public override object Exec(StringType firstOperand, object arg)
{
// * String WriteType and bounded type variables
if (TypeExpression.As <StringType>(this.secondOperand) != null)
{
return(0);
}
// * WriteType variable
TypeVariable typeVariable = this.secondOperand as TypeVariable;
if (typeVariable != null && typeVariable.Substitution == null)
{
// * A free variable is complete promotion
return(0);
}
// * Union type
UnionType unionType = TypeExpression.As <UnionType>(this.secondOperand);
if (unionType != null)
{
return(unionType.SuperType(firstOperand));
}
// * Field type and bounded type variable
FieldType fieldType = TypeExpression.As <FieldType>(this.secondOperand);
if (fieldType != null)
{
return(firstOperand.AcceptOperation(new PromotionLevelOperation(fieldType.FieldTypeExpression), arg));
}
// * Use the BCL object oriented approach
return(firstOperand.AsClassType().AcceptOperation(this, arg));
}
public override object Exec(StringType d, object arg)
{
return(d.AsClassType().AcceptOperation(this, arg));
}