Implemented simple expressions

src/build/Function.go

@@ -120,27 +120,61 @@ func (f *Function) CompileInstruction(line token.List) error {
 	return errors.New(&errors.InvalidInstruction{Instruction: expr.Token.Text()}, f.File, expr.Token.Position)
 }
 
-// isAssignment returns true if the expression is an assignment.
-func isAssignment(expr *expression.Expression) bool {
-	return expr.Token.Kind == token.Operator && expr.Token.Bytes[len(expr.Token.Bytes)-1] == '='
-}
-
-// isFunctionCall returns true if the expression is a function call.
-func isFunctionCall(expr *expression.Expression) bool {
-	return expr.Token.Kind == token.Operator && expr.Token.Text() == "λ"
-}
-
-// isVariableDefinition returns true if the expression is a variable definition.
-func isVariableDefinition(expr *expression.Expression) bool {
-	return expr.Token.Kind == token.Operator && expr.Token.Text() == ":="
-}
-
 // ExpressionToRegister moves the result of an expression into the given register.
 func (f *Function) ExpressionToRegister(root *expression.Expression, register cpu.Register) error {
 	if root.IsLeaf() {
 		return f.TokenToRegister(root.Token, register)
 	}
 
+	left := root.Children[0]
+	right := root.Children[1]
+
+	f.ExpressionToRegister(left, register)
+
+	if right.IsLeaf() {
+		value := right.Token.Text()
+		n, err := strconv.Atoi(value)
+
+		if err != nil {
+			return err
+		}
+
+		switch root.Token.Text() {
+		case "+":
+			f.Assembler.RegisterNumber(asm.ADD, register, n)
+
+		case "-":
+			f.Assembler.RegisterNumber(asm.SUB, register, n)
+
+		case "*":
+			f.Assembler.RegisterNumber(asm.MUL, register, n)
+
+		case "/":
+			f.Assembler.RegisterNumber(asm.DIV, register, n)
+		}
+
+		return nil
+	} else {
+		temporary, _ := f.CPU.FindFree()
+		f.CPU.Use(temporary)
+		f.ExpressionToRegister(right, temporary)
+		f.CPU.Free(temporary)
+
+		switch root.Token.Text() {
+		case "+":
+			f.Assembler.RegisterRegister(asm.ADD, register, temporary)
+
+		case "-":
+			f.Assembler.RegisterRegister(asm.SUB, register, temporary)
+
+		case "*":
+			f.Assembler.RegisterRegister(asm.MUL, register, temporary)
+
+		case "/":
+			f.Assembler.RegisterRegister(asm.DIV, register, temporary)
+		}
+	}
+
 	return errors.New(errors.NotImplemented, f.File, root.Token.Position)
 }
 
@@ -207,3 +241,18 @@ func (f *Function) identifierExists(name string) bool {
 	_, exists := f.Variables[name]
 	return exists
 }
+
+// isAssignment returns true if the expression is an assignment.
+func isAssignment(expr *expression.Expression) bool {
+	return expr.Token.Kind == token.Operator && expr.Token.Bytes[len(expr.Token.Bytes)-1] == '='
+}
+
+// isFunctionCall returns true if the expression is a function call.
+func isFunctionCall(expr *expression.Expression) bool {
+	return expr.Token.Kind == token.Operator && expr.Token.Text() == "λ"
+}
+
+// isVariableDefinition returns true if the expression is a variable definition.
+func isVariableDefinition(expr *expression.Expression) bool {
+	return expr.Token.Kind == token.Operator && expr.Token.Text() == ":="
+}