sub compatible {
my ($s1, $s2) = @_;
my $m = length($s1) - 1;
($s1 . $s2) !~ /^.{0,$m}?([^_]).{$m}(?!\1)[^_]/;
}
printf "%s v %s ? %s\n", @$_, compatible( @$_ ) ? 1 : 0
for [ qw[ _8__3__19 48____7__ ] ], # compat
[ qw[ _8__3__19 4_8___7__ ] ], # compat
[ qw[ _8__3__19 48_____7_ ] ]; # clash
Update:And this is wrong too.
Update:
sub compatible {
my ($s1, $s2) = @_;
my $m = length($s1) - 1;
my($n, $p) = ($m - 1, $m + 1);
($s1 . $s2) !~ /^.{0,$m}?([^_]).{$m}(?!\1)[^_]/ and
($s1 . $s2) !~ /^.{0,$m}?([^_])(?:.{0,$n}|.{$p,})\1/;
}
printf "%s v %s ? %s\n", @$_, compatible( @$_ ) ? 1 : 0
for [ qw[ _8__3__19 48____7__ ] ], # compat
[ qw[ _8__3__19 4_8___7__ ] ], # clash
[ qw[ __8_3__19 48____7__ ] ], # clash
[ qw[ __8_3__19 84____7__ ] ], # clash
[ qw[ _8__3__19 48_____7_ ] ]; # clash