_autoload.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * Common setup, class loaders etc.
 *
 * @package    auth_saml2
 * @copyright  Brendan Heywood <brendan@catalyst-au.net>
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

defined('MOODLE_INTERNAL') || die();

require_once('extlib/xmlseclibs/xmlseclibs.php');

spl_autoload_register(
    function($classname) {
        $map = [
            'SAML2'      => 'saml2/src/',
            'Twig'       => 'twig/twig/lib/',
            'Psr'        => 'php-fig-log/',
            'SimpleSAML' => 'simplesamlphp/lib/',
            'sspmod'     => 'simplesamlphp/modules/',
        ];
        foreach ($map as $namespace => $subpath) {
            $classpath = explode('_', $classname);
            if ($classpath[0] != $namespace) {
                $classpath = explode('\\', $classname);
                if ($classpath[0] != $namespace) {
                    continue;
                }
            }

            $subpath = __DIR__ . '/extlib/' . $subpath;
            if ($namespace == 'sspmod') {
                array_shift($classpath);
                $module = array_shift($classpath);
                $filepath = $subpath . "$module/lib/" . implode('/', $classpath) . '.php';
            } else {
                $filepath = $subpath . implode('/', $classpath) . '.php';
            }
            if (file_exists($filepath)) {
                require_once($filepath);
            }
        }
    }
);