chamilo-lms2/main/inc/lib/formvalidator/Rule/Date.php

<?php
/* For licensing terms, see /license.txt */
/** @author Bart Mollet, Julio Montoya */

/**
 * Class HTML_QuickForm_Rule_Date
 */
class HTML_QuickForm_Rule_Date extends HTML_QuickForm_Rule
{
    /**
     * Check a date
     * @see HTML_QuickForm_Rule
     * @param string $date example 2014-04-30
     * @param array $options
     *
     * @return boolean True if date is valid
     */
    public function validate($date, $options)
    {
        return api_is_valid_date($date, 'Y-m-d');
    }
}