CssStyleApplier updates (#2145)
* Update internal structure of _styleData * Rename parameter * Rename * Add docs
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@ -21,11 +21,17 @@
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*/
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class CssStyleApplier {
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/**
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* A CSS rule.
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* @typedef {object} CssRule
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* @property {string} selectors A CSS selector string representing one or more selectors.
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* @property {[string, string][]} styles A list of CSS property and value pairs.
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* @property {string} styles[][0] The CSS property.
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* @property {string} styles[][1] The CSS value.
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* @property {CssDeclaration[]} styles A list of CSS property and value pairs.
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*/
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/**
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* A single CSS property declaration.
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* @typedef {object} CssDeclaration
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* @property {string} property A CSS property's name, using kebab-case.
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* @property {string} value The property's value.
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*/
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/**
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@ -54,14 +60,24 @@ class CssStyleApplier {
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* Loads the data file for use.
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*/
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async prepare() {
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let styleData;
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let rawData;
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try {
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styleData = await this._fetchJsonAsset(this._styleDataUrl);
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rawData = await this._fetchJsonAsset(this._styleDataUrl);
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} catch (e) {
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console.error(e);
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}
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if (Array.isArray(styleData)) {
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this._styleData = styleData;
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const styleData = this._styleData;
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styleData.length = 0;
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for (const {selectors, styles} of rawData) {
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const selectors2 = selectors.join(',');
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const styles2 = [];
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for (const [property, value] of styles) {
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styles2.push({property, value});
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}
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styleData.push({
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selectors: selectors2,
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styles: styles2
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});
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}
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}
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@ -76,8 +92,8 @@ class CssStyleApplier {
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const className = element.getAttribute('class');
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if (className.length === 0) { continue; }
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let cssTextNew = '';
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for (const {selectorText, styles} of this._getCandidateCssRulesForClass(className)) {
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if (!element.matches(selectorText)) { continue; }
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for (const {selectors, styles} of this._getCandidateCssRulesForClass(className)) {
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if (!element.matches(selectors)) { continue; }
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cssTextNew += this._getCssText(styles);
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}
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cssTextNew += element.style.cssText;
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@ -95,6 +111,12 @@ class CssStyleApplier {
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// Private
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/**
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* Fetches and parses a JSON file.
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* @param {string} url The URL to the file.
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* @returns {Promise<*>} A JSON object.
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* @throws {Error} An error is thrown if the fetch fails.
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*/
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async _fetchJsonAsset(url) {
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const response = await fetch(url, {
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method: 'GET',
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@ -124,37 +146,52 @@ class CssStyleApplier {
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const classList = this._getTokens(className);
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for (const {selectors, styles} of this._styleData) {
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const selectorText = selectors.join(',');
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if (!this._selectorMatches(selectorText, classList)) { continue; }
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rules.push({selectorText, styles});
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if (!this._selectorMightMatch(selectors, classList)) { continue; }
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rules.push({selectors, styles});
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}
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return rules;
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}
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/**
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* Converts an array of CSS rules to a CSS string.
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* @param {CssRule[]} styles An array of CSS rules.
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* @returns {string} The CSS string.
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*/
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_getCssText(styles) {
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let cssText = '';
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for (const [property, value] of styles) {
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for (const {property, value} of styles) {
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cssText += `${property}:${value};`;
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}
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return cssText;
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}
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_selectorMatches(selectorText, classList) {
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/**
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* Checks whether or not a CSS string might match at least one class in a list.
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* @param {string} selectors A CSS selector string.
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* @param {string[]} classList An array of CSS classes.
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* @returns {boolean} `true` if the selector string might match one of the classes in `classList`, false otherwise.
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*/
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_selectorMightMatch(selectors, classList) {
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const pattern = this._patternClassNameCharacter;
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for (const item of classList) {
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const prefixedItem = `.${item}`;
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let start = 0;
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while (true) {
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const index = selectorText.indexOf(prefixedItem, start);
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const index = selectors.indexOf(prefixedItem, start);
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if (index < 0) { break; }
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start = index + prefixedItem.length;
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if (start >= selectorText.length || !pattern.test(selectorText[start])) { return true; }
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if (start >= selectors.length || !pattern.test(selectors[start])) { return true; }
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}
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}
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return false;
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}
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/**
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* Gets the whitespace-delimited tokens from a string.
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* @param {string} tokenListString The string to parse.
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* @returns {string[]} An array of tokens.
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*/
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_getTokens(tokenListString) {
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let start = 0;
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const pattern = this._patternHtmlWhitespace;
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