Optional.h

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#pragma once

#include <memory>

template <typename T>
class Optional
{
public:
    Optional() {}
    Optional(const T &value) { innerValue = std::unique_ptr<T>(new T(value)); } // copy
    Optional(T &&value) { innerValue = std::unique_ptr<T>(new T(std::move(value))); } // move
    bool hasValue() const { return innerValue != nullptr; }
    T &get()
    {
        T *innerPtr = innerValue.get();
        if (innerPtr != nullptr)
            return *innerPtr;
        else
            throw std::runtime_error("Can't extract a reference from a null pointer");
    }
    const T &get() const
    {
        T *innerPtr = innerValue.get();
        if (innerPtr != nullptr)
            return *innerPtr;
        else
            throw std::runtime_error("Can't extract a reference from a null pointer");
    }
    void set(const T &value) { innerValue.reset(new T(value)); }
    void set(T &&value) { innerValue.reset(new T(value)); }
    Optional<T> &operator=(const Optional<T> &value)
    {
        if (!value.hasValue())
            innerValue.reset();
        else
            innerValue.reset(new T(value.get())); // copy
        return *this;
    }
    void clear() { innerValue.reset(); }

private:
    std::unique_ptr<T> innerValue = nullptr;
};