[antlr-interest] Lexer bug?

[Clifford Heath]

The following will parse "10 .. 20" and "10 ..20", but not "10..20".
It looks to me very much like it should... what's up here? It gets
a "no viable alternate" exception.

Obviously if I changed FRACTION to use DIGIT* instead of DIGIT+, it's
not going to work in the third case above, but... without that change?

Clifford Heath.
----

grammar range;

range
:       NUMBER '..' NUMBER
;

NUMBER
:       SIGN? DIGIT+ FRACTION? EXPONENT?
|       SIGN? FRACTION EXPONENT?
;

fragment SIGN:          ('+' | '-');
fragment FRACTION:      '.' DIGIT+;
fragment EXPONENT:      ('e'|'E') SIGN? DIGIT+;
fragment DIGIT  :       '0'..'9';

WS:     (' '|'\t'|'\r'|'\n')+ {skip();};