componentReference.h

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#pragma once
 
#include <memory>
#include "../Entity/entity.h"
#include "componentContainer.h"
#include <iostream>
 
namespace Saga {
 
template <typename Component>
class ComponentReference {
public:
    ComponentReference() {}
    ComponentReference(std::shared_ptr<ComponentContainer<Component>> componentContainer, Entity entity) 
    : componentContainer(componentContainer), entity(entity) {}
 
    virtual ~ComponentReference() {};
 
    operator Component*() { return getVolatile(); }
 
    Component* operator->() { return getVolatile(); }
 
private:
    // will be wonky behaviour if you encounter the ABA problem. But if you do it's not really the engine's fault is it
    int lastReallocated = -1;
    Component* cachedComponent = nullptr; 
    std::shared_ptr<ComponentContainer<Component>> componentContainer;
    Entity entity;
 
    Component* getVolatile() {
        if (!componentContainer) return nullptr;
        // if reallocated, we need to fetch a new cache
        if (componentContainer->getLastReallocated() > lastReallocated) {
            cachedComponent = componentContainer->getComponent(entity);
            lastReallocated = componentContainer->getLastReallocated();
        }
        return cachedComponent;
    }
};
 
} // namespace Saga