Considerably more elegant (and correct) moveLeft and moveRight

spec/editor-spec.coffee

@@ -329,7 +329,7 @@ describe "Editor", ->
       it "moves the cursor by two rows up when the columnCount is longer than an entire line", ->
         editor.setCursorScreenPosition([2, 2])
         editor.moveLeft(34)
-        expect(editor.getCursorScreenPosition()).toEqual [0, 28]
+        expect(editor.getCursorScreenPosition()).toEqual [0, 29]
 
       it "moves the cursor to the beginning columnCount is longer than the position in the buffer", ->
         editor.setCursorScreenPosition([1, 0])
@@ -348,6 +348,12 @@ describe "Editor", ->
             editor.moveLeft(4)
             expect(editor.getCursorScreenPosition()).toEqual [0, 26]
 
+        describe "when the next line is empty", ->
+          it "wraps to the beginning of the previous line", ->
+            editor.setCursorScreenPosition([11, 0])
+            editor.moveLeft()
+            expect(editor.getCursorScreenPosition()).toEqual [10, 0]
+
         describe "when the cursor is on the first line", ->
           it "remains in the same position (0,0)", ->
             editor.setCursorScreenPosition(row: 0, column: 0)
@@ -399,9 +405,9 @@ describe "Editor", ->
         expect(editor.getCursorScreenPosition()).toEqual [3, 11]
 
       it "moves the cursor by two rows down when the columnCount is longer than an entire line", ->
-        editor.setCursorScreenPosition([0, 28])
-        editor.moveRight(32)
-        expect(editor.getCursorScreenPosition()).toEqual [2, 0]
+        editor.setCursorScreenPosition([0, 29])
+        editor.moveRight(34)
+        expect(editor.getCursorScreenPosition()).toEqual [2, 2]
 
       it "moves the cursor to the end of the buffer when columnCount is longer than the number of characters following the cursor position", ->
         editor.setCursorScreenPosition([11, 5])
@@ -420,6 +426,12 @@ describe "Editor", ->
             editor.moveRight(4)
             expect(editor.getCursorScreenPosition()).toEqual [1, 3]
 
+        describe "when the next line is empty", ->
+          it "wraps to the beginning of the next line", ->
+            editor.setCursorScreenPosition([9, 4])
+            editor.moveRight()
+            expect(editor.getCursorScreenPosition()).toEqual [10, 0]
+
         describe "when the cursor is on the last line", ->
           it "remains in the same position", ->
             lastLineIndex = buffer.getLines().length - 1

src/cursor.coffee

@@ -270,18 +270,13 @@ class Cursor extends Model
       @setScreenPosition(range.start)
     else
       {row, column} = @getScreenPosition()
-      newColumn = column - columnCount
 
-      if newColumn >= 0
-        column = newColumn
-      else
-        columnDelta = -(newColumn + 1)
-        while columnDelta >= 0 and row > 0
-          row--
-          rowLength = @editor.lineTextForScreenRow(row).length
-          column = rowLength - columnDelta
-          columnDelta -= rowLength
+      while columnCount > column and row > 0
+        columnCount -= column
+        column = @editor.lineTextForScreenRow(--row).length
+        columnCount-- # subtract 1 for the row move
 
+      column = column - columnCount
       @setScreenPosition({row, column})
 
   # Public: Moves the cursor right one screen column.
@@ -296,20 +291,19 @@ class Cursor extends Model
       @setScreenPosition(range.end)
     else
       { row, column } = @getScreenPosition()
-      newColumn = column + columnCount
+      maxLines = @editor.getScreenLineCount()
       rowLength = @editor.lineTextForScreenRow(row).length
+      columnsRemainingInLine = rowLength - column
 
-      if newColumn <= rowLength
-        column = newColumn
-      else
-        columnDelta = newColumn - rowLength - 1
-        maxLines = @editor.getScreenLineCount()
-        while columnDelta >= 0 and row < maxLines - 1
-          row++
-          rowLength = @editor.lineTextForScreenRow(row).length
-          column = columnDelta
-          columnDelta -= rowLength
+      while columnCount > columnsRemainingInLine and row < maxLines - 1
+        columnCount -= columnsRemainingInLine
+        columnCount-- # subtract 1 for the row move
 
+        column = 0
+        rowLength = @editor.lineTextForScreenRow(++row).length
+        columnsRemainingInLine = rowLength
+
+      column = column + columnCount
       @setScreenPosition({row, column}, skipAtomicTokens: true, wrapBeyondNewlines: true, wrapAtSoftNewlines: true)
 
   # Public: Moves the cursor to the top of the buffer.