337 lines
8.9 KiB
JavaScript
337 lines
8.9 KiB
JavaScript
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'use strict';
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/**
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* @typedef {import('css-tree').Rule} CsstreeRule
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* @typedef {import('./types').Specificity} Specificity
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* @typedef {import('./types').Stylesheet} Stylesheet
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* @typedef {import('./types').StylesheetRule} StylesheetRule
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* @typedef {import('./types').StylesheetDeclaration} StylesheetDeclaration
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* @typedef {import('./types').ComputedStyles} ComputedStyles
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* @typedef {import('./types').XastRoot} XastRoot
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* @typedef {import('./types').XastElement} XastElement
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* @typedef {import('./types').XastParent} XastParent
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* @typedef {import('./types').XastChild} XastChild
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*/
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const csstree = require('css-tree');
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const csswhat = require('css-what');
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const {
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syntax: { specificity },
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} = require('csso');
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const { visit, matches } = require('./xast.js');
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const {
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attrsGroups,
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inheritableAttrs,
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presentationNonInheritableGroupAttrs,
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} = require('../plugins/_collections.js');
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// @ts-ignore not defined in @types/csstree
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const csstreeWalkSkip = csstree.walk.skip;
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/**
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* @type {(ruleNode: CsstreeRule, dynamic: boolean) => StylesheetRule[]}
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*/
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const parseRule = (ruleNode, dynamic) => {
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/**
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* @type {StylesheetDeclaration[]}
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*/
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const declarations = [];
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// collect declarations
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ruleNode.block.children.forEach((cssNode) => {
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if (cssNode.type === 'Declaration') {
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declarations.push({
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name: cssNode.property,
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value: csstree.generate(cssNode.value),
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important: cssNode.important === true,
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});
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}
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});
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/** @type {StylesheetRule[]} */
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const rules = [];
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csstree.walk(ruleNode.prelude, (node) => {
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if (node.type === 'Selector') {
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const newNode = csstree.clone(node);
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let hasPseudoClasses = false;
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csstree.walk(newNode, (pseudoClassNode, item, list) => {
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if (pseudoClassNode.type === 'PseudoClassSelector') {
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hasPseudoClasses = true;
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list.remove(item);
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}
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});
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rules.push({
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specificity: specificity(node),
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dynamic: hasPseudoClasses || dynamic,
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// compute specificity from original node to consider pseudo classes
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selector: csstree.generate(newNode),
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declarations,
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});
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}
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});
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return rules;
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};
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/**
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* @type {(css: string, dynamic: boolean) => StylesheetRule[]}
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*/
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const parseStylesheet = (css, dynamic) => {
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/** @type {StylesheetRule[]} */
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const rules = [];
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const ast = csstree.parse(css, {
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parseValue: false,
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parseAtrulePrelude: false,
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});
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csstree.walk(ast, (cssNode) => {
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if (cssNode.type === 'Rule') {
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rules.push(...parseRule(cssNode, dynamic || false));
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return csstreeWalkSkip;
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}
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if (cssNode.type === 'Atrule') {
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if (
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cssNode.name === 'keyframes' ||
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cssNode.name === '-webkit-keyframes'
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) {
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return csstreeWalkSkip;
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}
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csstree.walk(cssNode, (ruleNode) => {
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if (ruleNode.type === 'Rule') {
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rules.push(...parseRule(ruleNode, dynamic || true));
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return csstreeWalkSkip;
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}
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});
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return csstreeWalkSkip;
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}
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});
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return rules;
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};
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/**
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* @type {(css: string) => StylesheetDeclaration[]}
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*/
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const parseStyleDeclarations = (css) => {
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/** @type {StylesheetDeclaration[]} */
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const declarations = [];
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const ast = csstree.parse(css, {
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context: 'declarationList',
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parseValue: false,
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});
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csstree.walk(ast, (cssNode) => {
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if (cssNode.type === 'Declaration') {
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declarations.push({
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name: cssNode.property,
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value: csstree.generate(cssNode.value),
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important: cssNode.important === true,
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});
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}
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});
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return declarations;
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};
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/**
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* @param {Stylesheet} stylesheet
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* @param {XastElement} node
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* @returns {ComputedStyles}
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*/
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const computeOwnStyle = (stylesheet, node) => {
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/** @type {ComputedStyles} */
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const computedStyle = {};
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const importantStyles = new Map();
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// collect attributes
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for (const [name, value] of Object.entries(node.attributes)) {
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if (attrsGroups.presentation.has(name)) {
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computedStyle[name] = { type: 'static', inherited: false, value };
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importantStyles.set(name, false);
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}
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}
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// collect matching rules
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for (const { selector, declarations, dynamic } of stylesheet.rules) {
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if (matches(node, selector)) {
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for (const { name, value, important } of declarations) {
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const computed = computedStyle[name];
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if (computed && computed.type === 'dynamic') {
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continue;
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}
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if (dynamic) {
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computedStyle[name] = { type: 'dynamic', inherited: false };
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continue;
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}
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if (
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computed == null ||
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important === true ||
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importantStyles.get(name) === false
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) {
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computedStyle[name] = { type: 'static', inherited: false, value };
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importantStyles.set(name, important);
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}
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}
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}
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}
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// collect inline styles
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const styleDeclarations =
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node.attributes.style == null
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? []
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: parseStyleDeclarations(node.attributes.style);
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for (const { name, value, important } of styleDeclarations) {
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const computed = computedStyle[name];
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if (computed && computed.type === 'dynamic') {
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continue;
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}
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if (
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computed == null ||
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important === true ||
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importantStyles.get(name) === false
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) {
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computedStyle[name] = { type: 'static', inherited: false, value };
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importantStyles.set(name, important);
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}
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}
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return computedStyle;
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};
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/**
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* Compares selector specificities.
