Add variables() method and supporting code.

src/wren/vm.cpp

@@ -68,6 +68,17 @@ namespace wren {
 			retval.finalize = funcs.finalize;
 			return retval;
 		}
+
+		template <typename T> T slot_specialized (WrenVM* vm, int slot_num);
+		template <> bool slot_specialized (WrenVM* vm, int slot_num) {
+			return wrenGetSlotBool(vm, slot_num);
+		}
+		template <> std::string slot_specialized (WrenVM* vm, int slot_num) {
+			return wrenGetSlotString(vm, slot_num);
+		}
+		template <> double slot_specialized (WrenVM* vm, int slot_num) {
+			return wrenGetSlotDouble(vm, slot_num);
+		}
 	} //unnamed namespace
 
 	struct VM::LocalData {
@@ -152,4 +163,27 @@ namespace wren {
 	void VM::interpret (const std::string& module_name, const std::string& script) {
 		return interpret(module_name.c_str(), script.c_str());
 	}
+
+	template <typename T>
+	T VM::slot (int slot_num) {
+		return slot_specialized<T>(m_local->wvm, slot_num);
+	}
+
+	template <>
+	int VM::slot (int slot_num) {
+		return static_cast<int>(slot<double>(slot_num));
+	}
+
+	void VM::ensure_slots (int num_slots) {
+		wrenEnsureSlots(m_local->wvm, num_slots);
+	}
+
+	void VM::variable(const char* module, const char* name, int slot) {
+		wrenGetVariable(m_local->wvm, module, name, slot);
+	}
+
+	template bool VM::slot<bool>(int);
+	template std::string VM::slot<std::string>(int);
+	template double VM::slot<double>(int);
+	template int VM::slot<int>(int);
 } //namespace wren

src/wren/vm.hpp

@@ -4,6 +4,11 @@
 #include "error_type.hpp"
 #include <string>
 #include <memory>
+#include <tuple>
+#include <utility>
+#if __cpp_concepts >= 201907
+#	include <concepts>
+#endif
 
 namespace wren {
 	class Configuration;
@@ -12,6 +17,7 @@ namespace wren {
 
 	typedef void(*foreign_method_t)(VM*);
 	typedef void(*finalizer_t)(void*);
+	typedef std::tuple<const char*, const char*> ModuleAndName;
 
 	struct foreign_class_t {
 		foreign_method_t allocate;
@@ -32,6 +38,10 @@ namespace wren {
 			VM* owner {nullptr};
 			DynafuncMaker* dynafunc {nullptr};
 		};
+
+#if __cpp_concepts >= 201907
+		template <typename T> concept ConstCharTuple = std::same_as<std::remove_cv_t<T>, ModuleAndName>;
+#endif
 	} //namespace detail
 
 	class VM {
@@ -45,6 +55,18 @@ namespace wren {
 		void interpret (const char* module_name, const char* script);
 		void interpret (const std::string& module_name, const std::string& script);
 
+		template <typename T> T slot (int slot_num);
+#if __cpp_concepts >= 201907
+		template <typename... Outs, detail::ConstCharTuple... Params>
+#else
+		template <typename... Outs, typename... Params>
+#endif
+		std::tuple<Outs...> variables(Params&&... modules_names);
+		//template <typename... Args> std::tuple<Args...> variables(const Handle& handle);
+
+		void ensure_slots(int num_slots);
+		void variable(const char* module, const char* name, int slot);
+
 	private:
 		struct LocalData;
 
@@ -54,6 +76,13 @@ namespace wren {
 		template <typename T>
 		detail::Callbacks to_callbacks (T& conf);
 
+#if __cpp_concepts >= 201907
+		template <typename... Outs, int... Indices, detail::ConstCharTuple... Params>
+#else
+		template <typename... Outs, int... Indices, typename... Params>
+#endif
+		std::tuple<Outs...> get_variables_impl (std::integer_sequence<int, Indices...>, Params&&... modules_names);
+
 		std::unique_ptr<LocalData> m_local;
 	};
 
@@ -122,4 +151,44 @@ namespace wren {
 		VM(static_cast<Configuration*>(conf), to_callbacks(*conf))
 	{
 	}
+
+#if __cpp_concepts >= 201907
+	template <typename... Outs, detail::ConstCharTuple... Params>
+#else
+	template <typename... Outs, typename... Params>
+#endif
+	std::tuple<Outs...> VM::variables(Params&&... modules_names) {
+		return get_variables_impl<Outs...>(std::make_integer_sequence<int, sizeof...(Outs)>(), std::forward<Params>(modules_names)...);
+	}
+
+#if __cpp_concepts >= 201907
+		template <typename... Outs, int... Indices, detail::ConstCharTuple... Params>
+#else
+		template <typename... Outs, int... Indices, typename... Params>
+#endif
+	inline std::tuple<Outs...> VM::get_variables_impl (
+		std::integer_sequence<int, Indices...>,
+		Params&&... modules_names
+	) {
+		if constexpr (sizeof...(Outs) == 0) {
+			return {};
+		}
+		else {
+			using std::get;
+			using std::tuple;
+
+			static_assert(sizeof...(Params) == sizeof...(Outs), "Expected a module/name pair per requested output");
+			static_assert(sizeof...(Outs) == sizeof...(Indices), "Mismatching index count");
+
+			ensure_slots(sizeof...(Outs));
+			(this->variable(get<0>(modules_names), get<1>(modules_names), Indices), ...);
+			return tuple<Outs...>(this->slot<Outs>(Indices)...);
+		}
+	}
+
+	//template <typename... Args>
+	//inline std::tuple<Args...> VM::variables(const Handle& handle) {
+	//	if constexpr (sizeof...(Args) == 0)
+	//		return {};
+	//}
 } //namespace wren