[antlr-interest] Tree grammars & optional AST nodes

Terence Parr parrt at cs.usfca.edu
Sat Oct 21 09:36:43 PDT 2006


On Oct 20, 2006, at 11:42 PM, Nicolas Rouquette wrote:

> 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.

Yes $op is op.

Ter



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