Issue 6940 - Use underscore prefixes lib/matcher.js

lib/matcher.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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 "use strict";
 
 /**
  * @fileOverview Matcher class implementing matching addresses against
  *               a list of filters.
  */
 
-const {WhitelistFilter} = require("./filterClasses");
+const {RegExpFilter, WhitelistFilter} = require("./filterClasses");
+
+/**
+ * Regular expression for matching a keyword in a filter.
+ * @type {RegExp}
+ */
+const keywordRegExp = /[^a-z0-9%*][a-z0-9%]{3,}(?=[^a-z0-9%*])/;
+
+/**
+ * Regular expression for matching all keywords in a filter.
+ * @type {RegExp}
+ */
+const allKeywordsRegExp = new RegExp(keywordRegExp, "g");
+
+/**
+ * Bitmask for "types" that are for exception rules only, like
+ * <code>$document</code>, <code>$elemhide</code>, and so on.
+ * @type {number}
+ */
+const WHITELIST_ONLY_TYPES = RegExpFilter.typeMap.DOCUMENT |
+                             RegExpFilter.typeMap.ELEMHIDE |
+                             RegExpFilter.typeMap.GENERICHIDE |
+                             RegExpFilter.typeMap.GENERICBLOCK;
+
+/**
+ * Checks whether a particular filter is slow.
+ * @param {RegExpFilter} filter
+ * @returns {boolean}
+ */
+function isSlowFilter(filter)
+{
+  return !filter.pattern || !keywordRegExp.test(filter.pattern);
+}
+
+exports.isSlowFilter = isSlowFilter;
 
 /**
  * Blacklist/whitelist filter matching
  */
 class Matcher
 {
   constructor()
   {
     /**
      * Lookup table for filters by their associated keyword
-     * @type {Map.<string,(Filter|Filter[])>}
+     * @type {Map.<string,(Filter|Set.<Filter>)>}
+     * @private
      */
-    this.filterByKeyword = new Map();
-
-    /**
-     * Lookup table for keywords by the filter
-     * @type {Map.<Filter,string>}
-     */
-    this._keywordByFilter = new Map();

[Manish Jethani, 2018/10/01 15:08:59]

I think we should add the `@private` tag here.

Other than this, the change looks good to me, but let's wait for the rebase.

[Manish Jethani, 2018/10/01 15:10:00]

I'm wondering where exactly it should be added. I guess let's make it a practice
of adding it last (after `@type` here).

[Jon Sonesen, 2018/10/21 03:07:07]

Done.

+    this._filterByKeyword = new Map();
   }
 
   /**
    * Removes all known filters
    */
   clear()
   {
-    this.filterByKeyword.clear();
-    this._keywordByFilter.clear();
+    this._filterByKeyword.clear();
   }
 
   /**
    * Adds a filter to the matcher
    * @param {RegExpFilter} filter
    */
   add(filter)
   {
-    if (this._keywordByFilter.has(filter))
-      return;
-
     // Look for a suitable keyword
     let keyword = this.findKeyword(filter);
-    let oldEntry = this.filterByKeyword.get(keyword);
-    if (typeof oldEntry == "undefined")
-      this.filterByKeyword.set(keyword, filter);
-    else if (oldEntry.length == 1)
-      this.filterByKeyword.set(keyword, [oldEntry, filter]);
+    let set = this._filterByKeyword.get(keyword);
+    if (typeof set == "undefined")
+    {
+      this._filterByKeyword.set(keyword, filter);
+    }
+    else if (set.size == 1)
+    {
+      if (filter != set)
+        this._filterByKeyword.set(keyword, new Set([set, filter]));
+    }
     else
-      oldEntry.push(filter);
-    this._keywordByFilter.set(filter, keyword);
+    {
+      set.add(filter);
+    }
   }
 
   /**
    * Removes a filter from the matcher
    * @param {RegExpFilter} filter
    */
   remove(filter)
   {
-    let keyword = this._keywordByFilter.get(filter);
-    if (typeof keyword == "undefined")
+    let keyword = this.findKeyword(filter);
+    let set = this._filterByKeyword.get(keyword);
+    if (typeof set == "undefined")
       return;
 
