Hi
I was going to suggest the same as what John suggests.
If it matters what type of IDENTIFIER it is, you can capture that in a rewrite
rule if your building an AST
rule1: IDENTIFIER ':' expression -> ^(NAME_ID expression) ;
rule2:
IDENTIFIER '+' expression -> ^('+' IDENTIFIER expression )
| IDENTIFIER '-' expression -> ^('-' IDENTIFIER expression )
;
David Weiler-Thiessen
Nestlé Purina PetCare
phone: 306-933-0232
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-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of John B. Brodie
Sent: Tuesday, August 23, 2011 3:58 PM
To: Scott Smith
Cc: [email protected]
Subject: Re: [antlr-interest] Lexer question
try
rule1: IDENTIFIER ':' expression ;
that is why bother differentiating the two tokens?
On Tue, 2011-08-23 at 21:19 +0000, Scott Smith wrote:
> I have a parser that is doing pretty much what I want. However, I want to do
> the following.
>
> I have a definition for an IDENTIFIER
>
> IDENTIFIER: LETTER (LETTER | NUMBER) // LETTER and NUMBER mean
> the usual thing
>
> Now in some of my rules, I'm looking for an IDENTIFIER and in one of my rules
> I look for a NAME. NAME has exactly the same definition as IDENTIFIER
> (starts with a letter followed by alphanumerics). However, you can tell by
> the token after whether it was a NAME or an IDENTIFIER. To be more explicit,
> a NAME is ALWAYS followed by a colon. An IDENTIFIER can be followed by a
> number of things, but NEVER by a colon.
>
> So, I have rules that looksomething like:
>
> rule1:
> NAME ':' expression
> ;
>
> rule2:
> IDENTIFIER '+' expression
> | IDENTIFIER '-' expression
> ;
>
> I don't seem to be able to make this work. Can someone suggest a solution?
> Do I have to turn on backtracking to make this work?
>
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