[antlr-interest] How can I make sure there's one such rule in the input ?

[devdoer bird]

Thanks。

2011/2/17 Jim Idle <jimi at temporal-wave.com>

> You don't. You add a counter and parse everything that comes up, then you
> issue a semantic error saying that there are too many inputStatements.
> Always push the errors as far down the chain as you can as they gain more
> context and are therefore clearer to the end user.
>
> Jim
>
> > -----Original Message-----
> > From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> > bounces at antlr.org] On Behalf Of devdoer bird
> > Sent: Wednesday, February 16, 2011 9:05 PM
> > To: antlr-interest Interest
> > Subject: [antlr-interest] How can I make sure there's one such rule in
> > the input ?
> >
> > HI:
> >
> > I have the grammar:
> >
> > statements:(inputStatement|schemaStatement|filtersStatement|COMMENT)*
> > EOF;
> >
> >
> > As you see ,it will match as many inputStatements as there are in the
> > input file.
> >
> >
> > How can change the grammar to  make sure there is only one
> > inputStatment in the input file?
> >
> >
> > Thanks.
> >
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