Apply a hybrid approach to handling events in snippets extension

src/extensions/snippets/snippets.coffee

@@ -3,38 +3,43 @@ PEG = require 'pegjs'
 _ = require 'underscore'
 
 module.exports =
-  class Snippets
-    @snippetsByExtension: {}
-    @snippetsParser: PEG.buildParser(fs.read(require.resolve 'extensions/snippets/snippets.pegjs'))
+  name: 'Snippets'
+  snippetsByExtension: {}
+  snippetsParser: PEG.buildParser(fs.read(require.resolve 'extensions/snippets/snippets.pegjs'))
 
-    @activate: (@rootView) ->
-      @loadSnippets()
+  activate: (@rootView) ->
+    @loadSnippets()
 
-      project = rootView.project
+    for editor in @rootView.editors()
+      @enableSnippetsInEditor(editor)
 
-      new Snippets(editSession) for editSession in project.editSessions
-      project.on 'new-edit-session', (editSession) => new Snippets(editSession)
+    @rootView.on 'editor-open', (e, editor) =>
+      @enableSnippetsInEditor(editor)
 
+  loadSnippets: ->
+    snippetsDir = fs.join(atom.configDirPath, 'snippets')
+    return unless fs.exists(snippetsDir)
+    @loadSnippetsFile(path) for path in fs.list(snippetsDir) when fs.extension(path) == '.snippets'
 
-    @loadSnippets: ->
-      snippetsDir = fs.join(atom.configDirPath, 'snippets')
-      return unless fs.exists(snippetsDir)
+  loadSnippetsFile: (path) ->
+    @evalSnippets(fs.base(path, '.snippets'), fs.read(path))
 
-      @loadSnippetsFile(path) for path in fs.list(snippetsDir) when fs.extension(path) == '.snippets'
+  evalSnippets: (extension, text) ->
+    @snippetsByExtension[extension] = @snippetsParser.parse(text)
 
-    @loadSnippetsFile: (path) ->
-      @evalSnippets(fs.base(path, '.snippets'), fs.read(path))
+  enableSnippetsInEditor: (editor) ->
+    editor.preempt 'tab', =>
+      editSession = editor.activeEditSession
+      editSession.snippetsSession ?= new SnippetsSession(editSession, @snippetsByExtension)
+      editSession.snippetsSession.expandSnippet()
 
-    @evalSnippets: (extension, text) ->
-      @snippetsByExtension[extension] = @snippetsParser.parse(text)
+class SnippetsSession
+  constructor: (@editSession, @snippetsByExtension) ->
 
-    constructor: (@editSession) ->
-      _.adviseBefore @editSession, 'insertTab', => @expandSnippet()
-
-    expandSnippet: ->
-      return unless snippets = @constructor.snippetsByExtension[@editSession.buffer.getExtension()]
-      prefix = @editSession.getLastCursor().getCurrentWordPrefix()
-      if body = snippets[prefix]?.body
-        @editSession.selectToBeginningOfWord()
-        @editSession.insertText(body)
-        false
+  expandSnippet: ->
+    return unless snippets = @snippetsByExtension[@editSession.buffer.getExtension()]
+    prefix = @editSession.getLastCursor().getCurrentWordPrefix()
+    if body = snippets[prefix]?.body
+      @editSession.selectToBeginningOfWord()
+      @editSession.insertText(body)
+      false