Function to escape single and double quotes in XPath queries using PHP

xpath_escape.php

<?php
function xpathEscape($query, $default_delim = '"')
{
    if (strpos($query, $default_delim) === false)
        return $default_delim . $query . $default_delim;
    preg_match_all("#(?:('+)|[^']+)#", $query, $matches);
    list($parts, $apos) = $matches;
    foreach ($parts as $i => &$part) {
        $delim = $apos[$i] ? '"' : "'";
        $part = $delim . $part . $delim;
    }
    return 'concat("",' . implode(',', $parts) . ')';
}