[antlr-interest] unexpected end of subtree

[Ric Klaren]

Hi,

On Mon, Jun 28, 2004 at 04:32:03AM -0700, Mr Torsten Curdt wrote:
>  > parse(ROOT)
>   > instruction(INSTRUCTION)
>    > literal(Format)
>    < literal(PARAMETER)
>    > literal(5.1)
>    < literal(null)
>    > literal(null)
> <AST>:0:0: unexpected end of subtree
>    < literal(<ASTNULL>)
>   < instruction(INSTRUCTION)
>   > instruction(INSTRUCTION)
>    > literal(Application)
>    < literal(PARAMETER)
>    > literal(somepackage)
>    < literal(null)
>    > literal(null)
> <AST>:0:0: unexpected end of subtree
>    < literal(<ASTNULL>)
>   < instruction(INSTRUCTION)
>   > instruction(INSTRUCTION)
>   ...

>
> For the following grammar:
>
> instruction
>   : #(INSTRUCTION inst=literal
>     (#(PARAMETER kn=literal kv=literal))+

By the look of the trace the kv literal is missing in your trees.... I find
it helpfull for debugging this stuff to put a custom error handler on the
rule giving trouble with a toStringList() on the #rule_in tree. That way
you can directly see the structure of the input to the rule.

> Hm.. but looking at the trace output
> it seems like the treeparser is exspecting
> literals, but gets nulls instead. ...which
> is because of the ()+ closure. And unfortunately
> it complains about it.

My guess is that you've forgotten something when building the tree for the
parameter part. The trace only shows PARAMETER and the 'kn'-literal. So it
does not even get to do a loop for the ()+ closure.

Cheers,

Ric
--
-----+++++*****************************************************+++++++++-------
    ---- Ric Klaren ----- j.klaren at utwente.nl ----- +31 53 4893755  ----
-----+++++*****************************************************+++++++++-------
     "Never argue with an idiot, for they will bring you down to their
              level and beat you with experience." --- Unknown



 
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