'use strict';
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var csstree = require('css-tree'),
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List = csstree.List,
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stable = require('stable'),
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specificity = require('csso/lib/restructure/prepare/specificity');
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/**
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* Flatten a CSS AST to a selectors list.
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*
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* @param {Object} cssAst css-tree AST to flatten
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* @return {Array} selectors
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*/
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function flattenToSelectors(cssAst) {
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var selectors = [];
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csstree.walk(cssAst, {visit: 'Rule', enter: function(node) {
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if (node.type !== 'Rule') {
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return;
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}
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var atrule = this.atrule;
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var rule = node;
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node.prelude.children.each(function(selectorNode, selectorItem) {
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var selector = {
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item: selectorItem,
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atrule: atrule,
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rule: rule,
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pseudos: []
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};
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selectorNode.children.each(function(selectorChildNode, selectorChildItem, selectorChildList) {
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if (selectorChildNode.type === 'PseudoClassSelector' ||
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selectorChildNode.type === 'PseudoElementSelector') {
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selector.pseudos.push({
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item: selectorChildItem,
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list: selectorChildList
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});
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}
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});
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selectors.push(selector);
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});
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}});
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return selectors;
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}
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/**
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* Filter selectors by Media Query.
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*
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* @param {Array} selectors to filter
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* @param {Array} useMqs Array with strings of media queries that should pass (<name> <expression>)
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* @return {Array} Filtered selectors that match the passed media queries
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*/
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function filterByMqs(selectors, useMqs) {
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return selectors.filter(function(selector) {
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if (selector.atrule === null) {
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return ~useMqs.indexOf('');
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}
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var mqName = selector.atrule.name;
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var mqStr = mqName;
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if (selector.atrule.expression &&
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selector.atrule.expression.children.first().type === 'MediaQueryList') {
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var mqExpr = csstree.generate(selector.atrule.expression);
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mqStr = [mqName, mqExpr].join(' ');
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}
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return ~useMqs.indexOf(mqStr);
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});
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}
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/**
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* Filter selectors by the pseudo-elements and/or -classes they contain.
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*
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* @param {Array} selectors to filter
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* @param {Array} usePseudos Array with strings of single or sequence of pseudo-elements and/or -classes that should pass
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* @return {Array} Filtered selectors that match the passed pseudo-elements and/or -classes
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*/
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function filterByPseudos(selectors, usePseudos) {
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return selectors.filter(function(selector) {
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var pseudoSelectorsStr = csstree.generate({
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type: 'Selector',
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children: new List().fromArray(selector.pseudos.map(function(pseudo) {
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return pseudo.item.data;
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}))
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});
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return ~usePseudos.indexOf(pseudoSelectorsStr);
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});
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}
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/**
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* Remove pseudo-elements and/or -classes from the selectors for proper matching.
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*
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* @param {Array} selectors to clean
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* @return {Array} Selectors without pseudo-elements and/or -classes
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*/
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function cleanPseudos(selectors) {
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selectors.forEach(function(selector) {
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selector.pseudos.forEach(function(pseudo) {
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pseudo.list.remove(pseudo.item);
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});
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});
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}
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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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* @param {Array} aSpecificity Specificity of selector A
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* @param {Array} bSpecificity Specificity of selector B
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* @return {Number} Score of selector specificity A compared to selector specificity B
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*/
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function compareSpecificity(aSpecificity, bSpecificity) {
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for (var i = 0; i < 4; i += 1) {
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if (aSpecificity[i] < bSpecificity[i]) {
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return -1;
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} else if (aSpecificity[i] > bSpecificity[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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* Compare two simple selectors.
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*
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* @param {Object} aSimpleSelectorNode Simple selector A
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* @param {Object} bSimpleSelectorNode Simple selector B
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* @return {Number} Score of selector A compared to selector B
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*/
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function compareSimpleSelectorNode(aSimpleSelectorNode, bSimpleSelectorNode) {
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var aSpecificity = specificity(aSimpleSelectorNode),
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bSpecificity = specificity(bSimpleSelectorNode);
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return compareSpecificity(aSpecificity, bSpecificity);
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}
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function _bySelectorSpecificity(selectorA, selectorB) {
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return compareSimpleSelectorNode(selectorA.item.data, selectorB.item.data);
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}
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/**
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* Sort selectors stably by their specificity.
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*
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* @param {Array} selectors to be sorted
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* @return {Array} Stable sorted selectors
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*/
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function sortSelectors(selectors) {
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return stable(selectors, _bySelectorSpecificity);
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}
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/**
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* Convert a css-tree AST style declaration to CSSStyleDeclaration property.
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*
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* @param {Object} declaration css-tree style declaration
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* @return {Object} CSSStyleDeclaration property
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*/
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function csstreeToStyleDeclaration(declaration) {
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var propertyName = declaration.property,
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propertyValue = csstree.generate(declaration.value),
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propertyPriority = (declaration.important ? 'important' : '');
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return {
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name: propertyName,
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value: propertyValue,
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priority: propertyPriority
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};
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}
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/**
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* Gets the CSS string of a style element
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*
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* @param {Object} element style element
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* @return {String|Array} CSS string or empty array if no styles are set
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*/
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function getCssStr(elem) {
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return elem.content[0].text || elem.content[0].cdata || [];
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}
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/**
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* Sets the CSS string of a style element
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*
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* @param {Object} element style element
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* @param {String} CSS string to be set
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* @return {Object} reference to field with CSS
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*/
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function setCssStr(elem, css) {
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// in case of cdata field
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if(elem.content[0].cdata) {
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elem.content[0].cdata = css;
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return elem.content[0].cdata;
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}
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// in case of text field + if nothing was set yet
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elem.content[0].text = css;
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return elem.content[0].text;
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}
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module.exports.flattenToSelectors = flattenToSelectors;
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module.exports.filterByMqs = filterByMqs;
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module.exports.filterByPseudos = filterByPseudos;
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module.exports.cleanPseudos = cleanPseudos;
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module.exports.compareSpecificity = compareSpecificity;
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module.exports.compareSimpleSelectorNode = compareSimpleSelectorNode;
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module.exports.sortSelectors = sortSelectors;
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module.exports.csstreeToStyleDeclaration = csstreeToStyleDeclaration;
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module.exports.getCssStr = getCssStr;
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module.exports.setCssStr = setCssStr;
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