Issue 6862 - Make Snippets module emit events

lib/snippets.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 Snippets implementation.
  */
 
+const {EventEmitter} = require("./events");
 const {Filter} = require("./filterClasses");
 
 const singleCharacterEscapes = new Map([
   ["n", "\n"], ["r", "\r"], ["t", "\t"]
 ]);
 
 let filters = new Set();
 
 /**
  * Container for snippet filters
  * @class
  */
-let Snippets = {
+let Snippets = Object.assign(new EventEmitter(), {
   /**
    * Removes all known filters
    */
   clear()
   {
+    if (filters.size == 0)
+      return;
+
     filters.clear();
+
+    this.emit("snippets.filtersCleared");
   },
 
   /**
    * Add a new snippet filter
    * @param {SnippetFilter} filter
    */
   add(filter)
   {
+    let {size} = filters;
+
     filters.add(filter.text);
+
+    if (size != filters.size)
+      this.emit("snippets.filterAdded", filter);
   },
 
   /**
    * Removes a snippet filter
    * @param {SnippetFilter} filter
    */
   remove(filter)
   {
+    let {size} = filters;
+
     filters.delete(filter.text);
+
+    if (size != filters.size)
+      this.emit("snippets.filterRemoved", filter);
   },
 
   /**
    * Returns a list of all scripts active on a particular domain
    * @param {string} domain
    * @return {string[]}
    */
   getScriptsForDomain(domain)
   {
     let result = [];
     for (let text of filters)
     {
       let filter = Filter.fromText(text);
       if (filter.isActiveOnDomain(domain))
         result.push(filter.script);
     }
     return result;
   }
-};
+});
 
 exports.Snippets = Snippets;
 
 /**
  * Parses a script and returns a list of all its commands and their arguments
  * @param {string} script
  * @return {Array.<string[]>}
  */
 function parseScript(script)
 {
@@ skipping 98 matching lines @@
           let value = imports[name];
           if (typeof value == "function")
             value(...args);
         }
       }
     }
   `;
 }
 
 exports.compileScript = compileScript;