Pathname#split_names

static VALUE
split_names(VALUE self, VALUE path)
{
    rb_encoding *enc = rb_enc_get(check_strpath(path));
    const char *beg = RSTRING_PTR(path), *ptr = beg;
    const char *end = RSTRING_END(path);
    const char *root = rb_enc_path_skip_prefix_root(ptr, end, enc);
    VALUE pre = rb_str_subseq(path, 0, root - ptr);
    VALUE names = rb_ary_new();
    while (ptr < end) {
        const char *next = rb_enc_path_next(ptr, end, enc);
        if (next > ptr) rb_ary_push(names, rb_str_subseq(path, ptr - beg, next - ptr));
        ptr = next;
        while (ptr < end && isdirsep(*ptr)) ++ptr;
    }
    return rb_assoc_new(pre, names);
}