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.

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
+            compiledMagic: 19,  // Increase when compiled format changes
-            selfieMagic: 18     // Increase when selfie 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.simpleSet$ = new Set();
-    this.setRegister1 = new Set();
+    this.complexSet$ = new Set();
-    this.setRegister2 = new Set();
+    this.specificSet$ = new Set();
-    this.mapRegister0 = new Map();
+    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 simpleSelectors = this.simpleSet$;
-    const complexSelectors = this.setRegister1;
+    const complexSelectors = this.complexSet$;
 
     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;
+        // Retrieve filters with a non-empty hostname
-        const proceduralSet = this.setRegister2;
-
         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();
+        specificSet.clear();
-        this.setRegister1.clear();
+        proceduralSet.clear();
-        this.setRegister2.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;
 };
 

src/js/messaging.js

@@ -500,6 +500,98 @@ vAPI.messaging.listen({
 
 const µb = µBlock;
 
+const retrieveContentScriptParameters = function(senderDetails, request) {
+    const { url, tabId, frameId } = senderDetails;
+    if ( url === undefined || tabId === undefined || frameId === undefined ) {
+        return;
+    }
+    if ( request.url !== url ) { return; }
+    const pageStore = µb.pageStoreFromTabId(tabId);
+    if ( pageStore === null || pageStore.getNetFilteringSwitch() === false ) {
+        return;
+    }
+
+    const noCosmeticFiltering = pageStore.noCosmeticFiltering === true;
+
+    const response = {
+        collapseBlocked: µb.userSettings.collapseBlocked,
+        noCosmeticFiltering,
+        noGenericCosmeticFiltering: noCosmeticFiltering,
+        noSpecificCosmeticFiltering: noCosmeticFiltering,
+    };
+
+    // https://github.com/uBlockOrigin/uAssets/issues/5704
+    //   `generichide` must be evaluated in the frame context.
+    if ( noCosmeticFiltering === false ) {
+        const genericHide =
+            µb.staticNetFilteringEngine.matchStringElementHide(
+                'generic',
+                request.url
+            );
+        response.noGenericCosmeticFiltering = genericHide === 2;
+        if ( genericHide !== 0 && µb.logger.enabled ) {
+            µBlock.filteringContext
+                .duplicate()
+                .fromTabId(tabId)
+                .setURL(request.url)
+                .setRealm('network')
+                .setType('generichide')
+                .setFilter(µb.staticNetFilteringEngine.toLogData())
+                .toLogger();
+        }
+    }
+
+    request.tabId = tabId;
+    request.frameId = frameId;
+    request.hostname = µb.URI.hostnameFromURI(request.url);
+    request.domain = µb.URI.domainFromHostname(request.hostname);
+    request.entity = µb.URI.entityFromDomain(request.domain);
+
+    // https://www.reddit.com/r/uBlockOrigin/comments/d6vxzj/
+    //   Add support for `specifichide`.
+    if ( noCosmeticFiltering === false ) {
+        const specificHide =
+            µb.staticNetFilteringEngine.matchStringElementHide(
+                'specific',
+                request.url
+            );
+        response.noSpecificCosmeticFiltering = specificHide === 2;
+        if ( specificHide !== 0 && µb.logger.enabled ) {
+            µBlock.filteringContext
+                .duplicate()
+                .fromTabId(tabId)
+                .setURL(request.url)
+                .setRealm('network')
+                .setType('specifichide')
+                .setFilter(µb.staticNetFilteringEngine.toLogData())
+                .toLogger();
+        }
+    }
+
+    // Cosmetic filtering can be effectively disabled when both specific and
+    // generic cosmetic filtering are disabled.
+    if (
+        noCosmeticFiltering === false &&
+        response.noGenericCosmeticFiltering &&
+        response.noSpecificCosmeticFiltering
+    ) {
+        response.noCosmeticFiltering = true;
+    }
+
+    response.specificCosmeticFilters =
+        µb.cosmeticFilteringEngine.retrieveSpecificSelectors(request, response);
+
+    if ( µb.canInjectScriptletsNow === false ) {
+        response.scriptlets = µb.scriptletFilteringEngine.retrieve(request);
+    }
+
+    if ( µb.logger.enabled && response.noCosmeticFiltering !== true ) {
+        µb.logCosmeticFilters(tabId, frameId);
+    }
+
+    return response;
+};
+
 const onMessage = function(request, sender, callback) {
     // Async
     switch ( request.what ) {
@@ -507,16 +599,11 @@ const onMessage = function(request, sender, callback) {
         break;
     }
 
