Issue 6916 - Encapsulate filter subscriptions

lib/filterClasses.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 23 matching lines @@
 /**
  * Abstract base class for filters
  *
  * @param {string} text   string representation of the filter
  * @constructor
  */
 function Filter(text)
 {
   this.text = text;
 
+  /**
+   * Subscriptions to which this filter belongs.
+   * @type {Set.<Subscription>}
+   * @private
+   */
   this._subscriptions = new Set();
 }
 exports.Filter = Filter;
 
 Filter.prototype =
 {
   /**
    * String representation of the filter
    * @type {string}
    */
   text: null,
 
   /**
    * Filter type as a string, e.g. "blocking".
    * @type {string}
    */
   get type()
   {
     throw new Error("Please define filter type in the subclass");
   },
 
   /**
-   * Yields filter subscriptions the filter belongs to
+   * Yields subscriptions to which the filter belongs.
    * @yields {Subscription}
    */
   *subscriptions()
   {
     yield* this._subscriptions;
   },
 
+  /**
+   * The number of subscriptions to which the filter belongs.
+   * @type {number}
+   */
+  get subscriptionCount()
+  {
+    return this._subscriptions.size;
+  },
+
+  /**
+   * Adds a subscription to the set of subscriptions to which the filter
+   * belongs.
+   * @param {Subscription} subscription
+   */
   addSubscription(subscription)
   {
     this._subscriptions.add(subscription);
   },
 
+  /**
+   * Removes a subscription from the set of subscriptions to which the filter
+   * belongs.
+   * @param {Subscription} subscription
+   */
   removeSubscription(subscription)
   {
     this._subscriptions.delete(subscription);
   },
 
   /**
    * Serializes the filter to an array of strings for writing out on the disk.
    * @param {string[]} buffer  buffer to push the serialization results into
    */
   serialize(buffer)
@@ skipping 1102 matching lines @@
 
   /**
    * Script that should be executed
    * @type {string}
    */
   get script()
   {
     return this.body;
   }
 });