When trying to compose operators that don't compose, the op stack is cleared

spec/atom/vim-mode-spec.coffee

@@ -2,7 +2,7 @@ Editor = require 'editor'
 VimMode = require 'vim-mode'
 
 describe "VimMode", ->
-  editor = null
+  [editor, vimMode] = []
 
   beforeEach ->
     editor = new Editor
@@ -36,6 +36,25 @@ describe "VimMode", ->
       editor.setCursorPosition([1, 0])
       expect(editor.getCursorPosition()).toEqual [1,0]
 
+    it "clears the operator stack when commands can't be composed", ->
+      editor.trigger keydownEvent('d')
+      expect(vimMode.opStack.length).toBe 1
+      editor.trigger keydownEvent('x')
+      expect(vimMode.opStack.length).toBe 0
+
+      editor.trigger keydownEvent('d')
+      expect(vimMode.opStack.length).toBe 1
+      editor.trigger keydownEvent('\\') # \ is an unused key in vim
+      expect(vimMode.opStack.length).toBe 0
+
+    describe "the esc keybinding", ->
+      it "clears the operator stack", ->
+        editor.trigger keydownEvent('d')
+        expect(vimMode.opStack.length).toBe 1
+
+        editor.trigger keydownEvent('esc')
+        expect(vimMode.opStack.length).toBe 0
+
     describe "the i keybinding", ->
       it "puts the editor into insert mode", ->
         expect(editor).not.toHaveClass 'insert-mode'

src/atom/vim-mode.coffee

@@ -21,24 +21,26 @@ class VimMode
     @setupCommandMode()
 
   setupCommandMode: ->
-    atom.bindKeys '.command-mode', (e) ->
+    atom.bindKeys '.command-mode', (e) =>
       if e.keystroke.match /^\d$/
         return 'command-mode:numeric-prefix'
       if e.keystroke.match /^.$/
+        @resetCommandMode()
         return false
 
     @bindCommandModeKeys
-      'i': 'insert'
-      'd': 'delete'
-      'x': 'delete-right'
-      'h': 'move-left'
-      'j': 'move-down'
-      'k': 'move-up'
-      'l': 'move-right'
-      'w': 'move-to-next-word'
-      'b': 'move-to-previous-word'
-      'left': 'move-left'
-      'right': 'move-right'
+      i: 'insert'
+      d: 'delete'
+      x: 'delete-right'
+      h: 'move-left'
+      j: 'move-down'
+      k: 'move-up'
+      l: 'move-right'
+      w: 'move-to-next-word'
+      b: 'move-to-previous-word'
+      esc: 'reset-command-mode'
+      left: 'move-left'
+      right: 'move-right'
 
     @handleCommands
       'insert': => @activateInsertMode()
@@ -51,6 +53,7 @@ class VimMode
       'move-to-next-word': => new motions.MoveToNextWord(@editor)
       'move-to-previous-word': => new motions.MoveToPreviousWord(@editor)
       'numeric-prefix': (e) => @numericPrefix(e)
+      'reset-command-mode': => @resetCommandMode()
 
   bindCommandModeKeys: (bindings) ->
     prefixedBindings = {}
@@ -78,6 +81,9 @@ class VimMode
 
     @editor.on 'cursor:position-changed', @moveCursorBeforeNewline
 
+  resetCommandMode: ->
+    @opStack = []
+
   moveCursorBeforeNewline: =>
     if not @editor.selection.modifyingSelection and @editor.cursor.isOnEOL() and @editor.getCurrentLine().length > 0
       @editor.setCursorColumn(@editor.getCurrentLine().length - 1)
@@ -107,10 +113,14 @@ class VimMode
 
   processOpStack: ->
     return unless @topOperator().isComplete()
+
     poppedOperator = @opStack.pop()
     if @opStack.length
-      @topOperator().compose(poppedOperator)
-      @processOpStack()
+      try
+        @topOperator().compose(poppedOperator)
+        @processOpStack()
+      catch e
+        (e instanceof operators.OperatorError) and @resetCommandMode() or throw e
     else
       poppedOperator.execute()
 

src/atom/vim-mode/motions.coffee

@@ -61,4 +61,4 @@ class MoveToNextWord extends Motion
       column = nextLineMatch?.index or 0
     { row, column }
 
-module.exports = { MoveLeft, MoveRight, MoveUp, MoveDown, MoveToNextWord, MoveToPreviousWord }
+module.exports = { Motion, MoveLeft, MoveRight, MoveUp, MoveDown, MoveToNextWord, MoveToPreviousWord }

src/atom/vim-mode/operators.coffee

@@ -1,5 +1,9 @@
 _ = require 'underscore'
 
+class OperatorError
+  constructor: (@message) ->
+    @name = "Operator Error"
+
 class NumericPrefix
   count: null
   complete: null
@@ -43,8 +47,11 @@ class Delete
       @editor.setCursorPosition([@editor.getCursorRow(), 0])
 
   compose: (motion) ->
+    if not motion.select
+      throw new OperatorError("Delete must compose with a motion")
+
     @motion = motion
     @complete = true
 
-module.exports = { NumericPrefix, Delete }
+module.exports = { NumericPrefix, Delete, OperatorError }