SplClassloader.php

<?php 

/**
 *  An SplClassLoader implementation that implements
 *  the PHP 5.3 standards.
 *
 *  @based on https://gist.github.com/221634
 */
class SplClassLoader {

    private $file_extension = '.php';
    private $namespace;
    private $include_path;
    private $namespace_separator = '\\';
    private $ignore_underscores = true;

    public function __construct($namespace = null, $include_path = null) {
        $this->namespace = $namespace;
        $this->include_path = $include_path;
    }

    public function get_or_set($property, $value=null) {
        if ($value === null) {
            return $this->{$property};
        } else {
            return $this->{$property} = $value;
        }
    }

    public function namespace_separator($separator = null) {
        return $this->get_or_set('namespace_separator', $separator);
    }

    public function include_path($path = null) {
        return $this->get_or_set('include_path', $path);
    }

    public function file_extension($extension = null) {
        return $this->get_or_set('file_extension', $extension);
    }

    public function ignore_underscores($ignore = null) {
        return $this->get_or_set('ignore_underscores', $ignore);
    }

    public function register() {
        spl_autoload_register(array($this, 'autoload_class'));
    }

    public function unregister() {
        spl_autoload_unregister(array($this, 'autoload_class'));
    }

    public function autoload_class($class) {

        // See if the registered namespace is in the class name.
        // We don't need to try and load this class if it's for
        // some other namespace.
        $registered_space = $this->namespace 
                          . $this->namespace_separator();
        $requested_space = substr($class, 0, strlen($registered_space));
        if ($this->namespace === null
           || $registered_space === $requested_space) {

            // Stub some values.
            $file = '';
            $name_space = '';
            
            // If there is a namespace in here, pull it out
            // and construct the file path from it.
            $last_slash = strripos($class, $this->namespace_separator());
            if ($last_slash !== false) {
                $namespace = substr($class, 0, $last_slash);
                $class = substr($class, $last_slash + 1);
                $file = str_replace(
                    $this->namespace_separator(),
                    DIRECTORY_SEPARATOR,
                    $namespace
                );
                $file .= DIRECTORY_SEPARATOR;
            }

            // If we're not ignoring underscores, turn them into 
            // directory separators (some frameworks use 
            // underscores in class names as a convention
            // to indicate subfolders). 
            if (!$this->ignore_underscores) {
                $file .= str_replace(
                    '_',
                    DIRECTORY_SEPARATOR,
                    $class
                );
            } else {
                $file .= $class;
            }

            // Add the file extension.
            $file .= $this->file_extension();

            // Add an include path if there is one.
            if ($this->include_path() === null) {
                $path = '';
            } else {
                $path = $this->include_path;
            }

            // Require the file
            $file = $path . DIRECTORY_SEPARATOR . $file;
            require $file;

        }
    }

}