intrusive_ptr.hpp

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#pragma once
 
#include <yaclib/util/ref.hpp>
 
#include <type_traits>
 
namespace yaclib {
 
struct NoRefTag final {};
 
/**
 * A intrusive pointer to objects with an embedded reference count
 *
 * https://www.boost.org/doc/libs/1_77_0/libs/smart_ptr/doc/html/smart_ptr.html#intrusive_ptr
 */
template <typename T>
class IntrusivePtr final {
  static_assert(std::is_base_of_v<IRef, T>, "T must be derived class of IRef");
 
 public:
  using Value = T;
 
  IntrusivePtr() noexcept;
 
  IntrusivePtr(T* other) noexcept;
  IntrusivePtr(IntrusivePtr&& other) noexcept;
  IntrusivePtr(const IntrusivePtr& other) noexcept;
 
  IntrusivePtr& operator=(T* other) noexcept;
  IntrusivePtr& operator=(IntrusivePtr&& other) noexcept;
  IntrusivePtr& operator=(const IntrusivePtr& other) noexcept;
 
  template <typename U>
  IntrusivePtr(IntrusivePtr<U>&& other) noexcept;
  template <typename U>
  IntrusivePtr(const IntrusivePtr<U>& other) noexcept;
 
  template <typename U>
  IntrusivePtr& operator=(IntrusivePtr<U>&& other) noexcept;
  template <typename U>
  IntrusivePtr& operator=(const IntrusivePtr<U>& other) noexcept;
 
  ~IntrusivePtr() noexcept;
 
  T* Get() const noexcept;
  T* Release() noexcept;
 
  explicit operator bool() const noexcept;
 
  T& operator*() const noexcept;
  T* operator->() const noexcept;
 
  void Swap(IntrusivePtr& other) noexcept;
 
  IntrusivePtr(NoRefTag, T* other) noexcept;
  void Reset(NoRefTag, T* other) noexcept;
 
 private:
  template <typename U>
  friend class IntrusivePtr;
 
  T* _ptr;
};
 
template <typename T, typename U>
inline bool operator==(const IntrusivePtr<T>& lhs, const IntrusivePtr<U>& rhs) noexcept {
  return lhs.Get() == rhs.Get();
}
 
template <typename T, typename U>
inline bool operator!=(const IntrusivePtr<T>& lhs, const IntrusivePtr<U>& rhs) noexcept {
  return lhs.Get() != rhs.Get();
}
 
template <typename T, typename U>
inline bool operator==(const IntrusivePtr<T>& lhs, U* rhs) noexcept {
  return lhs.Get() == rhs;
}
 
template <typename T, typename U>
inline bool operator!=(const IntrusivePtr<T>& lhs, U* rhs) noexcept {
  return lhs.Get() != rhs;
}
 
template <typename T, typename U>
inline bool operator==(T* lhs, const IntrusivePtr<U>& rhs) noexcept {
  return lhs == rhs.Get();
}
 
template <typename T, typename U>
inline bool operator!=(T* lhs, const IntrusivePtr<U>& rhs) noexcept {
  return lhs != rhs.Get();
}
 
template <typename T>
inline bool operator==(const IntrusivePtr<T>& lhs, std::nullptr_t) noexcept {
  return lhs.Get() == nullptr;
}
 
template <typename T>
inline bool operator==(std::nullptr_t, const IntrusivePtr<T>& rhs) noexcept {
  return rhs.Get() == nullptr;
}
 
template <typename T>
inline bool operator!=(const IntrusivePtr<T>& lhs, std::nullptr_t) noexcept {
  return lhs.Get() != nullptr;
}
 
template <typename T>
inline bool operator!=(std::nullptr_t, const IntrusivePtr<T>& rhs) noexcept {
  return rhs.Get() != nullptr;
}
 
template <typename T>
inline bool operator<(const IntrusivePtr<T>& lhs, const IntrusivePtr<T>& rhs) noexcept {
  return lhs.Get() < rhs.Get();
}
 
}  // namespace yaclib
 
#include <yaclib/util/detail/intrusive_ptr_impl.hpp>