Issue 4167 - getSelectorsForDomain criteria + keys

lib/elemHide.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 18 matching lines @@
  */
 var filterByKey = [];
 
 /**
  * Lookup table, keys of the filters by filter text
  * @type Object
  */
 var keyByFilter = Object.create(null);
 
 /**
- * Indicates whether we are using the getSelectorsForDomain function and
- * therefore mainting the required filtersByDomain, filtersBySelector and
- * unconditionalSelectors lookups. (Will be false for Firefox)
- * @type Boolean
- */
-var usingGetSelectorsForDomain = !("nsIStyleSheetService" in Ci);
-
-/**
  * Nested lookup table, filter (or false if inactive) by filter key by domain.
  * (Only contains filters that aren't unconditionally matched for all domains.)
  * @type Object
  */
 var filtersByDomain = Object.create(null);
 
 /**
- * Lookup table, filters by selector. (Only contains filters that have a
+ * Lookup table, filter keys by selector. (Only contains filters that have a
  * selector that is unconditionally matched for all domains.)
  */
-var filtersBySelector = Object.create(null);
+var filterKeysBySelector = Object.create(null);
 
 /**
- * This array caches the keys of filtersBySelector table (selectors which
+ * This array caches the keys of filterKeysBySelector table (selectors which
  * unconditionally apply on all domains). It will be null if the cache needs to
  * be rebuilt.
  */
 var unconditionalSelectors = null;
 
 /**
+ * This array caches the values of filterKeysBySelector table (filterIds for
+ * selectors which unconditionally apply on all domains). It will be null if the
+ * cache needs to be rebuilt. Note: Only the first filter key for each selector
+ * is cached.
+ */
+var unconditionalFilterKeys = null;
+
+/**
  * Object to be used instead when a filter has a blank domains property.
  */
 var defaultDomains = Object.create(null);
 defaultDomains[""] = true;
 
 /**
  * Lookup table, keys are known element hiding exceptions
  * @type Object
  */
 var knownExceptions = Object.create(null);
@@ skipping 11 matching lines @@
 var ElemHide = exports.ElemHide =
 {
   /**
    * Removes all known filters
    */
   clear: function()
   {
     filterByKey = [];
     keyByFilter = Object.create(null);
     filtersByDomain = Object.create(null);
-    filtersBySelector = Object.create(null);
-    unconditionalSelectors = null;
+    filterKeysBySelector = Object.create(null);
+    unconditionalSelectors = unconditionalFilterKeys = null;
     knownExceptions = Object.create(null);
     exceptions = Object.create(null);
     FilterNotifier.emit("elemhideupdate");
   },
 
-  _addToFiltersByDomain: function(filter)
+  _addToFiltersByDomain: function(key, filter)
   {
-    let key = keyByFilter[filter.text];
     let domains = filter.domains || defaultDomains;
     for (let domain in domains)
     {
       let filters = filtersByDomain[domain];
       if (!filters)
         filters = filtersByDomain[domain] = Object.create(null);
 
       if (domains[domain])
         filters[key] = filter;
       else
@@ skipping 10 matching lines @@
     if (filter instanceof ElemHideException)
     {
       if (filter.text in knownExceptions)
         return;
 
       let selector = filter.selector;
       if (!(selector in exceptions))
         exceptions[selector] = [];
       exceptions[selector].push(filter);
 
-      if (usingGetSelectorsForDomain)
+      // If this is the first exception for a previously unconditionally
+      // applied element hiding selector we need to take care to update the
+      // lookups.
+      let filterKeys = filterKeysBySelector[selector];
+      if (filterKeys)
       {
-        // If this is the first exception for a previously unconditionally
-        // applied element hiding selector we need to take care to update the
-        // lookups.
-        let unconditionalFilters = filtersBySelector[selector];
-        if (unconditionalFilters)
-        {
-          for (let f of unconditionalFilters)
-            this._addToFiltersByDomain(f);
-          delete filtersBySelector[selector];
-          unconditionalSelectors = null;
-        }
+        for (let filterKey of filterKeys)
+          this._addToFiltersByDomain(filterKey, filterByKey[filterKey]);
+        delete filterKeysBySelector[selector];
+        unconditionalSelectors = unconditionalFilterKeys = null;
       }
 
       knownExceptions[filter.text] = true;
     }
     else
     {
       if (filter.text in keyByFilter)
         return;
 
       let key = filterByKey.push(filter) - 1;
       keyByFilter[filter.text] = key;
 
