Parsing a genomic position with javacc

Parsing a genomic position (chrom:start-end) is an easy task but I've always been too lazy to create a library for this. Today I wrote a Java-CC-based parser for analyzing the various syntaxes of a genomic position. Here is the grammar I used:

COMMA: ","
LETTER: (["a"-"z"]|["A"-"Z"]|"_") ;
DIGIT: ["0"-"9"];
INT:<DIGIT> ( (<DIGIT>|<COMMA>)* <DIGIT>)? ;
BP: "b" ("p")? ;
KB: ("k") ("B")? ;
MB: ("m") ("B")? ;
GB: ("g") ("B")? ;
IDENTIFIER: <LETTER> (<DIGIT>|<LETTER>)* ;
COLON: ":" ;
DASH: "-" ;
PLUS: "+" ;
DELIM: ("|"|";") ;


java.util.List<Segment> many(): segment() ((<DELIM>)? segment() )* )? <EOF>);
Segment one(): segment() <EOF>;
Segment segment(): chromName() <COLON> position() (<DASH> position()| <PLUS> position())? );
BigInteger position():integer() (factor())?;
BigInteger factor(): ( <BP> | <KB>| <MB> | <GB> );
BigInteger integer():<INT> ;
String chromName():( integer() | identifier());
String identifier(): <IDENTIFIER> ;

Source code

Compiling

javacc SegmentParser.jj
javac SegmentParser.java

Running

echo " chrM:1-100,000"| java SegmentParser
chrM:1-100000
echo " c1:1000"| java SegmentParser
c1:1000-1001
echo "2:1Gb+1 " | java SegmentParser
chr2:999999999-1000000002
echo "chr2:10+100" | java SegmentParser
ParseException: -90 < 0)
echo "chrX:3147483647" | java SegmentParser
ParseException: 3147483647 > 2147483647 (int-max)
echo "2:1Gb+a azd " | java SegmentParser
ParseException: Encountered "a" at line 1, column 7

That's it,

Pierre