Fixed crash when emitting empty node

src/nodeevents.cpp

@@ -19,9 +19,10 @@ namespace YAML
 		return it->second;
 	}
 
-	NodeEvents::NodeEvents(const Node& node): m_pMemory(node.m_pMemory), m_root(*node.m_pNode)
+	NodeEvents::NodeEvents(const Node& node): m_pMemory(node.m_pMemory), m_root(node.m_pNode)
 	{
-		Setup(m_root);
+        if(m_root)
+            Setup(*m_root);
 	}
 
 	void NodeEvents::Setup(const detail::node& node)
@@ -47,7 +48,8 @@ namespace YAML
 		AliasManager am;
 		
 		handler.OnDocumentStart(Mark());
-		Emit(m_root, handler, am);
+        if(m_root)
+            Emit(*m_root, handler, am);
 		handler.OnDocumentEnd();
 	}
 

src/nodeevents.h

@@ -46,7 +46,7 @@ namespace YAML
 		
 	private:
 		detail::shared_memory_holder m_pMemory;
-		detail::node& m_root;
+		detail::node* m_root;
 		
 		typedef std::map<const detail::node_ref *, int> RefCount;
 		RefCount m_refCount;

src/ostream_wrapper.cpp

@@ -4,7 +4,7 @@
 
 namespace YAML
 {
-	ostream_wrapper::ostream_wrapper(): m_pStream(0), m_pos(0), m_row(0), m_col(0), m_comment(false)
+	ostream_wrapper::ostream_wrapper(): m_buffer(1), m_pStream(0), m_pos(0), m_row(0), m_col(0), m_comment(false)
 	{
 	}
 	

test/new-api/nodetests.cpp

@@ -506,6 +506,15 @@ namespace Test
             YAML_ASSERT(node.as<double>() == x);
             return true;
         }
+
+        TEST EmitEmptyNode()
+        {
+            YAML::Node node;
+            YAML::Emitter emitter;
+            emitter << node;
+            YAML_ASSERT(std::string(emitter.c_str()) == "");
+            return true;
+        }
     }
 	
 	void RunNodeTest(TEST (*test)(), const std::string& name, int& passed, int& total) {
@@ -569,6 +578,7 @@ namespace Test
         RunNodeTest(&Node::ResetNode, "reset node", passed, total);
         RunNodeTest(&Node::DereferenceIteratorError, "dereference iterator error", passed, total);
         RunNodeTest(&Node::FloatingPrecision, "floating precision", passed, total);
+        RunNodeTest(&Node::EmitEmptyNode, "emit empty node", passed, total);
 
 		std::cout << "Node tests: " << passed << "/" << total << " passed\n";
 		return passed == total;