-    let list = this.filterByKeyword.get(keyword);
-    if (list.length <= 1)
-      this.filterByKeyword.delete(keyword);
+    if (set.size == 1)
+    {
+      if (filter == set)
+        this._filterByKeyword.delete(keyword);
+    }
     else
     {
-      let index = list.indexOf(filter);
-      if (index >= 0)
-      {
-        list.splice(index, 1);
-        if (list.length == 1)
-          this.filterByKeyword.set(keyword, list[0]);
-      }
-    }
-
-    this._keywordByFilter.delete(filter);
+      set.delete(filter);
+
+      if (set.size == 1)
+        this._filterByKeyword.set(keyword, [...set][0]);
+    }
   }
 
   /**
    * Chooses a keyword to be associated with the filter
    * @param {Filter} filter
    * @returns {string} keyword or an empty string if no keyword could be found
+   * @protected
    */
   findKeyword(filter)
   {
     let result = "";
     let {pattern} = filter;
     if (pattern == null)
       return result;
 
-    let candidates = pattern.toLowerCase().match(
-      /[^a-z0-9%*][a-z0-9%]{3,}(?=[^a-z0-9%*])/g
-    );
+    let candidates = pattern.toLowerCase().match(allKeywordsRegExp);
     if (!candidates)
       return result;
 
-    let hash = this.filterByKeyword;
+    let hash = this._filterByKeyword;
     let resultCount = 0xFFFFFF;
     let resultLength = 0;
     for (let i = 0, l = candidates.length; i < l; i++)
     {
       let candidate = candidates[i].substr(1);
       let filters = hash.get(candidate);
-      let count = typeof filters != "undefined" ? filters.length : 0;
+      let count = typeof filters != "undefined" ? filters.size : 0;
       if (count < resultCount ||
           (count == resultCount && candidate.length > resultLength))
       {
         result = candidate;
         resultCount = count;
         resultLength = candidate.length;
       }
     }
     return result;
-  }
-
-  /**
-   * Checks whether a particular filter is being matched against.
-   * @param {RegExpFilter} filter
-   * @returns {boolean}
-   */
-  hasFilter(filter)
-  {
-    return this._keywordByFilter.has(filter);
-  }
-
-  /**
-   * Returns the keyword used for a filter, <code>null</code>
-   * for unknown filters.
-   * @param {RegExpFilter} filter
-   * @returns {?string}
-   */
-  getKeywordForFilter(filter)
-  {
-    let keyword = this._keywordByFilter.get(filter);
-    return typeof keyword != "undefined" ? keyword : null;
   }
 
   /**
    * Checks whether the entries for a particular keyword match a URL
    * @param {string} keyword
    * @param {string} location
    * @param {number} typeMask
    * @param {string} [docDomain]
    * @param {boolean} [thirdParty]
    * @param {string} [sitekey]
    * @param {boolean} [specificOnly]
    * @returns {?Filter}
-   */
-  _checkEntryMatch(keyword, location, typeMask, docDomain, thirdParty, sitekey,
-                   specificOnly)
-  {
-    let list = this.filterByKeyword.get(keyword);
-    if (typeof list == "undefined")
+   * @protected
+   */
+  checkEntryMatch(keyword, location, typeMask, docDomain, thirdParty, sitekey,
+                  specificOnly)
+  {
+    let set = this._filterByKeyword.get(keyword);
+    if (typeof set == "undefined")
       return null;
-    for (let i = 0; i < list.length; i++)
-    {
-      let filter = list[i];
-
+
+    for (let filter of set)
+    {
       if (specificOnly && filter.isGeneric() &&
           !(filter instanceof WhitelistFilter))
         continue;
 
       if (filter.matches(location, typeMask, docDomain, thirdParty, sitekey))
         return filter;
     }
     return null;
   }
 