-    // Sync
+    const senderDetails = µb.getMessageSenderDetails(sender);
-    let response,
+    const pageStore = µb.pageStoreFromTabId(senderDetails.tabId);
-        tabId, frameId,
-        pageStore = null;
 
-    if ( sender && sender.tab ) {
+    // Sync
-        tabId = sender.tab.id;
+    let response;
-        frameId = sender.frameId;
-        pageStore = µb.pageStoreFromTabId(tabId);
-    }
 
     switch ( request.what ) {
     case 'cosmeticFiltersInjected':
@@ -528,88 +615,42 @@ const onMessage = function(request, sender, callback) {
             id: request.id,
             hash: request.hash,
             netSelectorCacheCountMax:
-                µb.cosmeticFilteringEngine.netSelectorCacheCountMax
+                µb.cosmeticFilteringEngine.netSelectorCacheCountMax,
         };
         if (
             µb.userSettings.collapseBlocked &&
-            pageStore &&
+            pageStore && pageStore.getNetFilteringSwitch()
-            pageStore.getNetFilteringSwitch()
         ) {
             pageStore.getBlockedResources(request, response);
         }
         break;
 
     case 'maybeGoodPopup':
-        µb.maybeGoodPopup.tabId = tabId;
+        µb.maybeGoodPopup.tabId = senderDetails.tabId;
         µb.maybeGoodPopup.url = request.url;
         break;
 
     case 'shouldRenderNoscriptTags':
         if ( pageStore === null ) { break; }
-        const fctxt = µb.filteringContext.fromTabId(tabId);
+        const fctxt = µb.filteringContext.fromTabId(senderDetails.tabId);
         if ( pageStore.filterScripting(fctxt, undefined) ) {
-            vAPI.tabs.executeScript(tabId, {
+            vAPI.tabs.executeScript(senderDetails.tabId, {
                 file: '/js/scriptlets/noscript-spoof.js',
-                frameId: frameId,
+                frameId: senderDetails.frameId,
-                runAt: 'document_end'
+                runAt: 'document_end',
             });
         }
         break;
 
     case 'retrieveContentScriptParameters':
-        if (
+        response = retrieveContentScriptParameters(senderDetails, request);
-            pageStore === null ||
-            pageStore.getNetFilteringSwitch() === false ||
-            !request.url
-        ) {
-            break;
-        }
-        const noCosmeticFiltering = pageStore.noCosmeticFiltering === true;
-        response = {
-            collapseBlocked: µb.userSettings.collapseBlocked,
-            noCosmeticFiltering,
-            noGenericCosmeticFiltering: noCosmeticFiltering,
-        };
-        // https://github.com/uBlockOrigin/uAssets/issues/5704
-        //   `generichide` must be evaluated in the frame context.
-        if ( noCosmeticFiltering === false ) {
-            const genericHide =
-                µb.staticNetFilteringEngine.matchStringGenericHide(request.url);
-            response.noGenericCosmeticFiltering = genericHide === 2;
-            if ( genericHide !== 0 && µb.logger.enabled ) {
-                µBlock.filteringContext
-                    .duplicate()
-                    .fromTabId(tabId)
-                    .setURL(request.url)
-                    .setRealm('network')
-                    .setType('generichide')
-                    .setFilter(µb.staticNetFilteringEngine.toLogData())
-                    .toLogger();
-            }
-        }
-        request.tabId = tabId;
-        request.frameId = frameId;
-        request.hostname = µb.URI.hostnameFromURI(request.url);
-        request.domain = µb.URI.domainFromHostname(request.hostname);
-        request.entity = µb.URI.entityFromDomain(request.domain);
-        response.specificCosmeticFilters =
-            µb.cosmeticFilteringEngine.retrieveSpecificSelectors(
-                request,
-                response
-            );
-        if ( µb.canInjectScriptletsNow === false ) {
-            response.scriptlets = µb.scriptletFilteringEngine.retrieve(request);
-        }
-        if ( µb.logger.enabled && response.noCosmeticFiltering !== true ) {
-            µb.logCosmeticFilters(tabId, frameId);
-        }
         break;
 
