Issue 7097 - Make element hiding filter objects ephemeral

lib/subscriptionClasses.js

Index: lib/subscriptionClasses.js
===================================================================
--- a/lib/subscriptionClasses.js
+++ b/lib/subscriptionClasses.js
@@ -16,17 +16,17 @@
  */
 
 "use strict";
 
 /**
  * @fileOverview Definition of Subscription class and its subclasses.
  */
 
-const {ActiveFilter, BlockingFilter,
+const {Filter, ActiveFilter, BlockingFilter,
        WhitelistFilter, ElemHideBase} = require("./filterClasses");
 const {filterNotifier} = require("./filterNotifier");
 const {extend} = require("./coreUtils");
 
 /**
  * Abstract base class for filter subscriptions
  *
  * @param {string} url    download location of the subscription
@@ -163,27 +163,30 @@
   },
 
   /**
    * Yields the {@link Filter} object for each filter in the subscription.
    * @yields {Filter}
    */
   *filters()
   {
-    yield* this._filters;
+    for (let i = 0; i < this._filters.length; i++)
+      yield this._filters[i] || Filter.fromText(this._filterText[i]);
   },
 
   /**
    * Returns the {@link Filter} object at the given 0-based index.
    * @param {number} index
    * @returns {?Filter}
    */
   filterAt(index)
   {
-    return this._filters[index] || null;
+    return this._filters[index] ||
+           (index >= 0 && index < this._filters.length ?
+              Filter.fromText(this._filterText[index]) : null);
   },
 
   /**
    * Returns the 0-based index of the given filter.
    * @param {Filter} filter
    * @param {number} [fromIndex] The index from which to start the search.
    * @return {number}
    */
@@ -259,16 +262,22 @@
   },
 
   /**
    * Clears any in-memory caches held by the object.
    * @package
    */
   clearCaches()
   {
+    for (let i = 0; i < this._filters.length; i++)
+    {
+      if (this._filters[i] && this._filters[i].ephemeral)

[Manish Jethani, 2018/11/18 03:29:12]

filterClasses.js doesn't keep any references to ephemeral filter objects now.
Here we lose the only remaining references (after applying all the pathces).
This method is called by filterStorage.js after it dispatches the "load" event
and all the listeners have finished their business.

+        this._filters[i] = null;
+    }
+
     this._filterTextLookup = null;
   },
 
   /**
    * Serializes the subscription for writing out on disk.
    * @yields {string}
    */
   *serialize()