[antlr-interest] Tree grammars & optional AST nodes
Nicolas Rouquette
nicolas.rouquette at jpl.nasa.gov
Fri Oct 20 23:42:11 PDT 2006
Nicolas Rouquette <nicolas.rouquette at ...> writes:
>
> Terence Parr <parrt <at> ...> writes:
>
> > On Oct 19, 2006, at 5:09 PM, Nicolas Rouquette wrote:
> >
> > > <at> init { boolean flag=false; }
> > > : e1=conditionalExpression (op=assignmentOperator e2=expression
> > > {flag=true;})?
> > > -> {flag} ? ^($op $e1 $e2)
> > > -> $e1
> > > ;
> >
> > or use {$op!=null}? without the flag mumbojumbo.
Bizarre... {op!=null} works.
I surprised action.g didn't barf at this.
It seems to work which is perplexing.
-- Nicolas.
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