protected override IValue VisitUnaryMinusExpression(PrefixUnaryExpressionSyntax node)
{
var operand = Visit(node.Operand);
// Debug.Assert(node.OperatorToken.Kind == SyntaxKind.MinusToken);
Type t;
if (TypesUtil.IsNumberType(operand.ValueType))
{
t = operand.ValueType;
}
else
{
throw new NotSupportedException();
}
var a = new UnaryOperatorExpression(operand, "-", t);
return(Simplify(a));
}