Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 538 insertions, 0 deletions

diff --git a/xpcom/ds/nsDeque.h b/xpcom/ds/nsDeque.h
new file mode 100644
index 0000000000..4f0bf27037
--- /dev/null
+++ b/xpcom/ds/nsDeque.h
@@ -0,0 +1,538 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * MODULE NOTES:
+ *
+ * The Deque is a very small, very efficient container object
+ * than can hold items of type T*, offering the following features:
+ * - Its interface supports pushing, popping, and peeking of items at the back
+ *   or front, and retrieval from any position.
+ * - It can iterate over items via a ForEach method, range-for, or an iterator
+ *   class.
+ * - When full, it can efficiently resize dynamically.
+ *
+ * NOTE: The only bit of trickery here is that this deque is
+ * built upon a ring-buffer. Like all ring buffers, the first
+ * item may not be at index[0]. The mOrigin member determines
+ * where the first child is. This point is quietly hidden from
+ * customers of this class.
+ */
+
+#ifndef _NSDEQUE
+#define _NSDEQUE
+#include <cstddef>
+
+#include "mozilla/AlreadyAddRefed.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/fallible.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/RefPtr.h"
+#include "nsCOMPtr.h"
+#include "nsDebug.h"
+#include "nsISupports.h"
+
+namespace mozilla {
+
+namespace detail {
+/**
+ * The deque (double-ended queue) class is a common container type,
+ * whose behavior mimics a line in your favorite checkout stand.
+ * Classic CS describes the common behavior of a queue as FIFO.
+ * A deque allows insertion and removal at both ends of
+ * the container.
+ *
+ * nsDequeBase implements the untyped deque data structure while
+ * nsDeque provides the typed implementation and iterators.
+ */
+class nsDequeBase {
+ public:
+  /**
+   * Returns the number of items currently stored in
+   * this deque.
+   *
+   * @return  number of items currently in the deque
+   */
+  inline size_t GetSize() const { return mSize; }
+
+ protected:
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+  /**
+   * Constructs an empty deque.
+   *
+   * @param   aDeallocator Optional deallocator functor that will be called from
+   *                       Erase() and the destructor on any remaining item.
+   *                       The deallocator is owned by the deque and will be
+   *                       deleted at destruction time.
+   */
+  explicit nsDequeBase();
+
+  /**
+   * Deque destructor. Erases all items, deletes the deallocator.
+   */
+  ~nsDequeBase();
+
+  /**
+   * Appends new member at the end of the deque.
+   *
+   * @param   aItem item to store in deque
+   * @return  true if succeeded, false if failed to resize deque as needed
+   */
+  [[nodiscard]] bool Push(void* aItem, const fallible_t&);
+
+  /**
+   * Inserts new member at the front of the deque.
+   *
+   * @param   aItem item to store in deque
+   * @return  true if succeeded, false if failed to resize deque as needed
+   */
+  [[nodiscard]] bool PushFront(void* aItem, const fallible_t&);
+
+  /**
+   * Remove and return the last item in the container.
+   *
+   * @return  the item that was the last item in container
+   */
+  void* Pop();
+
+  /**
+   * Remove and return the first item in the container.
+   *
+   * @return  the item that was first item in container
+   */
+  void* PopFront();
+
+  /**
+   * Retrieve the last item without removing it.
+   *
+   * @return  the last item in container
+   */
+  void* Peek() const;
+
+  /**
+   * Retrieve the first item without removing it.
+   *
+   * @return  the first item in container
+   */
+  void* PeekFront() const;
+
+  /**
+   * Retrieve a member from the deque without removing it.
+   *
+   * @param   index of desired item
+   * @return  item in list, or nullptr if index is outside the deque
+   */
+  void* ObjectAt(size_t aIndex) const;
+
+  bool GrowCapacity();
+
+  /**
+   * Remove all items from container without destroying them.
