twig variable extractor #symfony #twig

VariableExtractor.php

<?php declare(strict_types=1);

namespace App\Twig;

use Twig\Environment;
use Twig\Node\Expression\ConditionalExpression;
use Twig\Node\Expression\Filter\DefaultFilter;
use Twig\Node\Expression\FilterExpression;
use Twig\Node\Expression\FunctionExpression;
use Twig\Node\Expression\NameExpression;
use Twig\Node\PrintNode;
use function iter\filter;
use function iter\flatten;
use function iter\func\operator;
use function iter\map;
use function iter\toArray;

final class VariableExtractor
{
    public function __construct(
        private Environment $twig,
    ) {
    }

    public function extract(string $path): ?array
    {
        $template = $this->twig->load($path);
        $source = $template->getSourceContext();
        $stream = $this->twig->tokenize($source);
        $mainNode = $this->twig->parse($stream);

        if (!$mainNode->hasNode('body')) {
            return null;
        }

        $cb = static function ($node) use (&$cb) {
            if ($node instanceof NameExpression) {
                return $node->getAttribute('name');
            }

            if ($node instanceof ConditionalExpression) {
                return $cb($node->getNode('expr1')->getNode('node'));
            }

            if ($node instanceof FilterExpression) {
                $node = $node->getNode('node');

                if ($node instanceof ConditionalExpression) {
                    return $cb($node->getNode('expr1'));
                }

                if ($node instanceof DefaultFilter) {
                    return $cb($node->getNode('node'));
                }

                return $node->getAttribute('name');
            }

            if ($node instanceof FunctionExpression) {
                return map($cb, toArray($node->getNode('arguments')->getIterator()));
            }

            if ($node instanceof PrintNode) {
                return $cb($node->getNode('expr'));
            }

            throw new \Exception('Something wrong with this node.');
        };

        return toArray(
            flatten(
                map(
                    $cb,
                    filter(
                        operator('instanceof', PrintNode::class),
                        $mainNode->getNode('body')->getNode('0')->getIterator(),
                    ),
                ),
            )
        );
    }
}