protected function pInfixOp($type, Node $leftNode, $operatorString, Node $rightNode) { list($precedence, $associativity) = $this->precedenceMap[$type]; return $this->pPrec($leftNode, $precedence, $associativity, -1) . $operatorString . $this->pPrec($rightNode, $precedence, $associativity, 1); }