[antlr-interest] Question on ambiguouity

[James Mello]

I'm relatively new to this whole parser grammer thing and I'm trying to get
up to speed as quickly as possible. This is a particularly troubling thing
as I can't quite grok why this doesn't work.... So given this simple set of
rules and productions....

class MyParser extends Parser;

options
{
	buildAST = true;	
	k = 2;
}

multipleIDs :
	(ID)+
	;

class MyLexer extends Lexer;

options
{
	k = 2;
	charVocabulary = '\u0000'..'\ufffe';
	caseSensitive = false;
}

ID : 
	'a'..'z'
	;

The expression for multipleIDs compiles cleanly...

When you change the multipleIDs rule to the following

multipleIDs : 
	ID (multipleIDs)*

You end up with a warning that says:

Nondeterminism upon K==1:ID K==2:ID between alt 1 and exit branch of block

I'm trying to figure out why this is the case as it seems to me that a
recursive rule like this should work. I've looked a bit for some info on the
faq and didn't find much on this.

Finally, since this is NOT the way to write recursive rules, how does one go
about doing this correctly?


James Mello : Software Engineer - ATS, Inc. 
web: www.intelligentdiscovery.com | (p) 360.698.7100x236 | (f) 360.698.7200