C++ Either类的简易实现

Either.hpp

#ifndef EITHER_HPP
#define EITHER_HPP

#include <type_traits>

template<typename T1, typename T2>
struct MaxTypeSizeHelper {
    const static auto size = (sizeof(T1) > sizeof(T2)) ? sizeof(T1) : sizeof(T2);
};

template<typename Left, typename Right>
class Either {
public:
    Either(void) = delete;
    Either(const Left& val) : is_left(true)
    {
        new (&data) Left(val);
    }
    Either(const Right& val) : is_left(false)
    {
        new (&data) Right(val);
    }
    Either(const Either& another) : is_left(another.is_left)
    {
        if (is_left) {
            new (&data) Left(*((Left*)&(another.data)));
        } else {
            new (&data) Right(*((Right*)&(another.data)));
        }
    }
    Either(Either&& another) : Either(another) {}
    ~Either()
    {
        if (is_left) {
            ((Left*)(&data))->~Left();
        } else {
            ((Right*)(&data))->~Right();
        }
    }
    template<typename F>
    Either& caseLeft(F func)
    {
        if (is_left) {
            func(*((Left*)&data));
        }
        return *this;
    }
    template<typename F>
    Either& caseRight(F func)
    {
        if (!is_left) {
            func(*((Right*)&data));
        }
        return *this;
    }
    bool isLeft(void)
    {
        return is_left;
    }
    bool isRight(void)
    {
        return !is_left;
    }
private:
    bool is_left;
    typename std::aligned_storage<MaxTypeSizeHelper<Left, Right>::size>::type data;
};

#endif // EITHER_HPP