API Implement kernel nesting

src/Control/Director.php

@@ -188,7 +188,6 @@ public static function test(
         $cookies = array(),
         &$request = null
     ) {
-
         Config::nest();
         Injector::nest();
 

src/Core/AppKernel.php

@@ -13,6 +13,7 @@
 use SilverStripe\Core\Config\ConfigLoader;
 use SilverStripe\Core\Config\CoreConfigFactory;
 use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Core\Injector\InjectorLoader;
 use SilverStripe\Core\Injector\SilverStripeServiceConfigurationLocator;
 use SilverStripe\Core\Manifest\ClassLoader;
 use SilverStripe\Core\Manifest\ClassManifest;
@@ -38,9 +39,10 @@ public function __construct($flush = false)
 
         // Initialise the dependency injector as soon as possible, as it is
         // subsequently used by some of the following code
+        $injectorLoader = InjectorLoader::inst();
         $injector = new Injector(array('locator' => SilverStripeServiceConfigurationLocator::class));
-        $this->setContainer($injector);
-        Injector::set_inst($injector);
+        $injectorLoader->pushManifest($injector);
+        $this->setInjectorLoader($injectorLoader);
 
         // Manifest cache factory
         $manifestCacheFactory = $this->buildManifestCacheFactory();

src/Core/Config/Config.php

@@ -87,7 +87,7 @@ public static function unnest()
     {
         // Unnest unless we would be left at 0 manifests
         $loader = ConfigLoader::inst();
-        if ($loader->countManifests() < 2) {
+        if ($loader->countManifests() <= 1) {
             user_error(
                 "Unable to unnest root Config, please make sure you don't have mis-matched nest/unnest",
                 E_USER_WARNING

src/Core/Config/ConfigLoader.php

@@ -82,14 +82,31 @@ public function countManifests()
     }
 
     /**
-     * Nest the current manifest
+     * Nest the config loader and activates it
      *
-     * @return ConfigCollectionInterface
+     * @return static
      */
     public function nest()
     {
-        $manifest = $this->getManifest()->nest();
-        $this->pushManifest($manifest);
-        return $manifest;
+        // Nest config
+        $manifest = clone $this->getManifest();
+
+        // Create new blank loader with new stack (top level nesting)
+        $newLoader = new self;
+        $newLoader->pushManifest($manifest);
+
+        // Activate new loader
+        return $newLoader->activate();
+    }
+
+    /**
+     * Mark this instance as the current instance
+     *
+     * @return $this
+     */
+    public function activate()
+    {
+        static::$instance = $this;
+        return $this;
     }
 }

src/Core/CoreKernel.php

@@ -5,6 +5,7 @@
 use InvalidArgumentException;
 use SilverStripe\Core\Config\ConfigLoader;
 use SilverStripe\Core\Injector\Injector;
+use SilverStripe\Core\Injector\InjectorLoader;
 use SilverStripe\Core\Manifest\ClassLoader;
 use SilverStripe\Core\Manifest\ModuleLoader;
 use SilverStripe\View\ThemeResourceLoader;
@@ -14,6 +15,11 @@
  */
 class CoreKernel implements Kernel
 {
+    /**
+     * @var Kernel
+     */
+    protected $nestedFrom = null;
+
     /**
      * @var Injector
      */
@@ -39,6 +45,11 @@ class CoreKernel implements Kernel
      */
     protected $configLoader = null;
 
+    /**
+     * @var InjectorLoader
+     */
+    protected $injectorLoader = null;
+
     /**
      * @var ThemeResourceLoader
      */
@@ -54,21 +65,44 @@ public function shutdown()
 
     public function nest()
     {
-        // TODO: Implement nest() method.
+        // Clone this kernel, nesting config / injector manifest containers
+        $kernel = clone $this;
+        $kernel->setConfigLoader($this->configLoader->nest());
+        $kernel->setInjectorLoader($this->injectorLoader->nest());
+        return $kernel;
+    }
+
+    public function activate()
+    {
+        $this->configLoader->activate();
+        $this->injectorLoader->activate();
+        return $this;
+    }
+
+    public function getNestedFrom()
+    {
+        return $this->nestedFrom;
     }
 
     public function getContainer()
     {
-        return $this->container;
+        return $this->getInjectorLoader()->getManifest();
     }
 
-    public function setContainer(Injector $container)
+    public function setInjectorLoader(InjectorLoader $injectorLoader)
     {
-        $this->container = $container;
-        $container->registerService($this, Kernel::class);
+        $this->injectorLoader = $injectorLoader;
+        $injectorLoader
+            ->getManifest()
+            ->registerService($this, Kernel::class);
         return $this;
     }
 
