/src/ClassLoader/UniversalClassLoader.php

<?php

namespace ClassLoader;

/**
 * UniversalClassLoader implements a "universal" autoloader for PHP 5.3.
 *
 * It is able to load classes that use either:
 *
 *  * The technical interoperability standards for PHP 5.3 namespaces and
 *    class names (http://groups.google.com/group/php-standards/web/psr-0-final-proposal);
 *
 *  * The PEAR naming convention for classes (http://pear.php.net/).
 *
 * Classes from a sub-namespace or a sub-hierarchy of PEAR classes can be
 * looked for in a list of locations to ease the vendoring of a sub-set of
 * classes for large projects.
 *
 * Example usage:
 *
 *     $loader = new UniversalClassLoader();
 *
 *     // register classes with namespaces
 *     $loader->registerNamespaces(array(
 *         'Symfony\Component' => __DIR__.'/component',
 *         'Symfony'           => __DIR__.'/framework',
 *         'Sensio'            => array(__DIR__.'/src', __DIR__.'/vendor'),
 *     ));
 *
 *     // register a library using the PEAR naming convention
 *     $loader->registerPrefixes(array(
 *         'Swift_' => __DIR__.'/Swift',
 *     ));
 *
 *     // activate the autoloader
 *     $loader->register();
 *
 * In this example, if you try to use a class in the Symfony\Component
 * namespace or one of its children (Symfony\Component\Console for instance),
 * the autoloader will first look for the class under the component/
 * directory, and it will then fallback to the framework/ directory if not
 * found before giving up.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 */
class UniversalClassLoader
{
    protected $namespaces = array();
    protected $prefixes = array();
    protected $namespaceFallback = array();
    protected $prefixFallback = array();

    /**
     * Gets the configured namespaces.
     *
     * @return array A hash with namespaces as keys and directories as values
     */
    public function getNamespaces()
    {
        return $this->namespaces;
    }

    /**
     * Gets the configured class prefixes.
     *
     * @return array A hash with class prefixes as keys and directories as values
     */
    public function getPrefixes()
    {
        return $this->prefixes;
    }

    /**
     * Gets the directory(ies) to use as a fallback for namespaces.
     *
     * @return array An array of directories
     */
    public function getNamespaceFallback()
    {
        return $this->namespaceFallback;
    }

    /**
     * Gets the directory(ies) to use as a fallback for class prefixes.
     *
     * @return array An array of directories
     */
    public function getPrefixFallback()
    {
        return $this->prefixFallback;
    }

    /**
     * Registers the directory to use as a fallback for namespaces.
     *
     * @param string|array $dirs A directory path or an array of directories
     */
    public function registerNamespaceFallback($dirs)
    {
        $this->namespaceFallback = (array) $dirs;
    }

    /**
     * Registers the directory to use as a fallback for class prefixes.
     *
     * @param string|array $dirs A directory path or an array of directories
     */
    public function registerPrefixFallback($dirs)
    {
        $this->prefixFallback = (array) $dirs;
    }

    /**
     * Registers an array of namespaces
     *
     * @param array $namespaces An array of namespaces (namespaces as keys and locations as values)
     */
    public function registerNamespaces(array $namespaces)
    {
        foreach ($namespaces as $namespace => $locations) {
            $this->namespaces[$namespace] = (array) $locations;
        }
    }

    /**
     * Registers a namespace.
     *
     * @param string       $namespace The namespace
     * @param array|string $paths     The location(s) of the namespace
     */
    public function registerNamespace($namespace, $paths)
    {
        $this->namespaces[$namespace] = (array) $paths;
    }

    /**
     * Registers an array of classes using the PEAR naming convention.
     *
     * @param array $classes An array of classes (prefixes as keys and locations as values)
     */
    public function registerPrefixes(array $classes)
    {
        foreach ($classes as $prefix => $locations) {
            $this->prefixes[$prefix] = (array) $locations;
        }
    }

    /**
     * Registers a set of classes using the PEAR naming convention.
     *
     * @param string       $prefix  The classes prefix
     * @param array|string $paths   The location(s) of the classes
     */
    public function registerPrefix($prefix, $paths)
    {
        $this->prefixes[$prefix] = (array) $paths;
    }

    /**
     * Registers this instance as an autoloader.
     *
     * @param Boolean $prepend Whether to prepend the autoloader or not
     */
    public function register($prepend = false)
    {
        spl_autoload_register(array($this, 'loadClass'), true, $prepend);
    }

    /**
     * Loads the given class or interface.
     *
     * @param string $class The name of the class
     */
    public function loadClass($class)
    {
        $class = ltrim($class, '\\');

        if (false !== ($pos = strrpos($class, '\\'))) {
            // namespaced class name
            $namespace = substr($class, 0, $pos);
            foreach ($this->namespaces as $ns => $dirs) {
                foreach ($dirs as $dir) {
                    if (0 === strpos($namespace, $ns)) {
                        $className = substr($class, $pos + 1);
                        $file = $dir.DIRECTORY_SEPARATOR.str_replace('\\', DIRECTORY_SEPARATOR, $namespace).DIRECTORY_SEPARATOR.str_replace('_', DIRECTORY_SEPARATOR, $className).'.php';
                        if (file_exists($file)) {
                            require $file;
                            return;
                        }
                    }
                }
            }

            foreach ($this->namespaceFallback as $dir) {
                $file = $dir.DIRECTORY_SEPARATOR.str_replace('\\', DIRECTORY_SEPARATOR, $class).'.php';
                if (file_exists($file)) {
                    require $file;
                    return;
                }
            }
        } else {
            // PEAR-like class name
            foreach ($this->prefixes as $prefix => $dirs) {
                foreach ($dirs as $dir) {
                    if (0 === strpos($class, $prefix)) {
                        $file = $dir.DIRECTORY_SEPARATOR.str_replace('_', DIRECTORY_SEPARATOR, $class).'.php';
                        if (file_exists($file)) {
                            require $file;
                            return;
                        }
                    }
                }
            }

            foreach ($this->prefixFallback as $dir) {
                $file = $dir.DIRECTORY_SEPARATOR.str_replace('_', DIRECTORY_SEPARATOR, $class).'.php';
                if (file_exists($file)) {
                    require $file;
                    return;
                }
            }
        }
    }
}