[antlr-interest] ambiguity when calling rule

[Corno]

Hi all,

I'm trying to understand why my grammar gives an error for ambiguity. First
I thought that the problem was somehow related to ll(k) and that it would
disappear when I reworked it to ll(*). Today I tried that with antlr3 but
the problem persisted.

Basically the problem is as follows; when I have 1 rule, say X, that is
called by both A and B, I get an error. When I literally copy the rule,
rename the copy to Y and let B call Y (while A still calls X) the error
disappears. I know that the combination A-X needs another lookahead than B-Y
but I thought ll(*) would determine a solution that fits both needs.

example

selection  :	'v' ( '.' 'w' )* ;
selection2 :	'v' ( '.' 'w' )* ;

statement 
:
	'<'
	(
		(
			'x' selection statement //error
			//'x' selection2 statement //fine
		|
			'y' selection '.' 'w' '<' ( 'z' ) *	'>'
		)
	) *
	'>'
;

Can somebody explain why this is and if there is a way to prevent having to
copy rules?

TIA,

Corno