method

cycle

v1_8_7_72 - Show latest stable - 0 notes - Class: Enumerable

cycle(...) public

Calls block for each element of enum repeatedly n times or forever if none or nil is given. If a non-positive number is given or the collection is empty, does nothing. Returns nil if the loop has finished without getting interrupted.

Enumerable#cycle saves elements in an internal array so changes to enum after the first pass have no effect.

   a = ["a", "b", "c"]
   a.cycle {|x| puts x }  # print, a, b, c, a, b, c,.. forever.
   a.cycle(2) {|x| puts x }  # print, a, b, c, a, b, c.

Show source

/*
 *  call-seq:
 *     enum.cycle {|obj| block }
 *     enum.cycle(n) {|obj| block }
 *
 *  Calls <i>block</i> for each element of <i>enum</i> repeatedly _n_
 *  times or forever if none or nil is given.  If a non-positive
 *  number is given or the collection is empty, does nothing.  Returns
 *  nil if the loop has finished without getting interrupted.
 *
 *  Enumerable#cycle saves elements in an internal array so changes
 *  to <i>enum</i> after the first pass have no effect.
 *
 *     a = ["a", "b", "c"]
 *     a.cycle {|x| puts x }  # print, a, b, c, a, b, c,.. forever.
 *     a.cycle(2) {|x| puts x }  # print, a, b, c, a, b, c.
 *
 */

static VALUE
enum_cycle(argc, argv, obj)
    int argc;
    VALUE *argv;
    VALUE obj;
{
    VALUE ary;
    VALUE nv = Qnil;
    long n, i, len;

    rb_scan_args(argc, argv, "01", &nv);

    RETURN_ENUMERATOR(obj, argc, argv);
    if (NIL_P(nv)) {
        n = -1;
    }
    else {
        n = NUM2LONG(nv);
        if (n <= 0) return Qnil;
    }
    ary = rb_ary_new();
    RBASIC(ary)->klass = 0;
    rb_block_call(obj, id_each, 0, 0, cycle_i, ary);
    len = RARRAY(ary)->len;
    if (len == 0) return Qnil;
    while (n < 0 || 0 < --n) {
        for (i=0; i<len; i++) {
            rb_yield(RARRAY(ary)->ptr[i]);
        }
    }
    return Qnil;                /* not reached */
}

cycle

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