5 files changed, 195 insertions, 0 deletions
diff --git a/mwe/ecs-memory-efficient/inc/ComponentManager.h b/mwe/ecs-memory-efficient/inc/ComponentManager.h
new file mode 100644
index 0000000..893aa56
--- /dev/null
+++ b/mwe/ecs-memory-efficient/inc/ComponentManager.h
@@ -0,0 +1,48 @@
+#pragma once
+
+#include "Components.h"
+#include <cstdint>
+#include <unordered_map>
+#include <vector>
+#include <typeindex>
+#include <memory>
+#include <utility>
+
+class ComponentManager {
+public:
+	static ComponentManager& GetInstance();	//Singleton
+
+	ComponentManager(const ComponentManager&) = delete;	//Singleton
+    ComponentManager(ComponentManager&&) = delete;	//Singleton
+    ComponentManager& operator=(const ComponentManager&) = delete;	//Singleton
+    ComponentManager& operator=(ComponentManager&&) = delete;	//Singleton
+
+	template <typename T, typename... Args>
+	void AddComponent(std::uint32_t id, Args&&... args);	//Add a component of a specific type
+	template <typename T>
+	void DeleteComponentsById(std::uint32_t id);	//Deletes all components of a specific type and id
+	template <typename T>
+	void DeleteComponents();	//Deletes all components of a specific type
+	void DeleteAllComponentsOfId(std::uint32_t id);	//Deletes all components of a specific id
+	void DeleteAllComponents();	//Deletes all components
+
+	template <typename T>
+    std::vector<std::reference_wrapper<T>> GetComponentsByID(std::uint32_t id) const;	//Get a vector<> of all components at specific type and id
+	template <typename T>
+	std::vector<std::pair<std::reference_wrapper<T>, std::uint32_t>> GetComponentsByType() const;	//Get a vector<> of all components of a specific type
+
+private:
+    static ComponentManager mInstance;	//Singleton
+
+    ComponentManager();	//Singleton
+
+	/*
+	 * The std::unordered_map<std::type_index, std::vector<std::vector<std::unique_ptr<Component>>>> below might seem a bit strange, let me explain this structure:
+	 * The std::unordered_map<> has a key and value. The key is a std::type_index and the value is a std::vector. So, a new std::vector will be created for each new std::type_index.
+	 * The first std::vector<> stores another vector<>. This first vector<> is to bind the entity's id to a component.
+	 * The second std::vector<> stores unique_ptrs. Each component can be gathered via an unique_ptr. This second vector<> allows multiple components of the same std::type_index for one entity (id).
+	 */
+	std::unordered_map<std::type_index, std::vector<std::vector<std::unique_ptr<Component>>>> mComponents;
+};
+
+#include "ComponentManager.hpp"
diff --git a/mwe/ecs-memory-efficient/inc/ComponentManager.hpp b/mwe/ecs-memory-efficient/inc/ComponentManager.hpp
new file mode 100644
index 0000000..53dfddd
--- /dev/null
+++ b/mwe/ecs-memory-efficient/inc/ComponentManager.hpp
@@ -0,0 +1,88 @@
+
+template <typename T, typename... Args>
+void ComponentManager::AddComponent(std::uint32_t id, Args&&... args) {
+    std::type_index type = typeid(T);	//Determine the type of T (this is used as the key of the unordered_map<>)
+
+    if (mComponents.find(type) == mComponents.end()) {	//Check if this component type is already in the unordered_map<>
+        mComponents[type] = std::vector<std::vector<std::unique_ptr<Component>>>();	//If not, create a new (empty) vector<> of vector<unique_ptr<Component>>
+    }
+
+    if (id >= mComponents[type].size()) {	//Resize the vector<> if the id is greater than the current size
+        mComponents[type].resize(id + 1);	//Initialize new slots to nullptr (resize does automatically init to nullptr)
+    }
+
+    mComponents[type][id].push_back(std::make_unique<T>(std::forward<Args>(args)...));	//Create a new component of type T using perfect forwarding and store its unique_ptr in the vector<>
+}
+
+template <typename T>
+void ComponentManager::DeleteComponentsById(std::uint32_t id) {
+	std::type_index type = typeid(T);	//Determine the type of T (this is used as the key of the unordered_map<>)
+
+	if (mComponents.find(type) != mComponents.end()) {	//Find the type (in the unordered_map<>)
+		std::vector<std::vector<std::unique_ptr<Component>>>& componentArray = mComponents[type];	//Get the correct vector<>
+
+        if (id < componentArray.size()) {	//Make sure that the id (that we are looking for) is within the boundaries of the vector<>
+            componentArray[id].clear();	//Clear the whole vector<> of this specific type and id
+        }
+	}
+}
+
+template <typename T>
+void ComponentManager::DeleteComponents() {
+	std::type_index type = typeid(T);	//Determine the type of T (this is used as the key of the unordered_map<>)
+
