[antlr-interest] How to remove this kind of warning

Edwards, Waverly Waverly.Edwards at genesys.com
Fri Sep 5 09:01:18 PDT 2008


I don't think I understand this.  Shouldn't IP address be defined as 
 
IPFRAG '.' IPFRAG '.' IPFRAG ''.' IPFRAG
 
where IPFRAG is fragment constrained to a maximum 3 digit integer 
You could later check to see if that value is 255 or less.
 
Would you look ahead to see if there were four dotted decimal integers before deciding to treat a number as a floating point or ip address?
Would that be painfully slow to check every time you came across a potential floating point number?
 
 
W.

________________________________

From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-bounces at antlr.org] On Behalf Of Jim Idle
Sent: Friday, September 05, 2008 11:20 AM
To: Ronghui Yu
Cc: antlr-interest at antlr.org
Subject: Re: [antlr-interest] How to remove this kind of warning


On Fri, 2008-09-05 at 22:15 +0800, Ronghui Yu wrote: 

	I would like to have it as a lexer rule, but in my parser, there is a Floating_Point_Constant like 

	Floating_Point_Constant: 

	   ('0'..'9')+ '.' ('0'..'9')* ('e'|'E')?; 

	Then when an IP appears in the stream, it is divided into serveral floating point tokens, but not a complete IP token
	
	Then I rewrite this rule to deal with double cases
	
	


fragment
IP_Address : ;



	Floating_Point_Constant:
	
	  ('0'..'9')+ '.' 
	
	  (
	
	       (('0'..'9')+ '.' ('0'..'9')+ '.' ('0'..'9')+) => ('0'..'9')+ '.' ('0'..'9')+ '.' ('0'..'9')+ {$type=IP_Address;}
	
	       |
	
	       ('0'..'9')* ('e'|'E')?;
	
	  )
	
	;
	
	This rule can deal with both cases well, but I need to define a token IP_Address first, then comes the story.
	
	

	If I define two rules for floating point and ip address respectively, seems one of them doesn't work properly. 


	  


________________________________


	From: Jim Idle [mailto:jimi at temporal-wave.com]
	Sent: 2008-9-5 (星期五) 21:59
	To: Ronghui Yu
	Cc: antlr-interest at antlr.org
	Subject: Re: [antlr-interest] How to remove this kind of warning
	
	
	

	On Fri, 2008-09-05 at 17:25 +0800, Ronghui Yu wrote: 
	

		 no lexer rule corresponding to token: IP_Address 
		Everytime when I define a token in token section, it always issues this kind of warning. 
		I hate warnings, is there any way to remove it?
		


	Don't define it in the tokens section, but as a lexer rule and it will go away.
	
	Jim 
	

		Thanks! 
		==============================
		Regards,
		Ronghui Yu
		Sierra Atlantic 
		
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