Implement backspace on Editor

spec/atom/buffer-spec.coffee

@@ -70,29 +70,47 @@ describe 'Buffer', ->
         expect(buffer.getLine(4)).toBe lineBelowOriginalLine
 
   describe ".backspace(position)", ->
-    it "can remove a character from middle of line", ->
-      originalLineLength = buffer.getLine(1).length
-      expect(buffer.getLine(1).charAt(6)).toBe 's'
-      buffer.backspace({row: 1, col: 7})
-      expect(buffer.getLine(1).charAt(6)).toBe 'o'
-      expect(buffer.getLine(1).length).toBe originalLineLength - 1
+    changeHandler = null
+    beforeEach ->
+      changeHandler = jasmine.createSpy('changeHandler')
+      buffer.on 'change', changeHandler
 
-    it "can remove a character from the end of the line", ->
-      originalLineLength = buffer.getLine(1).length
-      expect(buffer.getLine(1).charAt(originalLineLength - 1)).toBe '{'
-      buffer.backspace({row: 1, col: originalLineLength})
-      expect(buffer.getLine(1).length).toBe originalLineLength - 1
-      expect(buffer.getLine(1).charAt(originalLineLength - 2)).toBe '{'
+    describe "when the given position is in the middle of a line", ->
+      it "removes the preceding character and emits a change event", ->
+        originalLineLength = buffer.getLine(1).length
 
-    it "can remove a character from the begining of the line", ->
-      originalLineCount = buffer.getLines().length
-      originalLineLengthFromAbove = buffer.getLine(11).length
-      originalLineLength = buffer.getLine(12).length
-      expect(buffer.getLine(12).charAt(0)).toBe '}'
-      buffer.backspace({row: 12, col: 0})
-      expect(buffer.getLines().length).toBe originalLineCount - 1
-      expect(buffer.getLine(11).charAt(originalLineLengthFromAbove)).toBe '}'
-      expect(buffer.getLine(11).length).toBe originalLineLengthFromAbove + originalLineLength
+        expect(buffer.getLine(1)).toBe '  var sort = function(items) {'
+        buffer.backspace({row: 1, col: 7})
+        expect(buffer.getLine(1)).toBe '  var ort = function(items) {'
+        expect(buffer.getLine(1).length).toBe originalLineLength - 1
+
+        expect(changeHandler).toHaveBeenCalled()
+        [event] = changeHandler.argsForCall[0]
+        expect(event.string).toBe ''
+        expect(event.preRange.start).toEqual { row: 1, col: 6 }
+        expect(event.preRange.end).toEqual { row: 1, col: 7 }
+        expect(event.postRange.start).toEqual { row: 1, col: 6 }
+        expect(event.postRange.end).toEqual { row: 1, col: 6 }
+
+    describe "when the given position is at the beginning of a line", ->
+      it "appends the current line to the previous and emits a change event", ->
+        originalLineCount = buffer.getLines().length
+
+        lineAboveOriginalLine = buffer.getLine(11)
+        originalLine = buffer.getLine(12)
+
+        buffer.backspace({row: 12, col: 0})
+
+        expect(buffer.getLines().length).toBe(originalLineCount - 1)
+        expect(buffer.getLine(11)).toBe lineAboveOriginalLine + originalLine
+
+        expect(changeHandler).toHaveBeenCalled()
+        [event] = changeHandler.argsForCall[0]
+        expect(event.string).toBe ''
+        expect(event.preRange.start).toEqual { row: 11, col: lineAboveOriginalLine.length }
+        expect(event.preRange.end).toEqual { row: 12, col: 0 }
+        expect(event.postRange.start).toEqual { row: 11, col: lineAboveOriginalLine.length }
+        expect(event.postRange.end).toEqual { row: 11, col: lineAboveOriginalLine.length }
 
