8 files changed, 139 insertions, 11 deletions

diff --git a/src/crepe/api/AudioSource.h b/src/crepe/api/AudioSource.h
index 0950129..9d76f0b 100644
--- a/src/crepe/api/AudioSource.h
+++ b/src/crepe/api/AudioSource.h
@@ -2,6 +2,7 @@
 
 #include "../Component.h"
 #include "../types.h"
+#include "../util/Private.h"
 
 #include "GameObject.h"
 #include "Asset.h"
@@ -47,14 +48,8 @@ private:
 	bool rewind = false;
 
 private:
-	//! Value of \c active after last system update
-	bool last_active = false;
-	//! Value of \c playing after last system update
-	bool last_playing = false;
-	//! Value of \c volume after last system update
-	float last_volume = 1.0;
-	//! Value of \c loop after last system update
-	bool last_loop = false;
+	//! AudioSystem::ComponentPrivate
+	Private private_data;
 };
 
 } // namespace crepe
diff --git a/src/crepe/facade/Sound.h b/src/crepe/facade/Sound.h
index b0b80f8..f33ee58 100644
--- a/src/crepe/facade/Sound.h
+++ b/src/crepe/facade/Sound.h
@@ -9,6 +9,10 @@ namespace crepe {
 
 class SoundContext;
 
+struct SoundHandle {
+	SoLoud::handle handle;
+};
+
 /**
  * \brief Sound resource facade
  *
diff --git a/src/crepe/system/AudioSystem.cpp b/src/crepe/system/AudioSystem.cpp
index 97cf966..0f943be 100644
--- a/src/crepe/system/AudioSystem.cpp
+++ b/src/crepe/system/AudioSystem.cpp
@@ -1,6 +1,5 @@
 #include "AudioSystem.h"
 
-#include "../api/AudioSource.h"
 #include "../manager/ComponentManager.h"
 #include "../manager/ResourceManager.h"
 #include "../types.h"
@@ -13,12 +12,24 @@ void AudioSystem::update() {
 	ResourceManager & resource_manager = this->mediator.resource_manager;
 	RefVector<AudioSource> components = component_manager.get_components_by_type<AudioSource>();
 
-	for (auto component_ref : components) {
-		AudioSource & component = component_ref.get();
+	for (AudioSource & component : components) {
 		if (!component.active) continue;
 
 		Sound & sound = resource_manager.get<Sound>(component.source);
+		if (component.private_data.empty())
+			component.private_data.set<ComponentPrivate>();
+		auto & data = component.private_data.get<ComponentPrivate>();
 		// TODO: lots of state diffing
+
+
+		this->update_private(component, data);
 	}
 }
 
+void AudioSystem::update_private(const AudioSource & component, ComponentPrivate & data) {
+	data.last_active = component.active;
+	data.last_loop = component.loop;
+	data.last_playing = component.playing;
+	data.last_volume = component.volume;
+}
+
diff --git a/src/crepe/system/AudioSystem.h b/src/crepe/system/AudioSystem.h
index e037f51..7f41fda 100644
--- a/src/crepe/system/AudioSystem.h
+++ b/src/crepe/system/AudioSystem.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "../facade/SoundContext.h"
+#include "../api/AudioSource.h"
 
 #include "System.h"
 
@@ -12,6 +13,26 @@ public:
 	void update() override;
 
 private:
+	/**
+	 * \brief Private data stored by AudioSystem on AudioSource component
+	 */
+	struct ComponentPrivate {
+		//! This sample's voice handle
+		SoLoud::handle handle;
+
+		//! Value of \c active after last system update
+		bool last_active = false;
+		//! Value of \c playing after last system update
+		bool last_playing = false;
+		//! Value of \c volume after last system update
+		float last_volume = 1.0;
+		//! Value of \c loop after last system update
+		bool last_loop = false;
+	};
+
+	void update_private(const AudioSource & component, ComponentPrivate & data);
+
+private:
 	SoundContext context {};
 };
 
diff --git a/src/crepe/util/CMakeLists.txt b/src/crepe/util/CMakeLists.txt
index 94ed906..f49d851 100644
--- a/src/crepe/util/CMakeLists.txt
+++ b/src/crepe/util/CMakeLists.txt
@@ -1,6 +1,7 @@
 target_sources(crepe PUBLIC
 	LogColor.cpp
 	Log.cpp
+	Private.cpp
 )
 
 target_sources(crepe PUBLIC FILE_SET HEADERS FILES
@@ -11,5 +12,7 @@ target_sources(crepe PUBLIC FILE_SET HEADERS FILES
 	Proxy.hpp
 	OptionalRef.h
 	OptionalRef.hpp
+	Private.h
+	Private.hpp
 )
 
diff --git a/src/crepe/util/Private.cpp b/src/crepe/util/Private.cpp
new file mode 100644
index 0000000..c5b5b30
--- /dev/null
+++ b/src/crepe/util/Private.cpp
@@ -0,0 +1,29 @@
+#include "Private.h"
+
+using namespace crepe;
+
+bool Private::empty() const noexcept {
+	return this->instance == nullptr;
+}
+
+Private::~Private() {
+	if (this->instance == nullptr) return;
+	this->destructor(this->instance);
+}
+
+Private::Private(Private && other) {
+	*this = std::move(other);
+}
+
+Private & Private::operator=(Private && other) {
+	// TODO: ideally this function checks for self-assignment
+	this->instance = other.instance;
+	this->destructor = other.destructor;
+	this->type = other.type;
+
+	other.instance = nullptr;
+	other.destructor = [](void*){};
+
+	return *this;
+}
+
diff --git a/src/crepe/util/Private.h b/src/crepe/util/Private.h
new file mode 100644
index 0000000..fc3728f
--- /dev/null
+++ b/src/crepe/util/Private.h
@@ -0,0 +1,34 @@
+#pragma once
+
+#include <typeindex>
+#include <functional>
+
+namespace crepe {
+
+class Private {
+public:
+	Private() = default;
+	~Private();
+	Private(Private &&);
+	Private & operator=(Private &&);
+	Private(const Private &) = delete;
+	Private & operator=(const Private &) = delete;
+
+	template <typename T>
+	T & get();
+
+	template <typename T, typename... Args>
+	void set(Args &&... args);
+
+	bool empty() const noexcept;
+
+private:
+	std::function<void(void *)> destructor;
+	std::type_index type = typeid(void);
+	void * instance = nullptr;
+};
+
+}
+
+#include "Private.hpp"
+
diff --git a/src/crepe/util/Private.hpp b/src/crepe/util/Private.hpp
new file mode 100644
index 0000000..30c8146
--- /dev/null
+++ b/src/crepe/util/Private.hpp
@@ -0,0 +1,31 @@
+#pragma once
+
+#include <stdexcept>
+#include <format>
+
+#include "Private.h"
+
+namespace crepe {
+
+template <typename T, typename... Args>
+void Private::set(Args &&... args) {
+	T * instance = new T(std::forward<Args>(args)...);
+	this->instance = static_cast<void*>(instance);
+	this->destructor = [](void * instance) {
+		delete static_cast<T*>(instance);
+	};
+	this->type = typeid(T);
+}
+
+template <typename T>
+T & Private::get() {
+	using namespace std;
+	if (this->empty())
+		throw out_of_range("Private: get() called on empty object");
+	type_index requested_type = typeid(T);
+	if (this->type != requested_type)
+		throw logic_error(format("Private: get() called with [T = {}] (actual is [T = {}])", requested_type.name(), this->type.name()));
+	return *static_cast<T*>(this->instance);
+}
+
+}