CDATA ViewHelper for Fluid: Only wrapping if CDATA is necessary

FormatCdataViewHelper.php

<?php
namespace Swisscom\Finapp\ViewHelpers;

// Credits: https://git.typo3.org/Packages/TYPO3.CMS.git/blob_plain/HEAD:/typo3/sysext/fluid/Classes/ViewHelpers/Format/CdataViewHelper.php
// Extended with functionality to only wrap if CDATA is necessary.
// See $predeclaredCharacters

	/*                                                                        *
	 * This script is backported from the TYPO3 Flow package "TYPO3.Fluid".   *
	 *                                                                        *
	 * It is free software; you can redistribute it and/or modify it under    *
	 * the terms of the GNU Lesser General Public License, either version 3   *
	 *  of the License, or (at your option) any later version.                *
	 *                                                                        *
	 * The TYPO3 project - inspiring people to share!                         *
	 *                                                                        */

use TYPO3\Fluid\Core\ViewHelper\AbstractViewHelper;

/**
 * Outputs an argument/value without any escaping and wraps it with CDATA tags
 * if necessary.
 *
 * PAY SPECIAL ATTENTION TO SECURITY HERE (especially Cross Site Scripting),
 * as the output is NOT SANITIZED!
 *
 * = Examples =
 *
 * <code title="Child nodes">
 * <my:formatCdata>{string}</my:formatCdata>
 * </code>
 * <output>
 * <![CDATA[(Content of {string} without any conversion/escaping)]]>
 * </output>
 *
 * <code title="Value attribute">
 * <my:formatCdata value="{string}" />
 * </code>
 * <output>
 * <![CDATA[(Content of {string} without any conversion/escaping)]]>
 * </output>
 *
 * <code title="Inline notation">
 * {string -> my:formatCdata()}
 * </code>
 * <output>
 * <![CDATA[(Content of {string} without any conversion/escaping)]]>
 * </output>
 *
 * @api
 */
class FormatCdataViewHelper extends AbstractViewHelper {

	/**
	 * Disable the escaping interceptor because otherwise the child nodes would be escaped before this view helper
	 * can decode the text's entities.
	 *
	 * @var bool
	 */
	protected $escapingInterceptorEnabled = FALSE;

	/**
	 * Predeclared characters according to XML specification
	 * http://xml.silmaril.ie/specials.html
	 *
	 * @var array
	 */
	protected $predeclaredCharacters = array ('&', '<', '>', '"', "'");

	/**
	 * @param mixed $value The value to output
	 * @return string
	 */
	public function render($value = NULL) {
		if ($value === NULL) {
			$value = $this->renderChildren();
		}

		foreach ($this->predeclaredCharacters as $c) {
			if (stripos($value, $c) !== false) {
				return sprintf('<![CDATA[%s]]>', $value);
			}
		}

		return $value;
	}
}