Implement support for twig macro/import

Fixes #2526

modules/cms/twig/Loader.php

@@ -3,6 +3,8 @@
 use Event;
 use Twig_LoaderInterface;
 use Cms\Contracts\CmsObject;
+use System\Twig\Loader as LoaderBase;
+use Cms\Classes\Partial as CmsPartial;
 
 /**
  * This class implements a Twig template loader for the CMS.
@@ -10,13 +12,18 @@ use Cms\Contracts\CmsObject;
  * @package october\cms
  * @author Alexey Bobkov, Samuel Georges
  */
-class Loader implements Twig_LoaderInterface
+class Loader extends LoaderBase implements Twig_LoaderInterface
 {
     /**
      * @var \Cms\Classes\CmsCompoundObject A CMS object to load the template from.
      */
     protected $obj;
 
+    /**
+     * @var array Cache
+     */
+    protected $fallbackCache = [];
+
     /**
      * Sets a CMS object to load the template from.
      * @param \Cms\Contracts\CmsObject $obj Specifies the CMS object.
@@ -32,6 +39,10 @@ class Loader implements Twig_LoaderInterface
      */
     public function getSource($name)
     {
+        if (!$this->validateCmsObject($name)) {
+            return parent::getSource($name);
+        }
+
         $content = $this->obj->getTwigContent();
 
         /*
@@ -49,6 +60,10 @@ class Loader implements Twig_LoaderInterface
      */
     public function getCacheKey($name)
     {
+        if (!$this->validateCmsObject($name)) {
+            return parent::getCacheKey($name);
+        }
+
         return $this->obj->getTwigCacheKey();
     }
 
@@ -57,6 +72,71 @@ class Loader implements Twig_LoaderInterface
      */
     public function isFresh($name, $time)
     {
+        if (!$this->validateCmsObject($name)) {
+            return parent::isFresh($name, $time);
+        }
+
         return $this->obj->mtime <= $time;
     }
+
+    /**
+     * Returns the file name of the loaded template.
+     */
+    public function getFilename($name)
+    {
+        if (!$this->validateCmsObject($name)) {
+            return parent::getFilename($name);
+        }
+
+        return $this->obj->getFilePath();
+    }
+
+    /**
+     * Checks that the template exists.
+     */
+    public function exists($name)
+    {
+        if (!$this->validateCmsObject($name)) {
+            return parent::exists($name);
+        }
+
+        return $this->obj->exists;
+    }
+
+    /**
+     * Internal method that checks if the template name matches
+     * the loaded object, with fallback support to partials.
+     *
+     * @return bool
+     */
+    protected function validateCmsObject($name)
+    {
+        if ($name == $this->obj->getFilePath()) {
+            return true;
+        }
+
+        if ($fallbackObj = $this->findFallbackObject($name)) {
+            $this->obj = $fallbackObj;
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * Looks up a fallback CMS partial object.
+     * @return Cms\Classes\Partial
+     */
+    protected function findFallbackObject($name)
+    {
+        if (strpos($name, '::') !== false) {
+            return false;
+        }
+
+        if (array_key_exists($name, $this->fallbackCache)) {
+            return $this->fallbackCache[$name];
+        }
+
+        return $this->fallbackCache[$name] = CmsPartial::find($name);
+    }
 }