#!/usr/local/bin/perl
#use strict;
use warnings;
use 5.016;

# 1071296

while (<DATA>) {
# This section works OK.
    say "Positive lookaround first: ";
    if (/(?<=TAG1)(.*)(?=TAG2).*?/x) {
        print $1, "\n";
    }

   if (/^(?<!TAGS)(.*?)(?=TAG2).*$/x ) {
       say "\t Negative lookaround:";
       print $1, "\n";
   }
}

# Data now matches narrative; last item, stet, as out-of-spec test

__DATA__
TAG1 text one TAG2
TAG1 text two TAG2
TAG1 text three  TAG2
TAGS text four TAG2
TAG1 text five TAGT

##</code><code>##

Positive lookaround first:
 text one
         Negative lookaround:
TAG1 text one
Positive lookaround first:
 text two
         Negative lookaround:
TAG1 text two
Positive lookaround first:
 text three
         Negative lookaround:
TAG1 text three
Positive lookaround first:
         Negative lookaround:
TAGS text four
Positive lookaround first: