Add support for elemhide (through specifichide)

Related documentation:
- https://help.eyeo.com/en/adblockplus/how-to-write-filters#element-hiding

Related feedback/discussion:
- https://www.reddit.com/r/uBlockOrigin/comments/d6vxzj/

The `elemhide` filter option as per ABP semantic is
now supported. Previously uBO would consider `elemhide`
to be an alias of `generichide`.

The support of `elemhide` is through the convenient
conversion of `elemhide` option into existing
`generichide` option and new `specifichide` option.

The purpose of the new `specifichide` filter option
is to disable all specific cosmetic filters, i.e.
those who target a specific site.

Additionally, for convenience purpose, the filter
options `generichide`, `specifichide` and `elemhide`
can be aliased using the shorter forms `ghide`,
`shide` and `ehide` respectively.

Author: gorhill

src/js/background.js

@@ -33,7 +33,7 @@ if ( vAPI.webextFlavor === undefined ) {
 
 /******************************************************************************/
 
-const µBlock = (function() { // jshint ignore:line
+const µBlock = (( ) => { // jshint ignore:line
 
     const hiddenSettingsDefault = {
         allowGenericProceduralFilters: false,
@@ -84,7 +84,7 @@ const µBlock = (function() { // jshint ignore:line
             requestLogMaxEntries: 1000,
             showIconBadge: true,
             tooltipsDisabled: false,
-            webrtcIPAddressHidden: false
+            webrtcIPAddressHidden: false,
         },
 
         hiddenSettingsDefault: hiddenSettingsDefault,
@@ -133,22 +133,22 @@ const µBlock = (function() { // jshint ignore:line
 
         localSettings: {
             blockedRequestCount: 0,
-            allowedRequestCount: 0
+            allowedRequestCount: 0,
         },
         localSettingsLastModified: 0,
         localSettingsLastSaved: 0,
 
         // Read-only
         systemSettings: {
-            compiledMagic: 18,  // Increase when compiled format changes
-            selfieMagic: 18     // Increase when selfie format changes
+            compiledMagic: 19,  // Increase when compiled format changes
+            selfieMagic: 19,    // Increase when selfie format changes
         },
 
         restoreBackupSettings: {
             lastRestoreFile: '',
             lastRestoreTime: 0,
             lastBackupFile: '',
-            lastBackupTime: 0
+            lastBackupTime: 0,
         },
 
         commandShortcuts: new Map(),

src/js/cosmetic-filtering.js

@@ -23,7 +23,7 @@
 
 /******************************************************************************/
 
-µBlock.cosmeticFilteringEngine = (function(){
+µBlock.cosmeticFilteringEngine = (( ) => {
 
 /******************************************************************************/
 
@@ -238,10 +238,12 @@ const FilterContainer = function() {
     // is to prevent repeated allocation/deallocation overheads -- the
     // constructors/destructors of javascript Set/Map is assumed to be costlier
     // than just calling clear() on these.
-    this.setRegister0 = new Set();
-    this.setRegister1 = new Set();
-    this.setRegister2 = new Set();
-    this.mapRegister0 = new Map();
+    this.simpleSet$ = new Set();
+    this.complexSet$ = new Set();
+    this.specificSet$ = new Set();
+    this.exceptionSet$ = new Set();
+    this.proceduralSet$ = new Set();
+    this.dummySet$ = new Set();
 
     this.reset();
 };
@@ -830,11 +832,11 @@ FilterContainer.prototype.retrieveGenericSelectors = function(request) {
 
     //console.time('cosmeticFilteringEngine.retrieveGenericSelectors');
 
-    const simpleSelectors = this.setRegister0;
-    const complexSelectors = this.setRegister1;
+    const simpleSelectors = this.simpleSet$;
+    const complexSelectors = this.complexSet$;
 
     const cacheEntry = this.selectorCache.get(request.hostname);
-    const previousHits = cacheEntry && cacheEntry.cosmetic || this.setRegister2;
+    const previousHits = cacheEntry && cacheEntry.cosmetic || this.dummySet$;
 
     for ( const type in this.lowlyGeneric ) {
         const entry = this.lowlyGeneric[type];
@@ -891,6 +893,10 @@ FilterContainer.prototype.retrieveGenericSelectors = function(request) {
         excepted,
     };
 
