[lojban] Re: PEG left recursive definitions

[Robin Lee Powell <rlpowell@digitalkingdom.org>]

On Tue, Oct 30, 2007 at 07:44:38PM -0500, Chris Capel wrote:
> Does the PEG currently use left recursive definitions? 

The *only* place in Lojban that is unavoidably left-recursive is the
RPN mekso stuff.

> If not, would it be helpful if it could? For instance. Example
> input:
> 
> x ? x : x
> 
> To parse this, we could write
> 
> expr <- tri-cond / x
> tri-cond <- expr '?' expr ':' expr
> x <- 'x'
> 
> This would be translated to
> 
> expr-1 <- x
> tri-cond <- expr-1 '?' expr ':' expr / expr-1
> expr <- tri-cond / expr-1
> x <- 'x'

If you can show me how to fix the RPN productions in my PEG, I'd
really appreciate it; I never quite got it right.  It parses IFF it
should parse, but the resulting tree is wrong.

-Robin

-- 
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