+   */
+  void Empty();
+
+  size_t mSize;
+  size_t mCapacity;
+  size_t mOrigin;
+  void* mBuffer[8];
+  void** mData;
+
+  nsDequeBase& operator=(const nsDequeBase& aOther) = delete;
+  nsDequeBase(const nsDequeBase& aOther) = delete;
+};
+
+// This iterator assumes that the deque itself is const, i.e., it cannot be
+// modified while the iterator is used.
+// Also it is a 'const' iterator in that it provides copies of the deque's
+// elements, and therefore it is not possible to modify the deque's contents
+// by assigning to a dereference of this iterator.
+template <typename Deque>
+class ConstDequeIterator {
+ public:
+  ConstDequeIterator(const Deque& aDeque, size_t aIndex)
+      : mDeque(aDeque), mIndex(aIndex) {}
+  ConstDequeIterator& operator++() {
+    ++mIndex;
+    return *this;
+  }
+  bool operator==(const ConstDequeIterator& aOther) const {
+    return mIndex == aOther.mIndex;
+  }
+  bool operator!=(const ConstDequeIterator& aOther) const {
+    return mIndex != aOther.mIndex;
+  }
+  typename Deque::PointerType operator*() const {
+    // Don't allow out-of-deque dereferences.
+    MOZ_RELEASE_ASSERT(mIndex < mDeque.GetSize());
+    return mDeque.ObjectAt(mIndex);
+  }
+
+ private:
+  const Deque& mDeque;
+  size_t mIndex;
+};
+
+// It is a 'const' iterator in that it provides copies of the deque's
+// elements, and therefore it is not possible to modify the deque's contents
+// by assigning to a dereference of this iterator.
+// If the deque is modified in other ways, this iterator will stay at the same
+// index, and will handle past-the-end comparisons, but not dereferencing.
+template <typename Deque>
+class ConstIterator {
+ public:
+  // Special index for the end iterator, to track the possibly-shifting
+  // deque size.
+  static const size_t EndIteratorIndex = size_t(-1);
+
+  ConstIterator(const Deque& aDeque, size_t aIndex)
+      : mDeque(aDeque), mIndex(aIndex) {}
+  ConstIterator& operator++() {
+    // End-iterator shouldn't be modified.
+    MOZ_ASSERT(mIndex != EndIteratorIndex);
+    ++mIndex;
+    return *this;
+  }
+  bool operator==(const ConstIterator& aOther) const {
+    return EffectiveIndex() == aOther.EffectiveIndex();
+  }
+  bool operator!=(const ConstIterator& aOther) const {
+    return EffectiveIndex() != aOther.EffectiveIndex();
+  }
+  typename Deque::PointerType operator*() const {
+    // Don't allow out-of-deque dereferences.
+    MOZ_RELEASE_ASSERT(mIndex < mDeque.GetSize());
+    return mDeque.ObjectAt(mIndex);
+  }
+
+ private:
+  // 0 <= index < deque.GetSize() inside the deque, deque.GetSize() otherwise.
+  // Only used when comparing indices, not to actually access items.
+  size_t EffectiveIndex() const {
+    return (mIndex < mDeque.GetSize()) ? mIndex : mDeque.GetSize();
+  }
+
+  const Deque& mDeque;
+  size_t mIndex;  // May point outside the deque!
+};
+
+}  // namespace detail
+}  // namespace mozilla
+
+/**
+ * The nsDequeFunctor class is used when you want to create
+ * callbacks between the deque and your generic code.
+ * Use these objects in a call to ForEach(), and as custom deallocators.
+ */
+template <typename T>
+class nsDequeFunctor {
+ public:
+  virtual void operator()(T* aObject) = 0;
+  virtual ~nsDequeFunctor() = default;
+};
+
+/******************************************************
+ * Here comes the nsDeque class itself...
+ ******************************************************/
+
+/**
+ * The deque (double-ended queue) class is a common container type,
+ * whose behavior mimics a line in your favorite checkout stand.
+ * Classic CS describes the common behavior of a queue as FIFO.
+ * A deque allows insertion and removal at both ends of
+ * the container.
+ *
+ * The deque stores pointers to items.
