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lib/pkp/classes/db/DAORegistry.php

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+<?php
+
+/**
+ * @file classes/db/DAORegistry.php
+ *
+ * Copyright (c) 2014-2021 Simon Fraser University
+ * Copyright (c) 2000-2021 John Willinsky
+ * Distributed under the GNU GPL v3. For full terms see the file docs/COPYING.
+ *
+ * @class DAORegistry
+ *
+ * @ingroup db
+ *
+ * @see DAO
+ *
+ * @brief Maintains a static list of DAO objects so each DAO is instantiated only once.
+ */
+
+namespace PKP\db;
+
+use APP\core\Application;
+use PKP\core\Registry;
+
+class DAORegistry
+{
+    /**
+     * Get the current list of registered DAOs.
+     * This returns a reference to the static hash used to
+     * store all DAOs currently instantiated by the system.
+     *
+     * @return array
+     */
+    public static function &getDAOs()
+    {
+        $daos = & Registry::get('daos', true, []);
+        return $daos;
+    }
+
+    /**
+     * Register a new DAO with the system.
+     *
+     * @param string $name The name of the DAO to register
+     * @param object $dao A reference to the DAO to be registered
+     *
+     * @return object A reference to previously-registered DAO of the same
+     *    name, if one was already registered; null otherwise
+     */
+    public static function registerDAO($name, $dao)
+    {
+        $daos = & DAORegistry::getDAOs();
+
+        $returner = null;
+
+        if (isset($daos[$name])) {
+            $returner = $daos[$name];
+        }
+
+        $daos[$name] = $dao;
+        return $returner;
+    }
+
+    /**
+     * Retrieve a reference to the specified DAO.
+     *
+     * @param string $name the class name of the requested DAO
+     *
+     * @return DAO
+     */
+    public static function &getDAO($name)
+    {
+        $daos = & DAORegistry::getDAOs();
+        if (!isset($daos[$name])) {
+            // Import the required DAO class.
+            $application = Application::get();
+            $className = $application->getQualifiedDAOName($name);
+            if (!$className) {
+                throw new \Exception('Unrecognized DAO ' . $name . '!');
+            }
+
+            // Only instantiate each class of DAO a single time
+            $daos[$name] = new $className();
+        }
+
+        return $daos[$name];
+    }
+}
+
+if (!PKP_STRICT_MODE) {
+    class_alias('\PKP\db\DAORegistry', '\DAORegistry');
+}