-      if (usingGetSelectorsForDomain)
+      if (!(filter.domains || filter.selector in exceptions))
       {
-        if (!(filter.domains || filter.selector in exceptions))
+        // The new filter's selector is unconditionally applied to all domains
+        let filterKeys = filterKeysBySelector[filter.selector];
+        if (filterKeys)
         {
-          // The new filter's selector is unconditionally applied to all domains
-          let filters = filtersBySelector[filter.selector];
-          if (filters)
-          {
-            filters.push(filter);
-          }
-          else
-          {
-            filtersBySelector[filter.selector] = [filter];
-            unconditionalSelectors = null;
-          }
+          filterKeys.push(key);
         }
         else
         {
-          // The new filter's selector only applies to some domains
-          this._addToFiltersByDomain(filter);
+          filterKeysBySelector[filter.selector] = [key];
+          unconditionalSelectors = unconditionalFilterKeys = null;
         }
       }
+      else
+      {
+        // The new filter's selector only applies to some domains
+        this._addToFiltersByDomain(key, filter);
+      }
     }
 
     FilterNotifier.emit("elemhideupdate");
   },
 
+  _removeFilterKey: function(key, filter)
+  {
+    let filterKeys = filterKeysBySelector[filter.selector];
+    if (filterKeys)
+    {
+      let index = filterKeys.indexOf(key);
+      if (index >= 0)

[kzar, 2016/09/20 18:37:35]

It kind of bugs me how we check index twice, also how we potentially check that
filterKeys.length > 1 even if the index is bigger than 0. I can't see a cleaner
way however :(

+      {
+        if (filterKeys.length > 1)
+        {
+          filterKeys.splice(index, 1);
+          if (index == 0)
+            unconditionalFilterKeys = null;
+        }
+        else
+        {
+          delete filterKeysBySelector[filter.selector];
+          unconditionalSelectors = unconditionalFilterKeys = null;
+        }
+        return;
+      }
+    }
+
+    // We haven't found this filter in unconditional filters, look in
+    // filtersByDomain.
+    let domains = filter.domains || defaultDomains;
+    for (let domain in domains)
+    {
+      let filters = filtersByDomain[domain];
+      if (filters)
+        delete filters[key];
+    }
+  },
+
   /**
    * Removes an element hiding filter
    * @param {ElemHideFilter} filter
    */
   remove: function(filter)
   {
     if (filter instanceof ElemHideException)
     {
       if (!(filter.text in knownExceptions))
         return;
 
       let list = exceptions[filter.selector];
       let index = list.indexOf(filter);
       if (index >= 0)
         list.splice(index, 1);
       delete knownExceptions[filter.text];
     }
     else
     {
       if (!(filter.text in keyByFilter))
         return;
 
       let key = keyByFilter[filter.text];
       delete filterByKey[key];
       delete keyByFilter[filter.text];
-
-      if (usingGetSelectorsForDomain)
-      {
-        let filters = filtersBySelector[filter.selector];
-        if (filters)
-        {
-          if (filters.length > 1)
-          {
-            let index = filters.indexOf(filter);
-            filters.splice(index, 1);
-          }
-          else
-          {
-            delete filtersBySelector[filter.selector];
-            unconditionalSelectors = null;
-          }
-        }
-        else
-        {
-          let domains = filter.domains || defaultDomains;
-          for (let domain in domains)
-          {
-            let filters = filtersByDomain[domain];
-            if (filters)
-              delete filters[key];
-          }
-        }
-      }
+      this._removeFilterKey(key, filter);
     }
 
     FilterNotifier.emit("elemhideupdate");
   },
 
   /**
    * Checks whether an exception rule is registered for a filter on a particular
    * domain.
    */
   getException: function(/**Filter*/ filter, /**String*/ docDomain) /**ElemHideException*/
   {
     if (!(filter.selector in exceptions))
       return null;
 
     let list = exceptions[filter.selector];
     for (let i = list.length - 1; i >= 0; i--)
       if (list[i].isActiveOnDomain(docDomain))
         return list[i];
 
     return null;
   },
 
   /**
    * Retrieves an element hiding filter by the corresponding protocol key
    */
-  getFilterByKey: function(/**String*/ key) /**Filter*/
+  getFilterByKey: function(/**Number*/ key) /**Filter*/
   {
     return (key in filterByKey ? filterByKey[key] : null);
   },
 
