[antlr-interest] Matching the * character

[Steve O'Hara]

Thanks for your help Loring - unfortunately, it hasn't helped.

I've condensed the example down to something really simple;

 

subExpressionText :  QuotedString STAR? WS?;

QuotedString :'\'' (~'\'')* '\'' ( '\'' (~'\'')* '\'' )* ;

WS : (' ' | '\t' | '\n' | '\r')+ ;

STAR : '*' ;

 

The test string "'test'*" works fine but "'test'*    " doesn't.

It seems bizarre to me because if I substitute STAR for some other
character, it works fine.

 

e.g. STAR : '$' ; 

"'test'$    " works fine

 

Thanks,

Steve

 

From: Loring Craymer [mailto:lgcraymer at yahoo.com] 
Sent: 27 March 2008 23:59
To: Steve O'Hara; antlr-interest at antlr.org
Subject: Re: [antlr-interest] Matching the * character

 

This looks ok, except for the (STAR | QUESTION*)? idiom (equivalent to
(STAR | QUESTION+ | | ).  Try either changing QUESTION* to QUESTION+ or
remove the terminal ?.  I would have thought that ANTLR would issue a
warning about the two empty alts; maybe it did and you missed it.

--Loring

----- Original Message ----
From: Steve O'Hara <sohara at pivotal-solutions.co.uk>
To: antlr-interest at antlr.org
Sent: Thursday, March 27, 2008 4:27:33 PM
Subject: [antlr-interest] Matching the * character

I'm new to Antlr so forgive me if this is a stupid question...
I'm trying to match a database search criteria that looks like the
following;

 

'some text'*, *'more criteria' & 'more criteria'*


My grammar is;

 

expression

    : subExpression (WS? (COMMA | AMPERSAND) WS? subExpression)*

    ;

 

subExpression

    : WS? (Identifier | subExpressionText) WS?

    ;

 

subExpressionText

    :  (STAR | QUESTION*)? QuotedString  (STAR | QUESTION*)? WS?

    ;

 

Letter : 'a'..'z' | 'A'..'Z' | '_' | '\u0080'..'\ufffe' ;

Digit : '0'..'9' ;

Identifier : Letter (Letter | Digit)* ;

QuotedString :'\'' (~'\'')* '\'' ;

WS : (' ' | '\t' | '\n' | '\r')+ ;

 

COMMA : ',' ;

AMPERSAND : '&' ;

QUESTION : '?' ;

STAR : '*' ;


The parser finds the first quoted string (some text) but fails after
that with a NoViableAltException. If I change the * to ? it works fine.
I'm waiting for delivery of the reference manual so maybe I'm breaking
some sort of golden rule here, but any help would be greatly
appreciated.

Steve

 

Steve O'Hara
Pivotal Solutions  

( +44 (0)7802 484227
    +44 (0)208 660 7288 (Fax)
*  sohara at pivotal-solutions.co.uk <mailto:> 

 

 

 

________________________________

Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try
it now.
<http://us.rd.yahoo.com/evt=51733/*http:/mobile.yahoo.com/;_ylt=Ahu06i62
sR8HDtDypao8Wcj9tAcJ%20> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.antlr.org/pipermail/antlr-interest/attachments/20080328/5fdeec49/attachment-0001.html