[antlr-interest] distinguish "3 + 4" from "3 +4"

[Douglas Godfrey]

define a Number lexer rule that parses signed numbers with no intervening
whitespace between the "+" or "-" and the digits.

Then the parser will receive Number Number instead of  Number Plus Number.

The Plus rule will succeed any time there is whitespace between the sign
and the number.


On 10/5/11 7:14 AM, "Andreas Liebig" <liebigandreas at yahoo.com> wrote:

>Hello,
>I am not very experienced with ANTLR, and I would like to ask for some
>ideas how to solve this task:
>
>I have to distinguish input streams like
>"3 + 4" (parsed as three tokens NUMBER PLUS NUMBER) from
>"3 +4" (parsed as NUMBER NUMBER, because the + is part of the number +4).
>
>I would like to ignore whitespace in general using the "$channel=HIDDEN;"
>syntax. But only in this situation whitespace does matter.
>Can you guide me to a good explanation of a possible solution?
>
>Thanks
>Andreas
>
>List: http://www.antlr.org/mailman/listinfo/antlr-interest
>Unsubscribe: 
>http://www.antlr.org/mailman/options/antlr-interest/your-email-address