Language: PHP
Label: safe
CWE: CWE-79 \u2014 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.

Code:
    public function validateChildren($children, $config, $context)
    {
        $list_of_children = '';
        $nesting = 0; // depth into the nest
        foreach ($children as $node) {
            if (!empty($node->is_whitespace)) {
                continue;
            }
            $list_of_children .= $node->name . ',';
        }
        // add leading comma to deal with stray comma declarations
        $list_of_children = ',' . rtrim($list_of_children, ',');
        $okay =
            preg_match(
                '/^,?' . $this->_pcre_regex . '$/',
                $list_of_children
            );
        return (bool)$okay;
    }