added swap stack command, bump version (#2)

calc.go

@@ -51,6 +51,8 @@ debug                toggle debug output
 dump                 display the stack contents
 clear                clear the whole stack
 shift                remove the last element of the stack
+reverse              reverse the stack elements
+swap                 exchange the last two elements
 history              display calculation history
 help|?               show this message
 quit|exit|c-d|c-c    exit program
@@ -79,7 +81,7 @@ median               median of all values`
 // commands, constants and operators,  defined here to feed completion
 // and our mode switch in Eval() dynamically
 const (
-	Commands  string = `dump reverse debug undebug clear batch shift undo help history manual exit quit`
+	Commands  string = `dump reverse debug undebug clear batch shift undo help history manual exit quit swap`
 	Constants string = `Pi Phi Sqrt2 SqrtE SqrtPi SqrtPhi Ln2 Log2E Ln10 Log10E`
 )
 
@@ -191,20 +193,6 @@ func (c *Calc) Eval(line string) {
 			c.stack.Backup()
 			c.stack.Push(num)
 		} else {
-			/*
-				if contains(c.MathFunctions, item) {
-					// go builtin math function, if implemented
-					c.mathfunc(item)
-					continue
-				}
-
-				if contains(c.BatchFunctions, item) {
-					// math functions only supported in batch mode like max or mean
-					c.batchfunc(item)
-					continue
-				}
-			*/
-
 			if contains(c.Constants, item) {
 				// put the constant onto the stack
 				c.stack.Backup()
@@ -270,6 +258,13 @@ func (c *Calc) Eval(line string) {
 			case "reverse":
 				c.stack.Backup()
 				c.stack.Reverse()
+			case "swap":
+				if c.stack.Len() < 2 {
+					fmt.Println("stack too small, can't swap")
+				} else {
+					c.stack.Backup()
+					c.stack.Swap()
+				}
 			case "undo":
 				c.stack.Restore()
 			case "history":