squash/revert: fix memory merging

include/yaml-cpp/node/detail/memory.h

@@ -35,7 +35,25 @@ class YAML_CPP_API memory : public ref_counted {
   Nodes m_nodes;
 };
 
-typedef ref_holder<memory> shared_memory;
+struct memory_ref : ref_counted {
+
+  ref_holder<memory> m_ptr;
+
+  memory_ref() : m_ptr(new memory) {}
+  ~memory_ref() {}
+
+  node& create_node() { return m_ptr->create_node(); }
+
+  void merge(memory_ref& rhs) {
+    if (m_ptr == rhs.m_ptr) {
+       return;
+    }
+    m_ptr->merge(*rhs.m_ptr);
+    rhs.m_ptr = m_ptr;
+  };
+};
+
+typedef ref_holder<memory_ref> shared_memory;
 
 }
 }

include/yaml-cpp/node/impl.h

@@ -15,17 +15,17 @@
 #include <string>
 
 namespace YAML {
-inline Node::Node() : m_pMemory(new detail::memory), m_pNode(NULL) {}
+inline Node::Node() : m_pMemory(new detail::memory_ref), m_pNode(NULL) {}
 
 inline Node::Node(NodeType::value type)
-    : m_pMemory(new detail::memory),
+    : m_pMemory(new detail::memory_ref),
       m_pNode(&(m_pMemory->create_node())) {
   m_pNode->set_type(type);
 }
 
 template <typename T>
 inline Node::Node(const T& rhs)
-    : m_pMemory(new detail::memory),
+    : m_pMemory(new detail::memory_ref),
       m_pNode(&(m_pMemory->create_node())) {
   Assign(rhs);
 }
@@ -52,7 +52,7 @@ inline void Node::EnsureNodeExists() const {
   if (!isValid())
     throw InvalidNode();
   if (!m_pNode) {
-    m_pMemory.reset(new detail::memory);
+    m_pMemory.reset(new detail::memory_ref);
     m_pNode = &m_pMemory->create_node();
     m_pNode->set_null();
   }

src/nodebuilder.cpp

@@ -11,7 +11,7 @@ namespace YAML {
 struct Mark;
 
 NodeBuilder::NodeBuilder()
-    : m_pMemory(new detail::memory), m_pRoot(0), m_mapDepth(0) {
+    : m_pMemory(new detail::memory_ref), m_pRoot(0), m_mapDepth(0) {
   m_anchors.push_back(0);  // since the anchors start at 1
 }