Single-digit numeric prefixes can repeat commands in vim-mode

Vim mode has an operator stack. Every time an operator is pushed to the
stack, we ask if it is complete. If it's complete, we compose it with
the operator below it, then pop that operator if its complete. When no
operators remain on the stack, we call execute the final composed
operator. So far we only have DeleteChar (x) and NumericPrefix
operators.

src/atom/editor.coffee

@@ -61,7 +61,7 @@ class Editor extends Template
     getCursor: ->
       @getAceSession().getSelection().getCursor()
 
-    delete: ->
+    deleteChar: ->
       @aceEditor.remove 'right'
 
 

src/atom/global-keymap.coffee

@@ -19,10 +19,20 @@ class GlobalKeymap
       candidateBindingSets.sort (a, b) -> b.specificity - a.specificity
       for bindingSet in candidateBindingSets
         if command = bindingSet.commandForEvent(event)
-          $(event.target).trigger(command)
+          @triggerCommandEvent(event, command)
           return false
       currentNode = currentNode.parent()
     true
 
   reset: ->
     @BindingSets = []
+
+  triggerCommandEvent: (keyEvent, commandName) ->
+    commandEvent = $.Event(commandName)
+    keyEvent.char = @charForKeyEvent(keyEvent)
+    commandEvent.keyEvent = keyEvent
+    $(keyEvent.target).trigger(commandEvent)
+
+  charForKeyEvent: (keyEvent) ->
+    String.fromCharCode(keyEvent.which).toLowerCase()
+

src/atom/vim-mode-operators.coffee

@@ -0,0 +1,25 @@
+_ = require 'underscore'
+
+module.exports =
+  NumericPrefix: class
+    count: null
+    operatorToRepeat: null
+    complete: null
+
+    constructor: (@count) ->
+      @complete = false
+
+    compose: (@operatorToRepeat) ->
+      @complete = true
+
+    isComplete: -> @complete
+
+    execute: (editor) ->
+      _.times @count, => @operatorToRepeat.execute(editor)
+
+  DeleteChar: class
+    execute: (editor) ->
+      editor.deleteChar()
+
+    isComplete: -> true
+

src/atom/vim-mode.coffee

@@ -1,20 +1,23 @@
+_ = require 'underscore'
+$ = require 'jquery'
+{ NumericPrefix, DeleteChar } = require 'vim-mode-operators'
+
 module.exports =
 class VimMode
   editor: null
+  opStack: null
 
   constructor: (@editor) ->
-    atom.bindKeys '.command-mode'
-      'i': 'insert-mode:activate'
-      'x': 'command-mode:delete'
-
-    atom.bindKeys '.insert-mode'
-      '<esc>': 'command-mode:activate'
+    @opStack = []
+    atom.bindKeys '.command-mode', @commandModeBindings()
+    atom.bindKeys '.insert-mode', '<esc>': 'command-mode:activate'
 
     @editor.addClass('command-mode')
 
     @editor.on 'insert-mode:activate', => @activateInsertMode()
     @editor.on 'command-mode:activate', => @activateCommandMode()
-    @editor.on 'command-mode:delete', => @delete()
+    @editor.on 'command-mode:delete-char', => @deleteChar()
+    @editor.on 'command-mode:numeric-prefix', (e) => @numericPrefix(e)
 
   activateInsertMode: ->
     @editor.removeClass('command-mode')
@@ -24,5 +27,33 @@ class VimMode
     @editor.removeClass('insert-mode')
     @editor.addClass('command-mode')
 
-  delete: ->
-    @editor.delete()
+  deleteChar: ->
+    @pushOperator(new DeleteChar)
+
+  numericPrefix: (e) ->
+    @pushOperator(new NumericPrefix(e.keyEvent.char))
+
+  commandModeBindings: ->
+    bindings =
+      'i': 'insert-mode:activate'
+      'x': 'command-mode:delete-char'
+    for i in [0..9]
+      bindings[i] = 'command-mode:numeric-prefix'
+    bindings
+
+  pushOperator: (op) ->
+    @opStack.push(op)
+    @processOpStack()
+
+  processOpStack: ->
+    return unless @topOperator().isComplete()
+    poppedOperator = @opStack.pop()
+    if @opStack.length
+      @topOperator().compose(poppedOperator)
+      @processOpStack()
+    else
+      poppedOperator.execute(@editor)
+
+  topOperator: ->
+    _.last @opStack
+