Codechange: Add support for additional command result values.

2 files changed, 40 insertions, 6 deletions

diff --git a/src/script/api/script_object.cpp b/src/script/api/script_object.cpp
index ff109dbdf..dad79309a 100644
--- a/src/script/api/script_object.cpp
+++ b/src/script/api/script_object.cpp
@@ -173,6 +173,16 @@ ScriptObject::ActiveInstance::~ActiveInstance()
 	return GetStorage()->last_command_res;
 }
 
+/* static */ void ScriptObject::SetLastCommandResData(CommandDataBuffer data)
+{
+	GetStorage()->last_cmd_ret = std::move(data);
+}
+
+/* static */ const CommandDataBuffer &ScriptObject::GetLastCommandResData()
+{
+	return GetStorage()->last_cmd_ret;
+}
+
 /* static */ void ScriptObject::SetNewVehicleID(VehicleID vehicle_id)
 {
 	GetStorage()->new_vehicle_id = vehicle_id;
diff --git a/src/script/api/script_object.hpp b/src/script/api/script_object.hpp
index 11d9542c8..f9a66f8a8 100644
--- a/src/script/api/script_object.hpp
+++ b/src/script/api/script_object.hpp
@@ -62,6 +62,12 @@ public:
 	static void SetLastCommandRes(bool res);
 
 	/**
+	 * Store the extra data return by the last DoCommand.
+	 * @param data Extra data return by the command.
+	 */
+	static void SetLastCommandResData(CommandDataBuffer data);
+
+	/**
 	 * Get the currently active instance.
 	 * @return The instance.
 	 */
@@ -74,10 +80,11 @@ protected:
 	 * Templated wrapper that exposes the command parameter arguments
 	 * on the various DoCommand calls.
 	 * @tparam Tcmd The command-id to execute.
+	 * @tparam Tret Return type of the command.
 	 * @tparam Targs The command parameter types.
 	 */
-	template <Commands Tcmd, typename... Targs>
-	struct ScriptDoCommandHelper<Tcmd, CommandCost(*)(DoCommandFlag, Targs...)> {
+	template <Commands Tcmd, typename Tret, typename... Targs>
+	struct ScriptDoCommandHelper<Tcmd, Tret(*)(DoCommandFlag, Targs...)> {
 		static bool Do(Script_SuspendCallbackProc *callback, Targs... args)
 		{
 			return Execute(callback, std::forward_as_tuple(args...));
@@ -181,6 +188,11 @@ protected:
 	static bool GetLastCommandRes();
 
 	/**
+	 * Get the extra return data from the last DoCommand.
+	 */
+	static const CommandDataBuffer &GetLastCommandResData();
+
+	/**
 	 * Get the latest stored new_vehicle_id.
 	 */
 	static VehicleID GetNewVehicleID();
@@ -363,10 +375,17 @@ namespace ScriptObjectInternal {
 	{
 		((SetClientIdHelper(std::get<Tindices>(values))), ...);
 	}
+
+	/** Remove the first element of a tuple. */
+	template <template <typename...> typename Tt, typename T1, typename... Ts>
+	static inline Tt<Ts...> RemoveFirstTupleElement(const Tt<T1, Ts...> &tuple)
+	{
+		return std::apply([](auto &&, const auto&... args) { return std::tie(args...); }, tuple);
+	}
 }
 
-template <Commands Tcmd, typename... Targs>
-bool ScriptObject::ScriptDoCommandHelper<Tcmd, CommandCost(*)(DoCommandFlag, Targs...)>::Execute(Script_SuspendCallbackProc *callback, std::tuple<Targs...> args)
+template <Commands Tcmd, typename Tret, typename... Targs>
+bool ScriptObject::ScriptDoCommandHelper<Tcmd, Tret(*)(DoCommandFlag, Targs...)>::Execute(Script_SuspendCallbackProc *callback, std::tuple<Targs...> args)
 {
 	auto [err, estimate_only, networking] = ScriptObject::DoCommandPrep();
 	if (err) return false;
@@ -387,9 +406,14 @@ bool ScriptObject::ScriptDoCommandHelper<Tcmd, CommandCost(*)(DoCommandFlag, Tar
 	if (!estimate_only && networking) ScriptObject::SetLastCommand(tile, EndianBufferWriter<CommandDataBuffer>::FromValue(args), Tcmd);
 
 	/* Try to perform the command. */
-	CommandCost res = ::Command<Tcmd>::Unsafe((StringID)0, networking ? ScriptObject::GetDoCommandCallback() : nullptr, false, estimate_only, tile, args);
+	Tret res = ::Command<Tcmd>::Unsafe((StringID)0, networking ? ScriptObject::GetDoCommandCallback() : nullptr, false, estimate_only, tile, args);
 
-	return ScriptObject::DoCommandProcessResult(res, callback, estimate_only);
+	if constexpr (std::is_same_v<Tret, CommandCost>) {
+		return ScriptObject::DoCommandProcessResult(res, callback, estimate_only);
+	} else {
+		ScriptObject::SetLastCommandResData(EndianBufferWriter<CommandDataBuffer>::FromValue(ScriptObjectInternal::RemoveFirstTupleElement(res)));
+		return ScriptObject::DoCommandProcessResult(std::get<0>(res), callback, estimate_only);
+	}
 }
 
 #endif /* SCRIPT_OBJECT_HPP */