It's late and I'm tired, but I'm banging my head against a silly little problem. It's a long story as to why I need this, but I've stumbled on the following curious problem:

#!/usr/bin/perl

use strict;
use warnings;
use Test::More qw/no_plan/;

my $token  = '-----';
my $data   = "1,2,${token}0${token},4,5";
my $split  = qr/(?<!$token),(?!$token)/;
my @fields = split $split, $data;
my @expected = ( 1,2, "${token}0${token}", 4, 5 );
is_deeply \@fields, \@expected;

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I need to be able to split on a value if and only if that value is not immediately preceded and followed by the same fixed-width string. The code above actually assigns the following to @fields:

@fields = (
  '1',
  '2,-----0-----,4',
  '5'
);

[download]

It's as if it's doing a logical OR with the two zero-width assertions instead of a logical AND. I suppose it's not unreasonable that it do this, but is there some simple way I can enforce my desired behavior of splitting the resulting string to this?

@fields = (
  '1',
  '2',
  '-----0-----',
  '4',
  '5'
);

[download]

Also, where is this behavior documented? I'm sure it is somewhere. I just can't find it.

Cheers,
Ovid

New address of my CGI Course.

In reply to Zero-width assertions fail with split by Ovid

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