While editing Musicbrainz, I wanted to check something and at one point needed a quick script to munge data like this: 
Attacca Quartet:1,2,3,4,5,6,7,8,10,11,12,13,14,15,16,17,18,19,20,22,23
+,24,25,26,27,28
John Patitucci:1,2,3,5,8,11,12,13,14,15,16,17,19,25,26,27,28
Roomful of Teeth:1,3,5,7,9,12,14,16,19,21,24,26,28
Sō Percussion:1,3,4,5,6,7,8,11,12,13,14,15,16,18,19,21,22,23,24,2
+5,26,27,28

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into this: 
Attacca Quartet:1-8,10-20,22-28
John Patitucci:1-3,5,8,11-17,19,25-28
Roomful of Teeth:1,3,5,7,9,12,14,16,19,21,24,26,28
Sō Percussion:1,3-8,11-16,18-19,21-28

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So I thought: Perl must have an easy way to find consecutive numbers inside a regex. And indeed it does!

Here is my script, which was originally a one-liner. It consolidates ranges in text using the (??{code}) construct in the search pattern to find consecutive numbers, and leaves everything intact that doesn't look like a number range.

It passes all the tests I threw at it, as long as the ranges are sane, non-overlapping and sorted in ascending order. I made it so that it can handle pre-existing ranges in the input, since I needed some of that code anyway and now it looks cool and has some nice internal symmetry. It does not merge duplicate ranges, nor does it try to handle whitespace. So it is basically only useful if the input data for this stage is generated by your own code (or your own data manipulations in Vim, as in my case). Definitely don't use it for processing arbitrary user input, there are good modules for that!

#!/usr/bin/perl -wp
1 while s/-(\d+),(??{1+$1})-/-/
    or s/-(\d+),((??{1+$1}))\b/-$2/
    or s/\b(\d+),(??{1+$1})-/$1-/
    or s/\b(\d+),((??{1+$1}))\b/$1-$2/;

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This was an interesting learning experience to use the (??{code}) construct! Note that I put capturing parentheses around the (?{...}) items only where it was necessary.

If you want to sort your data before consolidating the ranges, you could first do something like this, but note that this does not ignore extra text:

perl -pe 'chomp; $_ = join(",", sort { $a <=> $b } split /,/) . "\n"'

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In reply to Consolidate ranges (quick and dirty with a cool regexp) by gpvos

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