     case 'retrieveGenericCosmeticSelectors':
-        request.tabId = tabId;
+        request.tabId = senderDetails.tabId;
-        request.frameId = frameId;
+        request.frameId = senderDetails.frameId;
         response = {
-            result: µb.cosmeticFilteringEngine.retrieveGenericSelectors(request)
+            result: µb.cosmeticFilteringEngine.retrieveGenericSelectors(request),
         };
         break;
 

src/js/reverselookup-worker.js

@@ -176,17 +176,18 @@ const fromCosmeticFilter = function(details) {
             let end = content.indexOf('\n', pos);
             if ( end === -1 ) { end = content.length; }
             pos = end;
-            let fargs = JSON.parse(content.slice(beg, end));
+            const fargs = JSON.parse(content.slice(beg, end));
+            const filterType = fargs[0];
 
             // https://github.com/gorhill/uBlock/issues/2763
-            if ( fargs[0] >= 0 && fargs[0] <= 5 && details.ignoreGeneric ) {
+            if ( filterType >= 0 && filterType <= 5 && details.ignoreGeneric ) {
                 continue;
             }
 
             // Do not confuse cosmetic filters with HTML ones.
-            if ( (fargs[0] === 64) !== isHtmlFilter ) { continue; }
+            if ( (filterType === 64) !== isHtmlFilter ) { continue; }
 
-            switch ( fargs[0] ) {
+            switch ( filterType ) {
             // Lowly generic cosmetic filters
             case 0: // simple id-based
                 if (
@@ -232,9 +233,17 @@ const fromCosmeticFilter = function(details) {
                 ) {
                     break;
                 }
-                if ( hostnameMatches(fargs[1]) ) {
+                if ( hostnameMatches(fargs[1]) === false ) { break; }
-                    found = fargs[1] + prefix + selector;
+                // https://www.reddit.com/r/uBlockOrigin/comments/d6vxzj/
+                //   Ignore match if specific cosmetic filters are disabled
+                if (
+                    filterType === 8 &&
+                    exception === false &&
+                    details.ignoreSpecific
+                ) {
+                    break;
                 }
+                found = fargs[1] + prefix + selector;
                 break;
             // Scriptlet injection
             case 32:

src/js/reverselookup.js

@@ -170,8 +170,16 @@ const fromCosmeticFilter = async function(details, callback) {
         id: id,
         domain: µBlock.URI.domainFromHostname(hostname),
         hostname: hostname,
-        ignoreGeneric: µBlock.staticNetFilteringEngine
+        ignoreGeneric:
-                             .matchStringGenericHide(details.url) === 2,
+            µBlock.staticNetFilteringEngine.matchStringElementHide(
+                'generic',
+                details.url
+            ) === 2,
+        ignoreSpecific:
+            µBlock.staticNetFilteringEngine.matchStringElementHide(
+                'specific',
+                details.url
+            ) === 2,
         rawFilter: details.rawFilter
     });
 };

src/js/static-ext-filtering.js

@@ -44,7 +44,7 @@
   optional.
 
