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Date: Tue, 14 Oct 2003 10:47:19 -0400
Message-ID: <NFBBJNKBNKCIKGKJIFPJEEHCGNAA.sklar@sklar.com>
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Subject: regex operators
From: sklar@sklar.com ("David Sklar")

I was thinking about adding one or two regex-related features to the engine:

1. "preg_case": this would behave just like case but instead of doing an
equality comparison, would match against a regular expression, e.g.

switch($data) {
   preg_case '/^\d{5}(-\d{4})?$/':
       print "US Postal Code";
       break;
   preg_case '/^[a-z]\d[a-z] ?\d[a-z]\d$/i';
       print "Canadian Postal Code";
       break;
   default:
       print "something else!";
}

Where should any captured subpatterns go?

2. A regex match operator that returns an array containing subpatterns. If
there is no match against the regex, then an empty array (or just false?)
would be returned.

if ($data =~ '/^(\d{5})(-\d{4})?$/') {
   print "The whole postal code is $data[0].";
   print "The first five digits is $data[1].";
   if ($data[2]) { print "The ZIP+4 is $data[2].";}
}

Some issues with adding these features:

- It creates an engine dependency on the PCRE library.
- There would have to be some new opcodes and parser tokens
- Ideally the code that implements these operators could share as much as
possible with what's already been done in the PCRE extension -- is that
possible?

Comments?

Thanks,
David