   describe ".save()", ->
     describe "when the buffer has a path", ->

spec/atom/editor-spec.coffee

@@ -261,4 +261,16 @@ describe "Editor", ->
 
         expect(editor.lines.find('pre:eq(2)')).toHaveHtml ' '
         expect(editor.getPosition()).toEqual(row: 2, col: 0)
-      
+
+  describe "when backspace is pressed", ->
+    describe "when the cursor is on the middle of the line", ->
+      it "removes the character before the cursor", ->
+        editor.setPosition(row: 1, col: 7)
+        spyOn(buffer, 'backspace').andCallThrough()
+
+        editor.trigger keydownEvent('backspace')
+
+        expect(buffer.backspace).toHaveBeenCalledWith(row: 1, col: 7)
+        expect(editor.lines.find('pre:eq(1)')).toHaveText buffer.getLine(1)
+        expect(editor.getPosition()).toEqual {row: 1, col: 6}
+

spec/fixtures/sample.js

@@ -10,4 +10,4 @@ var quicksort = function () {
   };
 
   return sort(Array.apply(this, arguments));
-};
+};

src/atom/buffer.coffee

@@ -43,10 +43,22 @@ class Buffer
 
   backspace: ({row, col}) ->
     line = @lines[row]
+
+    preRange =
+      start: { row, col }
+      end: { row, col }
+
     if col == 0
+      preRange.start.col = @lines[row - 1].length
+      preRange.start.row--
       @lines[row-1..row] = @lines[row - 1] + @lines[row]
     else
-      @lines[row] = line[row..col] + line[col + 1..]
+      preRange.start.col--
+      @lines[row] = line[0...col-1] + line[col..]
+
+    postRange = { start: preRange.start, end: preRange.start }
+
+    @trigger 'change', { preRange, postRange,  string: '' }
 
   numLines: ->
     @getLines().length

src/atom/cursor.coffee

@@ -18,6 +18,9 @@ class Cursor extends Template
         else
           @setColumn(@getColumn() + e.string.length)
 
+    bufferChanged: (e) ->
+      @setPosition(e.postRange.end)
+
     setPosition: (point) ->
       @point = @editor.clipPosition(point)
       @goalColumn = null

src/atom/editor.coffee

@@ -35,12 +35,14 @@ class Editor extends Template
         down: 'move-down'
         up: 'move-up'
         enter: 'newline'
+        backspace: 'backspace'
 
       @on 'move-right', => @moveRight()
       @on 'move-left', => @moveLeft()
       @on 'move-down', => @moveDown()
       @on 'move-up', => @moveUp()
       @on 'newline', => @buffer.insert @getPosition(), "\n"
+      @on 'backspace', => @buffer.backspace @getPosition()
 
     handleEvents: ->
       @on 'focus', =>
@@ -70,12 +72,32 @@ class Editor extends Template
 
       @buffer.on 'insert', (e) =>
         {row} = e.range.start
-
         updatedLine = @buildLineElement(@buffer.getLine(row))
         @lines.find('pre').eq(row).replaceWith(updatedLine)
         if e.string == '\n'
           updatedLine.after @buildLineElement(@buffer.getLine(row + 1))
 
+      @buffer.on 'change', (e) =>
+        curRow = e.preRange.start.row
+        while curRow <= e.preRange.end.row
+          if curRow <= e.postRange.end.row
+            @updateLineElement(curRow)
+          else
+            @removeLineElement(curRow)
+          curRow++
+
+        console.log @buffer.getText()
+        @cursor.bufferChanged(e)
+
+    updateLineElement: (row) ->
+      @getLineElement(row).replaceWith(@buildLineElement(@buffer.getLine(row)))
+
+    removeLineElement: (row) ->
+      @getLineElement(row).remove()
+
+    getLineElement: (row) ->
+      @lines.find("pre:eq(#{row})")
+
     clipPosition: ({row, col}) ->
       line = @buffer.getLine(row)
       { row: row, col: Math.min(line.length, col) }

test.txt

@@ -0,0 +1,2 @@
+0123
+abcd