<?php

use Twig\Extension\AbstractExtension;
use Twig\Node\Expression\Binary\AbstractBinary;
use Twig\Compiler;

// creating Twig Tag as Extension
class MyTwigOperators extends AbstractExtension
{
    public function getName()
    {
        return 'MyOperators';
    }
    
    public function getOperators()
    {
        return [
        [], // unary operator.
        [ // binary operator
            'isIn' => [
                'class' => 'IsIn',
                'precedence' => 20,
                'associativity' => Twig\ExpressionParser::OPERATOR_LEFT,
            ],
        ]];
    }
}

class IsIn extends AbstractBinary
{
    public function compile(Compiler $compiler) : void
    {
        $compiler
            ->raw('(in_array(')
            ->subcompile($this->getNode('left'))
            ->raw(', ')
            ->subcompile($this->getNode('right'))
            ->raw('))')
        ;
    }

    public function operator(Compiler $compiler) : Compiler
    {
        return $compiler->raw('');
    }
}

$path = __DIR__ . '/templates/';
$file = 'operator.html.twig';

echo '<b>- template content:</b>' . PHP_EOL;
echo file_get_contents($path . $file) . PHP_EOL;

$loader = new Twig\Loader\FilesystemLoader($path);
$twig = new Twig\Environment($loader);
$twig->addExtension(new MyTwigOperators());

echo '<b>- rendered template:</b>' . PHP_EOL;
echo $twig->render($file);

- template content:
{% set needle = "foo" %}
{% set haystack1 = ["bar","baz"] %}
{% set haystack2 = ["bar","foo","baz"] %}

haystack1:
{% if needle isIn haystack1 %}
it is in array 1
{% endif %}

haystack2:
{% if needle isIn haystack2 %}
it is in array 2
{% endif %}

- rendered template:

haystack1:

haystack2:
it is in array 2

• Serialization to Yaml, XML or Json with JMS Serializer
• Whoops, the error handler for debugging
• Carbon - An extended DateTime API

PHP 8.2, Laminas MVC 3.2, Symfony 5.2, Laravel 8.28, PHPUnit 9.5, Doctrine ORM 2.8