/*
 *  call-seq:
 *     enum.detect(ifnone = nil) {| obj | block }  => obj or nil
 *     enum.find(ifnone = nil)   {| obj | block }  => obj or nil
 *  
 *  Passes each entry in <i>enum</i> to <em>block</em>. Returns the
 *  first for which <em>block</em> is not <code>false</code>.  If no
 *  object matches, calls <i>ifnone</i> and returns its result when it
 *  is specified, or returns <code>nil</code>
 *     
 *     (1..10).detect  {|i| i % 5 == 0 and i % 7 == 0 }   #=> nil
 *     (1..100).detect {|i| i % 5 == 0 and i % 7 == 0 }   #=> 35
 *     
 */

static VALUE
enum_find(int argc, VALUE *argv, VALUE obj)
{
    VALUE memo = Qundef;
    VALUE if_none;

    rb_scan_args(argc, argv, "01", &if_none);
    RETURN_ENUMERATOR(obj, argc, argv);
    rb_block_call(obj, id_each, 0, 0, find_i, (VALUE)&memo);
    if (memo != Qundef) {
        return memo;
    }
    if (!NIL_P(if_none)) {
        return rb_funcall(if_none, rb_intern("call"), 0, 0);
    }
    return Qnil;
}