Improve performance when working with large numbers of resources

src/Document.php

@@ -66,6 +66,10 @@ protected function getIncluded(ElementInterface $element, $includeParent = false
         $included = [];
 
         foreach ($element->getResources() as $resource) {
+            if ($resource->isIdentifier()) {
+                continue;
+            }
+
             if ($includeParent) {
                 $included = $this->mergeResource($included, $resource);
             }
@@ -79,7 +83,13 @@ protected function getIncluded(ElementInterface $element, $includeParent = false
             }
         }
 
-        return $included;
+        $flattened = [];
+
+        array_walk_recursive($included, function($a) use (&$flattened) {
+            $flattened[] = $a;
+        });
+
+        return $flattened;
     }
 
     /**
@@ -92,16 +102,12 @@ protected function mergeResource(array $resources, Resource $newResource)
         $type = $newResource->getType();
         $id = $newResource->getId();
 
-        foreach ($resources as $resource) {
-            if ($resource->getType() === $type && $resource->getId() === $id) {
-                $resource->merge($newResource);
-
-                return $resources;
-            }
+        if (isset($resources[$type][$id])) {
+            $resources[$type][$id]->merge($newResource);
+        } else {
+            $resources[$type][$id] = $newResource;
         }
 
-        $resources[] = $newResource;
-
         return $resources;
     }
 

src/Resource.php

@@ -87,6 +87,17 @@ public function toArray()
         return $array;
     }
 
+    /**
+     * Check whether or not this resource is an identifier (i.e. does it have
+     * any data attached?)
+     *
+     * @return bool
+     */
+    public function isIdentifier()
+    {
+        return ! is_object($this->data) && ! is_array($this->data);
+    }
+
     /**
      * {@inheritdoc}
      */