159 lines
4.1 KiB
TypeScript
159 lines
4.1 KiB
TypeScript
/**
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* Copyright 2023 Google Inc. All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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type CSSSelector = string;
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export type PSelector =
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| {
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name: string;
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value: string;
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}
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| CSSSelector;
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const PUPPETEER_PSEUDO_ELEMENT = /^::-p-([-a-zA-Z_]+)\(/;
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class PSelectorParser {
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#input: string;
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#escaped = false;
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#quoted = false;
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// The first level are deep roots. The second level are shallow roots.
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#selectors: PSelector[][][] = [[[]]];
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constructor(input: string) {
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this.#input = input;
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}
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get selectors(): PSelector[][][] {
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return this.#selectors;
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}
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parse(): void {
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for (let i = 0; i < this.#input.length; ++i) {
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if (this.#escaped) {
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this.#escaped = false;
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continue;
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}
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switch (this.#input[i]) {
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case '\\': {
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this.#escaped = true;
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break;
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}
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case '"': {
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this.#quoted = !this.#quoted;
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break;
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}
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default: {
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if (this.#quoted) {
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break;
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}
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const remainder = this.#input.slice(i);
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if (remainder.startsWith('>>>>')) {
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this.#push(this.#input.slice(0, i));
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this.#input = remainder.slice('>>>>'.length);
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this.#parseDeepChild();
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} else if (remainder.startsWith('>>>')) {
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this.#push(this.#input.slice(0, i));
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this.#input = remainder.slice('>>>'.length);
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this.#parseDeepDescendent();
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} else {
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const result = PUPPETEER_PSEUDO_ELEMENT.exec(remainder);
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if (!result) {
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continue;
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}
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const [match, name] = result;
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this.#push(this.#input.slice(0, i));
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this.#input = remainder.slice(match.length);
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this.#push({
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name: name as string,
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value: this.#scanParameter(),
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});
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}
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}
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}
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}
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this.#push(this.#input);
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}
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#push(selector: PSelector) {
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if (typeof selector === 'string') {
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// We only trim the end only since `.foo` and ` .foo` are different.
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selector = selector.trimEnd();
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if (selector.length === 0) {
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return;
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}
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}
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const roots = this.#selectors[this.#selectors.length - 1]!;
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roots[roots.length - 1]!.push(selector);
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}
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#parseDeepChild() {
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this.#selectors[this.#selectors.length - 1]!.push([]);
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}
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#parseDeepDescendent() {
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this.#selectors.push([[]]);
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}
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#scanParameter(): string {
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const char = this.#input[0];
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switch (char) {
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case "'":
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case '"':
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this.#input = this.#input.slice(1);
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const parameter = this.#scanEscapedValueTill(char);
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if (!this.#input.startsWith(')')) {
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throw new Error("Expected ')'");
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}
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this.#input = this.#input.slice(1);
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return parameter;
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default:
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return this.#scanEscapedValueTill(')');
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}
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}
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#scanEscapedValueTill(end: string): string {
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let string = '';
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for (let i = 0; i < this.#input.length; ++i) {
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if (this.#escaped) {
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this.#escaped = false;
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string += this.#input[i];
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continue;
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}
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switch (this.#input[i]) {
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case '\\': {
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this.#escaped = true;
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break;
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}
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case end: {
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this.#input = this.#input.slice(i + 1);
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return string;
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}
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default: {
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string += this.#input[i];
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}
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}
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}
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throw new Error(`Expected \`${end}\``);
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}
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}
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export function parsePSelectors(selector: string): PSelector[][][] {
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const parser = new PSelectorParser(selector);
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parser.parse();
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return parser.selectors;
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}
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