NotUnary example

$targets[] = $this->parseExpression();
            if (!$this->parser->getStream()->nextIf(/* Token::PUNCTUATION_TYPE */ 9, ',')) {
                break;
            }
        }

        return new Node($targets);
    }

    private function parseNotTestExpression(Node $node): NotUnary
    {
        return new NotUnary($this->parseTestExpression($node), $this->parser->getCurrentToken()->getLine());
    }

    private function parseTestExpression(Node $node): TestExpression
    {
        $stream = $this->parser->getStream();
        list($name, $test) = $this->getTest($node->getTemplateLine());

        $class = $this->getTestNodeClass($test);
        $arguments = null;
        if ($stream->test(/* Token::PUNCTUATION_TYPE */ 9, '(')) {
            $arguments = $this->parseArguments(true);
        }

use Twig\Node\Node;

class NullCoalesceExpression extends ConditionalExpression
{
    public function __construct(Node $left, Node $right, int $lineno)
    {
        $test = new DefinedTest(clone $left, 'defined', new Node(), $left->getTemplateLine());
        // for "block()", we don't need the null test as the return value is always a string         if (!$left instanceof BlockReferenceExpression) {
            $test = new AndBinary(
                $test,
                new NotUnary(new NullTest($left, 'null', new Node(), $left->getTemplateLine()), $left->getTemplateLine()),
                $left->getTemplateLine()
            );
        }

        parent::__construct($test, $left, $right, $lineno);
    }

    public function compile(Compiler $compiler): void
    {
        /* * This optimizes only one case. PHP 7 also supports more complex expressions * that can return null. So, for instance, if log is defined, log("foo") ?? "..." works, * but log($a["foo"]) ?? "..." does not if $a["foo"] is not defined. More advanced * cases might be implemented as an optimizer node visitor, but has not been done * as benefits are probably not worth the added complexity. */