Salutations, dearest monks.

I am trying to write a parsery sort of thing, but ran into a Perl syntax problem. This is the layout of the code I have: 

for my $syn (@syntax) {
    my ($re, $cb) = @$syn;

    if (my (@matches) = ($line =~ $re)) {
        $cb->(@matches);
        last;
    }
}

[download]

As you can see, I have an array of possible syntax elements (@syntax) that each houses a regexp ($re) and then a callback function ($cb). The callback function expects the regexp's capture groups as arguments.

It then occurred to me that the code won't run if the regexp has no capture groups!

I can, of course, say if ($line =~ $re) { ... } but then I lose the captures. I need the captures.

I need a) to know that the regexp matched, and b) the capture groups returned by the regexp.

What to do? Is there a syntax that allows both? Do I run my regexp twice? Or do I just add a dummy capture group into every regexp?

In reply to How to know that a regexp matched, and get its capture groups? by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.