slice!

/*
 *  call-seq:
 *     array.slice!(index)         -> obj or nil
 *     array.slice!(start, length) -> sub_array or nil
 *     array.slice!(range)         -> sub_array or nil 
 *  
 *  Deletes the element(s) given by an index (optionally with a length)
 *  or by a range. Returns the deleted object, subarray, or
 *  <code>nil</code> if the index is out of range. Equivalent to:
 *     
 *     def slice!(*args)
 *       result = self[*args]
 *       self[*args] = nil
 *       result
 *     end
 *     
 *     a = [ "a", "b", "c" ]
 *     a.slice!(1)     #=> "b"
 *     a               #=> ["a", "c"]
 *     a.slice!(-1)    #=> "c"
 *     a               #=> ["a"]
 *     a.slice!(100)   #=> nil
 *     a               #=> ["a"]
 */

static VALUE
rb_ary_slice_bang(argc, argv, ary)
    int argc;
    VALUE *argv;
    VALUE ary;
{
    VALUE arg1, arg2;
    long pos, len;

    if (rb_scan_args(argc, argv, "11", &arg1, &arg2) == 2) {
        pos = NUM2LONG(arg1);
        len = NUM2LONG(arg2);
      delete_pos_len:
        if (pos < 0) {
            pos = RARRAY(ary)->len + pos;
        }
        arg2 = rb_ary_subseq(ary, pos, len);
        rb_ary_splice(ary, pos, len, Qnil);    /* Qnil/rb_ary_new2(0) */
        return arg2;
    }

    if (!FIXNUM_P(arg1) && rb_range_beg_len(arg1, &pos, &len, RARRAY(ary)->len, 1)) {
        goto delete_pos_len;
    }

    return rb_ary_delete_at(ary, NUM2LONG(arg1));
}