Re: design question? or puzzle?

It's verbose, but couldn't you do something like:

expression: ursum.
    -ursum: urproduct; sum.
       sum: product+addop.
-urproduct: urfactor; product.
etc

This is (correctly) ambiguous, but the first parse according to  the order of rule would return `<expression><number>3</number></expression>` - which I think is what you would want?

Tom

_________________
Tomos Hillman
eXpertML Ltd
+44 7793 242058
On 12 Apr 2021, 01:25 +0100, C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com>, wrote:
>
> Is there a way to write the ixml grammar so as to achieve the goal of serializing a nonterminal as an element if and only if it has two element children, and not to serialize it when it has only one element child?