Issue 7181 - Keep a keyword-by-filter map after all

lib/matcher.js

Index: lib/matcher.js
===================================================================
--- a/lib/matcher.js
+++ b/lib/matcher.js
@@ -146,16 +146,23 @@
 /**
  * Blacklist/whitelist filter matching
  */
 class Matcher
 {
   constructor()
   {
     /**
+     * Lookup table for keywords by their associated filter
+     * @type {Map.<RegExpFilter,string>}
+     * @private
+     */
+    this._keywordsByFilter = new Map();
+
+    /**
      * Lookup table for simple filters by their associated keyword
      * @type {Map.<string,(RegExpFilter|Set.<RegExpFilter>)>}
      * @private
      */
     this._simpleFiltersByKeyword = new Map();
 
     /**
      * Lookup table for complex filters by their associated keyword
@@ -173,35 +180,41 @@
     this._filterMapsByType = new Map();
   }
 
   /**
    * Removes all known filters
    */
   clear()
   {
+    this._keywordsByFilter.clear();
     this._simpleFiltersByKeyword.clear();
     this._complexFiltersByKeyword.clear();
     this._filterMapsByType.clear();
   }
 
   /**
    * Adds a filter to the matcher
    * @param {RegExpFilter} filter
    */
   add(filter)
   {
+    if (this._keywordsByFilter.has(filter))
+      return;
+
     // Look for a suitable keyword
     let keyword = this.findKeyword(filter);
     let locationOnly = filter.isLocationOnly();
 
     addFilterByKeyword(filter, keyword,
                        locationOnly ? this._simpleFiltersByKeyword :
                          this._complexFiltersByKeyword);
 
+    this._keywordsByFilter.set(filter, keyword);
+
     if (locationOnly)
       return;
 
     for (let type of nonDefaultTypes(filter.contentType))
     {
       let map = this._filterMapsByType.get(type);
       if (!map)
         this._filterMapsByType.set(type, map = new Map());
@@ -211,23 +224,28 @@
   }
 
   /**
    * Removes a filter from the matcher
    * @param {RegExpFilter} filter
    */
   remove(filter)
   {
-    let keyword = this.findKeyword(filter);
+    let keyword = this._keywordsByFilter.get(filter);
+    if (typeof keyword == "undefined")
+      return;
+
     let locationOnly = filter.isLocationOnly();
 
     removeFilterByKeyword(filter, keyword,
                           locationOnly ? this._simpleFiltersByKeyword :
                             this._complexFiltersByKeyword);
 
+    this._keywordsByFilter.delete(filter);
+
     if (locationOnly)
       return;
 
     for (let type of nonDefaultTypes(filter.contentType))
     {
       let map = this._filterMapsByType.get(type);
       if (map)
         removeFilterByKeyword(filter, keyword, map);