Re: [lojban] Computer grammar question: non-left recursive RPN?

[Raphaël Poss <grey.havens@online.fr>]

Le 7 nov. 04, à 09:18, Robin Lee Powell a écrit :

> Lojban has a reverse polish (i.e. postfix math) mode built in.
>
> The ABNF form of this rule is:
>
> rp-expression = rp-operand rp-operand operator
>
> rp-operand = operand / rp-expression
>
> which does exactly what you'd expect.
>
> I can't figure out a way to convert this into a version without left
> recursion.  I've got:
>
> rp-expression = operand rp-expression-tail
> rp-expression-tail = rp-expression operator rp-expression-tail / ()
>
> (where () is the empty production), but I'm not at all certain it's
> equivalent, and the parse trees it produces look very wrong (i.e.
> not left recursive at all).
>
> Help?

(I assume from the ABNF grammar above that a RP expression has at least 
2 operands and 1 operator)

What about :

rp-expression = operand operand rp-tail
rp-tail = operand rp-tail / operator

?

--
Raphaël

Attachment: PGP.sig
Description: =?ISO-8859-1?Q?Ceci_est_une_signature_=E9lectronique_PGP?=