@@ skipping 15 matching lines @@
    *   matching filter or <code>null</code>
    */
   matchesAny(location, typeMask, docDomain, thirdParty, sitekey, specificOnly)
   {
     let candidates = location.toLowerCase().match(/[a-z0-9%]{3,}/g);
     if (candidates === null)
       candidates = [];
     candidates.push("");
     for (let i = 0, l = candidates.length; i < l; i++)
     {
-      let result = this._checkEntryMatch(candidates[i], location, typeMask,
-                                         docDomain, thirdParty, sitekey,
-                                         specificOnly);
+      let result = this.checkEntryMatch(candidates[i], location, typeMask,
+                                        docDomain, thirdParty, sitekey,
+                                        specificOnly);
       if (result)
         return result;
     }
 
     return null;
   }
 }
 
 exports.Matcher = Matcher;
 
 /**
  * Combines a matcher for blocking and exception rules, automatically sorts
  * rules into two {@link Matcher} instances.
  */
 class CombinedMatcher
 {
   constructor()
   {
     /**
      * Maximal number of matching cache entries to be kept
      * @type {number}
      */
     this.maxCacheEntries = 1000;
 
     /**
      * Matcher for blocking rules.
      * @type {Matcher}
+     * @private
      */
-    this.blacklist = new Matcher();
+    this._blacklist = new Matcher();
 
     /**
      * Matcher for exception rules.
      * @type {Matcher}
+     * @private
      */
-    this.whitelist = new Matcher();
+    this._whitelist = new Matcher();
 
     /**
      * Lookup table of previous {@link Matcher#matchesAny} results
      * @type {Map.<string,Filter>}
+     * @private
      */
-    this.resultCache = new Map();
+    this._resultCache = new Map();
   }
 
   /**
    * @see Matcher#clear
    */
   clear()
   {
-    this.blacklist.clear();
-    this.whitelist.clear();
-    this.resultCache.clear();
+    this._blacklist.clear();
+    this._whitelist.clear();
+    this._resultCache.clear();
   }
 
   /**
    * @see Matcher#add
    * @param {Filter} filter
    */
   add(filter)
   {
     if (filter instanceof WhitelistFilter)
-      this.whitelist.add(filter);
+      this._whitelist.add(filter);
     else
-      this.blacklist.add(filter);
-
-    this.resultCache.clear();
+      this._blacklist.add(filter);
+
+    this._resultCache.clear();
   }
 
   /**
    * @see Matcher#remove
    * @param {Filter} filter
    */
   remove(filter)
   {
     if (filter instanceof WhitelistFilter)
-      this.whitelist.remove(filter);
+      this._whitelist.remove(filter);
     else
-      this.blacklist.remove(filter);
-
-    this.resultCache.clear();
+      this._blacklist.remove(filter);
+
+    this._resultCache.clear();
   }
 
   /**
    * @see Matcher#findKeyword
    * @param {Filter} filter
    * @returns {string} keyword
+   * @protected
    */
   findKeyword(filter)
   {
     if (filter instanceof WhitelistFilter)
-      return this.whitelist.findKeyword(filter);
-    return this.blacklist.findKeyword(filter);
-  }
-
-  /**
-   * @see Matcher#hasFilter
-   * @param {Filter} filter
-   * @returns {boolean}
-   */
-  hasFilter(filter)
-  {
-    if (filter instanceof WhitelistFilter)
-      return this.whitelist.hasFilter(filter);
-    return this.blacklist.hasFilter(filter);
-  }
-
-  /**
-   * @see Matcher#getKeywordForFilter
-   * @param {Filter} filter
-   * @returns {string} keyword
-   */
-  getKeywordForFilter(filter)
-  {
-    if (filter instanceof WhitelistFilter)
-      return this.whitelist.getKeywordForFilter(filter);
-    return this.blacklist.getKeywordForFilter(filter);
-  }
-
-  /**
-   * Checks whether a particular filter is slow
-   * @param {RegExpFilter} filter
-   * @returns {boolean}
-   */
-  isSlowFilter(filter)
-  {
-    let matcher = (
-      filter instanceof WhitelistFilter ? this.whitelist : this.blacklist
-    );
-    let keyword = matcher.getKeywordForFilter(filter);
-    if (keyword != null)
-      return !keyword;
-    return !matcher.findKeyword(filter);
+      return this._whitelist.findKeyword(filter);
+    return this._blacklist.findKeyword(filter);
   }
 
