276 lines
7.9 KiB
PHP
276 lines
7.9 KiB
PHP
<?php
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/**
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* This file is part of RSS-Bridge, a PHP project capable of generating RSS and
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* Atom feeds for websites that don't have one.
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*
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* For the full license information, please view the UNLICENSE file distributed
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* with this source code.
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*
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* @package Core
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* @license http://unlicense.org/ UNLICENSE
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* @link https://github.com/rss-bridge/rss-bridge
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*/
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/**
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* Factory class responsible for creating bridge objects from a given working
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* directory, limited by a whitelist.
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*
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* This class is capable of:
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* - Locating bridge classes in the specified working directory (see {@see Bridge::$workingDir})
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* - Filtering bridges based on a whitelist (see {@see Bridge::$whitelist})
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* - Creating new bridge instances based on the bridge's name (see {@see Bridge::create()})
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*
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* The following example illustrates the intended use for this class.
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*
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* ```PHP
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* require_once __DIR__ . '/rssbridge.php';
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*
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* // Step 1: Set the working directory
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* Bridge::setWorkingDir(__DIR__ . '/../bridges/');
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*
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* // Step 2: Add bridges to the whitelist
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* Bridge::setWhitelist(array('GitHubIssue', 'GoogleSearch', 'Facebook', 'Twitter'));
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*
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* // Step 3: Create a new instance of a bridge (based on the name)
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* $bridge = Bridge::create('GitHubIssue');
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* ```
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*/
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class Bridge {
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/**
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* Holds a path to the working directory.
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*
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* Do not access this property directly!
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* Use {@see Bridge::setWorkingDir()} and {@see Bridge::getWorkingDir()} instead.
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*
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* @var string
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*/
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protected static $workingDir;
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/**
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* Holds a list of whitelisted bridges.
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*
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* Do not access this property directly!
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* Use {@see Bridge::getWhitelist()} instead.
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*
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* @var array
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*/
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private static $whitelist = array();
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/**
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* Throws an exception when trying to create a new instance of this class.
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* Use {@see Bridge::create()} to instanciate a new bridge from the working
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* directory.
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*
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* @throws \LogicException if called.
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*/
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public function __construct(){
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throw new \LogicException('Use ' . __CLASS__ . '::create($name) to create bridge objects!');
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}
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/**
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* Creates a new bridge object from the working directory.
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*
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* @throws \InvalidArgumentException if the requested bridge name is invalid.
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* @throws \Exception if the requested bridge doesn't exist in the working
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* directory.
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* @param string $nameBridge Name of the bridge object.
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* @return object|bool The bridge object or false if the class is not instantiable.
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*/
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public static function create($nameBridge){
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if(!preg_match('@^[A-Z][a-zA-Z0-9-]*$@', $nameBridge)) {
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throw new \InvalidArgumentException('Bridge name invalid!');
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}
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$nameBridge = self::sanitizeBridgeName($nameBridge) . 'Bridge';
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$pathBridge = self::getWorkingDir() . $nameBridge . '.php';
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if(!file_exists($pathBridge)) {
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throw new \Exception('Cache file ' . $pathBridge . ' does not exist!');
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}
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require_once $pathBridge;
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if((new \ReflectionClass($nameBridge))->isInstantiable()) {
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return new $nameBridge();
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}
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return false;
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}
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/**
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* Sets the working directory.
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*
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* @param string $dir Path to the directory containing bridges.
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* @throws \LogicException if the provided path is not a valid string.
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* @throws \Exception if the provided path does not exist.
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* @return void
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*/
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public static function setWorkingDir($dir){
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if(!is_string($dir)) {
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throw new \InvalidArgumentException('Working directory is not a valid string!');
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}
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if(!file_exists($dir)) {
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throw new \Exception('Working directory does not exist!');
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}
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self::$workingDir = $dir;
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}
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/**
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* Returns the working directory.
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* The working directory must be specified with {@see Bridge::setWorkingDir()}!
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*
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* @throws \LogicException if the working directory is not set.
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* @return string The current working directory.
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*/
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public static function getWorkingDir(){
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if(is_null(self::$workingDir)) {
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throw new \LogicException('Working directory is not set!');
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}
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return self::$workingDir;
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}
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/**
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* Returns the list of bridge names based on the working directory.
