109 lines
3.4 KiB
PHP
109 lines
3.4 KiB
PHP
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<?php
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// Autoloader.php
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// Created: 2021-05-04
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// Updated: 2021-05-12
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namespace Index;
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use InvalidArgumentException;
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/**
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* Provides a simple PSR-4 style autoloader.
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*
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* Only basic types should be used in this class because this is the first file included
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* and obviously can't autoload things before it has been set up.
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*/
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final class Autoloader {
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private const EXTENSION = '.php';
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private static array $namespaces = [];
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/**
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* Registers this autoloader with PHP.
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*/
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public static function register(): void {
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spl_autoload_register([self::class, 'autoloader']);
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}
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/**
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* Unregistered this autoloader with PHP.
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*/
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public static function unregister(): void {
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spl_autoload_unregister([self::class, 'autoloader']);
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}
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/**
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* Cleans a PHP class path for file system look up.
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*
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* @param string $name A PHP class path.
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* @return string A cleaned PHP class path.
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*/
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public static function cleanName(string $name): string {
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return trim($name, '\\');
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}
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/**
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* Tries to find a class in the registered namespaces directories.
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*
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* Only supports the .php extension, others are silly and only add overhead.
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*
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* @param string $className Target class path.
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*/
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public static function autoloader(string $className): void {
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$classPath = explode('\\', self::cleanName($className));
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for($i = 0; $i < count($classPath); ++$i) {
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$rootSpace = implode('\\', array_slice($classPath, 0, $i + 1));
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if(isset(self::$namespaces[$rootSpace])) {
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$path = self::$namespaces[$rootSpace]
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. DIRECTORY_SEPARATOR
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. implode(DIRECTORY_SEPARATOR, array_slice($classPath, $i + 1))
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. self::EXTENSION;
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if(is_file($path)) {
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require_once $path;
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return;
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}
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}
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}
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}
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/**
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* Registers a directory with a namespace. Projects making use of Index may use this.
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*
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* @param string $namespace Target namespace.
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* @param string $directory Directory containing the classes of this namespace.
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* @throws InvalidArgumentException if $namespace is an empty string.
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* @throws InvalidArgumentException if $directory is a non-existent directory.
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* @throws InvalidArgumentException if $namespace is already registered.
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*/
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public static function addNamespace(string $namespace, string $directory): void {
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if(empty($namespace))
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throw new InvalidArgumentException('$namespace may not be an empty string.');
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if(!is_dir($directory))
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throw new InvalidArgumentException('$directory must point to an existing directory.');
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$namespace = self::cleanName($namespace);
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$directory = rtrim(realpath($directory), DIRECTORY_SEPARATOR);
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if(isset(self::$namespaces[$namespace]))
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throw new InvalidArgumentException("{$namespace} is already a registered namespace.");
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self::$namespaces[$namespace] = $directory;
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}
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/**
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* Removes a registered namespace.
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*
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* Attempts to unregister Index are ignored.
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*
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* @param string $namespace Namespace to be removed.
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*/
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public static function removeNamespace(string $namespace): void {
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$namespace = self::cleanName($namespace);
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if($namespace !== 'Index')
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unset(self::$namespaces[$namespace]);
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}
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}
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