use strict;
use warnings;
use Data::Dumper ();

my $S = {};

sub splitTo {
    my ($pH, $pA, $leaf) = @_;
    $pA = [ grep $_, split /\//, $pA ] unless ref $pA;
    return $leaf unless @$pA;
    my $nxt = shift @$pA;
    my $pHN = ref $pH->{$nxt} ? $pH->{$nxt} : {};
    $pH->{$nxt} = splitTo($pHN, $pA, $leaf);
    $pH;
}

splitTo($S, 'foo/bar', 'oops');
splitTo($S, 'foo/bar/baz', '\\o/');
splitTo($S, 'foo/gnu', 'gnat');

print Data::Dumper->Dump([$S], ['S']);