Issue 6652 - Do not push to unconditional selectors array

lib/elemHide.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present 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 24 matching lines @@
  * Lookup table, filter by selector. (Only used for selectors that are
  * unconditionally matched for all domains.)
  * @type {Map.<string,Filter>}
  */
 let filterBySelector = new Map();
 
 /**
  * This array caches the keys of filterBySelector table (selectors
  * which unconditionally apply on all domains). It will be null if the
  * cache needs to be rebuilt.
+ * @type {?string[]}
  */
 let unconditionalSelectors = null;
 
 /**
  * Map to be used instead when a filter has a blank domains property.
+ * @type {Map.<string,boolean>}
+ * @const
  */
 let defaultDomains = new Map([["", true]]);
 
 /**
  * Set containing known element hiding and exception filters
  * @type {Set.<ElemHideBase>}
  */
 let knownFilters = new Set();
 
 /**
  * Lookup table, lists of element hiding exceptions by selector
  * @type {Map.<string,Filter>}
  */
 let exceptions = new Map();
+
+/**
+ * Adds a filter to the lookup table of filters by domain.
+ * @param {Filter}
+ */
+function addToFiltersByDomain(filter)
+{
+  let domains = filter.domains || defaultDomains;
+  for (let [domain, isIncluded] of domains)
+  {
+    // There's no need to note that a filter is generically disabled.
+    if (!isIncluded && domain == "")
+      continue;
+
+    let filters = filtersByDomain.get(domain);
+    if (!filters)
+      filtersByDomain.set(domain, filters = new Map());
+    filters.set(filter, isIncluded);
+  }
+}
 
 /**
  * Returns a list of selectors that apply on each website unconditionally.
  * @returns {string[]}
  */
 function getUnconditionalSelectors()
 {
   if (!unconditionalSelectors)
     unconditionalSelectors = [...filterBySelector.keys()];
+
   return unconditionalSelectors;

[Manish Jethani, 2018/05/08 17:15:15]

Note that now that's this function is private to the module there's no need to
create a copy. The caller can decide what's best. For example in the current
patch the caller is using Array.concat, which creates a copy anyway.

 }
 
 /**
  * Container for element hiding filters
  * @class
  */
 let ElemHide = exports.ElemHide = {
   /**
    * Removes all known filters
    */
   clear()
   {
     for (let collection of [filtersByDomain, filterBySelector,
                             knownFilters, exceptions])
     {
       collection.clear();
     }
     unconditionalSelectors = null;
     FilterNotifier.emit("elemhideupdate");
-  },
-
-  _addToFiltersByDomain(filter)
-  {
-    let domains = filter.domains || defaultDomains;
-    for (let [domain, isIncluded] of domains)
-    {
-      // There's no need to note that a filter is generically disabled.
-      if (!isIncluded && domain == "")
-        continue;
-
-      let filters = filtersByDomain.get(domain);
-      if (!filters)
-        filtersByDomain.set(domain, filters = new Map());
-      filters.set(filter, isIncluded);
-    }
   },
 
   /**
    * Add a new element hiding filter
    * @param {ElemHideBase} filter
    */
   add(filter)
   {
     if (knownFilters.has(filter))
       return;
 
     if (filter instanceof ElemHideException)
     {
       let {selector} = filter;
       let list = exceptions.get(selector);
       if (list)
         list.push(filter);
       else
         exceptions.set(selector, [filter]);
 
       // If this is the first exception for a previously unconditionally
       // applied element hiding selector we need to take care to update the
       // lookups.
       let unconditionalFilterForSelector = filterBySelector.get(selector);
       if (unconditionalFilterForSelector)
       {
-        this._addToFiltersByDomain(unconditionalFilterForSelector);
+        addToFiltersByDomain(unconditionalFilterForSelector);
         filterBySelector.delete(selector);
         unconditionalSelectors = null;
       }
     }
     else if (!(filter.domains || exceptions.has(filter.selector)))
     {
       // The new filter's selector is unconditionally applied to all domains
       filterBySelector.set(filter.selector, filter);
       unconditionalSelectors = null;
     }
     else
     {
       // The new filter's selector only applies to some domains
-      this._addToFiltersByDomain(filter);
+      addToFiltersByDomain(filter);
     }
 
     knownFilters.add(filter);
     FilterNotifier.emit("elemhideupdate");
   },
 
   /**
    * Removes an element hiding filter
    * @param {ElemHideBase} filter
    */
@@ skipping 29 matching lines @@
     }
 
     knownFilters.delete(filter);
     FilterNotifier.emit("elemhideupdate");
   },
 
   /**
    * Checks whether an exception rule is registered for a filter on a particular
    * domain.
    * @param {Filter} filter
-   * @param {string} docDomain
-   * @return {ElemHideException}
+   * @param {?string} docDomain
+   * @return {?ElemHideException}
    */
   getException(filter, docDomain)
   {
     let list = exceptions.get(filter.selector);
     if (!list)
       return null;
 
     for (let i = list.length - 1; i >= 0; i--)
     {
       if (list[i].isActiveOnDomain(docDomain))
         return list[i];
     }
 
     return null;
   },
 
   /**
    * Constant used by getSelectorsForDomain to return all selectors applying to
    * a particular hostname.
+   * @type {number}
+   * @const
    */
   ALL_MATCHING: 0,
 
   /**
    * Constant used by getSelectorsForDomain to exclude selectors which apply to
    * all websites without exception.
+   * @type {number}
+   * @const
    */
   NO_UNCONDITIONAL: 1,
 
   /**
    * Constant used by getSelectorsForDomain to return only selectors for filters
    * which specifically match the given host name.
+   * @type {number}
+   * @const
    */
   SPECIFIC_ONLY: 2,
 
   /**
    * Determines from the current filter list which selectors should be applied
    * on a particular host name.
    * @param {string} domain
    * @param {number} [criteria]
    *   One of the following: ElemHide.ALL_MATCHING, ElemHide.NO_UNCONDITIONAL or
    *                         ElemHide.SPECIFIC_ONLY.
    * @returns {string[]}
    *   List of selectors.
    */
-  getSelectorsForDomain(domain, criteria)
+  getSelectorsForDomain(domain, criteria = ElemHide.ALL_MATCHING)
   {
     let selectors = [];
-
-    let unconditionalSelectors = null;
-
-    if (typeof criteria == "undefined")
-      criteria = ElemHide.ALL_MATCHING;
-    if (criteria < ElemHide.NO_UNCONDITIONAL)
-      unconditionalSelectors = getUnconditionalSelectors();
 
     let specificOnly = (criteria >= ElemHide.SPECIFIC_ONLY);
     let excluded = new Set();
     let currentDomain = domain ? domain.toUpperCase() : "";
 
     // This code is a performance hot-spot, which is why we've made certain
     // micro-optimisations. Please be careful before making changes.
     while (true)
     {
       if (specificOnly && currentDomain == "")
@@ skipping 16 matching lines @@
         }
       }
 
       if (currentDomain == "")
         break;
 
       let nextDot = currentDomain.indexOf(".");
       currentDomain = nextDot == -1 ? "" : currentDomain.substr(nextDot + 1);
     }
 
-    if (unconditionalSelectors)
-      selectors = unconditionalSelectors.concat(selectors);
+    if (criteria < ElemHide.NO_UNCONDITIONAL)
+      selectors = getUnconditionalSelectors().concat(selectors);
 
     return selectors;
   }
 };