* $loader = new Autoloader('classes');
* $loader->loadClass('FooBar'); // Includes file 'classes/foo_bar.php'
*
*
* An Autoloader instance can register itself to the SPL autoload stack, so
* that explicit 'include' statements for classes are not necessary anymore.
* Applied to the example above:
*
* $loader = new Autoloader('classes');
* $loader->register();
* $foobar = new FooBar(); // File 'classes/foo_bar.php' is automatically included
*
*
* Namespaces are assumed to indicate subdirectories:
*
* Autoloader::create('classes')->register();
* $bar = new Foo\Bar(); // Includes 'classes/foo/bar.php'
* $baz = new Foo\Bar\Baz(); // Includes 'classes/foo/bar/baz.php'
*
*
* Multiple autoloaders can be registered at the same time:
*
*
* File structure:
* classes/
* | foo.php // Contains class 'Foo'
* other_classes/
* | bar.php // Contains class 'Bar'
*
* Autoloader::create('classes')->register();
* Autoloader::create('other_classes', true)->register();
* $foo = new Foo(); // Includes 'classes/foo.php'
* $bar = new Bar(); // Includes 'other_classes/bar.php', since 'classes/bar.php' does not exist
* $baz = new Baz(); // Throws a FileNotFoundError, since 'other_classes/baz.php' does not exist
*
*
* @package WebBasics
*/
class Autoloader extends Base {
/**
* The root directory to look in.
*
* @var string
*/
private $root_directory;
/**
* The namespace classes in the root directory are expected to be in.
*
* This namespace is removed from the beginning of loaded class names.
*
* @var string
*/
private $root_namespace = '\\';
/**
* Whether to throw an exception when a class file does not exist.
*
* @var bool
*/
private $throw_errors;
/**
* Create a new Autoloader instance.
*
* @param string $root_directory Root directory of the autoloader.
* @param string $root_namespace Root namespace of classes loaded by the autoloader.
* @param bool $throw Whether to throw an exception when a class file does not exist.
*/
function __construct($root_directory, $root_namespace='\\', $throw=false) {
$this->setRootDirectory($root_directory);
$this->setRootNamespace($root_namespace);
$this->setThrowErrors($throw);
}
/**
* Set whether to throw an exception when a class file does not exist.
*
* @param bool $throw Whether to throw exceptions.
*/
function setThrowErrors($throw) {
$this->throw_errors = !!$throw;
}
/**
* Whether an exception is thrown when a class file does not exist.
*
* @return bool
*/
function getThrowErrors() {
return $this->throw_errors;
}
/**
* Set the root directory from which classes are loaded.
*
* @param string $directory The new root directory.
*/
function setRootDirectory($directory) {
$this->root_directory = self::pathWithSlash($directory);
}
/**
* Get the root directory from which classes are loaded.
*
* @return string
*/
function getRootDirectory() {
return $this->root_directory;
}
/**
* Set the root namespace that loaded classes are expected to be in.
*
* @param string $namespace The new root namespace.
*/
function setRootNamespace($namespace) {
// Assert that the namespace ends with a backslash
if ($namespace[strlen($namespace) - 1] != '\\')
$namespace .= '\\';
$this->root_namespace = $namespace;
}
/**
* Get the root namespace that loaded classes are expected to be in.
*
* @return string
*/
function getRootNamespace() {
return $this->root_namespace;
}
/**
* Convert a class name to a file name.
*
* Uppercase letters are converted to lowercase and prepended
* by an underscore ('_').
*
* @param string $classname The class name to convert.
* @return string
*/
static function classnameToFilename($classname) {
return strtolower(preg_replace('/(?<=.)([A-Z])/', '_\\1', $classname));
}
/**
* Strip the root namespace from the beginning of a class name.
*
* @param string $classname The name of the class to strip the namespace from.
* @return string The stripped class name.
*/
private function stripRootNamespace($classname) {
$begin = substr($classname, 0, strlen($this->root_namespace));
if ($begin == $this->root_namespace)
$classname = substr($classname, strlen($this->root_namespace));
return $classname;
}
/**
* Create the path to a class file.
*
* Any namespace prepended to the class name is split on '\', the
* namespace levels are used to indicate directory names.
*
* @param string $classname The name of the class to create the file path of.
*/
function createPath($classname) {
$namespaces = array_filter(explode('\\', $classname));
$dirs = array_map('self::classnameToFilename', $namespaces);
$path = $this->root_directory;
if (count($dirs) > 1)
$path .= implode('/', array_slice($dirs, 0, count($dirs) - 1)).'/';
$path .= end($dirs).'.php';
return strtolower($path);
}
/**
* Load a class.
*
* Any namespace prepended to the class name is split on '\', the
* namespace levels are used to indicate directory names.
*
* @param string $classname The name of the class to load, including pepended namespace.
* @param bool $throw Whether to throw an exception if the class file does not exist.
* @return bool
* @throws FileNotFoundError If the class file does not exist.
*/
function loadClass($classname, $throw=null) {
$classname = $this->stripRootNamespace($classname);
$path = $this->createPath($classname);
if (!file_exists($path)) {
if ($throw || ($throw === null && $this->throw_errors))
throw new FileNotFoundError($path);
return false;
}
require_once $path;
return true;
}
/**
* Register the autoloader object to the SPL autoload stack.
*
* @param bool $prepend Whether to prepend the autoloader function to
* the stack, instead of appending it.
*/
function register($prepend=false) {
spl_autoload_register(array($this, 'loadClass'), true, $prepend);
}
}
?>