterator(this);
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}
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// $FlowIssue[unsupported-syntax] Flow does not support computed properties in classes.
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[Symbol.iterator](): Iterator<T> {
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return createValueIterator(this);
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}
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}
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/**
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* This is an internal method to create instances of `NodeList`,
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* which avoids leaking its constructor to end users.
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* We can do that because the external definition of `NodeList` lives in
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* `NodeList.js.flow`, not here.
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*/
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export function createNodeList<T>(elements: $ReadOnlyArray<T>): NodeList<T> {
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return new NodeList(elements);
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}
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