Stack partials, store components, unstack partials - Fixes #1373

Fixes instances where nested repeating partials are destroying the partial component stack and causing breaking errors.
Nesting example:

Partial (with components)
^-> Calls component default markup
^-> Refers to partial override (with repeating partial calls)
^-> Calls another partial (with components)
^-> Components not found (destroyed by repeating calls above)

modules/cms/classes/Controller.php

@@ -111,7 +111,7 @@ class Controller
     /**
      * @var array Component partial stack, used internally.
      */
-    protected $partialComponentStack = [];
+    protected $partialStack = [];
 
     /**
      * Creates the controller.
@@ -127,6 +127,7 @@ class Controller
 
         $this->assetPath = Config::get('cms.themesPath', '/themes').'/'.$this->theme->getDirName();
         $this->router = new Router($this->theme);
+        $this->partialStack = new PartialStack;
         $this->initTwigEnvironment();
 
         self::$instance = $this;
@@ -847,6 +848,8 @@ class Controller
          */
 
         if ($partial instanceof Partial) {
+            $this->partialStack->stackPartial();
+
             $manager = ComponentManager::instance();
 
             foreach ($partial->settings['components'] as $component => $properties) {
@@ -868,10 +871,7 @@ class Controller
                 $componentObj->alias = $alias;
                 $parameters[$alias] = $partial->components[$alias] = $componentObj;
 
-                array_push($this->partialComponentStack, [
-                    'name' => $alias,
-                    'obj' => $componentObj
-                ]);
+                $this->partialStack->addComponent($alias, $componentObj);
 
                 $this->setComponentPropertiesFromParams($componentObj, $parameters);
                 $componentObj->init();
@@ -890,7 +890,7 @@ class Controller
         }
 
         /*
-         * Render the parital
+         * Render the partial
          */
         CmsException::mask($partial, 400);
         $this->loader->setObject($partial);
@@ -899,9 +899,7 @@ class Controller
         CmsException::unmask();
 
         if ($partial instanceof Partial) {
-            if ($this->partialComponentStack) {
-                array_pop($this->partialComponentStack);
-            }
+            $this->partialStack->unstackPartial();
         }
 
         $this->vars = $vars;
@@ -1224,10 +1222,9 @@ class Controller
             return $this->layout->components[$name];
         }
 
-        foreach ($this->partialComponentStack as $componentInfo) {
-            if ($componentInfo['name'] == $name) {
-                return $componentInfo['obj'];
-            }
+        $partialComponent = $this->partialStack->getComponent($name);
+        if ($partialComponent !== null) {
+            return $partialComponent;
         }
 
         return null;

modules/cms/classes/PartialStack.php

@@ -0,0 +1,89 @@
+<?php namespace Cms\Classes;
+
+/**
+ * Manager class for stacking nested partials and keeping track
+ * of their components. Partial "objects" store the components
+ * used by that partial for deferred retrieval.
+ *
+ * @package october\cms
+ * @author Alexey Bobkov, Samuel Georges
+ */
+class PartialStack
+{
+    /**
+     * @var array The current partial "object" being rendered.
+     */
+    public $activePartial = null;
+
+    /**
+     * @var array Collection of previously rendered partial "objects".
+     */
+    protected $partialStack = [];
+
+    /**
+     * Partial entry point, appends a new partial to the stack.
+     */
+    public function stackPartial()
+    {
+        if ($this->activePartial !== null) {
+            array_unshift($this->partialStack, $this->activePartial);
+        }
+
+        $this->activePartial = [
+            'components' => []
+        ];
+    }
+
+    /**
+     * Partial exit point, removes the active partial from the stack.
+     */
+    public function unstackPartial()
+    {
+        $this->activePartial = array_shift($this->partialStack);
+    }
+
+    /**
+     * Adds a component to the active partial stack.
+     */
+    public function addComponent($alias, $componentObj)
+    {
+        array_push($this->activePartial['components'], [
+            'name' => $alias,
+            'obj' => $componentObj
+        ]);
+    }
+
+    /**
+     * Returns a component by its alias from the partial stack.
+     */
+    public function getComponent($name)
+    {
+        $component = $this->findComponentFromStack($name, $this->activePartial);
+        if ($component !== null) {
+            return $component;
+        }
+
+        foreach ($this->partialStack as $stack) {
+            $component = $this->findComponentFromStack($name, $stack);
+            if ($component !== null) {
+                return $component;
+            }
+        }
+
+        return null;
+    }
+
+    /**
+     * Locates a component by its alias from the supplied stack.
+     */
+    protected function findComponentFromStack($name, $stack)
+    {
+        foreach ($stack['components'] as $componentInfo) {
+            if ($componentInfo['name'] == $name) {
+                return $componentInfo['obj'];
+            }
+        }
+
+        return null;
+    }
+}