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

Andreas Liebig liebigandreas at yahoo.com
Wed Oct 5 05:26:35 PDT 2011


I think I found the solution here:

http://www.antlr.org/wiki/pages/viewpage.action?pageId=557063 ("How do I access hidden tokens from parser?")

This will allow to check for whitespace before or after the + or -.

If you know an easier solution, please let me know.

Thanks
Andreas


________________________________
From: Andreas Liebig <liebigandreas at yahoo.com>
To: "antlr-interest at antlr.org" <antlr-interest at antlr.org>
Sent: Wednesday, October 5, 2011 1:14 PM
Subject: [antlr-interest] distinguish "3 + 4" from "3 +4"

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

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