Autoloader for Official Parse PHP SDK

autoload.php

<?php

/**
 * You only need this file if you are not using composer.
 * Adapted from the Facebook PHP SDK 4.0.x autoloader
 */

if (version_compare(PHP_VERSION, '5.4.0', '<')) {
  throw new Exception('The Parse SDK requires PHP version 5.4 or higher.');
}

/**
 * Register the autoloader for the Parse SDK
 * Based off the official PSR-4 autoloader example found here:
 * https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-4-autoloader-examples.md
 *
 * @param string $class The fully-qualified class name.
 * @return void
 */
spl_autoload_register(function ($class)
{
  // Parse class prefix
  $prefix = 'Parse\\';

  // base directory for the namespace prefix
  $base_dir = defined('PARSE_SDK_DIR') ? PARSE_SDK_DIR : __DIR__ . '/Parse/';

  // does the class use the namespace prefix?
  $len = strlen( $prefix );
  if ( strncmp($prefix, $class, $len) !== 0 ) {
    // no, move to the next registered autoloader
    return;
  }

  // get the relative class name
  $relative_class = substr( $class, $len );

  // replace the namespace prefix with the base directory, replace namespace
  // separators with directory separators in the relative class name, append
  // with .php
  $file = $base_dir . str_replace( '\\', '/', $relative_class ) . '.php';
  
  // echo $relative_class . '<br/>';

  // if the file exists, require it
  if ( file_exists( $file ) ) {
    require $file;
  }
});