re-added matched selectors cache

lib/single-file/css-rules-matcher.js

@@ -39,14 +39,15 @@ this.RulesMatcher = this.RulesMatcher || (() => {
 		constructor(doc) {
 			this.doc = doc;
 			this.mediaAllInfo = createMediaInfo(MEDIA_ALL);
+			const matchedElementsCache = new Map();
 			doc.querySelectorAll("style").forEach((styleElement, styleIndex) => {
 				if (styleElement.sheet) {
 					if (styleElement.media && styleElement.media != MEDIA_ALL) {
 						const mediaInfo = createMediaInfo(styleElement.media);
 						this.mediaAllInfo.medias.set(styleIndex + "-" + styleElement.media, mediaInfo);
-						getMatchedElementsRules(doc, styleElement.sheet.cssRules, mediaInfo, styleIndex);
+						getMatchedElementsRules(doc, styleElement.sheet.cssRules, mediaInfo, styleIndex, matchedElementsCache);
 					} else {
-						getMatchedElementsRules(doc, styleElement.sheet.cssRules, this.mediaAllInfo, styleIndex);
+						getMatchedElementsRules(doc, styleElement.sheet.cssRules, this.mediaAllInfo, styleIndex, matchedElementsCache);
 					}
 				}
 			});
@@ -69,14 +70,14 @@ this.RulesMatcher = this.RulesMatcher || (() => {
 		}
 	};
 
-	function getMatchedElementsRules(doc, cssRules, mediaInfo, sheetIndex) {
+	function getMatchedElementsRules(doc, cssRules, mediaInfo, sheetIndex, matchedElementsCache) {
 		Array.from(cssRules).forEach((cssRule, ruleIndex) => {
 			const cssRuleType = cssRule.type;
 			if (cssRuleType == CSSRule.MEDIA_RULE) {
 				const cssRuleMedia = cssRule.media;
 				const ruleMediaInfo = createMediaInfo(cssRuleMedia);
 				mediaInfo.medias.set(cssRuleMedia, ruleMediaInfo);
-				getMatchedElementsRules(doc, cssRule.cssRules, ruleMediaInfo, sheetIndex);
+				getMatchedElementsRules(doc, cssRule.cssRules, ruleMediaInfo, sheetIndex, matchedElementsCache);
 			} else if (cssRuleType == CSSRule.STYLE_RULE) {
 				const selectorText = cssRule.selectorText;
 				if (selectorText) {
@@ -88,15 +89,19 @@ this.RulesMatcher = this.RulesMatcher || (() => {
 					}
 					if (selectors) {
 						const selectorsText = selectors.map(selector => cssWhat.stringify([selector]));
-						selectors.forEach((selector, selectorIndex) => getMatchedElementsSelector(doc, cssRule, selector, selectorsText[selectorIndex], selectorsText, mediaInfo, ruleIndex, sheetIndex));
+						selectors.forEach((selector, selectorIndex) => getMatchedElementsSelector(doc, cssRule, selector, selectorsText[selectorIndex], selectorsText, mediaInfo, ruleIndex, sheetIndex, matchedElementsCache));
 					}
 				}
 			}
 		});
 	}
 
-	function getMatchedElementsSelector(doc, cssRule, selector, selectorText, selectorsText, mediaInfo, ruleIndex, sheetIndex) {
-		const matchedElements = doc.querySelectorAll(selectorText);
+	function getMatchedElementsSelector(doc, cssRule, selector, selectorText, selectorsText, mediaInfo, ruleIndex, sheetIndex, matchedElementsCache) {
+		const cachedMatchedElements = matchedElementsCache.get(selectorText);
+		const matchedElements = cachedMatchedElements || doc.querySelectorAll(selectorText);
+		if (!cachedMatchedElements) {
+			matchedElementsCache.set(selectorText, matchedElements);
+		}
 		if (matchedElements.length) {
 			matchedElements.forEach(element => addRule(element, cssRule, selector, selectorText, selectorsText, mediaInfo, ruleIndex, sheetIndex));
 		}