Twig tag to remove indentation at the start of each line: {% indentless %}...{%endindetless %}

twig-indentless.php

<?php

/**
 * Remove whitespace at the start of each line.
 *
 * Based on Twig's Twig_TokenParser_Spaceless class
 */
class TwigIndentlessTokenParser extends Twig_TokenParser
{
    /**
     * Parses a token and returns a node.
     *
     * @param Twig_Token $token A Twig_Token instance
     *
     * @return Twig_NodeInterface A Twig_NodeInterface 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 TwigIndentlessNode($body, $lineno, $this->getTag());
    }

    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';
    }
}

/**
 * Represents an indentless node.
 *
 * Based on Twig's Twig_Node_Spaceless class
 */
class TwigIndentlessNode extends Twig_Node
{
    public function __construct(Twig_NodeInterface $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");
    }
}

twig-setup.php

<?php
$twig = new Twig_Environment($loader);
$twig->addTokenParser(new TwigIndentlessTokenParser());