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#pragma once
#include <functional>
#include <typeindex>
namespace crepe {
/**
* \brief Utility for storing type hidden from user
*
* This class can be used to store types which cannot be used in the API directly due to header
* distribution limitations. This class is similar to `std::any`, but provides a method for
* retrieving a mutable reference to the stored object.
*/
class Private {
public:
Private() = default;
~Private();
/**
* \name Copy
*
* \note These functions do not do anything, resulting in `*this` being an empty (default)
* instance.
*
* \{
*/
Private(const Private &);
Private & operator=(const Private &);
//! \}
/**
* \name Move
*
* These functions actually move the stored type if present.
*
* \{
*/
Private(Private &&);
Private & operator=(Private &&);
//! \}
/**
* \brief Get the stored object
*
* \tparam T Type of stored object
*
* \returns Mutable reference to stored object
*
* \throws std::out_of_range if this instance does not contain any object
* \throws std::logic_error if the stored type and requested type differ
*/
template <typename T>
T & get() const;
/**
* \brief Create and store an arbitrary object
*
* \tparam T Type of object
* \tparam Args Perfect forwarding arguments
* \param args Perfect forwarding arguments
*
* All arguments to this function are forwarded using `std::forward` to the constructor of T.
*
* \returns Mutable reference to stored object
*
* \note If this instance already contained an object, this function implicitly destroys the
* previous object.
*/
template <typename T, typename... Args>
T & set(Args &&... args);
/**
* \brief Check if this instance contains an object
*
* \returns `true` if this instance is empty, `false` if it contains an object
*/
bool empty() const noexcept;
private:
//! Wrapper for destructor call of stored object type
std::function<void(void *)> destructor;
//! Stored object's type
std::type_index type = typeid(void);
//! Stored object
void * instance = nullptr;
};
} // namespace crepe
#include "Private.hpp"
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