lib: Add API documentation

lib/CacheInterface.php

@@ -1,7 +1,51 @@
 <?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
+ */
+
+/**
+ * The cache interface
+ *
+ * @todo Add missing function to the interface
+ * @todo Explain parameters and return values in more detail
+ * @todo Return self more often (to allow call chaining)
+ */
 interface CacheInterface {
+
+	/**
+	 * Loads data from cache
+	 *
+	 * @return mixed The cache data
+	 */
 	public function loadData();
+
+	/**
+	 * Stores data to the cache
+	 *
+	 * @param mixed $datas The data to store
+	 * @return self The cache object
+	 */
 	public function saveData($datas);
+
+	/**
+	 * Returns the timestamp for the curent cache file
+	 *
+	 * @return int Timestamp
+	 */
 	public function getTime();
+
+	/**
+	 * Removes any data that is older than the specified duration from cache
+	 *
+	 * @param int $duration The cache duration in seconds
+	 */
 	public function purgeCache($duration);
 }