[antlr-interest] Lexer rule problem - ANTLR 2.7.7
Edwards, Waverly
Waverly.Edwards at genesys.com
Thu Jan 31 08:53:17 PST 2008
I'm not sure I understand the problem but shouldn't float be
fragment
FLOAT
: DOT INT
| INT DOT INT
;
INT DOT (DIGIT)* says you have and integer followed by a dot followed
by zero or more digits so you could end up
with something unstable like this
5000.
It also looks to me that you need two different types of ranges,
an int range and a float range.
What would happen if you ran across unvalidated input such as this
5800:2.0
fragment
INTRANGE
: INT COLON INT
;
fragment
FLOATRANGE
: FLOAT COLON FLOAT
;
I don't know if that solves your issue but it eliminates another.
W.
________________________________
From: antlr-interest-bounces at antlr.org
[mailto:antlr-interest-bounces at antlr.org] On Behalf Of
clive.i.hill at jpmorgan.com
Sent: Thursday, January 31, 2008 11:36 AM
To: antlr-interest at antlr.org
Subject: [antlr-interest] Lexer rule problem - ANTLR 2.7.7
Hi,
I have a lexer rule that is meant to match a range of integers or
numbers in the following style format:
5800:6000
or
1.8:2.0
The lexer rule I have for this is given by:
protected
RANGE
: (INT | FLOAT) COLON (INT | FLOAT)
;
where INT,FLOAT, DIGIT, DOT and COLON are given at the end of this
email.
When I run my parser against the grammar file (attached) with the
following string:
"ftse dec 5800:6000 c"
I get the following exception:
antlr.TokenStreamRecognitionException: expecting '.', found ':'
This is because the lexer is attempting to parse a RANGE token
correctly, but is expecting a FLOAT. My RANGE lexer rule,, it seems to
me, should check for an INT or a FLOAT.
This rule seems very uncomplicated, so I can't tell why it is going
wrong. Can anyone provide any suggestions?
Thanks in advance,
Clive
protected
FLOAT
: DOT INT
| INT DOT (DIGIT)*
;
protected
INT
: (DIGIT)+
;
protected
DIGIT
: '0' .. '9'
;
COLON
: ':'
;
protected
DOT
: '.'
;
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