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#pragma once
#include <memory>
#include <exception>
#include <stdexcept>
namespace nix {
/* A simple non-nullable reference-counted pointer. Actually a wrapper
around std::shared_ptr that prevents non-null constructions. */
template<typename T>
class ref
{
private:
std::shared_ptr<T> p;
public:
ref<T>(const ref<T> & r)
: p(r.p)
{ }
explicit ref<T>(const std::shared_ptr<T> & p)
: p(p)
{
if (!p)
throw std::invalid_argument("null pointer cast to ref");
}
explicit ref<T>(T * p)
: p(p)
{
if (!p)
throw std::invalid_argument("null pointer cast to ref");
}
T* operator ->() const
{
return &*p;
}
T& operator *() const
{
return *p;
}
operator std::shared_ptr<T> ()
{
return p;
}
template<typename T2>
ref<T2> cast()
{
return ref<T2>(std::dynamic_pointer_cast<T2>(p));
}
template<typename T2>
operator ref<T2> ()
{
return ref<T2>((std::shared_ptr<T2>) p);
}
private:
template<typename T2, typename... Args>
friend ref<T2>
make_ref(Args&&... args);
};
template<typename T, typename... Args>
inline ref<T>
make_ref(Args&&... args)
{
auto p = std::make_shared<T>(std::forward<Args>(args)...);
return ref<T>(p);
}
}
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