[antlr-interest] Re: Lexer rules for numbers and intervals

[beckersheinzsb]

thanks for your effort

but the problem is, that I've not only integers but also floating 
point values which use the dot as decimal point.

That means that 1.5..4.6 should also be possible.

If I try to pars 5..6 the lexer splits this into 5. and .6
and then then the parser throws an exception.

Heinz

--- In antlr-interest at yahoogroups.com, Peggy Fieland 
<madcapmaggie at y...> wrote:
> 
> Yes,
> 
> I added:
> 
> protected DOT_DOT:  "..";
> to the lexer and
> 
> interval:
>    variable DOT_DOT variable
> to the parser
> This works fine for variables.
> I ended up with:
> 
> (   integer DOT DOT integer ) => integer DOT DOT
> integer
> 
> for the integer ranges. 
> 
> Peggy
> 
> --- beckersheinzsb <beckersheinzsb at y...> wrote:
> 
> > Hello
> > 
> > I have the following rules in my lexer:
> > 
> > protected
> > DOT     :   '.'        ;
> > 
> > protected
> > DIGIT   :   '0'..'9'   ;
> > 
> > NUMBER  : (DOT (DIGIT)+)
> >         | (DIGIT)+ (DOT (DIGIT)*)?;
> > 
> > 
> > This piece works fine but now i want to add
> > intervals, e.g. 5..9
> > If I try to define a rule like
> > 
> > INTERVAL_SIGN  : DOT DOT ;
> > 
> > I get a nondeterminism.
> > 
> > I see that it is difficult to distinguish between
> > the second subrule 
> > of NUMBER and an interval 5..9 (NUMBER INTERVAL_SIGN
> > NUMBER). Do I 
> > have to left-factor? 
> > Or is there a possibility to achieve that the lexer
> > recognizes two 
> > following dots as an interval sign at all?
> > 
> > Could you please give me a hint
> > 
> > thanks a lot
> > greets
> > 
> > heinz
> > 
> > 
> > 
> > 
> > 
> >  
> > Yahoo! Groups Links
> > 
> > 
> >     antlr-interest-unsubscribe at yahoogroups.com
> > 
> >  
> > 
> > 
> 
> 
> 
> 		
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