   /**
    * Optimized filter matching testing both whitelist and blacklist matchers
    * simultaneously. For parameters see
      {@link Matcher#matchesAny Matcher.matchesAny()}.
    * @see Matcher#matchesAny
    * @inheritdoc
-   */
-  matchesAnyInternal(location, typeMask, docDomain, thirdParty, sitekey,
-                     specificOnly)
+   * @private
+   */
+  _matchesAnyInternal(location, typeMask, docDomain, thirdParty, sitekey,
+                      specificOnly)
   {
     let candidates = location.toLowerCase().match(/[a-z0-9%]{3,}/g);
     if (candidates === null)
       candidates = [];
     candidates.push("");
 
+    let whitelistHit = null;
     let blacklistHit = null;
-    for (let i = 0, l = candidates.length; i < l; i++)
-    {
-      let substr = candidates[i];
-      let result = this.whitelist._checkEntryMatch(
-        substr, location, typeMask, docDomain, thirdParty, sitekey
-      );
-      if (result)
-        return result;
-      if (blacklistHit === null)
+
+    // If the type mask includes no types other than whitelist-only types, we
+    // can skip the blacklist.
+    if ((typeMask & ~WHITELIST_ONLY_TYPES) != 0)
+    {
+      for (let i = 0, l = candidates.length; !blacklistHit && i < l; i++)
       {
-        blacklistHit = this.blacklist._checkEntryMatch(
-          substr, location, typeMask, docDomain, thirdParty, sitekey,
-          specificOnly
-        );
+        blacklistHit = this._blacklist.checkEntryMatch(candidates[i], location,
+                                                       typeMask, docDomain,
+                                                       thirdParty, sitekey,
+                                                       specificOnly);
       }
     }
-    return blacklistHit;
+
+    // If the type mask includes any whitelist-only types, we need to check the
+    // whitelist.
+    if (blacklistHit || (typeMask & WHITELIST_ONLY_TYPES) != 0)
+    {
+      for (let i = 0, l = candidates.length; !whitelistHit && i < l; i++)
+      {
+        whitelistHit = this._whitelist.checkEntryMatch(candidates[i], location,
+                                                       typeMask, docDomain,
+                                                       thirdParty, sitekey);
+      }
+    }
+
+    return whitelistHit || blacklistHit;
   }
 
   /**
    * @see Matcher#matchesAny
    * @inheritdoc
    */
   matchesAny(location, typeMask, docDomain, thirdParty, sitekey, specificOnly)
   {
     let key = location + " " + typeMask + " " + docDomain + " " + thirdParty +
       " " + sitekey + " " + specificOnly;
 
-    let result = this.resultCache.get(key);
+    let result = this._resultCache.get(key);
     if (typeof result != "undefined")
       return result;
 
-    result = this.matchesAnyInternal(location, typeMask, docDomain,
-                                     thirdParty, sitekey, specificOnly);
-
-    if (this.resultCache.size >= this.maxCacheEntries)
-      this.resultCache.clear();
-
-    this.resultCache.set(key, result);
+    result = this._matchesAnyInternal(location, typeMask, docDomain,
+                                      thirdParty, sitekey, specificOnly);
+
+    if (this._resultCache.size >= this.maxCacheEntries)
+      this._resultCache.clear();
+
+    this._resultCache.set(key, result);
 
     return result;
   }
 }
 
 exports.CombinedMatcher = CombinedMatcher;
 
 /**
  * Shared {@link CombinedMatcher} instance that should usually be used.
  * @type {CombinedMatcher}
  */
 let defaultMatcher = new CombinedMatcher();
 
 exports.defaultMatcher = defaultMatcher;