380 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			380 lines
		
	
	
		
			12 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
'use strict';
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/**
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 * @typedef {import('../lib/types').Specificity} Specificity
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 * @typedef {import('../lib/types').XastElement} XastElement
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 * @typedef {import('../lib/types').XastParent} XastParent
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 */
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const csstree = require('css-tree');
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// @ts-ignore not defined in @types/csso
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const specificity = require('csso/lib/restructure/prepare/specificity');
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const stable = require('stable');
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const {
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  visitSkip,
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  querySelectorAll,
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  detachNodeFromParent,
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} = require('../lib/xast.js');
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exports.type = 'visitor';
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exports.name = 'inlineStyles';
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exports.active = true;
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exports.description = 'inline styles (additional options)';
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/**
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 * Compares two selector specificities.
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 * extracted from https://github.com/keeganstreet/specificity/blob/master/specificity.js#L211
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 *
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 * @type {(a: Specificity, b: Specificity) => number}
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 */
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const compareSpecificity = (a, b) => {
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  for (var 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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/**
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 * Moves + merges styles from style elements to element styles
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 *
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 * Options
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 *   onlyMatchedOnce (default: true)
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 *     inline only selectors that match once
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 *
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 *   removeMatchedSelectors (default: true)
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 *     clean up matched selectors,
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 *     leave selectors that hadn't matched
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 *
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 *   useMqs (default: ['', 'screen'])
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 *     what media queries to be used
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 *     empty string element for styles outside media queries
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 *
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 *   usePseudos (default: [''])
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 *     what pseudo-classes/-elements to be used
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 *     empty string element for all non-pseudo-classes and/or -elements
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 *
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 * @author strarsis <strarsis@gmail.com>
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 *
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 * @type {import('../lib/types').Plugin<{
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 *   onlyMatchedOnce?: boolean,
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 *   removeMatchedSelectors?: boolean,
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 *   useMqs?: Array<string>,
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 *   usePseudos?: Array<string>
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 * }>}
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 */
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exports.fn = (root, params) => {
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  const {
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    onlyMatchedOnce = true,
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    removeMatchedSelectors = true,
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    useMqs = ['', 'screen'],
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    usePseudos = [''],
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  } = params;
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  /**
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   * @type {Array<{ node: XastElement, parentNode: XastParent, cssAst: csstree.StyleSheet }>}
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   */
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  const styles = [];
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  /**
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   * @type {Array<{
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   *   node: csstree.Selector,
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   *   item: csstree.ListItem<csstree.CssNode>,
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   *   rule: csstree.Rule,
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   *   matchedElements?: Array<XastElement>
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   * }>}
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   */
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  let selectors = [];
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  return {
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    element: {
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      enter: (node, parentNode) => {
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        // skip <foreignObject /> content
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        if (node.name === 'foreignObject') {
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          return visitSkip;
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        }
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        // collect only non-empty <style /> elements
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        if (node.name !== 'style' || node.children.length === 0) {
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          return;
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        }
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        // values other than the empty string or text/css are not used
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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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          return;
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        }
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        // parse css in style element
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        let cssText = '';
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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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            cssText += child.value;
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          }
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        }
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        /**
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         * @type {null | csstree.CssNode}
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         */
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        let cssAst = null;
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        try {
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          cssAst = csstree.parse(cssText, {
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            parseValue: false,
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            parseCustomProperty: false,
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          });
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        } catch {
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          return;
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        }
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        if (cssAst.type === 'StyleSheet') {
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          styles.push({ node, parentNode, cssAst });
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        }
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        // collect selectors
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        csstree.walk(cssAst, {
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          visit: 'Selector',
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          enter(node, item) {
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            const atrule = this.atrule;
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            const rule = this.rule;
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            if (rule == null) {
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              return;
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            }
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            // skip media queries not included into useMqs param
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            let mq = '';
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            if (atrule != null) {
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              mq = atrule.name;
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              if (atrule.prelude != null) {
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                mq += ` ${csstree.generate(atrule.prelude)}`;
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              }
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            }
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            if (useMqs.includes(mq) === false) {
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              return;
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            }
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            /**
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             * @type {Array<{
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             *   item: csstree.ListItem<csstree.CssNode>,
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             *   list: csstree.List<csstree.CssNode>
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             * }>}
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             */
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            const pseudos = [];
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            if (node.type === 'Selector') {
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              node.children.each((childNode, childItem, childList) => {
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                if (
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                  childNode.type === 'PseudoClassSelector' ||
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                  childNode.type === 'PseudoElementSelector'
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                ) {
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                  pseudos.push({ item: childItem, list: childList });
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                }
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              });
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            }
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            // skip pseudo classes and pseudo elements not includes into usePseudos param
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            const pseudoSelectors = csstree.generate({
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              type: 'Selector',
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              children: new csstree.List().fromArray(
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                pseudos.map((pseudo) => pseudo.item.data)
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              ),
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            });
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            if (usePseudos.includes(pseudoSelectors) === false) {
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              return;
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            }
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            // remove pseudo classes and elements to allow querySelector match elements
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            // TODO this is not very accurate since some pseudo classes like first-child
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            // are used for selection
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            for (const pseudo of pseudos) {
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              pseudo.list.remove(pseudo.item);
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            }
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            selectors.push({ node, item, rule });
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          },
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        });
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      },
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    },
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    root: {
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      exit: () => {
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        if (styles.length === 0) {
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          return;
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        }
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        // stable sort selectors
