Added support for emitting and represeting null

src/conversion.cpp

@@ -83,6 +83,12 @@ namespace YAML
 		return false;
 	}
 	
+	template <>
+	bool Converter<_Null>::Convert(const std::string& input, _Null& /*output*/)
+	{
+		return input.empty() || input == "~" || input == "null" || input == "Null" || input == "NULL";
+	}
+
 	template <>
 	bool Converter<std::wstring>::Convert(const std::string& input, std::wstring& output)
 	{

src/emitter.cpp

@@ -666,4 +666,16 @@ namespace YAML
 		Utils::WriteComment(m_stream, comment.content, m_pState->GetPostCommentIndent());
 		return *this;
 	}
+
+	Emitter& Emitter::Write(const _Null& /*null*/)
+	{
+		if(!good())
+			return *this;
+		
+		PreAtomicWrite();
+		EmitSeparationIfNecessary();
+		m_stream << "~";
+		PostAtomicWrite();
+		return *this;
+	}
 }

src/node.cpp

@@ -10,6 +10,7 @@
 #include "aliascontent.h"
 #include "iterpriv.h"
 #include "emitter.h"
+#include <stdexcept>
 
 namespace YAML
 {
@@ -85,6 +86,9 @@ namespace YAML
 				m_pContent = new Map;
 				break;
 			default:
+//				std::stringstream str;
+//				str << TokenNames[pScanner->peek().type];
+//				throw std::runtime_error(str.str());
 				break;
 		}
 

src/null.cpp

@@ -0,0 +1,6 @@
+#include "null.h"
+
+namespace YAML
+{
+	_Null Null;
+}