Implement split-left

spec/atom/root-view-spec.coffee

@@ -62,6 +62,33 @@ describe "RootView", ->
         expect(editor1.lines.find('.line:first').text()).toContain 'ABC'
         expect(editor2.lines.find('.line:first').text()).toContain 'ABC'
 
+    describe "when split-left is triggered on the editor", ->
+      it "places the a new editor to the left of the current editor in a .horizontal div, and focuses the new editor", ->
+        rootView.attachToDom()
+
+        expect(rootView.find('.horizontal')).not.toExist()
+
+        editor1 = rootView.find('.editor').view()
+        editor1.setBuffer(new Buffer(require.resolve 'fixtures/sample.js'))
+        editor1.setCursorScreenPosition([3, 2])
+        editor1.trigger 'split-left'
+
+        expect(rootView.find('.horizontal')).toExist()
+        expect(rootView.find('.horizontal .editor').length).toBe 2
+        expect(rootView.find('.horizontal .editor:eq(1)').view()).toBe editor1
+        editor2 = rootView.find('.horizontal .editor:eq(0)').view()
+        expect(editor2.buffer).toBe editor1.buffer
+        expect(editor2.getCursorScreenPosition()).toEqual [3, 2]
+        expect(editor1).toHaveClass 'split'
+        expect(editor2).toHaveClass 'split'
+
+        expect(editor1.has(':focus')).not.toExist()
+        expect(editor2.has(':focus')).toExist()
+
+        # insertion reflected in both buffers
+        editor1.buffer.insert([0, 0], 'ABC')
+        expect(editor1.lines.find('.line:first').text()).toContain 'ABC'
+        expect(editor2.lines.find('.line:first').text()).toContain 'ABC'
 
   describe ".addPane(view)", ->
     it "adds the given view to the rootView (at the bottom by default)", ->

src/atom/editor.coffee

@@ -72,6 +72,7 @@ class Editor extends View
       'alt-meta-w': 'toggle-soft-wrap'
       'alt-meta-f': 'fold-selection'
       'alt-meta-right': 'split-right'
+      'alt-meta-left': 'split-left'
 
     @on 'save', => @save()
     @on 'move-right', => @moveCursorRight()
@@ -93,6 +94,7 @@ class Editor extends View
     @on 'toggle-soft-wrap', => @toggleSoftWrap()
     @on 'fold-selection', => @foldSelection()
     @on 'split-right', => @splitRight()
+    @on 'split-left', => @splitLeft()
 
   buildCursorAndSelection: ->
     @cursor = new Cursor(this)
@@ -407,13 +409,22 @@ class Editor extends View
     @renderer.logLines()
 
   splitRight: ->
+    @splitVertically(true)
+
+  splitLeft: ->
+    @splitVertically(false)
+
+  splitVertically: (right) ->
     unless @parent().is('.horizontal')
       horizontal = $$ -> @div class: 'horizontal'
       horizontal.insertBefore(this).append(this.detach())
 
     editor = new Editor({@buffer})
     editor.setCursorScreenPosition(@getCursorScreenPosition())
-    @after(editor)
+    if right
+      @after(editor)
+    else
+      @before(editor)
     @addClass 'split'
     editor.addClass('split')