[antlr-interest] Floats and Integers

[Anthony W Youngman]

In my grammar, I've got this:
 
NUMBER_LITERAL : ( INT (DECIMAL (INT)?)? | DECIMAL INT ) ;

Presumably you need something like
 
NUMBER : ( INT | FLOAT ) ;
 
maybe protected. Dunno what you're trying to do, but that should work.
 
Cheers,
Wol

-----Original Message-----
From: Tom Zagotta [mailto:tzagotta1 at sienasystems.com] 
Sent: 23 September 2003 16:14
To: antlr-interest at yahoogroups.com
Subject: [antlr-interest] Floats and Integers


Hello everyone,
 
I have a grammar that needs to accept both floating-point numbers and
integers. A simplified form of the grammar (whitespace skipping not
shown) is like this:

class TestParser extends Parser;
abc:"ABC" FLOAT INT;
 
class TestLexer extends Lexer;
INT: ('0'..'9')+;
FLOAT: INT '.' INT;

The problem I have is with input like this:

ABC 3 5

In this case, I need the "3" to match the FLOAT token for the abc rule.
It seems that the only way to do this is to change the rule to the
following:

abc: "ABC" (FLOAT|INT) INT;

But the problem with that is that there are a really large number of
such rules in my grammar.
 
Is there a better/alternative way to handle this? Ideally I'd like to
define a token that can match both int and float, but I still need a
separate token for int. It seems this is not possible.
 
Thanks in advance,
 
- Tom
 

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