[antlr-interest] "!" operator and hidden tokens

Ric Klaren klaren at cs.utwente.nl
Thu Jul 22 02:21:50 PDT 2004


On Wed, Jul 21, 2004 at 10:12:34PM -0000, johnj1984 wrote:
> Now I have a question with regards to maintaining comments:
>   When using CommonASTWithHiddenTokens ast nodes, does the "!"
> operator transfer the hidden tokens to the surrounding non-matched
> nodes?

No it leaves out these tokens completely.

>  If the "!" operator does not link the hidden tokens to the
> surrounding tokens, what is the general strategy for dealing with
> this? Override the match() method  to copy the links?

All the examples I've seen (see also in the distro
examples/java/preserveWhitespace) people used a TokenStream filter to mask
out certain tokens. See TokenStreamHiddenTokenFilter.java in the antlr
sources. You could probably combine that filter with Monty's TokenFiltering
approach for fancier stuff:

http://www.codetransform.com/filterexample.html

>   Also defined as, are there any examples of spitting out comments in
> across AST tree translation/manipulations?

I'm only aware of the above preserveWhitespace example.

Cheers,

Ric
--
-----+++++*****************************************************+++++++++-------
    ---- Ric Klaren ----- j.klaren at utwente.nl ----- +31 53 4893755  ----
-----+++++*****************************************************+++++++++-------
  "I think we better split up."
  "Good idea. We can do more damage that way."
  --- Ghostbusters



 
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/antlr-interest/

<*> To unsubscribe from this group, send an email to:
    antlr-interest-unsubscribe at yahoogroups.com

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/
 



More information about the antlr-interest mailing list