   /**
    * Returns a list of all selectors as a nested map. On first level, the keys
    * are all values of `ElemHideBase.selectorDomain` (domains on which these
    * selectors should apply, ignoring exceptions). The values are maps again,
    * with the keys being selectors and values the corresponding filter keys.
    * @returns {Map.<String,Map<String,String>>}
@@ skipping 12 matching lines @@
 
       if (!domains.has(domain))
         domains.set(domain, new Map());
       domains.get(domain).set(selector, key);
     }
 
     return domains;
   },
 
   /**
-   * Returns a list of all selectors active on a particular domain, must not be
-   * used in Firefox (when usingGetSelectorsForDomain is false).
+   * Returns a list of selectors that apply on each website unconditionally.
+   * @returns {String[]}
    */
-  getSelectorsForDomain: function(/**String*/ domain, /**Boolean*/ specificOnly)
+  getUnconditionalSelectors: function()
   {
-    if (!usingGetSelectorsForDomain)
-      throw new Error("getSelectorsForDomain can not be used in Firefox!");
+    if (!unconditionalSelectors)
+      unconditionalSelectors = Object.keys(filterKeysBySelector);
+    return unconditionalSelectors.slice();
+  },
 
-    if (!unconditionalSelectors)
-      unconditionalSelectors = Object.keys(filtersBySelector);
-    let selectors = specificOnly ? [] : unconditionalSelectors.slice();
+  /**
+   * Returns a list of all selectors active on a particular domain.
+   * Returns a list of filterKeys for selectors that apply on each website
+   * unconditionally.
+   * @returns {Number[]}
+   */
+  getUnconditionalFilterKeys: function()
+  {
+    if (!unconditionalFilterKeys)
+    {
+      let selectors = this.getUnconditionalSelectors();
+      unconditionalFilterKeys = [];
+      for (let selector of selectors)
+        unconditionalFilterKeys.push(filterKeysBySelector[selector][0]);
+    }
+    return unconditionalFilterKeys.slice();
+  },
 
+
+  /**
+   * Constant used by getSelectorsForDomain's when matching all selectors.
+   */
+  ALL_MATCHING: 0,
+
+  /**
+   * Constant used by getSelectorsForDomain's when not matching unconditional
+   * selectors.
+   */
+  NO_UNCONDITIONAL: 1,
+
+  /**
+   * Constant used by getSelectorsForDomain's when only matching specific
+   * selectors.
+   */
+  SPECIFIC_ONLY: 2,
+
+  /**
+   * Returns a list of all selectors active on a particular domain. Optionally
+   * a list of corresponding filter keys for the selectors can be returned too.
+   * The optional criteria parameter restricts the results, and must have the
+   * value of ALL_MATCHING, NO_UNCONDITIONAL or SPECIFIC_ONLY if provided.

[Wladimir Palant, 2016/09/26 14:56:54]

Nit: You are documenting return value and parameters here, not the function. How
about documenting everything properly rather than inline:

  Determines from the current filter list which selectors should be applied on a
particular host name.

  @param {String} domain
  @param {Number} [criteria]
    One of ALL_MATCHING, NO_UNCONDITIONAL or SPECIFIC_ONLY.
  @param {Boolean} [provideFilterKeys]
    If true, will return a list of corresponding filter keys in addition to
selectors.
  @returns {string[]|Array.<string[]>} List of selectors or an array with two
elements (list of selectors and list of corresponding keys) if provideFilterKeys
is true.

[kzar, 2016/09/27 12:40:22]

Done.

+   */
+  getSelectorsForDomain: function(/**String*/ domain,
+                                  /**Number*/ criteria,
+                                  /**Boolean*/ provideFilterKeys)
+  {
+    let filterKeys = [];
+    let selectors = [];
+
+    if (typeof criteria == "undefined")
+      criteria = ElemHide.ALL_MATCHING;
+    if (criteria < ElemHide.NO_UNCONDITIONAL)
+    {
+      selectors = this.getUnconditionalSelectors();
+      if (provideFilterKeys)
+        filterKeys = this.getUnconditionalFilterKeys();
+    }
+
+    let specificOnly = (criteria >= ElemHide.SPECIFIC_ONLY);
     let seenFilters = Object.create(null);
     let currentDomain = domain ? domain.toUpperCase() : "";
     while (true)
     {
       if (specificOnly && currentDomain == "")
         break;
 
       let filters = filtersByDomain[currentDomain];
       if (filters)
       {
         for (let filterKey in filters)
         {
           if (filterKey in seenFilters)
             continue;
           seenFilters[filterKey] = true;
 
           let filter = filters[filterKey];
           if (filter && !this.getException(filter, domain))
+          {
             selectors.push(filter.selector);
+            // It is faster to always push the key, even if not required.
+            filterKeys.push(filterKey);
+          }
         }
       }
 
       if (currentDomain == "")
         break;
 
       let nextDot = currentDomain.indexOf(".");
       currentDomain = nextDot == -1 ? "" : currentDomain.substr(nextDot + 1);
     }
 
-    return selectors;
+    if (provideFilterKeys)
+      return [selectors, filterKeys];
+    else
+      return selectors;
   }
 };