Refactor json return type generation.

libsolidity/interface/InterfaceHandler.h

@@ -37,6 +37,8 @@ namespace solidity
 
 // Forward declarations
 class ContractDefinition;
+class Type;
+using TypePointer = std::shared_ptr<Type const>;
 struct DocTag;
 enum class DocumentationType: uint8_t;
 
@@ -84,6 +86,14 @@ public:
 	static Json::Value devDocumentation(ContractDefinition const& _contractDef);
 
 private:
+	/// @returns a json value suitable for a list of types in function input or output
+	/// parameters or other places. If @a _forLibrary is true, complex types are referenced
+	/// by name, otherwise they are anonymously expanded.
+	static Json::Value formatTypeList(
+		std::vector<std::string> const& _names,
+		std::vector<TypePointer> const& _types,
+		bool _forLibrary
+	);
 	/// @returns concatenation of all content under the given tag name.
 	static std::string extractDoc(std::multimap<std::string, DocTag> const& _tags, std::string const& _name);
 };