antlr - How to lex 0 .. 255? -
I want to accept a decimal number from 0 to 255. This is the best I can come up with:
Piece my_token: ('0' .. '9'). // 0 -> 9 ('1' .. '9' '0' .. '9'). // 0 -> 99 ('1' '0' .. '9' '0' .. '9'). // 100-> 199 ('2' '0' .. '4' '0' .. '9'). // 200 -> 24 9 ('25' '0' .. '5'); // 250 -> 255
But Surelry is a better way I am just an NGN00b?
If you lexer relax and defer later check Lex NUMBER
, then when If you convert it later, the value is out of bounds, you can provide a very specific error message if you enter a strong and powerful 256 error message, which results in any ambiguity for the first Grammar has not been created.
Number: '0' .. '9';
Comments
Post a Comment