Suppose I want to match the occurrence of 4 characters in a string with the condition that all 4 must occur at least once and in any order.
Well, with a regex engine that implements greedy alternation I could have one single regex such as this egrep example: 
$ echo 1b22a3d3c | egrep -o 'a|b|c|d'
b
a
d
c

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But with perl(no greedy alternation) I would need to construct a large-ish if statement 
echo 1b22a3d3c | perl -ne'if(/a/&&/b/&&/c/&&/d/){print"Match!\n";}'

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If I am curious about in which order the 4 chars actually occurred in I can test each permutation using List::Permutor 
use strict;
use warnings;
use List::Permutor;

my $test_string="1b22a3d3c"; 
my @regex_parts=("a","b","c","d");   
my $permutated_regex_parts=new List::Permutor @regex_parts;
while (my @set = $permutated_regex_parts->next){
      my $pattern=construct_regex(@set);
      if($test_string =~ /$pattern/){
        print("a match! pattern is: $pattern\n");
      }
  }

sub construct_regex{
        my $regex=".*";
        foreach my $s (@_){
                $regex.="$s.*";  
        }
        return $regex;
}

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I have toyed with this problem a bit...I am sure I missed several possible insights into better/shorter ways to accomplish this. Any advice?

In reply to How to replace greedy alternation? by adamcrussell

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