in reply to Decompiling Regular Expressions

I'm not quite sure what you mean by "pulling out expressions", but you might want to know that Regexp::Common groups the patterns in classes, and you can selectively load the classes. For instance: 
    use Regexp::Common qw /number URI/;

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only loads the number and URI patterns. Currently, there are 11 different classes.

From your post, I didn't get any idea what you mean by "getting the source form of a regex" in relation to Regexp::Common, nor what YAPE::Regex::Explain is doing for you.

Abigail

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Re: Re: Decompiling Regular Expressions
by shotgunefx (Parson) on Apr 03, 2003 at 21:10 UTC
    My question I'm sure could have been phrased better. Basically what I was thinking is there are certain times when you might want to use an expression without requiring the module. (Normally I would just want to stick with "use"ing it and getting the benefit of the module's maintainence), so I was curious if there was a way to go from a compiled expression to something I could add to a script without requiring the module for the one regex.

    A simple example but if I wanted a pattern to match a real but didn't want to require Regexp::Common I could do something like this. 
    #!/usr/bin/perl
use warnings;
use strict;

use Regexp::Common qw/number/;
use YAPE::Regex::Explain;

print YAPE::Regex::Explain->new($RE{num}{real})->explain();
__END__
The regular expression:

(?-imsx:(?:(?i)(?:[+-]?)(?:(?=[0123456789]|[.])(?:[0123456789]*)(?:(?:
+[.])(?:[0123456789]{0,}))?)(?:(?:[E])(?:(?:[+-]?)(?:[0123456789]+))|)
+))

matches as follows:
  
NODE                     EXPLANATION
------------------------------------------------------------BLAH BLAH 
+BLAH

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    and just add 
    $thing=~/(?-imsx:(?:(?i)(?:[+-]?)(?:(?=[0123456789]|[.])(?:[0123456789
+]*)(?:(?:[.])(?:[0123456789]{0,}))?)(?:(?:[E])(?:(?:[+-]?)(?:[0123456
+789]+))|)))
/

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    to my code.

    Which seems like it works but as regex's are my weakest Perl strength, I didn't know if this is a any caveats (things known not to work) with this approach or if there is a more reliable way of doing it. Obviously "cutting and pasting" is a bad idea without total understanding is in general though as far as regexes, I'm willing to put stock in a few monks work (yourself included), but I didn't know if there was anything inherently wrong with the approach.

    -Lee

    "To be civilized is to deny one's nature."
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[d/l]
[select]
      That's like going from London to Greenwhich via Sydney. Why not just: 
          perl -MRegexp::Common -wle 'print $RE{num}{real}'

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      Note that this (or the YAPE::) approach doesn't work with recursive regexps.

      Abigail

[reply]
[d/l]
        slaps($self);
        I knew I must have been missing something because I couldn't find anyone who had asked. I could have sworn I tried that and got a bunch of binary characters which is why I thought it needed to be decompiled.

        Thanks,
        -Lee

        "To be civilized is to deny one's nature."
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