[antlr-interest] White space needed in the parsing.

[Jim Idle]

On Thu, 2008-09-18 at 22:42 +0200, Markus Fröb wrote:

> > -----Ursprüngliche Nachricht-----
> > Von: "jack zhang" <jackgzhang2 at yahoo.com>
> > Gesendet: 18.09.08 22:22:29
> > An: antlr-interest at antlr.org
> > Betreff: [antlr-interest] White space needed in the parsing.
> 
> > 
> > 
> > Thanks! it works. Another question is that (Sorry that I am pretty 
> > new to Antlr) in the tree walker, how to walk the WORD+ parser.
> > 
> > Currently I have following tree walker:
> > 
> ------------------ CUT ----------------------
> > 
> > expr returns [String s]
> >  : ^(NOT a=expr) {
> >  s = "(not " + a + ")";
> >  }
> >  |
> >  ^(AND a=expr b=expr) {
> >  s = "(" + a + " and " + b + ")";
> >  }
> >  | ^(OR a=expr b=expr) {
> >  s = "(" + a + " or " + b + ")";
> >  }
> >  | WORD {
> >  s = dateParser.parse($WORD.text);
> >  }
> >  ;
> > 
> > 
> > 
> > 
> > 
> > But it only matches the first word and totally ignored the rest. Is 
> > there a way to do this:
> > 
> > WORD+ { for (String WORD :WORD+ { // do something to each WORD} }
> > 
> > Thx !
> 
> Your expression matches only one word, as you only specified one. I think the following should work (but I cannot guarantee this, as I haven't worked much with tree parsers yet):
> 
> expr returns [String s]:
> ... and, or, not
>  | w=word_expr { s = w; }
>  ;
> 
> word_expr returns [String s]
>  : w=WORD e=word_expr { s = w + e; }
>  | { s = ""; }
>  ;


Its simpler than that (though I don't know what the dateParser call is
for:

| ( WORD {  $s = $s + " " + $WORD.text);  })+

Jim
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.antlr.org/pipermail/antlr-interest/attachments/20080918/d69665b6/attachment.html