autoload.php

<?php
/* ===========================================================================
 * Copyright 2018 Zindex Software
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ============================================================================ */

spl_autoload_register(function ($class) {

    $class = ltrim($class, '\\');
    $dir = __DIR__ . '/src';
    $namespace = 'Opis\Database';

    if (strpos($class, $namespace) === 0) {
        $class = substr($class, strlen($namespace));
        $path = '';
        if (($pos = strripos($class, '\\')) !== false) {
            $path = str_replace('\\', '/', substr($class, 0, $pos)) . '/';
            $class = substr($class, $pos + 1);
        }
        $path .= str_replace('_', '/', $class) . '.php';
        $dir .= '/' . $path;

        if (file_exists($dir)) {
            include $dir;
            return true;
        }

        return false;
    }

    return false;
});