You can just say "optional dot" instead, i.e.

[.]?
[download]

Working example:

#!/usr/bin/perl
use warnings;
use strict;
use experimental qw( signatures );

sub match($entry) {
    $entry =~ m{^ (\d+) [.]? \s+ (.*?) \s+(-|\N{EN DASH}|\N{EM DASH})\
+s+ (.*?) $}x;
}

use Test::More tests => 3;

ok match('123 Festival - Sunday');
ok match('456. Pool Party - Tuesday');
ok ! match('789| Gig - Friday');
[download]

Moreover, the | matches itself in a character class which is not what you want (try the last test against the original regex).

[\.|\s] \s+ matches either a dot (or a pipe - thanks, LanX) or a space but then followed by at least one other space. Only one of your test strings matches this pattern.

Update: added bracketed clause to specify the pipe - see reply

> [\.|\s]

> either a dot or a space

or a literal pipe symbol | ²

The OP seems to think he can have two alternative character classes inside [...]

To achieve this he needs (?:[CLASS1]|[CLASS2]) ... (the ?: is for not catching).°

Probably he just confused it with (\.|\s) or (?:\.|\s)

Cheers Rolf
_{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)
Wikisyntax for the Monastery}

edit

°) Sorry, in hindsight this doesn't make much sense (?:[CLASS1]|[CLASS2]) is the same like [CLASS1CLASS2] , 'or'-operations follow associative law

²) and the [\.] is redundant, it's the same like [.] and won't match everything

and the [\.] is redundant, it's the same like [.] and won't match everything

Yes, I am aware of that. However the OP's question was to explain why the regex he provided, in all its baroque splendour, did not match both the input lines. I think it would be distracting to go changing his regex and then explain how the modified form works rather than answer the question as posed. There are plenty of things I would change about the given regex to achieve the same end were I to write it of which this is merely one. Although the first thing would be to lose the /x which is causing far more confusion than it removes in this case IMHO.

or a literal pipe symbol |

That's a good observation and I'll amend my post to mention it. Thanks.

---

🦛