Hi, I found a thread which started with
A proposal for more powerful text processing to be built in to Perl: Flex
and Pushdown Expressions.
> One of the great strengths of Perl is that, more than any other
> language I know, it helps you cross between the "data" space and the
> "program" space: eval(), built in regex notation, etc. Even with the
> considerable expressive power already at our disposal, I would like to
> suggest that there might be a trifling additional feature or two that
> perhaps would round out the language by their addition. My apologies
> if these have been discussed before.
> Flex - Put all of flex right into Perl. Flex is simply an event
> engine (-compiler) for driving calls against code according to regular
> expression matching events. While it is often convenient to have the
* ...
Why change perl ?
It is possible to use flex directly in perl with XS or Inline. I have a
module that does that and I plan an Inline::Yacc and an Inline::Recdecent. I
just mailed to the Inline group and I will upload it to Cpan as soon as I
get a green light.
one of the answers to the message was :
> Don't we already have that in Perl 5?
>
> if ( /\G\s+/gc ) { # whitespaces }
> elsif ( /\G[*/+-]/gc ) { # operator }
> elsif ( /\G\d+/gc ) { # term }
> elsif ( /\G.+/gc ) { # unrecognized token }
>
> Tad McClellan
The answer is NO, regexes and a lexer are totally different. I would
recommend Tad to study a bit more what parsing is before thinking it's jut
about writing regexes. Having a lexer allows perl do some kind of text
processing (raw lexing and parsing) at a much faster. If it is of some
interest I could benchmark a simple example.
Nadim.
