Refactored the operator >> and Node::Read default functions, as well as the conversion functions, to more easily read new types as keys (this uncovered an error, in example 2.11 of the spec)

include/nodereadimpl.h

@@ -0,0 +1,65 @@
+#pragma once
+
+namespace YAML
+{
+	// implementation for Node::Read
+	// (the goal is to call ConvertScalar if we can, and fall back to operator >> if not)
+	// thanks to litb from stackoverflow.com
+	// http://stackoverflow.com/questions/1386183/how-to-call-a-templated-function-if-it-exists-and-something-else-otherwise/1386390#1386390
+	
+	template<bool>
+	struct read_impl;
+	
+	// ConvertScalar available
+	template<>
+	struct read_impl<true> {
+		template<typename T>
+		static bool read(const Node& node, T& value) {
+			return ConvertScalar(node, value);
+		}
+	};
+
+	// ConvertScalar not available
+	template<>
+	struct read_impl<false> {
+		template<typename T>
+		static bool read(const Node& node, T& value) {
+			try {
+				node >> value;
+			} catch(const Exception&) {
+				return false;
+			}
+			return true;
+		}
+	};
+	
+	namespace fallback {
+		// sizeof > 1
+		struct flag { char c[2]; };
+		flag Convert(...);
+		
+		char (& operator,(flag, flag) )[1];
+		
+		template<typename T>
+		void operator,(flag, T const&);
+		
+		char (& operator,(char(&)[1], flag) )[1];
+	}
+
+	template <typename T>
+	inline bool Node::Read(T& value) const {
+		using namespace fallback;
+
+		return read_impl<sizeof (fallback::flag(), Convert(std::string(), value), fallback::flag()) != 1>::read(*this, value);
+	}
+	
+	// the main conversion function
+	template <typename T>
+	inline bool ConvertScalar(const Node& node, T& value) {
+		std::string scalar;
+		if(!node.GetScalar(scalar))
+			return false;
+		
+		return Convert(scalar, value);
+	}
+}