each_slice

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

    if (size <= 0) rb_raise(rb_eArgError, "invalid slice 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_slice_i, (VALUE)args);

    ary = args[0];
    if (RARRAY_LEN(ary) > 0) rb_yield(ary);

    return Qnil;
}