dynamic regex switch (Perl5)

dynamic.regex.switch.pl

#!/usr/bin/perl
use feature say;
my @a = (
    "  asd",
    "    asd ",
    "      bsd",
    "    XXX",
    "10000"
);

my $spacer;

foreach(@a) {
    /^\s+/ and length($spacer) < length($&) and ( $spacer = $& );
    /^${spacer}/
        and say("Spacer with length ".length($spacer)." is present in [$_]")
        or say("Spacer with length ".length($spacer)." is not present in [$_]");
}