#!/usr/bin/perl

use warnings;
use strict;

$\ = $/;

my $A = "1112"
#	. ''
;

@_ = ( 'a' .. 'i' );

$A =~ /1+
	(??{
		print "[$&]";
		$_ .= shift @_;
		s!\B!shift@_!e;
		print "\$_:[$_]";
		})
	$
	/x;