Move shared files in net/quic/ into net/quic/core/

net/quic/quic_arena_scoped_ptr.h

-// Copyright (c) 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// unique_ptr-style pointer that stores values that may be from an arena. Takes
-// up the same storage as the platform's native pointer type. Takes ownership
-// of the value it's constructed with; if holding a value in an arena, and the
-// type has a non-trivial destructor, the arena must outlive the
-// QuicArenaScopedPtr. Does not support array overloads.
-
-#ifndef NET_QUIC_QUIC_ARENA_SCOPED_PTR_H_
-#define NET_QUIC_QUIC_ARENA_SCOPED_PTR_H_
-
-#include <cstdint>  // for uintptr_t
-
-#include "base/logging.h"
-#include "base/macros.h"
-#include "net/quic/quic_utils.h"
-
-namespace net {
-
-template <typename T>
-class QuicArenaScopedPtr {
-  static_assert(QUIC_ALIGN_OF(T*) > 1,
-                "QuicArenaScopedPtr can only store objects that are aligned to "
-                "greater than 1 byte.");
-
- public:
-  // Constructs an empty QuicArenaScopedPtr.
-  QuicArenaScopedPtr();
-
-  // Constructs a QuicArenaScopedPtr referencing the heap-allocated memory
-  // provided.
-  explicit QuicArenaScopedPtr(T* value);
-
-  template <typename U>
-  QuicArenaScopedPtr(QuicArenaScopedPtr<U>&& other);  // NOLINT
-  template <typename U>
-  QuicArenaScopedPtr& operator=(QuicArenaScopedPtr<U>&& other);
-  ~QuicArenaScopedPtr();
-
-  // Returns a pointer to the value.
-  T* get() const;
-
-  // Returns a reference to the value.
-  T& operator*() const;
-
-  // Returns a pointer to the value.
-  T* operator->() const;
-
-  // Swaps the value of this pointer with |other|.
-  void swap(QuicArenaScopedPtr& other);
-
-  // Resets the held value to |value|.
-  void reset(T* value = nullptr);
-
-  // Returns true if |this| came from an arena. Primarily exposed for testing
-  // and assertions.
-  bool is_from_arena();
-
- private:
-  // Friends with other derived types of QuicArenaScopedPtr, to support the
-  // derived-types case.
-  template <typename U>
-  friend class QuicArenaScopedPtr;
-  // Also befriend all known arenas, only to prevent misuse.
-  template <uint32_t ArenaSize>
-  friend class QuicOneBlockArena;
-
-  // Tag to denote that a QuicArenaScopedPtr is being explicitly created by an
-  // arena.
-  enum class ConstructFrom { kHeap, kArena };
-
-  // Constructs a QuicArenaScopedPtr with the given representation.
-  QuicArenaScopedPtr(void* value, ConstructFrom from);
-
-  // Low-order bits of value_ that determine if the pointer came from an arena.
-  static const uintptr_t kFromArenaMask = 0x1;
-
-  // Every platform we care about has at least 4B aligned integers, so store the
-  // is_from_arena bit in the least significant bit.
-  void* value_;
-
-  DISALLOW_COPY_AND_ASSIGN(QuicArenaScopedPtr);
-};
-
-template <typename T>
-bool operator==(const QuicArenaScopedPtr<T>& left,
-                const QuicArenaScopedPtr<T>& right) {
-  return left.get() == right.get();
-}
-
-template <typename T>
-bool operator!=(const QuicArenaScopedPtr<T>& left,
-                const QuicArenaScopedPtr<T>& right) {
-  return left.get() != right.get();
-}
-
-template <typename T>
-bool operator==(std::nullptr_t, const QuicArenaScopedPtr<T>& right) {
-  return nullptr == right.get();
-}
-
-template <typename T>
-bool operator!=(std::nullptr_t, const QuicArenaScopedPtr<T>& right) {
-  return nullptr != right.get();
-}
-
-template <typename T>
-bool operator==(const QuicArenaScopedPtr<T>& left, std::nullptr_t) {
-  return left.get() == nullptr;
-}
-
-template <typename T>
-bool operator!=(const QuicArenaScopedPtr<T>& left, std::nullptr_t) {
-  return left.get() != nullptr;
-}
-
-template <typename T>
-QuicArenaScopedPtr<T>::QuicArenaScopedPtr()
-    : value_(nullptr) {}
-
-template <typename T>
-QuicArenaScopedPtr<T>::QuicArenaScopedPtr(T* value)
-    : QuicArenaScopedPtr(value, ConstructFrom::kHeap) {}
-
-template <typename T>
-template <typename U>
-QuicArenaScopedPtr<T>::QuicArenaScopedPtr(QuicArenaScopedPtr<U>&& other)
-    : value_(other.value_) {
-  static_assert(
-      std::is_base_of<T, U>::value || std::is_same<T, U>::value,
-      "Cannot construct QuicArenaScopedPtr; type is not derived or same.");
-  other.value_ = nullptr;
-}
-
-template <typename T>
-template <typename U>
-QuicArenaScopedPtr<T>& QuicArenaScopedPtr<T>::operator=(
-    QuicArenaScopedPtr<U>&& other) {
-  static_assert(
-      std::is_base_of<T, U>::value || std::is_same<T, U>::value,
-      "Cannot assign QuicArenaScopedPtr; type is not derived or same.");
-  swap(other);
-  return *this;
-}
-
-template <typename T>
-QuicArenaScopedPtr<T>::~QuicArenaScopedPtr() {
-  reset();
-}
-
-template <typename T>
-T* QuicArenaScopedPtr<T>::get() const {
-  return reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(value_) &
-                              ~kFromArenaMask);
-}
-
-template <typename T>
-T& QuicArenaScopedPtr<T>::operator*() const {
-  return *get();
-}
-
-template <typename T>
-T* QuicArenaScopedPtr<T>::operator->() const {
-  return get();
-}
-
-template <typename T>
-void QuicArenaScopedPtr<T>::swap(QuicArenaScopedPtr& other) {
-  using std::swap;
-  swap(value_, other.value_);
-}
-
-template <typename T>
-bool QuicArenaScopedPtr<T>::is_from_arena() {
-  return (reinterpret_cast<uintptr_t>(value_) & kFromArenaMask) != 0;
-}
-
-template <typename T>
-void QuicArenaScopedPtr<T>::reset(T* value) {
-  if (value_ != nullptr) {
-    if (is_from_arena()) {
-      // Manually invoke the destructor.
-      get()->~T();
-    } else {
-      delete get();
-    }
-  }
-  DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(value) & kFromArenaMask);
-  value_ = value;
-}
-
-template <typename T>
-QuicArenaScopedPtr<T>::QuicArenaScopedPtr(void* value, ConstructFrom from_arena)
-    : value_(value) {
-  DCHECK_EQ(0u, reinterpret_cast<uintptr_t>(value_) & kFromArenaMask);
-  switch (from_arena) {
-    case ConstructFrom::kHeap:
-      break;
-    case ConstructFrom::kArena:
-      value_ = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(value_) |
-                                       QuicArenaScopedPtr<T>::kFromArenaMask);
-      break;
-  }
-}
-
-}  // namespace net
-
-#endif  // NET_QUIC_QUIC_ARENA_SCOPED_PTR_H_