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rlpowell posts: 14214

Deep in to talking to myself now.

On Sat, Nov 06, 2004 at 11:32:06PM -0800, Robin Lee Powell wrote:
> On Sat, Nov 06, 2004 at 11:27:12PM -0800, Robin Lee Powell wrote:
> > On Sat, Nov 06, 2004 at 10:53:31PM -0800, Robin Lee Powell
> > wrote:
> > > On Sat, Nov 06, 2004 at 10:39:15PM -0800, Jorge Llamb?as
> > > wrote:
> > > > But even if {zo zei zei} were not allowed, I see no reason
> > > > to complicate ZEI by not letting it work by order of
> > > > appearance, like everything else. It looks like an exception
> > > > to me.
> > >
> > > True.
> > >
> > > I hate to bring this up, but right-grouping (which is what
> > > you're talking about) is very hard in PEGs. I'm sure it's
> > > possible, but I've had some troubles.
> >
> > Errrm. Left grouping. Duh. The current version right groups.
> > The *only* place that I've found in the grammar where bare left
> > grouping is actually required is the RPN stuff, and as I
> > mentioned I haven't tested that well.
>
> I just re-tested it, and am in fact certain that it does *not*
> work properly.

I'm no longer certain this is true. In fact, I have yet to find
something that doesn't parse properly, but I'm really bad with RPN.
Having someone who isn't beat on it would be lovely.

> It may only parse valid left-grouped RPN expressions, but they
> certainly aren't parsed in a left-grouped fashion.

This is definately true, but maybe unavoidable. Certainly I'm not
good enough to fix it.

Regardless, the left-grouping ZEI change is a very different thing.
It was just a matter of removing a special case that told ZEI not to
work when there was a ZEI following.

I still think there's no point in allowing left-grouping or
right-grouping ZEI strings, and that if we allow them at all they
should be treated as equivalent to a single ZEI.

-Robin

 


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