zircon/system/ulib/fbl/include/fbl/intrusive_pointer_traits.h

// Copyright 2016 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef FBL_INTRUSIVE_POINTER_TRAITS_H_
#define FBL_INTRUSIVE_POINTER_TRAITS_H_

#include <stdint.h>
#include <zircon/compiler.h>

#include <memory>

#include <fbl/ref_ptr.h>

namespace fbl {
namespace internal {

// Declaration of the base type which will be used to control what type of
// pointers are permitted to be in containers.
template <typename T>
struct ContainerPtrTraits;

// Traits for managing raw pointers.
template <typename T>
struct ContainerPtrTraits<T*> {
  using ValueType = T;
  using RefType = T&;
  using ConstRefType = const T&;
  using PtrType = T*;
  using ConstPtrType = const T*;
  using RawPtrType = T*;
  using ConstRawPtrType = const T*;

  static constexpr bool IsManaged = false;
  static constexpr bool CanCopy = true;

  static inline T* GetRaw(const PtrType& ptr) { return ptr; }
  static inline T* Copy(const RawPtrType& ptr) { return ptr; }

  static inline RawPtrType Leak(PtrType& ptr) __WARN_UNUSED_RESULT { return ptr; }

  static inline PtrType Reclaim(RawPtrType ptr) { return ptr; }
};

// Traits for managing std::unique_ptrs to objects (arrays of objects are not supported)
template <typename T, typename Deleter>
struct ContainerPtrTraits<::std::unique_ptr<T, Deleter>> {
  using ValueType = T;
  using RefType = T&;
  using ConstRefType = const T&;
  using PtrType = ::std::unique_ptr<T, Deleter>;
  using ConstPtrType = ::std::unique_ptr<const T, Deleter>;
  using RawPtrType = T*;
  using ConstRawPtrType = const T*;

  static constexpr bool IsManaged = true;
  static constexpr bool CanCopy = false;

  static inline T* GetRaw(const PtrType& ptr) { return ptr.get(); }

  static inline RawPtrType Leak(PtrType& ptr) __WARN_UNUSED_RESULT { return ptr.release(); }

  static inline PtrType Reclaim(RawPtrType ptr) { return PtrType(ptr); }
};

// Traits for managing ref_counted pointers.
template <typename T>
struct ContainerPtrTraits<::fbl::RefPtr<T>> {
  using ValueType = T;
  using RefType = T&;
  using ConstRefType = const T&;
  using PtrType = ::fbl::RefPtr<T>;
  using ConstPtrType = ::fbl::RefPtr<const T>;
  using RawPtrType = T*;
  using ConstRawPtrType = const T*;

  static constexpr bool IsManaged = true;
  static constexpr bool CanCopy = true;

  static inline T* GetRaw(const PtrType& ptr) { return ptr.get(); }
  static inline PtrType Copy(const RawPtrType& ptr) { return PtrType(ptr); }

  static inline RawPtrType Leak(PtrType& ptr) __WARN_UNUSED_RESULT {
    return fbl::ExportToRawPtr(&ptr);
  }

  static inline PtrType Reclaim(RawPtrType ptr) { return ::fbl::ImportFromRawPtr(ptr); }
};

}  // namespace internal
}  // namespace fbl

#endif  // FBL_INTRUSIVE_POINTER_TRAITS_H_