moveSemantics

#include <iostream>

#define NOTHING 0
#define MOVE    1
#define DEEP_COPY   2
#define MOVE_RVAL   3

#define METHOD NOTHING

class Entity
{
    int num;
public:
    Entity(int n = 0)  : num{n} { std::cout << "Entity constructed\n";};
    ~Entity() {std::cout << "Entity destructed\n";}
    void print() { std::cout << "Entity = " << num << "\n";};
};

class SmartPtr
{
    Entity* ptr;
public:
    SmartPtr(Entity* eptr = nullptr) : ptr{eptr} {};
#if METHOD == MOVE
    SmartPtr(SmartPtr& sPtr);
    SmartPtr& operator=(SmartPtr& sPtr);
#endif
#if METHOD == MOVE_RVAL
    SmartPtr(SmartPtr&& sPtr);
    SmartPtr& operator=(SmartPtr&& sPtr);
#endif
#if METHOD == DEEP_COPY
    SmartPtr(const SmartPtr& sPtr);
    SmartPtr& operator=(const SmartPtr& sPtr);
#endif
    Entity& operator*() {return *ptr;};
    Entity* operator->() {return ptr;};
    bool isEmpty() { return ptr == nullptr;};
    ~SmartPtr() { delete ptr; };
};

#if METHOD == MOVE
SmartPtr::SmartPtr(SmartPtr& sPtr) // Move
: ptr{sPtr.ptr}
{
    sPtr.ptr = nullptr;
}

SmartPtr& SmartPtr::operator =(SmartPtr& sPtr) // Move
{
    if ( this == &sPtr) { return *this; };

    delete ptr;
    ptr = sPtr.ptr;
    sPtr.ptr = nullptr;

    return *this;
}
#endif

#if METHOD == MOVE_RVAL
SmartPtr::SmartPtr(SmartPtr&& sPtr) // Move rvalue
: ptr{sPtr.ptr}
{
    sPtr.ptr = nullptr;
}

SmartPtr& SmartPtr::operator =(SmartPtr&& sPtr) // Move rvalue
{
    if ( this == &sPtr) { return *this; };

    delete ptr;
    ptr = sPtr.ptr;
    sPtr.ptr = nullptr;

    return *this;
}
#endif

#if METHOD == DEEP_COPY
SmartPtr::SmartPtr(const SmartPtr& sPtr) // Deep copy
: ptr{new Entity}
{
    *ptr = *sPtr.ptr;
}

SmartPtr& SmartPtr::operator =(const SmartPtr& sPtr) // Deep copy
{
    if ( this == &sPtr) { return *this; };

    delete ptr;
    ptr = new Entity;
    *ptr = *sPtr.ptr;

    return *this;
}
#endif

SmartPtr generateEntity()
{
    SmartPtr sPtr{new Entity{33}};
    return sPtr;
}

int main()
{
    SmartPtr ePtr{new Entity{42}};
    ePtr->print();
    std::cout <<"ePtr.isEmpty: " << ePtr.isEmpty() << '\n';

#if METHOD == DEEP_COPY || METHOD == MOVE || METHOD == NOTHING
    SmartPtr ePtr1{ePtr};
    ePtr1->print();
    std::cout <<"ePtr.isEmpty: " << ePtr.isEmpty() << '\n';
#endif

#if METHOD == MOVE_RVAL
    SmartPtr ePtr1{std::move(ePtr)};
    ePtr1->print();
    std::cout <<"ePtr.isEmpty: " << ePtr.isEmpty() << '\n';
#endif

#if METHOD == MOVE || METHOD == DEEP_COPY || METHOD == MOVE_RVAL
    SmartPtr ePtr2 = generateEntity();
    ePtr2->print();
    std::cout <<"ePtr2.isEmpty: " << ePtr2.isEmpty() << '\n';
#endif

}