Lars Henrik Mathiesen <[EMAIL PROTECTED]> wrote,
> > From: "Manuel M. T. Chakravarty" <[EMAIL PROTECTED]>
> > Date: Fri, 29 Sep 2000 10:17:56 +1100
>
> > I agree that usually the predicates as proposed by you would
> > be better. The problem is that a scanner that wants to use
> > the usual finite deterministic automation techniques for
> > scanning, needs to be able to compute the overlap between
> > different predicates.
>
> If the predicates are functions, computing the overlap as another
> function is easy.
Ok, I should have been more precise. The problem is to make
it efficient. Usually, this is achieved by having a table
into which you index with the input character to compute
what state to enter next. If you have many predicates and
potentially have to test a large number of them for each
input character before being able to determine the next
state, this might adversely influence the performance of the
scanner.
Manuel
