code: public function searchGroupClassAction()
      {
          if (!$this->getRequest()->isPost()) {
              $this->getResponse()->setHttpResponseCode(405);
              return;
          }
  
          $uri = (string)$this->getRequest()->getPost('uri');
          $groupType = $this->getRequest()->getPost('group');
  
          $groupTypes = array($groupType);
          if ($groupType == 'all') {
              $groupTypes = array('model', 'block', 'helper');
          }
  
          $items = array();
  
          if ($uri) {
              foreach ($groupTypes as $type) {
                  $items[$type]['class'] = Mage::getConfig()->getGroupedClassName($type, $uri);
                  $items[$type]['filepath'] = mageFindClassFile($items[$type]['class']);
              }
  
              $block = $this->getLayout()->createBlock('sheep_debug/array');
              $block->setTemplate('sheep_debug/grouped_class_search.phtml');
              $block->assign('items', $items);
              $this->getResponse()->setBody($block->toHtml());
          } else {
              $this->getResponse()->setBody($this->__('Please fill in a search query'));
          }
      }
docs: Search grouped class