Twig tag to remove indentation at the start of each line: {% indentless %}...{% endindentless %} + symfony3 and twig2 compatibility

IndentlessExtension.php

<?php

/**
 * Created by PhpStorm.
 * User: Thomas Kekeisen <thomas@kekeisen.it>
 * Date: 01/03/2017
 * Time: 19:32
 */

namespace AppBundle\Twig;

/**
 * Class IndentlessExtension
 *
 * @author Thomas Kekeisen <thomas@kekeisen.it>
 * @package AppBundle\Twig
 */
class IndentlessExtension extends \Twig_Extension
{
    /**
     * @return array
     */
    public function getTokenParsers()
    {
        return [
            new IndentlessTokenParser()
        ];
    }

    /**
     * @return string
     */
    public function getName()
    {
        return 'indentless';
    }
}

IndentlessNode.php

<?php

/**
 * Created by PhpStorm.
 * User: Thomas Kekeisen <thomas@kekeisen.it>
 * Date: 01/03/2017
 * Time: 19:33
 */

namespace AppBundle\Twig;

/**
 * Represents an indentless node.
 *
 * Based on Twig's Twig_Node_Spaceless class
 *
 * @see https://gist.github.com/seamusleahy/36c8737efc057704a2cd
 */
class IndentlessNode extends \Twig_Node
{
    /**
     * TwigIndentlessNode constructor.
     * @param \Twig_Node $body
     * @param $lineno
     * @param string $tag
     */
    public function __construct(\Twig_Node $body, $lineno, $tag = 'indentless')
    {
        parent::__construct(array('body' => $body), array(), $lineno, $tag);
    }

    /**
     * Compiles the node to PHP.
     *
     * @param \Twig_Compiler $compiler A Twig_Compiler instance
     */
    public function compile(\Twig_Compiler $compiler)
    {
        $compiler
            ->addDebugInfo($this)
            ->write("ob_start();\n")
            ->subcompile($this->getNode('body'))
            ->write("echo trim(preg_replace('/^[ \t]+/m', '', ob_get_clean()));\n")
        ;
    }
}

IndentlessTokenParser.php

<?php

/**
 * Created by PhpStorm.
 * User: Thomas Kekeisen <thomas@kekeisen.it>
 * Date: 01/03/2017
 * Time: 19:33
 */

namespace AppBundle\Twig;

/**
 * Remove whitespace at the start of each line.
 *
 * Based on Twig's \Twig_TokenParser_Spaceless class
 *
 * @see https://gist.github.com/seamusleahy/36c8737efc057704a2cd
 */
class IndentlessTokenParser extends \Twig_TokenParser
{
    /**
     * Parses a token and returns a node.
     *
     * @param \Twig_Token $token A Twig_Token instance
     *
     * @return \Twig_Node A Twig_Node instance
     */
    public function parse(\Twig_Token $token)
    {
        $lineno = $token->getLine();

        $this->parser->getStream()->expect(\Twig_Token::BLOCK_END_TYPE);

        $body = $this->parser->subparse(array($this, 'decideIndentlessEnd'), true);

        $this->parser->getStream()->expect(\Twig_Token::BLOCK_END_TYPE);

        return new IndentlessNode($body, $lineno, $this->getTag());
    }

    /**
     * @param \Twig_Token $token
     * @return mixed
     */
    public function decideIndentlessEnd(\Twig_Token $token)
    {
        return $token->test('endindentless');
    }

    /**
     * Gets the tag name associated with this token parser.
     *
     * @return string The tag name
     */
    public function getTag()
    {
        return 'indentless';
    }
}

services.yml

app.twig.indentless:
    class: AppBundle\Twig\IndentlessExtension
    public: false
    tags:
        - { name: twig.extension }