在Joomla中查找PHP文件引用

我的编辑.php文件中$this变量是什么意思？ 其他文件中没有"包含"或"要求"！我的意思是我怎样才能找到$this所指的类。其中是包含使用此编辑.php文件的类的主 PHP 文件

编辑.php

 <?php
/**
* @package RSForm! Pro
* @copyright (C) 2007-2014 www.rsjoomla.com
* @license GPL, http://www.gnu.org/copyleft/gpl.html
*/
defined('_JEXEC') or die('Restricted access'); 
JHtml::_('behavior.keepalive');
?>
<script type="text/javascript">
function directorySave(task) {
    var form = document.getElementById('directoryEditForm');
    form.task.value = task;
    form.submit();
}
</script>
<form action="<?php echo JRoute::_('index.php?     option=com_rsform&view=directory&layout=edit&id='.$this->app->input->getInt('id',0)); ?>"     method="post" name="adminForm" id="directoryEditForm" enctype="multipart/form-data">
    <table class="table table-condensed table-striped table-hover table-bordered category">
        <?php foreach ($this->fields as $field) { ?>
        <tr>
            <td width="200" style="width: 200px;">
            <?php echo $field[0]; ?> <?php echo $field[2]; ?>
        </td>
        <td>
            <?php echo $field[1]; ?>
        </td>
    </tr>
    <?php } ?>
   </table>
<div class="form-actions">
    <button type="button" onclick="directorySave('apply');" class="btn btn-primary button"><?php    echo JText::_('RSFP_SUBM_DIR_APPLY'); ?></button> 
    <button type="button" onclick="directorySave('save');" class="btn btn-primary button"><?php    echo JText::_('RSFP_SUBM_DIR_SAVE'); ?></button> 
    <button type="button" onclick="directorySave('back')" class="btn button"><?php echo     JText::_('RSFP_SUBM_DIR_BACK'); ?></button>
    <?php       /* <--! I am Ahmad Mobaraki     --> */?>
    <button type="button" onclick="directorySave('delete')" class="btn btn-primary button"><?php echo JText::_('RSFP_SUBM_DIR_DELETE'); ?></button>
    <?php      /*  end ahmad*/ ?>
</div>
<input type="hidden" name="option" value="com_rsform">
<input type="hidden" name="controller" value="directory">
<input type="hidden" name="task" value="">
<input type="hidden" name="id" value="<?php echo $this->app->input->getInt('id',0); ?>">
<input type="hidden" name="formId" value="<?php echo $this->params->get('formId'); ?>">
</form>