DigiComp.FluidRenderFunctions/Classes/ViewHelpers/RegisterRenderFunctionViewHelper.php

<?php

declare(strict_types=1);

namespace DigiComp\FluidRenderFunctions\ViewHelpers;

use DigiComp\FluidRenderFunctions\Utils\NodeRenderTransfer;
use Neos\FluidAdaptor\Core\ViewHelper\AbstractViewHelper;
use TYPO3Fluid\Fluid\Core\Compiler\TemplateCompiler;
use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\RootNode;
use TYPO3Fluid\Fluid\Core\Parser\SyntaxTree\ViewHelperNode;

class RegisterRenderFunctionViewHelper extends AbstractViewHelper
{
    /**
     * @throws \Neos\FluidAdaptor\Core\ViewHelper\Exception
     */
    public function initializeArguments(): void
    {
        parent::initializeArguments();
        $this->registerArgument('as', 'string', 'Name of the registered render function', false, 'renderFunc');
        $this->registerArgument(
            'subjectName',
            'string',
            'Name of the argument passed to render function',
            false,
            'subject'
        );
    }

    public function compile(
        $argumentsName,
        $closureName,
        &$initializationPhpCode,
        ViewHelperNode $node,
        TemplateCompiler $compiler
    ) {
        // we disable compiling, because we will need access to the AST, which is not available if compiled
        // a cool improvement would be to drop the need to the AST and so become compilable
        $compiler->disable();
        return "''";
    }

    public function render(): string
    {
        $transferNode = new RootNode();
        foreach ($this->childNodes as $childNode) {
            $transferNode->addChildNode($childNode);
        }
        $renderer = new NodeRenderTransfer($transferNode, $this->arguments['subjectName']);
        $this->renderingContext->getViewHelperVariableContainer()
            ->add(static::class, $this->arguments['as'], $renderer);
        return '';
    }
}