Issue 6862 - Make Snippets module emit events

lib/snippets.js

Index: lib/snippets.js
===================================================================
--- a/lib/snippets.js
+++ b/lib/snippets.js
@@ -16,53 +16,69 @@
  */
 
 "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)
@@ -71,17 +87,17 @@
     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[]>}
  */