Fergus Henderson <[EMAIL PROTECTED]> wrote,
> On 15-Sep-2000, Manuel M. T. Chakravarty <[EMAIL PROTECTED]> wrote:
> > Doug Ransom <[EMAIL PROTECTED]> wrote,
> >
> > > Are combinator parsers recursive decent? Do they have any disadvantages
> > > over generated parsers like that yacc would produce?
> >
> > Yes, they are recursive decent. As a consequence you have
> > to left-factorise left-recursive productions in the grammar;
> > otherwise, the parser won't terminate. Other than that,
> > there are two disadvantages that I see: Speed and clarity of
> > error messages during *development* of the parser.
> >
> > As for speed, Doitase Swierstra et al. came up with a very
> > clever scheme of computing a parse table in a combinator
> > parser on-the-fly during parsing, which makes things a lot
> > faster:
>
> Doesn't that technique also solve the problem of left-recursion?
The parse table generated is essentially a table for an
SLL(1) parser and those can't handle left recursion.
Manuel
