feat: implement Object resolver and possible types merge

Author: wravery

include/graphqlservice/GraphQLService.h

@@ -824,6 +824,9 @@ class [[nodiscard("unnecessary construction")]] Object : public std::enable_shar
 	GRAPHQLSERVICE_EXPORT explicit Object(TypeNames&& typeNames, ResolverMap&& resolvers) noexcept;
 	GRAPHQLSERVICE_EXPORT virtual ~Object() = default;
 
+	[[nodiscard("unnecessary call")]] GRAPHQLSERVICE_EXPORT std::shared_ptr<Object> StitchObject(
+		const std::shared_ptr<const Object>& added) const;
+
 	[[nodiscard("unnecessary call")]] GRAPHQLSERVICE_EXPORT AwaitableResolver resolve(
 		const SelectionSetParams& selectionSetParams, const peg::ast_node& selection,
 		const FragmentMap& fragments, const response::Value& variables) const;
@@ -846,6 +849,7 @@ class [[nodiscard("unnecessary construction")]] Object : public std::enable_shar
 private:
 	TypeNames _typeNames;
 	ResolverMap _resolvers;
+	std::vector<std::shared_ptr<const Object>> _stitched;
 };
 
 // Test if this Type inherits from Object.
@@ -1466,6 +1470,7 @@ class [[nodiscard("unnecessary construction")]] Request
 	collectRegistrations(std::string_view field, RequestDeliverFilter&& filter) const noexcept;
 
 	const TypeMap _operations;
+	const std::shared_ptr<schema::Schema> _schema;
 	mutable std::mutex _validationMutex {};
 	const std::unique_ptr<ValidateExecutableVisitor> _validation;
 	mutable std::mutex _subscriptionMutex {};

src/GraphQLService.cpp

@@ -1222,6 +1222,37 @@ Object::Object(TypeNames&& typeNames, ResolverMap&& resolvers) noexcept
 {
 }
 
+std::shared_ptr<Object> Object::StitchObject(const std::shared_ptr<const Object>& added) const
+{
+	auto typeNames = _typeNames;
+
+	for (const auto& name : added->_typeNames)
+	{
+		typeNames.emplace(name);
+	}
+
+	auto resolvers = _resolvers;
+	bool hasStitchedResolvers = false;
+
+	for (const auto& [name, resolver] : added->_resolvers)
+	{
+		hasStitchedResolvers = resolvers.emplace(name, resolver).second || hasStitchedResolvers;
+	}
+
+	std::vector<std::shared_ptr<const Object>> stitched { shared_from_this() };
+
+	if (hasStitchedResolvers)
+	{
+		stitched.push_back(added);
+	}
+
+	auto object = std::make_shared<Object>(std::move(typeNames), std::move(resolvers));
+
+	object->_stitched = std::move(stitched);
+
+	return object;
+}
+
 AwaitableResolver Object::resolve(const SelectionSetParams& selectionSetParams,
 	const peg::ast_node& selection, const FragmentMap& fragments,
 	const response::Value& variables) const