   The static extended filtering engine also offers parsing capabilities which
-  are available to all other specialized fitlering engines. For example,
+  are available to all other specialized filtering engines. For example,
   cosmetic and html filtering can ask the extended filtering engine to
   compile/validate selectors.
 
@@ -303,7 +303,7 @@
             [ ':nth-ancestor', compileNthAncestorSelector ],
             [ ':spath', compileSpathExpression ],
             [ ':watch-attr', compileAttrList ],
-            [ ':xpath', compileXpathExpression ]
+            [ ':xpath', compileXpathExpression ],
         ]);
 
         // https://github.com/gorhill/uBlock/issues/2793#issuecomment-333269387
@@ -517,7 +517,11 @@
             this.timer = undefined;
             this.strToIdMap = new Map();
             this.hostnameToSlotIdMap = new Map();
-            this.hostnameSlots = [];
+            // Avoid heterogeneous arrays. Thus:
+            this.hostnameSlots = [];        // array of integers
+            // IMPORTANT: initialize with an empty array because -0 is NOT < 0.
+            this.hostnameSlotsEx = [ [] ];  // Array of arrays of integers
+            // Array of strings (selectors and pseudo-selectors)
             this.strSlots = [];
             this.size = 0;
             if ( selfie !== undefined ) {
@@ -543,24 +547,27 @@
                 this.hostnameSlots.push(strId);
                 return;
             }
-            const bucket = this.hostnameSlots[iHn];
+            if ( iHn < 0 ) {
-            if ( Array.isArray(bucket) ) {
+                this.hostnameSlotsEx[-iHn].push(strId);
-                bucket.push(strId);
+                return;
-            } else {
-                this.hostnameSlots[iHn] = [ bucket, strId ];
             }
+            const strIdEx = -this.hostnameSlotsEx.length;
+            this.hostnameToSlotIdMap.set(hn, strIdEx);
+            this.hostnameSlotsEx.push([ this.hostnameSlots[iHn], strId ]);
+            this.hostnameSlots[iHn] = strIdEx;
         }
 
         clear() {
             this.hostnameToSlotIdMap.clear();
             this.hostnameSlots.length = 0;
+            this.hostnameSlotsEx.length = 1;    // IMPORTANT: 1, not 0
             this.strSlots.length = 0;
             this.strToIdMap.clear();
             this.size = 0;
         }
 
-        collectGarbage(async = false) {
+        collectGarbage(later = false) {
-            if ( async === false ) {
+            if ( later === false ) {
                 if ( this.timer !== undefined ) {
                     self.cancelIdleCallback(this.timer);
                     this.timer = undefined;
@@ -578,23 +585,39 @@
             );
         }
 
-        retrieve(hostname, out) {
+        // modifiers = 1: return only specific items
+        // modifiers = 2: return only generic items
+        //
+        retrieve(hostname, out, modifiers = 0) {
+            if ( modifiers === 2 ) {
+                hostname = '';
+            }
             const mask = out.length - 1; // out.length must be power of two
             for (;;) {
                 const filterId = this.hostnameToSlotIdMap.get(hostname);
                 if ( filterId !== undefined ) {
-                    const bucket = this.hostnameSlots[filterId];
+                    if ( filterId < 0 ) {
-                    if ( Array.isArray(bucket) ) {
+                        const bucket = this.hostnameSlotsEx[-filterId];
-                        for ( const id of bucket ) {
+                        for ( const strId of bucket ) {
-                            out[id & mask].add(this.strSlots[id >>> this.nBits]);
+                            out[strId & mask].add(
+                                this.strSlots[strId >>> this.nBits]
+                            );
                         }
                     } else {
-                        out[bucket & mask].add(this.strSlots[bucket >>> this.nBits]);
+                        const strId = this.hostnameSlots[filterId];
+                        out[strId & mask].add(
+                            this.strSlots[strId >>> this.nBits]
+                        );
                     }
                 }
                 if ( hostname === '' ) { break; }
                 const pos = hostname.indexOf('.');
-                hostname = pos !== -1 ? hostname.slice(pos + 1) : '';
+                if ( pos === -1 ) {
+                    if ( modifiers === 1 ) { break; }
+                    hostname = '';
+                } else {
+                    hostname = hostname.slice(pos + 1);
+                }
             }
         }
 
