each_cons

/*
 *  call-seq:
 *    each_cons(n) {...}
 *    each_cons(n)
 *
 *  Iterates the given block for each array of consecutive <n>
 *  elements.  If no block is given, returns an enumerator.a
 *
 *  e.g.:
 *      (1..10).each_cons(3) {|a| p a}
 *      # outputs below
 *      [1, 2, 3]
 *      [2, 3, 4]
 *      [3, 4, 5]
 *      [4, 5, 6]
 *      [5, 6, 7]
 *      [6, 7, 8]
 *      [7, 8, 9]
 *      [8, 9, 10]
 *
 */
static VALUE
enum_each_cons(obj, n)
    VALUE obj, n;
{
    long size = NUM2LONG(n);
    VALUE args[2];

    if (size <= 0) rb_raise(rb_eArgError, "invalid size");
    RETURN_ENUMERATOR(obj, 1, &n);
    args[0] = rb_ary_new2(size);
    args[1] = (VALUE)size;

    rb_block_call(obj, SYM2ID(sym_each), 0, 0, each_cons_i, (VALUE)args);

    return Qnil;
}