Re^4: Regex help

Hm, I'd think that

(?!\w) and (?=\W)

and also

(?<=\w) and (?<!\W)

are equivalent!?

This would unify your "descripted" \b and japhy's "left side boundary".

Also, if it ... flies like a duck, quacks like a duck. .. It probably is a duck?!:

my $rt = [
    [AM => [(qr/\b/) x 2]],
    [japhy1 => [qr/(?:(?=\w)(?<!\w)|(?=\W)(?<!\W))/, qr/(?:(?<=\w)(?!\
+w)|(?<=\W)(?!\W))/]],
    [japhy2 => [qr/(?(?=\w)(?<!\w)|(?<!\W))/, qr/(?(?<=\w)(?!\w)|(?!\W
+))/]],
    [ysth => [(qr/(?:(?=\w)(?<!\w)|(?!\w)(?<=\w))/) x 2]],
];

for my $thing (qw(, th this)) {
    for (@$rt) {
        my $try = $_->[0] . (' ' x (6 - length $_->[0]));    # propose
+r
        my ($lb, $rb) = @{$_->[1]};
        (my $text = "this,that & this, that & this ,that & this , that
+ this")
        =~ s/$lb($thing)$rb/>>$1<</g;
        print "[$try|$thing]$text\n";
    }
}
[download]

Do I have the wrong test cases?

Comment on Re^4: Regex help Select or Download Code

Replies are listed 'Best First'.
Re^5: Regex help by ysth (Canon) on Jan 15, 2006 at 19:49 UTC
`(?!\w)` and `(?=\W)` differ at the end of the string. `(?<=\w)` and `(?<!\W)` differ at the start of the string.	[reply] [d/l] [select]
Re^6: Regex help by pKai (Priest) on Jan 16, 2006 at 10:27 UTC
Oh, I was vaguely aware of it. But I didn't realize that that was the exact point japhy addressed! Read more... (911 Bytes) `[\b ]this, [(?:(?=\w)(?<!\w)\|(?=\W)(?<!\W))]this, [(?:(?<=\w)(?!\w)\|(?<=\W)(?!\W))]this, [(?(?=\w)(?<!\w)\|(?<!\W)) ]this, [(?(?<=\w)(?!\w)\|(?!\W)) ]this,* [(?:(?=\w)(?<!\w)\|(?!\w)(?<=\w))]this, [\b ],that [(?:(?=\w)(?<!\w)\|(?=\W)(?<!\W))],that [(?:(?<=\w)(?!\w)\|(?<=\W)(?!\W))],that [(?(?=\w)(?<!\w)\|(?<!\W)) ],that* [(?(?<=\w)(?!\w)\|(?!\W)) ],that [(?:(?=\w)(?<!\w)\|(?!\w)(?<=\w))],that` [download]	[reply] [d/l] [select]