libcryfs/pointer/optional_ownership_ptr.h

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#pragma once
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#ifndef MESSMER_CPPUTILS_POINTER_OPTIONALOWNERSHIPPOINTER_H_
#define MESSMER_CPPUTILS_POINTER_OPTIONALOWNERSHIPPOINTER_H_
#include "unique_ref.h"
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#include <functional>
/**
* optional_ownership_ptr can be used to hold a pointer to an instance of an object.
* The pointer might or might not have ownership of the object.
*
* If it has ownership, it will delete the stored object in its destructor.
* If it doesn't have ownership, it won't.
*
* You can create such pointers with
* - WithOwnership(ptr)
* - WithoutOwnership(ptr)
* - null()
*/
namespace cpputils {
template<typename T>
using optional_ownership_ptr = std::unique_ptr<T, std::function<void(T*)>>;
template<typename T>
optional_ownership_ptr<T> WithOwnership(std::unique_ptr<T> obj) {
auto deleter = obj.get_deleter();
return optional_ownership_ptr<T>(obj.release(), [deleter](T* obj){deleter(obj);});
}
template <typename T>
optional_ownership_ptr<T> WithOwnership(unique_ref<T> obj) {
return WithOwnership(to_unique_ptr(std::move(obj)));
}
template<typename T>
optional_ownership_ptr<T> WithoutOwnership(T *obj) {
return optional_ownership_ptr<T>(obj, [](T*){});
}
template<typename T>
optional_ownership_ptr<T> null() {
return WithoutOwnership<T>(nullptr);
}
}
#endif