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        const sortedSelectors = stable(selectors, (a, b) => {
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          const aSpecificity = specificity(a.item.data);
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          const bSpecificity = specificity(b.item.data);
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          return compareSpecificity(aSpecificity, bSpecificity);
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        }).reverse();
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        for (const selector of sortedSelectors) {
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          // match selectors
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          const selectorText = csstree.generate(selector.item.data);
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          /**
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           * @type {Array<XastElement>}
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           */
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          const matchedElements = [];
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          try {
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            for (const node of querySelectorAll(root, selectorText)) {
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              if (node.type === 'element') {
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                matchedElements.push(node);
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              }
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            }
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          } catch (selectError) {
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            continue;
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          }
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          // nothing selected
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          if (matchedElements.length === 0) {
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            continue;
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          }
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          // apply styles to matched elements
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          // skip selectors that match more than once if option onlyMatchedOnce is enabled
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          if (onlyMatchedOnce && matchedElements.length > 1) {
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            continue;
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          }
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          // apply <style/> to matched elements
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          for (const selectedEl of matchedElements) {
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            const styleDeclarationList = csstree.parse(
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              selectedEl.attributes.style == null
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                ? ''
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                : selectedEl.attributes.style,
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              {
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                context: 'declarationList',
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                parseValue: false,
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              }
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            );
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            if (styleDeclarationList.type !== 'DeclarationList') {
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              continue;
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            }
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            const styleDeclarationItems = new Map();
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            csstree.walk(styleDeclarationList, {
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              visit: 'Declaration',
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              enter(node, item) {
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                styleDeclarationItems.set(node.property, item);
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              },
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            });
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            // merge declarations
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            csstree.walk(selector.rule, {
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              visit: 'Declaration',
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              enter(ruleDeclaration) {
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                // existing inline styles have higher priority
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                // no inline styles, external styles,                                    external styles used
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                // inline styles,    external styles same   priority as inline styles,   inline   styles used
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                // inline styles,    external styles higher priority than inline styles, external styles used
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                const matchedItem = styleDeclarationItems.get(
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                  ruleDeclaration.property
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                );
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                const ruleDeclarationItem =
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                  styleDeclarationList.children.createItem(ruleDeclaration);
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                if (matchedItem == null) {
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                  styleDeclarationList.children.append(ruleDeclarationItem);
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                } else if (
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                  matchedItem.data.important !== true &&
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                  ruleDeclaration.important === true
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                ) {
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                  styleDeclarationList.children.replace(
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                    matchedItem,
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                    ruleDeclarationItem
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                  );
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                  styleDeclarationItems.set(
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                    ruleDeclaration.property,
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                    ruleDeclarationItem
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                  );
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                }
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              },
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            });
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            selectedEl.attributes.style =
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              csstree.generate(styleDeclarationList);
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          }
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          if (
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            removeMatchedSelectors &&
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            matchedElements.length !== 0 &&
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            selector.rule.prelude.type === 'SelectorList'
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          ) {
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            // clean up matching simple selectors if option removeMatchedSelectors is enabled
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            selector.rule.prelude.children.remove(selector.item);
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          }
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          selector.matchedElements = matchedElements;
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        }
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        // no further processing required
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        if (removeMatchedSelectors === false) {
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          return;
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        }
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        // clean up matched class + ID attribute values
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        for (const selector of sortedSelectors) {
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          if (selector.matchedElements == null) {
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            continue;
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          }
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          if (onlyMatchedOnce && selector.matchedElements.length > 1) {
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            // skip selectors that match more than once if option onlyMatchedOnce is enabled
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            continue;
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          }
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          for (const selectedEl of selector.matchedElements) {
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            // class
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            const classList = new Set(
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              selectedEl.attributes.class == null
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                ? null
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                : selectedEl.attributes.class.split(' ')
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            );
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            const firstSubSelector = selector.node.children.first();
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            if (
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              firstSubSelector != null &&
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              firstSubSelector.type === 'ClassSelector'
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            ) {
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              classList.delete(firstSubSelector.name);
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            }
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            if (classList.size === 0) {
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              delete selectedEl.attributes.class;
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            } else {
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              selectedEl.attributes.class = Array.from(classList).join(' ');
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            }
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            // ID
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            if (
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              firstSubSelector != null &&
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              firstSubSelector.type === 'IdSelector'
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            ) {
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              if (selectedEl.attributes.id === firstSubSelector.name) {
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                delete selectedEl.attributes.id;
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              }
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            }
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          }
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        }
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        for (const style of styles) {
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          csstree.walk(style.cssAst, {
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            visit: 'Rule',
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            enter: function (node, item, list) {
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              // clean up <style/> rulesets without any css selectors left
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              if (
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                node.type === 'Rule' &&
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                node.prelude.type === 'SelectorList' &&
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                node.prelude.children.isEmpty()
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              ) {
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                list.remove(item);
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              }
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            },
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          });
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          if (style.cssAst.children.isEmpty()) {
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            // remove emtpy style element
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            detachNodeFromParent(style.node, style.parentNode);
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          } else {
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            // update style element if any styles left
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            const firstChild = style.node.children[0];
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            if (firstChild.type === 'text' || firstChild.type === 'cdata') {
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              firstChild.value = csstree.generate(style.cssAst);
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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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};
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