<?php
/*
 *  $Id$
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information, see
 * <http://www.doctrine-project.org>.
 */

namespace Doctrine\Common;

/**
 * EventArgs is the base class for classes containing event data.
 *
 * This class contains no event data and cannot be instantiated.
 * It is used by events that do not pass state information to an event handler
 * when an event is raised. The single empty EventArgs instance can be obtained
 * through {@link getEmptyInstance()}.
 *
 * @author      Konsta Vesterinen <kvesteri@cc.hut.fi>
 * @author      Roman Borschel
 * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL
 * @link        www.doctrine-project.org
 * @since       2.0
 * @version     $Revision$
 */
class EventArgs
{
    private static $_emptyEventArgsInstance;
    private $_defaultPrevented;

    protected function __construct()
    {
        $this->_defaultPrevented = false;
    }

    public function preventDefault()
    {
        $this->_defaultPrevented = true;
    }

    public function getDefaultPrevented()
    {
        return $this->_defaultPrevented;
    }

    public static function getEmptyInstance()
    {
        if ( ! self::$_emptyEventArgsInstance) {
            self::$_emptyEventArgsInstance = new EventArgs;
        }
        return self::$_emptyEventArgsInstance;
    }
}