@@ -602,6 +625,7 @@
             return {
                 hostnameToSlotIdMap: Array.from(this.hostnameToSlotIdMap),
                 hostnameSlots: this.hostnameSlots,
+                hostnameSlotsEx: this.hostnameSlotsEx,
                 strSlots: this.strSlots,
                 size: this.size
             };
@@ -610,6 +634,7 @@
         fromSelfie(selfie) {
             this.hostnameToSlotIdMap = new Map(selfie.hostnameToSlotIdMap);
             this.hostnameSlots = selfie.hostnameSlots;
+            this.hostnameSlotsEx = selfie.hostnameSlotsEx;
             this.strSlots = selfie.strSlots;
             this.size = selfie.size;
         }

src/js/static-net-filtering.js

@@ -68,12 +68,13 @@ const typeNameToTypeValue = {
           'popunder': 12 << 4,
         'main_frame': 13 << 4,  // start of 1st-party-only behavorial filtering
        'generichide': 14 << 4,
-       'inline-font': 15 << 4,
+      'specifichide': 15 << 4,
-     'inline-script': 16 << 4,
+       'inline-font': 16 << 4,
-              'data': 17 << 4,  // special: a generic data holder
+     'inline-script': 17 << 4,
-          'redirect': 18 << 4,
+              'data': 18 << 4,  // special: a generic data holder
-            'webrtc': 19 << 4,
+          'redirect': 19 << 4,
-       'unsupported': 20 << 4
+            'webrtc': 20 << 4,
+       'unsupported': 21 << 4,
 };
 
 const otherTypeBitValue = typeNameToTypeValue.other;
@@ -110,12 +111,13 @@ const typeValueToTypeName = {
     12: 'popunder',
     13: 'document',
     14: 'generichide',
-    15: 'inline-font',
+    15: 'specifichide',
-    16: 'inline-script',
+    16: 'inline-font',
-    17: 'data',
+    17: 'inline-script',
-    18: 'redirect',
+    18: 'data',
-    19: 'webrtc',
+    19: 'redirect',
-    20: 'unsupported'
+    20: 'webrtc',
+    21: 'unsupported'
 };
 
 const BlockImportant = BlockAction | Important;
@@ -1848,11 +1850,11 @@ FilterParser.prototype.toNormalizedType = {
               'data': 'data',
                'doc': 'main_frame',
           'document': 'main_frame',
-          'elemhide': 'generichide',
               'font': 'font',
              'frame': 'sub_frame',
       'genericblock': 'unsupported',
        'generichide': 'generichide',
+             'ghide': 'generichide',
              'image': 'image',
        'inline-font': 'inline-font',
      'inline-script': 'inline-script',
@@ -1864,6 +1866,8 @@ FilterParser.prototype.toNormalizedType = {
           'popunder': 'popunder',
              'popup': 'popup',
             'script': 'script',
+      'specifichide': 'specifichide',
+             'shide': 'specifichide',
         'stylesheet': 'stylesheet',
        'subdocument': 'sub_frame',
                'xhr': 'xmlhttprequest',
@@ -2017,7 +2021,8 @@ FilterParser.prototype.parseOptions = function(s) {
             this.dataStr = '';
             continue;
         }
-        // Used by Adguard, purpose is unclear -- just ignore for now.
+        // Used by Adguard:
+        // https://kb.adguard.com/en/general/how-to-create-your-own-ad-filters?aid=16593#empty-modifier
         if ( opt === 'empty' || opt === 'mp4' ) {
             if ( this.redirect !== 0 ) {
                 this.unsupported = true;
@@ -2031,6 +2036,13 @@ FilterParser.prototype.parseOptions = function(s) {
             this.badFilter = true;
             continue;
         }
+        // https://www.reddit.com/r/uBlockOrigin/comments/d6vxzj/
+        //   Add support for `elemhide`. Rarely used but it happens.
+        if ( opt === 'elemhide' || opt === 'ehide' ) {
+            this.parseTypeOption('specifichide', not);
+            this.parseTypeOption('generichide', not);
+            continue;
+        }
         // Unrecognized filter option: ignore whole filter.
         this.unsupported = true;
         break;
@@ -3055,17 +3067,19 @@ FilterContainer.prototype.realmMatchString = function(
 //   filter if and only if there was a hit on an exception filter.
 // https://github.com/gorhill/uBlock/issues/2103
 //   User may want to override `generichide` exception filters.
+// https://www.reddit.com/r/uBlockOrigin/comments/d6vxzj/
+//   Add support for `specifichide`.
 
