code review of new script tag filtering code

src/js/contentscript-start.js

@@ -74,7 +74,6 @@ var localMessager = vAPI.messaging.channel('contentscript-start.js');
 var cosmeticFilters = function(details) {
     var donthideCosmeticFilters = {};
     var hideCosmeticFilters = {};
-    var scriptTagFilters = [];
     var donthide = details.cosmeticDonthide;
     var hide = details.cosmeticHide;
     var i;
@@ -92,14 +91,9 @@ var cosmeticFilters = function(details) {
             selector = hide[i];
             if ( donthideCosmeticFilters[selector] ) {
                 hide.splice(i, 1);
-                continue;
+            } else {
+                hideCosmeticFilters[selector] = true;
             }
-            if ( selector.lastIndexOf('script//:', 0) === 0 ) {
-                scriptTagFilters.push(selector.slice(9));
-                hide.splice(i, 1);
-                continue;
-            }
-            hideCosmeticFilters[selector] = true;
         }
     }
     if ( hide.length !== 0 ) {
@@ -117,11 +111,6 @@ var cosmeticFilters = function(details) {
     }
     vAPI.donthideCosmeticFilters = donthideCosmeticFilters;
     vAPI.hideCosmeticFilters = hideCosmeticFilters;
-
-    if ( scriptTagFilters.length !== 0 ) {
-        vAPI.reScriptTagFilters = new RegExp(scriptTagFilters.join('|'));
-        document.addEventListener('beforescriptexecute', onBeforeScriptExecuteHandler);
-    }
 };
 
 var netFilters = function(details) {
@@ -140,13 +129,14 @@ var netFilters = function(details) {
 };
 
 var onBeforeScriptExecuteHandler = function(ev) {
-    if ( vAPI.reScriptTagFilters.test(ev.target.textContent) ) {
+    if ( vAPI.reScriptTagRegex.test(ev.target.textContent) ) {
         ev.preventDefault();
         ev.stopPropagation();
     }
 };
 
 var filteringHandler = function(details) {
+    var value;
     var styleTagCount = vAPI.styles.length;
 
     vAPI.skipCosmeticFiltering = !details || details.skipCosmeticFiltering;
@@ -157,6 +147,11 @@ var filteringHandler = function(details) {
         if ( details.netHide.length !== 0 ) {
             netFilters(details);
         }
+        value = details.scriptTagRegex;
+        if ( typeof value === 'string' && value.length !== 0 ) {
+            vAPI.reScriptTagRegex = new RegExp(value);
+            document.addEventListener('beforescriptexecute', onBeforeScriptExecuteHandler);
+        }
         // The port will never be used again at this point, disconnecting allows
         // the browser to flush this script from memory.
     }

src/js/cosmetic-filtering.js

@@ -237,6 +237,7 @@ var FilterParser = function() {
     this.invalid = false;
     this.cosmetic = true;
     this.reParser = /^\s*([^#]*)(##|#@#)(.+)\s*$/;
+    this.reScriptSelectorParser = /^script:contains\(\/.+?\/\)$/;
 };
 
 /******************************************************************************/
@@ -286,8 +287,8 @@ FilterParser.prototype.parse = function(s) {
     // Script tag filters: pre-process them so that can be used with minimal
     // overhead in the content script.
     if (
-        this.suffix.lastIndexOf('script:contains(/', 0) === 0 &&
+        this.suffix.charAt(0) === 's' &&
-        this.suffix.slice(-2) === '/)'
+        this.reScriptSelectorParser.test(this.suffix)
     ) {
         // Currently supported only as non-generic selector.
         if ( this.prefix.length === 0 ) {
@@ -568,6 +569,8 @@ FilterContainer.prototype.reset = function() {
     // hostname, entity-based filters
     this.hostnameFilters = {};
     this.entityFilters = {};
+    this.scriptTagFilters = {};
+    this.scriptTagFilterCount = 0;
 };
 
 /******************************************************************************/
@@ -807,6 +810,11 @@ FilterContainer.prototype.fromCompiledContent = function(text, lineBeg, skip) {
 