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*
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* The list is cached internally to allow for successive calls.
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*
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* @return array List of bridge names
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*/
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public static function listBridges(){
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static $listBridge = array(); // Initialized on first call
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if(empty($listBridge)) {
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$dirFiles = scandir(self::getWorkingDir());
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if($dirFiles !== false) {
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foreach($dirFiles as $fileName) {
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if(preg_match('@^([^.]+)Bridge\.php$@U', $fileName, $out)) {
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$listBridge[] = $out[1];
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}
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}
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}
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}
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return $listBridge;
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}
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/**
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* Checks if a bridge is whitelisted.
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*
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* @param string $name Name of the bridge.
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* @return bool True if the bridge is whitelisted.
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*/
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public static function isWhitelisted($name){
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return in_array(self::sanitizeBridgeName($name), self::getWhitelist());
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}
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/**
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* Returns the whitelist.
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*
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* On first call this function reads the whitelist from {@see WHITELIST}.
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* * Each line in the file specifies one bridge on the whitelist.
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* * An empty file disables all bridges.
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* * If the file only only contains `*`, all bridges are whitelisted.
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*
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* Use {@see Bridge::setWhitelist()} to specify a default whitelist **before**
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* calling this function! The list is cached internally to allow for
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* successive calls. If {@see Bridge::setWhitelist()} gets called after this
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* function, the whitelist is **not** updated again!
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*
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* @return array Array of whitelisted bridges
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*/
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public static function getWhitelist() {
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static $firstCall = true; // Initialized on first call
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if($firstCall) {
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// Create initial whitelist or load from disk
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if (!file_exists(WHITELIST) && !empty(self::$whitelist)) {
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file_put_contents(WHITELIST, implode("\n", self::$whitelist));
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} else {
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$contents = trim(file_get_contents(WHITELIST));
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if($contents === '*') { // Whitelist all bridges
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self::$whitelist = self::listBridges();
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} else {
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self::$whitelist = array_map('self::sanitizeBridgeName', explode("\n", $contents));
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}
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}
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}
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return self::$whitelist;
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}
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/**
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* Sets the (default) whitelist.
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*
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* If this function is called **before** {@see Bridge::getWhitelist()}, the
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* provided whitelist will be replaced by a custom whitelist specified in
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* {@see WHITELIST} (if it exists).
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*
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* If this function is called **after** {@see Bridge::getWhitelist()}, the
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* provided whitelist is taken as is (not updated by the custom whitelist
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* again).
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*
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* @param array $default The whitelist as array of bridge names.
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* @return void
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*/
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public static function setWhitelist($default = array()) {
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self::$whitelist = array_map('self::sanitizeBridgeName', $default);
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}
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/**
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* Returns the sanitized bridge name.
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*
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* The bridge name can be specified in various ways:
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* * The PHP file name (i.e. `GitHubIssueBridge.php`)
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* * The PHP file name without file extension (i.e. `GitHubIssueBridge`)
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* * The bridge name (i.e. `GitHubIssue`)
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*
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* Casing is ignored (i.e. `GITHUBISSUE` and `githubissue` are the same).
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*
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* A bridge file matching the given bridge name must exist in the working
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* directory!
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*
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* @param string $name The bridge name
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* @return string|null The sanitized bridge name if the provided name is
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* valid, null otherwise.
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*/
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private static function sanitizeBridgeName($name) {
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if(is_string($name)) {
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// Trim trailing '.php' if exists
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if(preg_match('/(.+)(?:\.php)/', $name, $matches)) {
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$name = $matches[1];
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}
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// Trim trailing 'Bridge' if exists
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if(preg_match('/(.+)(?:Bridge)/i', $name, $matches)) {
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$name = $matches[1];
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}
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// The name is valid if a corresponding bridge file is found on disk
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if(in_array(strtolower($name), array_map('strtolower', self::listBridges()))) {
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$index = array_search(strtolower($name), array_map('strtolower', self::listBridges()));
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return self::listBridges()[$index];
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}
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Debug::log('Invalid bridge name specified: "' . $name . '"!');
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}
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return null; // Bad parameter
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}
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}
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