composer/src/bootstrap.php

<?php

/*
 * This file is part of Composer.
 *
 * (c) Nils Adermann <naderman@naderman.de>
 *     Jordi Boggiano <j.boggiano@seld.be>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

function includeIfExists($file)
{
    if (file_exists($file)) {
        return include $file;
    }
}

if ((!$loader = includeIfExists(__DIR__.'/../vendor/autoload.php')) && (!$loader = includeIfExists(__DIR__.'/../../../autoload.php'))) {
    echo 'You must set up the project dependencies, run the following commands:'.PHP_EOL.
        'curl -s http://getcomposer.org/installer | php'.PHP_EOL.
        'php composer.phar install'.PHP_EOL;
    exit(1);
}

return $loader;