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* Derived from https://github.com/keeganstreet/specificity/blob/8757133ddd2ed0163f120900047ff0f92760b536/specificity.js#L207
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*
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* @param {Specificity} a
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* @param {Specificity} b
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* @returns {number}
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*/
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const compareSpecificity = (a, b) => {
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for (let i = 0; i < 4; i += 1) {
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if (a[i] < b[i]) {
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return -1;
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} else if (a[i] > b[i]) {
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return 1;
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}
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}
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return 0;
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};
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exports.compareSpecificity = compareSpecificity;
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/**
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* @type {(root: XastRoot) => Stylesheet}
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*/
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const collectStylesheet = (root) => {
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/** @type {StylesheetRule[]} */
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const rules = [];
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/** @type {Map<XastElement, XastParent>} */
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const parents = new Map();
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visit(root, {
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element: {
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enter: (node, parentNode) => {
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parents.set(node, parentNode);
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if (node.name !== 'style') {
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return;
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}
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if (
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node.attributes.type == null ||
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node.attributes.type === '' ||
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node.attributes.type === 'text/css'
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) {
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const dynamic =
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node.attributes.media != null && node.attributes.media !== 'all';
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for (const child of node.children) {
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if (child.type === 'text' || child.type === 'cdata') {
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rules.push(...parseStylesheet(child.value, dynamic));
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}
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}
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}
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},
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},
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});
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// sort by selectors specificity
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rules.sort((a, b) => compareSpecificity(a.specificity, b.specificity));
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return { rules, parents };
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};
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exports.collectStylesheet = collectStylesheet;
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/**
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* @param {Stylesheet} stylesheet
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* @param {XastElement} node
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* @returns {ComputedStyles}
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*/
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const computeStyle = (stylesheet, node) => {
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const { parents } = stylesheet;
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const computedStyles = computeOwnStyle(stylesheet, node);
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let parent = parents.get(node);
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while (parent != null && parent.type !== 'root') {
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const inheritedStyles = computeOwnStyle(stylesheet, parent);
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for (const [name, computed] of Object.entries(inheritedStyles)) {
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if (
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computedStyles[name] == null &&
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inheritableAttrs.has(name) &&
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!presentationNonInheritableGroupAttrs.has(name)
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) {
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computedStyles[name] = { ...computed, inherited: true };
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}
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}
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parent = parents.get(parent);
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}
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return computedStyles;
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};
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exports.computeStyle = computeStyle;
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/**
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* Determines if the CSS selector includes or traverses the given attribute.
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*
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* Classes and IDs are generated as attribute selectors, so you can check for
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* if a `.class` or `#id` is included by passing `name=class` or `name=id`
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* respectively.
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*
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* @param {csstree.ListItem<csstree.CssNode>|string} selector
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* @param {string} name
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* @param {?string} value
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* @param {boolean} traversed
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* @returns {boolean}
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*/
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const includesAttrSelector = (
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selector,
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name,
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value = null,
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traversed = false,
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) => {
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const selectors =
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typeof selector === 'string'
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? csswhat.parse(selector)
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: csswhat.parse(csstree.generate(selector.data));
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for (const subselector of selectors) {
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const hasAttrSelector = subselector.some((segment, index) => {
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if (traversed) {
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if (index === subselector.length - 1) {
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return false;
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}
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const isNextTraversal = csswhat.isTraversal(subselector[index + 1]);
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if (!isNextTraversal) {
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return false;
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}
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}
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if (segment.type !== 'attribute' || segment.name !== name) {
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return false;
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}
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return value == null ? true : segment.value === value;
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});
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if (hasAttrSelector) {
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return true;
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}
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}
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return false;
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};
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exports.includesAttrSelector = includesAttrSelector;
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