-FilterContainer.prototype.matchStringGenericHide = function(requestURL) {
+FilterContainer.prototype.matchStringElementHide = function(type, url) {
-    const typeBits = typeNameToTypeValue['generichide'] | 0x80000000;
+    const typeBits = typeNameToTypeValue[`${type}hide`] | 0x80000000;
 
     // Prime tokenizer: we get a normalized URL in return.
-    urlRegister = this.urlTokenizer.setURL(requestURL);
+    urlRegister = this.urlTokenizer.setURL(url);
     this.filterRegister = null;
 
     // These registers will be used by various filters
     pageHostnameRegister = requestHostnameRegister =
-        µb.URI.hostnameFromURI(requestURL);
+        µb.URI.hostnameFromURI(url);
 
     // Exception filters
     if ( this.realmMatchString(AllowAction, typeBits, FirstParty) ) {

src/js/utils.js

@@ -707,3 +707,18 @@
         window.dispatchEvent(new CustomEvent(name));
     }
 };
+
+/******************************************************************************/
+
+µBlock.getMessageSenderDetails = function(sender) {
+    const r = {};
+    if ( sender instanceof Object ) {
+        r.url = sender.url;
+        r.frameId = sender.frameId;
+        const tab = sender.tab;
+        if ( tab instanceof Object ) {
+            r.tabId = tab.id;
+        }
+    }
+    return r;
+};

src/logger-ui.html

@@ -61,7 +61,7 @@
                             <div><span data-filtex="!" data-i18n="loggerRowFiltererBuiltinNot"></span>
                                 <span style="flex-direction: column;">
                                     <div style="margin-bottom: 1px;"><span data-filtex="\t(?:css|(?:inline-)?font)\t">css/font</span><span data-filtex="\timage\t">image</span><span data-filtex="\tmedia\t">media</span><span data-filtex="\t(?:inline-)?script(?:ing)?\t">script</span></div>
-                                    <div><span data-filtex="\t(?:websocket|xhr)\t">xhr</span><span data-filtex="\tframe\t">frame</span><span data-filtex="\t(?:beacon|csp_report|ping|other)\t">other</span><span data-filtex="\t(?:dom|generichide)\t">dom</span></div>
+                                    <div><span data-filtex="\t(?:websocket|xhr)\t">xhr</span><span data-filtex="\tframe\t">frame</span><span data-filtex="\t(?:beacon|csp_report|ping|other)\t">other</span><span data-filtex="\t(?:dom|g(?:eneric)?hide|s(?:pecific)?hide)\t">dom</span></div>
                                 </span>
                             </div>
                             <div><span data-filtex="!" data-i18n="loggerRowFiltererBuiltinNot"></span><span data-filtex="\t(?:0,)?1\t" data-i18n="loggerRowFiltererBuiltin1p"></span><span data-filtex="\t(?:3(?:,\d)?|0,3)\t" data-i18n="loggerRowFiltererBuiltin3p"></span></div>