[antlr-interest] How can I work around approximate LALL limitation?

[Case, Scott]

Maybe try this -
table: 
	(INTEGER 
	  ( (SPACE INTEGER)=> SPACE INTEGER
	  | (SPACE NEWLINE)=> SPACE
	  )*
	NEWLINE)+
		;


/*
INTEGER NEWLINE
INTEGER SPACE NEWLINE
INTEGER SPACE INTEGER NEWLINE
INTEGER SPACE INTEGER SPACE NEWLINE
*/

- Scott

-----Original Message-----
From: Pete Forman [mailto:pete.forman at westerngeco.com]
Sent: Monday, November 11, 2002 7:07 AM
To: antlr-interest at yahoogroups.com
Subject: [antlr-interest] How can I work around approximate LALL
limitation?


[apologies for previous partial message]

I've run into a problem which is exemplified thus.

class ExampleParser extends Parser;
options { k = 2;}

table: (INTEGER (SPACE INTEGER)* (SPACE)? NEWLINE)+;


ANTLR Parser Generator   Version 2.7.1   1989-2000 jGuru.com
example.g:4: warning: nondeterminism upon
example.g:4:    k==1:SPACE
example.g:4:    k==2:INTEGER
example.g:4:    between alt 1 and exit branch of block

(The problem is the same with 2.7.2a4 (20021027-1))

Now I think that I understand what the problem is.  It is described
in http://www.jguru.com/faq/view.jsp?EID=264825.  What is not obvious
is how to work around it.  Discarding SPACE tokens is not an option in
the full grammar that I want to fix.

Both the following have no errors.
table: (INTEGER (SPACE INTEGER)* SPACE NEWLINE)+;
table: (INTEGER (SPACE INTEGER)* NEWLINE)+;

But this doesn't work.
table: (INTEGER (SPACE INTEGER)* (SPACE NEWLINE|NEWLINE))+;


-- 
Pete Forman                -./\.-  Disclaimer: This post is originated
WesternGeco                  -./\.-   by myself and does not represent
pete.forman at westerngeco.com    -./\.-   opinion of Schlumberger, Baker
http://petef.port5.com           -./\.-   Hughes or their divisions.


 

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