Prepare for floats

tree.go

@@ -57,13 +57,25 @@ type Expression interface {
 	Previous        () (previous Expression)
 	Render          (target stone.Buffer, offset int) (moved int)
 	Solution        () (solution int64, err error)
-	// InexactSolution () (solution float64, err error)
+	InexactSolution () (solution float64, err error)
 }
 
 type Operation struct {
 	parent *Operation
 	opcode Opcode
 	operands []Expression
+
+	// TODO: add bool to make this into a float
+	// when it is a float:
+	// - displays with parentheses instead of brackets
+	// - compute solution in floating point manner
+	// - return floating point solution for both Solution and
+	//   InexactSolution, instead of the other way around, casting as
+	//   necessary
+	// - ask children for InexactSolution instead of Solution
+	//
+	// TODO: have some control to make the readout call InexactSolution
+	// instead of Solution and display the floating point data properly
 }
 
 func (operation *Operation) Parent () (parent *Operation) {
@@ -406,6 +418,13 @@ func (operation *Operation) Solution () (solution int64, err error) {
 	return
 }
 
+func (operation *Operation) InexactSolution (solution float64, err error) {
+	var intSolution int64
+	intSolution, err = operation.Solution()
+	solution = float64(intSolution)
+	return
+}
+
 func integerPower (x, y int64) (result int64) {
 	if y == 0 {
 		result = 1