[antlr-interest] How to access member of CommonTree subclass

[Jim Idle]

You can probably do:

id : ( ^(AST_ID tok+=ID+) -> ^(AST_ID whatever) { action  } ;

Or get your method to return the node object and use it to rewrite the tree.

Jim

> -----Original Message-----
> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> bounces at antlr.org] On Behalf Of Kaleb Pederson
> Sent: Monday, October 26, 2009 4:35 PM
> To: antlr-interest at antlr.org
> Subject: Re: [antlr-interest] How to access member of CommonTree
> subclass
> 
> On Monday 26 October 2009 04:18:21 pm Jim Idle wrote:
> ...
> > > I'm working with a tree parser that is creating ASTs of a custom
> type.
> > > This CommonTree subclass contains a member named elementType that
> > > identifies the type represented by the tree.  How do I set the
> > > elementType dynamically within an action?
> > >
> > > I tried in the following way:
> > >
> > > id:
> > >   ^(AST_ID tok+=ID+)
> > >   {
> > >     $tree.setElementType(
> typeResolver.resolve(StringUtils.join($tok,
> > > ".")) );
> > >   }
> > >   ;
> > >
> > > This, however, doesn't work since the tree has not yet been set:
> >
> > I presume that this is a tree walker that is producing another AST as
> output?
> 
> Correct.
> 
> > Anyway, why not return the value of typeResolver from the id rule,
> then set the resulting tree value?
> 
> That thought crossed my mind, but it seemed like it should be
> unnecessary. I gather then that it's not possible to set it directly?
> 
> >id : resolveID { $resovleID.tree.setElementType($resolveID.type); } ;
> >
> >resolveId
> >returns [ xxx type]
> >
> >: ^AST_ID tok+=ID+) { $type =
> >: typeResolver.resolve(StringUtils.join($tok,".")) );
> >}
> >;
> 
> Thanks for the suggestions.
> 
> --
> Kaleb Pederson
> 
> Twitter - http://twitter.com/kalebpederson
> Blog - http://kalebpederson.com
> 
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