+    // Important: always clear used registers before leaving.
+    simpleSelectors.clear();
+    complexSelectors.clear();
+
     // Cache and inject (if user stylesheets supported) looked-up low generic
     // cosmetic filters.
     if (
@@ -931,10 +937,6 @@ FilterContainer.prototype.retrieveGenericSelectors = function(request) {
         });
     }
 
-    // Important: always clear used registers before leaving.
-    this.setRegister0.clear();
-    this.setRegister1.clear();
-
     //console.timeEnd('cosmeticFilteringEngine.retrieveGenericSelectors');
 
     return out;
@@ -946,8 +948,6 @@ FilterContainer.prototype.retrieveSpecificSelectors = function(
     request,
     options
 ) {
-    //console.time('cosmeticFilteringEngine.retrieveSpecificSelectors');
-
     const hostname = request.hostname;
     const cacheEntry = this.selectorCache.get(hostname);
 
@@ -976,7 +976,11 @@ FilterContainer.prototype.retrieveSpecificSelectors = function(
     };
 
     if ( options.noCosmeticFiltering !== true ) {
-        const specificSet = this.setRegister1;
+        const specificSet = this.specificSet$;
+        const proceduralSet = this.proceduralSet$;
+        const exceptionSet = this.exceptionSet$;
+        const dummySet = this.dummySet$;
+
         // Cached cosmetic filters: these are always declarative.
         if ( cacheEntry !== undefined ) {
             cacheEntry.retrieve('cosmetic', specificSet);
@@ -986,17 +990,30 @@ FilterContainer.prototype.retrieveSpecificSelectors = function(
             }
         }
 
-        const exceptionSet = this.setRegister0;
-        const proceduralSet = this.setRegister2;
-
+        // Retrieve filters with a non-empty hostname
         this.specificFilters.retrieve(
             hostname,
-            [ specificSet, exceptionSet, proceduralSet, exceptionSet ]
+            options.noSpecificCosmeticFiltering !== true
+                ? [ specificSet, exceptionSet, proceduralSet, exceptionSet ]
+                : [ dummySet, exceptionSet, dummySet, exceptionSet ],
+            1
         );
+        // Retrieve filters with an empty hostname
+        this.specificFilters.retrieve(
+            hostname,
+            options.noGenericCosmeticFiltering !== true
+                ? [ specificSet, exceptionSet, proceduralSet, exceptionSet ]
+                : [ dummySet, exceptionSet, dummySet, exceptionSet ],
+            2
+        );
+        // Retrieve filters with a non-empty entity
         if ( request.entity !== '' ) {
             this.specificFilters.retrieve(
                 `${hostname.slice(0, -request.domain.length)}${request.entity}`,
-                [ specificSet, exceptionSet, proceduralSet, exceptionSet ]
+                options.noSpecificCosmeticFiltering !== true
+                    ? [ specificSet, exceptionSet, proceduralSet, exceptionSet ]
+                    : [ dummySet, exceptionSet, dummySet, exceptionSet ],
+                1
             );
         }
 
@@ -1060,9 +1077,10 @@ FilterContainer.prototype.retrieveSpecificSelectors = function(
         }
 
         // Important: always clear used registers before leaving.
-        this.setRegister0.clear();
-        this.setRegister1.clear();
-        this.setRegister2.clear();
+        specificSet.clear();
+        proceduralSet.clear();
+        exceptionSet.clear();
+        dummySet.clear();
     }
 
     // CSS selectors for collapsible blocked elements
@@ -1115,8 +1133,6 @@ FilterContainer.prototype.retrieveSpecificSelectors = function(
         }
     }
 
-    //console.timeEnd('cosmeticFilteringEngine.retrieveSpecificSelectors');
-
     return out;
 };