+    public function getInjectorLoader()
+    {
+        return $this->injectorLoader;
+    }
+
     public function getClassLoader()
     {
         return $this->classLoader;

src/Core/HTTPApplication.php

@@ -106,10 +106,14 @@ public function handle(HTTPRequest $request)
      */
     public function execute(callable $callback)
     {
-        return $this->callMiddleware(function () use ($callback) {
-            // Pre-request boot
-            $this->getKernel()->boot();
-            return call_user_func($callback);
-        });
+        try {
+            return $this->callMiddleware(function () use ($callback) {
+                // Pre-request boot
+                $this->getKernel()->boot();
+                return call_user_func($callback);
+            });
+        } finally {
+            $this->getKernel()->shutdown();
+        }
     }
 }

src/Core/Injector/Injector.php

@@ -236,18 +236,7 @@ public function __construct($config = null)
      */
     public static function inst()
     {
-        return self::$instance;
-    }
-
-    /**
-     * Sets the default global injector instance.
-     *
-     * @param Injector $instance
-     * @return Injector Reference to new active Injector instance
-     */
-    public static function set_inst(Injector $instance)
-    {
-        return self::$instance = $instance;
+        return InjectorLoader::inst()->getManifest();
     }
 
     /**
@@ -262,11 +251,10 @@ public static function set_inst(Injector $instance)
      */
     public static function nest()
     {
-        $current = self::$instance;
-
-        $new = clone $current;
-        $new->nestedFrom = $current;
-        return self::set_inst($new);
+        // Clone current injector and nest
+        $new = clone self::inst();
+        InjectorLoader::inst()->pushManifest($new);
+        return $new;
     }
 
     /**
@@ -277,15 +265,17 @@ public static function nest()
      */
     public static function unnest()
     {
-        if (self::inst()->nestedFrom) {
-            self::set_inst(self::inst()->nestedFrom);
-        } else {
+        // Unnest unless we would be left at 0 manifests
+        $loader = InjectorLoader::inst();
+        if ($loader->countManifests() <= 1) {
             user_error(
                 "Unable to unnest root Injector, please make sure you don't have mis-matched nest/unnest",
                 E_USER_WARNING
             );
+        } else {
+            $loader->popManifest();
         }
-        return self::inst();
+        return static::inst();
     }
 
     /**

src/Core/Injector/InjectorLoader.php

@@ -0,0 +1,109 @@
+<?php
+
+namespace SilverStripe\Core\Injector;
+
+use BadMethodCallException;
+
+/**
+ * Registers chained injectors
+ */
+class InjectorLoader
+{
+    /**
+     * @internal
+     * @var self
+     */
+    private static $instance;
+
+    /**
+     * @var Injector[] map of injector instances
+     */
+    protected $manifests = array();
+
+    /**
+     * @return self
+     */
+    public static function inst()
+    {
+        return self::$instance ? self::$instance : self::$instance = new self();
+    }
+
+    /**
+     * Returns the currently active class manifest instance that is used for
+     * loading classes.
+     *
+     * @return Injector
+     */
+    public function getManifest()
+    {
+        if (empty($this->manifests)) {
+            throw new BadMethodCallException("No injector manifests available");
+        }
+        return $this->manifests[count($this->manifests) - 1];
+    }
+
+    /**
+     * Returns true if this class loader has a manifest.
+     *
+     * @return bool
+     */
+    public function hasManifest()
+    {
+        return (bool)$this->manifests;
+    }
+
+    /**
+     * Pushes a class manifest instance onto the top of the stack.
+     *
+     * @param Injector $manifest
+     */
+    public function pushManifest(Injector $manifest)
+    {
+        $this->manifests[] = $manifest;
+    }
+
+    /**
+     * @return Injector
+     */
+    public function popManifest()
+    {
+        return array_pop($this->manifests);
+    }
+
+    /**
+     * Check number of manifests
+     *
+     * @return int
+     */
+    public function countManifests()
+    {
+        return count($this->manifests);
+    }
+
+    /**
+     * Nest the config loader
+     *
+     * @return static
+     */
+    public function nest()
+    {
+        // Nest config
+        $manifest = $this->getManifest()->nest();
+
+        // Create new blank loader with new stack (top level nesting)
+        $newLoader = new self;
+        $newLoader->pushManifest($manifest);
+
+        // Activate new loader
+        $newLoader->activate();
+        return $newLoader;
+    }
+
+    /**
+     * Mark this instance as the current instance
+     */
+    public function activate()
+    {
+        static::$instance = $this;
+    }
+}