CssStyleApplier updates (#2145)

* Update internal structure of _styleData

* Rename parameter

* Rename

* Add docs
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toasted-nutbread 2022-05-18 19:40:47 -04:00 committed by GitHub
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commit a33a00f5ae
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@ -21,11 +21,17 @@
*/ */
class CssStyleApplier { class CssStyleApplier {
/** /**
* A CSS rule.
* @typedef {object} CssRule * @typedef {object} CssRule
* @property {string} selectors A CSS selector string representing one or more selectors. * @property {string} selectors A CSS selector string representing one or more selectors.
* @property {[string, string][]} styles A list of CSS property and value pairs. * @property {CssDeclaration[]} styles A list of CSS property and value pairs.
* @property {string} styles[][0] The CSS property. */
* @property {string} styles[][1] The CSS value.
/**
* A single CSS property declaration.
* @typedef {object} CssDeclaration
* @property {string} property A CSS property's name, using kebab-case.
* @property {string} value The property's value.
*/ */
/** /**
@ -54,14 +60,24 @@ class CssStyleApplier {
* Loads the data file for use. * Loads the data file for use.
*/ */
async prepare() { async prepare() {
let styleData; let rawData;
try { try {
styleData = await this._fetchJsonAsset(this._styleDataUrl); rawData = await this._fetchJsonAsset(this._styleDataUrl);
} catch (e) { } catch (e) {
console.error(e); console.error(e);
} }
if (Array.isArray(styleData)) { const styleData = this._styleData;
this._styleData = styleData; styleData.length = 0;
for (const {selectors, styles} of rawData) {
const selectors2 = selectors.join(',');
const styles2 = [];
for (const [property, value] of styles) {
styles2.push({property, value});
}
styleData.push({
selectors: selectors2,
styles: styles2
});
} }
} }
@ -76,8 +92,8 @@ class CssStyleApplier {
const className = element.getAttribute('class'); const className = element.getAttribute('class');
if (className.length === 0) { continue; } if (className.length === 0) { continue; }
let cssTextNew = ''; let cssTextNew = '';
for (const {selectorText, styles} of this._getCandidateCssRulesForClass(className)) { for (const {selectors, styles} of this._getCandidateCssRulesForClass(className)) {
if (!element.matches(selectorText)) { continue; } if (!element.matches(selectors)) { continue; }
cssTextNew += this._getCssText(styles); cssTextNew += this._getCssText(styles);
} }
cssTextNew += element.style.cssText; cssTextNew += element.style.cssText;
@ -95,6 +111,12 @@ class CssStyleApplier {
// Private // Private
/**
* Fetches and parses a JSON file.
* @param {string} url The URL to the file.
* @returns {Promise<*>} A JSON object.
* @throws {Error} An error is thrown if the fetch fails.
*/
async _fetchJsonAsset(url) { async _fetchJsonAsset(url) {
const response = await fetch(url, { const response = await fetch(url, {
method: 'GET', method: 'GET',
@ -124,37 +146,52 @@ class CssStyleApplier {
const classList = this._getTokens(className); const classList = this._getTokens(className);
for (const {selectors, styles} of this._styleData) { for (const {selectors, styles} of this._styleData) {
const selectorText = selectors.join(','); if (!this._selectorMightMatch(selectors, classList)) { continue; }
if (!this._selectorMatches(selectorText, classList)) { continue; } rules.push({selectors, styles});
rules.push({selectorText, styles});
} }
return rules; return rules;
} }
/**
* Converts an array of CSS rules to a CSS string.
* @param {CssRule[]} styles An array of CSS rules.
* @returns {string} The CSS string.
*/
_getCssText(styles) { _getCssText(styles) {
let cssText = ''; let cssText = '';
for (const [property, value] of styles) { for (const {property, value} of styles) {
cssText += `${property}:${value};`; cssText += `${property}:${value};`;
} }
return cssText; return cssText;
} }
_selectorMatches(selectorText, classList) { /**
* Checks whether or not a CSS string might match at least one class in a list.
* @param {string} selectors A CSS selector string.
* @param {string[]} classList An array of CSS classes.
* @returns {boolean} `true` if the selector string might match one of the classes in `classList`, false otherwise.
*/
_selectorMightMatch(selectors, classList) {
const pattern = this._patternClassNameCharacter; const pattern = this._patternClassNameCharacter;
for (const item of classList) { for (const item of classList) {
const prefixedItem = `.${item}`; const prefixedItem = `.${item}`;
let start = 0; let start = 0;
while (true) { while (true) {
const index = selectorText.indexOf(prefixedItem, start); const index = selectors.indexOf(prefixedItem, start);
if (index < 0) { break; } if (index < 0) { break; }
start = index + prefixedItem.length; start = index + prefixedItem.length;
if (start >= selectorText.length || !pattern.test(selectorText[start])) { return true; } if (start >= selectors.length || !pattern.test(selectors[start])) { return true; }
} }
} }
return false; return false;
} }
/**
* Gets the whitespace-delimited tokens from a string.
* @param {string} tokenListString The string to parse.
* @returns {string[]} An array of tokens.
*/
_getTokens(tokenListString) { _getTokens(tokenListString) {
let start = 0; let start = 0;
const pattern = this._patternHtmlWhitespace; const pattern = this._patternHtmlWhitespace;