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<?php
/**
* This file is part of RSS-Bridge, a PHP project capable of generating RSS and
* Atom feeds for websites that don't have one.
*
* For the full license information, please view the UNLICENSE file distributed
* with this source code.
*
* @package Core
* @license http://unlicense.org/ UNLICENSE
* @link https://github.com/rss-bridge/rss-bridge
*/
/**
* Factory class responsible for creating cache objects from a given working
* directory.
*
* This class is capable of:
* - Locating cache classes in the specified working directory (see {@see Cache::$workingDir})
* - Creating new cache instances based on the cache's name (see {@see Cache::create()})
*
* The following example illustrates the intended use for this class.
*
* ```PHP
* require_once __DIR__ . '/rssbridge.php';
*
* // Step 1: Set the working directory
* Cache::setWorkingDir(__DIR__ . '/../caches/');
*
* // Step 2: Create a new instance of a cache object (based on the name)
* $cache = Cache::create('FileCache');
* ```
*/
class Cache {
/**
* Holds a path to the working directory.
*
* Do not access this property directly!
* Use {@see Cache::setWorkingDir()} and {@see Cache::getWorkingDir()} instead.
*
* @var string|null
*/
protected static $workingDir = null;
/**
* Throws an exception when trying to create a new instance of this class.
* Use {@see Cache::create()} to create a new cache object from the working
* directory.
*
* @throws \LogicException if called.
*/
public function __construct(){
throw new \LogicException('Use ' . __CLASS__ . '::create($name) to create cache objects!');
}
/**
* Creates a new cache object from the working directory.
*
* @throws \InvalidArgumentException if the requested cache name is invalid.
* @throws \Exception if the requested cache file doesn't exist in the
* working directory.
* @param string $name Name of the cache object.
* @return object|bool The cache object or false if the class is not instantiable.
*/
public static function create($name){
$name = self::sanitizeCacheName($name) . 'Cache';
if(!self::isCacheName($name)) {
throw new \InvalidArgumentException('Cache name invalid!');
}
$filePath = self::getWorkingDir() . $name . '.php';
if(!file_exists($filePath)) {
throw new \Exception('Cache file ' . $filePath . ' does not exist!');
}
require_once $filePath;
if((new \ReflectionClass($name))->isInstantiable()) {
return new $name();
}
return false;
}
/**
* Sets the working directory.
*
* @param string $dir Path to a directory containing cache classes
* @throws \InvalidArgumentException if $dir is not a string.
* @throws \Exception if the working directory doesn't exist.
* @throws \InvalidArgumentException if $dir is not a directory.
* @return void
*/
public static function setWorkingDir($dir){
self::$workingDir = null;
if(!is_string($dir)) {
throw new \InvalidArgumentException('Working directory is not a valid string!');
}
if(!file_exists($dir)) {
throw new \Exception('Working directory does not exist!');
}
if(!is_dir($dir)) {
throw new \InvalidArgumentException('Working directory is not a directory!');
}
self::$workingDir = realpath($dir) . '/';
}
/**
* Returns the working directory.
* The working directory must be set with {@see Cache::setWorkingDir()}!
*
* @throws \LogicException if the working directory is not set.
* @return string The current working directory.
*/
public static function getWorkingDir(){
if(is_null(self::$workingDir)) {
throw new \LogicException('Working directory is not set!');
}
return self::$workingDir;
}
/**
* Returns true if the provided name is a valid cache name.
*
* A valid cache name starts with a capital letter ([A-Z]), followed by
* zero or more alphanumeric characters or hyphen ([A-Za-z0-9-]).
*
* @param string $name The cache name.
* @return bool true if the name is a valid cache name, false otherwise.
*/
public static function isCacheName($name){
return is_string($name) && preg_match('/^[A-Z][a-zA-Z0-9-]*$/', $name) === 1;
}
/**
* Returns a list of cache names from the working directory.
*
* The list is cached internally to allow for successive calls.
*
* @return array List of cache names
*/
public static function getCacheNames(){
static $cacheNames = array(); // Initialized on first call
if(empty($cacheNames)) {
$files = scandir(self::getWorkingDir());
if($files !== false) {
foreach($files as $file) {
if(preg_match('/^([^.]+)Cache\.php$/U', $file, $out)) {
$cacheNames[] = $out[1];
}
}
}
}
return $cacheNames;
}
/**
* Returns the sanitized cache name.
*
* The cache name can be specified in various ways:
* * The PHP file name (i.e. `FileCache.php`)
* * The PHP file name without file extension (i.e. `FileCache`)
* * The cache name (i.e. `file`)
*
* Casing is ignored (i.e. `FILE` and `fIlE` are the same).
*
* A cache file matching the given cache name must exist in the working
* directory!
*
* @param string $name The cache name
* @return string|null The sanitized cache name if the provided name is
* valid, null otherwise.
*/
protected static function sanitizeCacheName($name) {
if(is_string($name)) {
// Trim trailing '.php' if exists
if(preg_match('/(.+)(?:\.php)/', $name, $matches)) {
$name = $matches[1];
}
// Trim trailing 'Cache' if exists
if(preg_match('/(.+)(?:Cache)$/i', $name, $matches)) {
$name = $matches[1];
}
// The name is valid if a corresponding file is found on disk
if(in_array(strtolower($name), array_map('strtolower', self::getCacheNames()))) {
$index = array_search(strtolower($name), array_map('strtolower', self::getCacheNames()));
return self::getCacheNames()[$index];
}
Debug::log('Invalid cache name specified: "' . $name . '"!');
}
return null; // Bad parameter
}
}
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