1 files changed, 51 insertions, 0 deletions
diff --git a/lib/private/AppFramework/Bootstrap/FunctionInjector.php b/lib/private/AppFramework/Bootstrap/FunctionInjector.php
new file mode 100644
index 00000000000..973fc13aa2c
--- /dev/null
+++ b/lib/private/AppFramework/Bootstrap/FunctionInjector.php
@@ -0,0 +1,51 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2020 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OC\AppFramework\Bootstrap;
+
+use Closure;
+use OCP\AppFramework\QueryException;
+use Psr\Container\ContainerInterface;
+use ReflectionFunction;
+use ReflectionParameter;
+use function array_map;
+
+class FunctionInjector {
+	/** @var ContainerInterface */
+	private $container;
+
+	public function __construct(ContainerInterface $container) {
+		$this->container = $container;
+	}
+
+	public function injectFn(callable $fn) {
+		$reflected = new ReflectionFunction(Closure::fromCallable($fn));
+		return $fn(...array_map(function (ReflectionParameter $param) {
+			// First we try by type (more likely these days)
+			if (($type = $param->getType()) !== null) {
+				try {
+					return $this->container->get($type->getName());
+				} catch (QueryException $ex) {
+					// Ignore and try name as well
+				}
+			}
+			// Second we try by name (mostly for primitives)
+			try {
+				return $this->container->get($param->getName());
+			} catch (QueryException $ex) {
+				// As a last resort we pass `null` if allowed
+				if ($type !== null && $type->allowsNull()) {
+					return null;
+				}
+
+				// Nothing worked, time to bail out
+				throw $ex;
+			}
+		}, $reflected->getParameters()));
+	}
+}