http://qs321.pair.com?node_id=556134


in reply to Re: Parse::RecDescent for simple syntax-directed translation
in thread Parse::RecDescent for simple syntax-directed translation

Thanks for answering my question. The regex solution is cool.

I should have qualified my statement by saying that standard regular grammars cannot handle this sort of pattern, whereas Perl's regexes can do everything and anything.

In fact embedded actions within a Perl regex can do anything Perl can do - Therefore Perl regex's can do anything Perl can do. :)

I guess I can see from your use of Parse::RecDescent, Update: And from re-reading the very long manual last night, that the answer to my question is something like:

my $grammar = q{ match : part(s) { print join('', @{$item[1]}) } part : AnB part : 'a' part : /[^a]+/ AnB : 'a' AnB 'b' { 'c' . $item[2] . 'd' } AnB : 'ab' { 'cd' } }

-Andrew.

Replies are listed 'Best First'.
Re^3: Parse::RecDescent for simple syntax-directed translation
by ikegami (Patriarch) on Jun 20, 2006 at 23:52 UTC

    Close. Your grammar strips out all whitespace. Replace
    match : part(s) { print join('', @{$item[1]}) }
    with
    match : <skip:''> part(s) { print join('', @{$item[2]}) }

    A slight improvement is to replace
    match : <skip:''> part(s) { print join('', @{$item[2]}) }
    with
    process : <skip:''> part(s) { join('', @{$item[2]}) }
    so you can do
    $filter = Parse::RecDescent->new($grammar);
    print $filter->process('eeeeaaaabbbeeee');