public function createChildExpression() { $expression = new Expression(); $this->_nested_expressions[] = $expression; $expression->setParent($this); return $expression; }
public function getToExpressionLevel(Expression $expression, $level = 0) { if ($level == 0) { return $expression; } if ($level < 0) { throw new \Exception("no"); } return $this->getToExpressionLevel($expression->getLastChild(), --$level); }