+	if (mComponents.find(type) != mComponents.end()) {	//Find the type (in the unordered_map<>)
+		mComponents[type].clear();	//Clear the whole vector<> of this specific type
+	}
+}
+
+template <typename T>
+std::vector<std::reference_wrapper<T>> ComponentManager::GetComponentsByID(std::uint32_t id) const {
+    std::type_index type = typeid(T);	//Determine the type of T (this is used as the key of the unordered_map<>)
+
+	std::vector<std::reference_wrapper<T>> componentVector;	//Create an empty vector<>
+
+    if (mComponents.find(type) != mComponents.end()) {	//Find the type (in the unordered_map<>)
+
+        const std::vector<std::vector<std::unique_ptr<Component>>>& componentArray = mComponents.at(type);	//Get the correct vector<>
+
+        if (id < componentArray.size()) {	//Make sure that the id (that we are looking for) is within the boundaries of the vector<>
+            for (const std::unique_ptr<Component>& componentPtr : componentArray[id]) {	//Loop trough the whole vector<>
+                T* castedComponent = static_cast<T*>(componentPtr.get());	//Cast the unique_ptr to a raw pointer
+
+                if (castedComponent) {	//Ensure that the cast was successful
+                    componentVector.push_back(*castedComponent); //Add the dereferenced raw pointer to the vector<>
+                }
+            }
+        }
+    }
+
+    return componentVector; //Return the vector<>
+}
+
+template <typename T>
+std::vector<std::pair<std::reference_wrapper<T>, std::uint32_t>> ComponentManager::GetComponentsByType() const {
+    std::type_index type = typeid(T);	//Determine the type of T (this is used as the key of the unordered_map<>)
+
+    std::vector<std::pair<std::reference_wrapper<T>, std::uint32_t>> componentVector;	//Create an empty vector<>
+	std::uint32_t id = 0;	//Set the id to 0 (the id will also be stored in the returned vector<>)
+
+    if (mComponents.find(type) != mComponents.end()) {	//Find the type (in the unordered_map<>)
+
+        const std::vector<std::vector<std::unique_ptr<Component>>>& componentArray = mComponents.at(type);	//Get the correct vector<>
+
+        for (const std::vector<std::unique_ptr<Component>>& component : componentArray) {	//Loop through the whole vector<>
+            for (const std::unique_ptr<Component>& componentPtr : component) {	//Loop trough the whole vector<>
+                T* castedComponent = static_cast<T*>(componentPtr.get());	//Cast the unique_ptr to a raw pointer
+
+                if (castedComponent) {	//Ensure that the cast was successful
+                    componentVector.emplace_back(std::ref(*castedComponent), id);	//Pair the dereferenced raw pointer and the id and add it to the vector<>
+                }
+            }
+
+			++id;	//Increase the id (the id will also be stored in the returned vector<>)
+        }
+    }
+
+    return componentVector;	//Return the vector<>
+}
diff --git a/mwe/ecs-memory-efficient/inc/Components.h b/mwe/ecs-memory-efficient/inc/Components.h
new file mode 100644
index 0000000..98c5fe7
--- /dev/null
+++ b/mwe/ecs-memory-efficient/inc/Components.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include <string>
+
+class Component {
+public:
+	Component();
+
+	bool mActive;
+};
+
+class Sprite : public Component {
+public:
+	Sprite(std::string path);
+
+	std::string mPath;
+};
+
+class Rigidbody : public Component {
+public:
+	Rigidbody(int mass, int gravityScale, int bodyType);
+
+	int mMass;
+	int mGravityScale;
+	int mBodyType;
+};
+
+class Colider : public Component {
+public:
+	Colider(int size);
+
+	int mSize;
+};
diff --git a/mwe/ecs-memory-efficient/inc/GameObjectMax.h b/mwe/ecs-memory-efficient/inc/GameObjectMax.h
new file mode 100644
index 0000000..f0bcec9
--- /dev/null
+++ b/mwe/ecs-memory-efficient/inc/GameObjectMax.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <cstdint>
+#include <string>
+
+class GameObject {
+public:
+	GameObject(std::uint32_t id, std::string name, std::string tag, int layer);
+
+	template <typename T, typename... Args>
+	void AddComponent(Args&&... args);
+
+	std::uint32_t mId;
+	std::string mName;
+	std::string mTag;
+	bool mActive;
+	int mLayer;
+};
+
+#include "GameObjectMax.hpp"
diff --git a/mwe/ecs-memory-efficient/inc/GameObjectMax.hpp b/mwe/ecs-memory-efficient/inc/GameObjectMax.hpp
new file mode 100644
index 0000000..1e952ba
--- /dev/null
+++ b/mwe/ecs-memory-efficient/inc/GameObjectMax.hpp
@@ -0,0 +1,6 @@
+#include "ComponentManager.h"
+
+template <typename T, typename... Args>
+void GameObject::AddComponent(Args&&... args) {
+	ComponentManager::GetInstance().AddComponent<T>(mId, std::forward<Args>(args)...);
+}