Codechange: Manage script event queue using smart pointers.

src/script/api/script_event.cpp

@@ -9,64 +9,27 @@
 
 #include "../../stdafx.h"
 #include "script_event_types.hpp"
-
-#include <queue>
+#include "../script_storage.hpp"
 
 #include "../../safeguards.h"
 
-/** The queue of events for a script. */
-struct ScriptEventData {
-	std::queue<ScriptEvent *> stack; ///< The actual queue.
-};
-
-/* static */ void ScriptEventController::CreateEventPointer()
-{
-	assert(ScriptObject::GetEventPointer() == nullptr);
-
-	ScriptObject::GetEventPointer() = new ScriptEventData();
-}
-
-/* static */ void ScriptEventController::FreeEventPointer()
-{
-	ScriptEventData *data = (ScriptEventData *)ScriptObject::GetEventPointer();
-
-	/* Free all waiting events (if any) */
-	while (!data->stack.empty()) {
-		ScriptEvent *e = data->stack.front();
-		data->stack.pop();
-		e->Release();
-	}
-
-	/* Now kill our data pointer */
-	delete data;
-}
-
 /* static */ bool ScriptEventController::IsEventWaiting()
 {
-	if (ScriptObject::GetEventPointer() == nullptr) ScriptEventController::CreateEventPointer();
-	ScriptEventData *data = (ScriptEventData *)ScriptObject::GetEventPointer();
-
-	return !data->stack.empty();
+	return !ScriptObject::GetEventQueue().empty();
 }
 
 /* static */ ScriptEvent *ScriptEventController::GetNextEvent()
 {
-	if (ScriptObject::GetEventPointer() == nullptr) ScriptEventController::CreateEventPointer();
-	ScriptEventData *data = (ScriptEventData *)ScriptObject::GetEventPointer();
+	auto &queue = ScriptObject::GetEventQueue();
+	if (queue.empty()) return nullptr;
 
-	if (data->stack.empty()) return nullptr;
-
-	ScriptEvent *e = data->stack.front();
-	data->stack.pop();
-	return e;
+	auto *result = queue.front().release();
+	queue.pop();
+	return result;
 }
 
 /* static */ void ScriptEventController::InsertEvent(ScriptEvent *event)
 {
-	if (ScriptObject::GetEventPointer() == nullptr) ScriptEventController::CreateEventPointer();
-	ScriptEventData *data = (ScriptEventData *)ScriptObject::GetEventPointer();
-
-	event->AddRef();
-	data->stack.push(event);
+	ScriptObject::GetEventQueue().push(event);
 }
 

src/script/api/script_object.cpp

@@ -239,9 +239,9 @@ ScriptObject::ActiveInstance::~ActiveInstance()
 	return GetStorage()->allow_do_command && squirrel->CanSuspend();
 }
 
-/* static */ void *&ScriptObject::GetEventPointer()
+/* static */ ScriptEventQueue &ScriptObject::GetEventQueue()
 {
-	return GetStorage()->event_data;
+	return GetStorage()->event_queue;
 }
 
 /* static */ ScriptLogTypes::LogData &ScriptObject::GetLogData()

src/script/api/script_object.hpp

@@ -327,12 +327,12 @@ protected:
 	static bool CanSuspend();
 
 	/**
-	 * Get the pointer to store event data in.
+	 * Get the reference to the event queue.
 	 */
-	static void *&GetEventPointer();
+	static struct ScriptEventQueue &GetEventQueue();
 
 	/**
-	 * Get the pointer to store log message in.
+	 * Get the reference to the log message storage.
 	 */
 	static ScriptLogTypes::LogData &GetLogData();
 
@@ -467,6 +467,14 @@ public:
 		if (this->data != nullptr) this->data->Release();
 	}
 
+	/**
+	 * Transfer ownership to the caller.
+	 */
+	[[nodiscard]] T *release()
+	{
+		return std::exchange(this->data, nullptr);
+	}
+
 	/**
 	 * Dereferencing this reference returns a reference to the reference
 	 * counted object

src/script/script_instance.cpp

@@ -33,11 +33,7 @@
 #include "../safeguards.h"
 
 ScriptStorage::ScriptStorage() = default;
-ScriptStorage::~ScriptStorage()
-{
-	/* Free our pointers */
-	if (event_data != nullptr) ScriptEventController::FreeEventPointer();
-}
+ScriptStorage::~ScriptStorage() = default;
 
 /**
  * Callback called by squirrel when a script uses "print" and for error messages.

src/script/script_storage.hpp

@@ -10,6 +10,8 @@
 #ifndef SCRIPT_STORAGE_HPP
 #define SCRIPT_STORAGE_HPP
 
+#include <queue>
+
 #include "../signs_func.h"
 #include "../vehicle_func.h"
 #include "../road_type.h"
@@ -19,6 +21,13 @@
 
 #include "script_types.hpp"
 #include "script_log_types.hpp"
+#include "script_object.hpp"
+
+class ScriptEvent;
+
+/* This is a "struct", so we can forward declare it, and use as incomplete type. */
+struct ScriptEventQueue : std::queue<ScriptObjectRef<ScriptEvent>> {
+};
 
 /**
  * The callback function for Mode-classes.
@@ -60,7 +69,7 @@ private:
 	RoadType road_type = INVALID_ROADTYPE; ///< The current roadtype we build.
 	RailType rail_type = INVALID_RAILTYPE; ///< The current railtype we build.
 
-	void *event_data = nullptr; ///< Event queue for this script.
+	ScriptEventQueue event_queue; ///< Event queue for this script.
 	ScriptLogTypes::LogData log_data; ///< Log data storage.
 
 public: