genesys: Simplify access to nodes that are newly added to image pipeline

backend/genesys/image_pipeline.h

@@ -556,32 +556,22 @@ public:
     void clear();
 
     template<class Node, class... Args>
-    void push_first_node(Args&&... args)
-    {
-        push_first_node(std::unique_ptr<Node>(new Node(std::forward<Args>(args)...)));
-    }
-
-    template<class Node>
-    void push_first_node(std::unique_ptr<Node>&& node)
+    Node& push_first_node(Args&&... args)
     {
         if (!nodes_.empty()) {
             throw SaneException("Trying to append first node when there are existing nodes");
         }
-        nodes_.emplace_back(std::move(node));
+        nodes_.emplace_back(std::unique_ptr<Node>(new Node(std::forward<Args>(args)...)));
+        return static_cast<Node&>(*nodes_.back());
     }
 
     template<class Node, class... Args>
-    void push_node(Args&&... args)
+    Node& push_node(Args&&... args)
     {
         ensure_node_exists();
-        push_node(std::unique_ptr<Node>(new Node(*nodes_.back(), std::forward<Args>(args)...)));
-    }
-
-    template<class Node, class... Args>
-    void push_node(std::unique_ptr<Node>&& node)
-    {
-        ensure_node_exists();
-        nodes_.emplace_back(std::move(node));
+        nodes_.emplace_back(std::unique_ptr<Node>(new Node(*nodes_.back(),
+                                                           std::forward<Args>(args)...)));
+        return static_cast<Node&>(*nodes_.back());
     }
 
     bool get_next_row_data(std::uint8_t* out_data)

backend/genesys/low.cpp

@@ -915,11 +915,9 @@ ImagePipelineStack build_image_pipeline(const Genesys_Device& dev, const ScanSes
     // certain circumstances.
     buffer_size = align_multiple_ceil(buffer_size, 2);
 
-    auto node = std::unique_ptr<ImagePipelineNodeBufferedCallableSource>(
-                new ImagePipelineNodeBufferedCallableSource(
-                    width, lines, format, buffer_size, read_data_from_usb));
-    node->set_last_read_multiple(2);
-    pipeline.push_first_node(std::move(node));
+    auto& src_node = pipeline.push_first_node<ImagePipelineNodeBufferedCallableSource>(
+                          width, lines, format, buffer_size, read_data_from_usb);
+    src_node.set_last_read_multiple(2);
 
     if (log_image_data) {
         pipeline.push_node<ImagePipelineNodeDebug>(debug_prefix + "_0_from_usb.tiff");