<?php

/**
 * Normalises and removes any unknown characters from a string, making it safe
 * for use as a filename.
 * @param	string  $string		The string to slugificate.
 * @param	integer $maxlength	The maximum desired length of the resultant string.
 * @return	string				The slugified string.
 */
function slugify($string, $maxlength = 50) {
	return substr(preg_replace([
			'/\s+/',
			'/[^a-z0-9\-_]/'
		], [
			'-',
			''
		],
		strtolower(trim($string))
	), 0, $maxlength);
}

/**
 * Escapes a string ready for inclusion in an XML document.
 * @param  string $string The string to escape.
 * @return string         The escaped string.
 */
function escape4xml($string) {
	return htmlspecialchars($string, ENT_QUOTES | ENT_XML1);
}

/**
 * Renders a SimpleXML element node to a pretty-printed XML document.
 * @param	SimpleXmlElement	$simplexml_node The SimpleXML node to render.
 * @return	string				The pretty-printed XML representation of the provided SimpleXML node.
 */
function simplexml_asxml_pretty($simplexml_node) {
	libxml_disable_entity_loader(false);
	$dom = new DomDocument;
	$dom->preserveWhiteSpace = false;
	$dom->formatOutput = true;
	$dom->loadXML($simplexml_node->asXML(), LIBXML_NONET);
	return $dom->saveXML();
}