[antlr-interest] Please help with arbitrary arrangements and old BNF syntax

[sohail at taggedtype.net]

> Suppose I have the following parser rule snipped from edif.org:
>
> written :
> 	LP! "written"
> 	     timeStamp
> 	     ( < author > | < program > | < dataOrigin > |
> 	     property | comment | userData )*
> 	RP!;
>
> Where the angle brackets mean that those can only appear once (in an
> arbitrary order). How do I enforce this in an ANTLR grammar?

Personally, I don't think this should be done in the parser. You should do
this as part of your semantic analysis (i.e. TreeParser). But thats just
IMHO.

> In a similar vein, is this the right way to limit an identifier length?
>
> IDENTIFIER
> 	options {testLiterals=true;} //make sure it's not a built in
> function
> 	:	(ALPHA|'&')	a:('_'|ALPHA|DIGIT)*
> {a.getText().length() < 256}? ; //less than 256 chars total

Its the easiest isn't it :)