[antlr-interest] Re: second lexical pass - yeah
idontwantanidwith2000init
idontwantanidwith2000init at yahoo.com
Sun Apr 11 13:32:34 PDT 2004
It recognized DATE in the parser :)
Now, could you review it:
protected
DATE
: YEAR
'-' MONTH
'-' DAY
' ' HOUR
':' MINUTES
':' SECONDS
;
// string literals
STRING_LITERAL
: '"'! (~('"'|'\n'|'\r'|'\\')|'\\' .)*'"'!
{
try
{
ScriptLexer scriptLexer = new
ScriptLexer(new StringReader($getText));
scriptLexer.mDATE(false);
$setType(DATE);
}catch(ANTLRException exp){
$setType(STRING);
}
}
;
I've done all the neccesary imports.
If you like it, Terr, maybe it deserve a place in the FAQ...
This is just great.
Tal.
--- In antlr-interest at yahoogroups.com, "idontwantanidwith2000init"
<idontwantanidwith2000init at y...> wrote:
> I've ment multiple values of course :)
> That's what I wanted to do, Terr, more or less. :)
> I'm sad though. With lex I could handle it without a second parser.
> But it seems a better aproch then putting it all together in one
> parser.
> Let me explain why:
> '"'YYYY-MM-DD hh:mm:ss'"' is a STRING.
> and there isn't a simple way to express this relationship.
> Maybe it's an idea for improving the lexer.
>
> What do you think?
>
> --- In antlr-interest at yahoogroups.com, Terence Parr <parrt at c...>
> wrote:
> >
> > On Apr 11, 2004, at 6:25 AM, idontwantanidwith2000init wrote:
> >
> > > Is there an elegant way to do a second lexical path instead of
> > > writing two lexers?
> > >
> > > For instance:
> > > STRING_LITERAL:
> > > '"' (~('\r'|'n'|'\\') | '\\' .) '"' ;
> > >
> > > now STRING_LITERAL will colide with any special string you'd
> like to
> > > match, for instance:
> > > DATE_TIME : '"'YYYY-MM-DD hh:mm:ss'"'
> > >
> > > I've managed to merge it with:
> > > '"'(LETTER)*'"'
> > > '"'(LETTER)*'.'(LETTER)*'"'
> > > '"'(LETTER)*'-'(LETTER)*'"'
> > > Which was a diffucult task but doable.
> > >
> > >
> > > I thought about it and merging these rules is possible, but it
> will
> > > take me days to write it and we haven't talked about
validation.
> > > (It is a good to write down my thoughts I'm starting to
convince
> > > myself that it is a good idea)
> > >
> > > What do you think is a proper solution?
> >
> > My first thought is that you have a two-level grammatical issue
> here.
> > First you have to match a string and then determine if it
> satisfies a
> > "nested structure" which is the date/time stuff. You can't
really
> use
> > another rule in the same lexer object as it will consume the
> input.
> > Perhaps a compromise. Make a new lexer rule that will match
> DATE_TIME
> > as you've done and make it protected. Then, make a *new*
instance
> of
> > your lexer. Set it up with a copy of the text matched inside
the
> > string and then directly call DATE_TIME with a try/catch around
it
> to
> > catch failure. Gotta love LL based lexers :)
> >
> > Ter
> > --
> > Professor Comp. Sci., University of San Francisco
> > Creator, ANTLR Parser Generator, http://www.antlr.org
> > Cofounder, http://www.jguru.com
> > Cofounder, http://www.knowspam.net enjoy email again!
> > Cofounder, http://www.peerscope.com pure link sharing
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