cppparser/cppparser/src/optional.h at master · satya-das/cppparser · GitHub

History

81 lines (70 loc) · 1.46 KB

Raw

#ifndef E9D70610_1760_4E50_93F3_1129D8E51D1B

#define E9D70610_1760_4E50_93F3_1129D8E51D1B

#include <exception>

#include <optional>

/**

* @brief Similar to std::optional.

* A trivially constructible optional value class that can be used as a member of a union.

* @note std::optional objects cannot be a member of a union.

* @warning Init() must be called to properly initialize the object before using it.

template <typename T>

class Optional

{

public:

static_assert(std::is_trivially_constructible_v<T>);

bool hasValue() const

{

return initialized_;

}

const T& value() const

{

if (!initialized_)

{

throw std::bad_optional_access();

}

return *reinterpret_cast<const T*>(storage);

}

Optional<T> operator=(const T& rhs)

{

if (initialized_)

{

*reinterpret_cast<T*>(storage) = rhs;

}

else

{

new (static_cast<void*>(storage)) T(rhs);

}

initialized_ = true;

return *this;

}

operator std::optional<T>() const

{

if (initialized_)

{

return std::optional<T>(value());

}

else

{

return std::optional<T>();

}

private:

template <typename U>

friend void Init(Optional<U>& opt);

bool initialized_;

char storage[sizeof(T)];

};

template <typename T>

void Init(Optional<T>& opt)

{

opt.initialized_ = false;

}

template <typename T>

void Init(Optional<T>& opt, const T& val)

{

Init(opt);

opt = val;

}

#endif /* E9D70610_1760_4E50_93F3_1129D8E51D1B */

cppparser/cppparser/src/optional.h at master · satya-das/cppparser · GitHub

Expand file tree

Breadcrumbs

optional.h

Latest commit

History

Breadcrumbs

optional.h

File metadata and controls