Improve left and right moving

main.go

@@ -43,13 +43,19 @@ func main() {
 		} else if ac.Key == prompt.Enter || ac.Key == prompt.ControlJ {
 			buffer.InsertText("\n", false, true)
 		} else if ac.Key == prompt.Left {
-			buffer.CursorLeft(1)
+			l := buffer.CursorLeft(1)
+			if l == 0 {
+				continue
+			}
 			out.CursorDown(1)
 			out.CursorBackward(1)
 			out.EraseDown()
 			out.CursorUp(1)
 		} else if ac.Key == prompt.Right {
-			buffer.CursorRight(1)
+			l := buffer.CursorRight(1)
+			if l == 0 {
+				continue
+			}
 			out.CursorDown(1)
 			out.EraseDown()
 			out.CursorForward(1)

prompt/buffer.go

@@ -99,13 +99,17 @@ func (b *Buffer) setDocument(d *Document) {
 }
 
 // CursorLeft move to left on the current line.
-func (b *Buffer) CursorLeft(count int) {
-	b.CursorPosition += b.Document().GetCursorLeftPosition(count)
+func (b *Buffer) CursorLeft(count int) int {
+	l := b.Document().GetCursorLeftPosition(count)
+	b.CursorPosition += l
+	return -l
 }
 
 // CursorRight move to right on the current line.
-func (b *Buffer) CursorRight(count int) {
-	b.CursorPosition += b.Document().GetCursorRightPosition(count)
+func (b *Buffer) CursorRight(count int) int {
+	l := b.Document().GetCursorRightPosition(count)
+	b.CursorPosition += l
+	return l
 }
 
 // CursorUp move cursor to the previous line.