legal identifier check

[Saaa]

>> I know use this (in the ddata thread above):
>>
>> foreach(char c; identifier)
>> {
>>  if( !inPattern( c, `_a-zA-Z0-9`) )
>>  {
>>   return false;
>>  }
>> }
>
> That's not correct.  http://digitalmars.com/d/1.0/lex.html#identifier
Which is why I asked for it here :)
It isn't extremely important as it is just a data format, but I would like 
to be as D as possible.