         // h	ir	twitter.com	.promoted-tweet
         if ( fields[0] === 'h' ) {
+            // Special filter: script tags. Not a real CSS selector.
+            if ( fields[3].lastIndexOf('script//:', 0) === 0 ) {
+                this.createScriptTagFilter(fields[2], fields[3].slice(9));
+                continue;
+            }
             filter = new FilterHostname(fields[3], fields[2]);
             bucket = this.hostnameFilters[fields[1]];
             if ( bucket === undefined ) {
@@ -838,6 +846,11 @@ FilterContainer.prototype.fromCompiledContent = function(text, lineBeg, skip) {
 
         // entity	selector
         if ( fields[0] === 'e' ) {
+            // Special filter: script tags. Not a real CSS selector.
+            if ( fields[2].lastIndexOf('script//:', 0) === 0 ) {
+                this.createScriptTagFilter(fields[1], fields[2].slice(9));
+                continue;
+            }
             bucket = this.entityFilters[fields[1]];
             if ( bucket === undefined ) {
                 this.entityFilters[fields[1]] = [fields[2]];
@@ -903,6 +916,49 @@ FilterContainer.prototype.skipCompiledContent = function(text, lineBeg) {
 
 /******************************************************************************/
 
+FilterContainer.prototype.createScriptTagFilter = function(hostname, s) {
+    if ( this.scriptTagFilters.hasOwnProperty(hostname) ) {
+        this.scriptTagFilters[hostname] += '|' + s;
+    } else {
+        this.scriptTagFilters[hostname] = s;
+    }
+    this.scriptTagFilterCount += 1;
+};
+
+/******************************************************************************/
+
+FilterContainer.prototype.retrieveScriptTagRegex = function(domain, hostname) {
+    if ( this.scriptTagFilterCount === 0 ) {
+        return;
+    }
+    var out = [], hn = hostname, pos;
+    for (;;) {
+        if ( this.scriptTagFilters.hasOwnProperty(hn) ) {
+            out.push(this.scriptTagFilters[hn]);
+        }
+        if ( hn === domain ) {
+            break;
+        }
+        pos = hn.indexOf('.');
+        if ( pos === -1 ) {
+            break;
+        }
+        hn = hn.slice(pos + 1);
+    }
+    pos = domain.indexOf('.');
+    if ( pos !== -1 ) {
+        hn = domain.slice(0, pos);
+        if ( this.scriptTagFilters.hasOwnProperty(hn) ) {
+            out.push(this.scriptTagFilters[hn]);
+        }
+    }
+    if ( out.length !== 0 ) {
+        return out.join('|');
+    }
+};
+
+/******************************************************************************/
+
 FilterContainer.prototype.freeze = function() {
     this.duplicateBuster = {};
 
@@ -956,7 +1012,9 @@ FilterContainer.prototype.toSelfie = function() {
         highMediumGenericHideCount: this.highMediumGenericHideCount,
         highHighGenericHide: this.highHighGenericHide,
         highHighGenericHideCount: this.highHighGenericHideCount,
-        genericDonthide: this.genericDonthide
+        genericDonthide: this.genericDonthide,
+        scriptTagFilters: this.scriptTagFilters,
+        scriptTagFilterCount: this.scriptTagFilterCount
     };
 };
 
@@ -1017,6 +1075,8 @@ FilterContainer.prototype.fromSelfie = function(selfie) {
     this.highHighGenericHide = selfie.highHighGenericHide;
     this.highHighGenericHideCount = selfie.highHighGenericHideCount;
     this.genericDonthide = selfie.genericDonthide;
+    this.scriptTagFilters = selfie.scriptTagFilters;
+    this.scriptTagFilterCount = selfie.scriptTagFilterCount;
     this.frozen = true;
 };
 
@@ -1197,6 +1257,7 @@ FilterContainer.prototype.retrieveDomainSelectors = function(request) {
         cosmeticHide: [],
         cosmeticDonthide: [],
         netHide: [],
+        scriptTagRegex: this.retrieveScriptTagRegex(domain, hostname),
         netCollapse: µb.userSettings.collapseBlocked
     };