DbSelectParenthesis: allow to defer Db Expr...

...stringification when required to apply parenthesis (-> union)

library/Director/Db/DbSelectParenthesis.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Icinga\Module\Director\Db;
+
+class DbSelectParenthesis extends \Zend_Db_Expr
+{
+    protected $select;
+
+    public function __construct(\Zend_Db_Select $select)
+    {
+        parent::__construct('');
+        $this->select = $select;
+    }
+
+    public function getSelect()
+    {
+        return $this->select;
+    }
+
+    public function __toString()
+    {
+        return '(' . $this->select . ')';
+    }
+}