Re: Indirect left recursion in iXML grammars

This is what I mean by ixml can handle left-recursion:


steven@steven-XPS-9320$ cat left.ixml
ants: antstring.
antstring: antstring, "ant"; {}.
steven@steven-XPS-9320$ cat left.inp
antantant

steven@steven-XPS-9320$ ixml left

<ants>
   <antstring>
      <antstring>
         <antstring>
            <antstring/>ant</antstring>ant</antstring>ant</antstring>
</ants>
steven@steven-XPS-9320:~/Common/ixml/tests/misc$ 


On Monday 09 February 2026 17:14:33 (+01:00), Norm Tovey-Walsh wrote:

> Steven Pemberton <steven.pemberton@cwi.nl> writes:
> > It's true that some parsing algorithms can't handle left-recursion, but ixml can, so again, I'm not sure what the use-case is here.
> 
> I’m not sure what you mean by “iXML can handle left-recursion”. The grammar can express left-recursive structures, sure, but it isn’t a parsing technology. (Maybe it could be, but I’m not aware of any “native iXML parsers”; all of the implementations I’ve seen implement iXML on top of Early or GLL or some other (combination of) parsers.)
> 
> If you want to implement iXML, you have to choose a parsing technology that can support hidden left recursion or you have to remove it somehow. I think the question here is, can it be removed in a way that preserves the structure of the original grammar.
> 
>                                         Be seeing you,
>                                           norm
> 
> --
> Norm Tovey-Walsh
> Saxonica
>

Received on Monday, 9 February 2026 17:13:40 UTC