+ */
+template <typename T>
+class nsDeque : public mozilla::detail::nsDequeBase {
+  typedef mozilla::fallible_t fallible_t;
+
+ public:
+  using PointerType = T*;
+  using ConstDequeIterator = mozilla::detail::ConstDequeIterator<nsDeque<T>>;
+  using ConstIterator = mozilla::detail::ConstIterator<nsDeque<T>>;
+
+  /**
+   * Constructs an empty deque.
+   *
+   * @param   aDeallocator Optional deallocator functor that will be called from
+   *                       Erase() and the destructor on any remaining item.
+   *                       The deallocator is owned by the deque and will be
+   *                       deleted at destruction time.
+   */
+  explicit nsDeque(nsDequeFunctor<T>* aDeallocator = nullptr) {
+    MOZ_COUNT_CTOR(nsDeque);
+    mDeallocator = aDeallocator;
+  }
+
+  /**
+   * Deque destructor. Erases all items, deletes the deallocator.
+   */
+  ~nsDeque() {
+    MOZ_COUNT_DTOR(nsDeque);
+
+    Erase();
+    SetDeallocator(nullptr);
+  }
+
+  /**
+   * Appends new member at the end of the deque.
+   *
+   * @param   aItem item to store in deque
+   */
+  inline void Push(T* aItem) {
+    if (!nsDequeBase::Push(aItem, mozilla::fallible)) {
+      NS_ABORT_OOM(mSize * sizeof(T*));
+    }
+  }
+
+  /**
+   * Appends new member at the end of the deque.
+   *
+   * @param   aItem item to store in deque
+   * @return  true if succeeded, false if failed to resize deque as needed
+   */
+  [[nodiscard]] inline bool Push(T* aItem, const fallible_t& aFaillible) {
+    return nsDequeBase::Push(aItem, aFaillible);
+  }
+
+  /**
+   * Inserts new member at the front of the deque.
+   *
+   * @param   aItem item to store in deque
+   */
+  inline void PushFront(T* aItem) {
+    if (!nsDequeBase::PushFront(aItem, mozilla::fallible)) {
+      NS_ABORT_OOM(mSize * sizeof(T*));
+    }
+  }
+
+  /**
+   * Inserts new member at the front of the deque.
+   *
+   * @param   aItem item to store in deque
+   * @return  true if succeeded, false if failed to resize deque as needed
+   */
+  [[nodiscard]] bool PushFront(T* aItem, const fallible_t& aFallible) {
+    return nsDequeBase::PushFront(aItem, aFallible);
+  }
+
+  /**
+   * Remove and return the last item in the container.
+   *
+   * @return  the item that was the last item in container
+   */
+  inline T* Pop() { return static_cast<T*>(nsDequeBase::Pop()); }
+
+  /**
+   * Remove and return the first item in the container.
+   *
+   * @return  the item that was first item in container
+   */
+  inline T* PopFront() { return static_cast<T*>(nsDequeBase::PopFront()); }
+
+  /**
+   * Retrieve the last item without removing it.
+   *
+   * @return  the last item in container
+   */
+  inline T* Peek() const { return static_cast<T*>(nsDequeBase::Peek()); }
+
+  /**
+   * Retrieve the first item without removing it.
+   *
+   * @return  the first item in container
+   */
+  inline T* PeekFront() const {
+    return static_cast<T*>(nsDequeBase::PeekFront());
+  }
+
+  /**
+   * Retrieve a member from the deque without removing it.
+   *
+   * @param   index of desired item
+   * @return  item in list, or nullptr if index is outside the deque
+   */
+  inline T* ObjectAt(size_t aIndex) const {
+    if (NS_WARN_IF(aIndex >= GetSize())) {
+      return nullptr;
+    }
+    return static_cast<T*>(nsDequeBase::ObjectAt(aIndex));
+  }
+
+  /**
+   * Remove and delete all items from container.
+   * Deletes are handled by the deallocator nsDequeFunctor
+   * which is specified at deque construction.
+   */
+  void Erase() {
+    if (mDeallocator && mSize) {
+      ForEach(*mDeallocator);
+    }
+    Empty();
+  }
+
+  /**
+   * Call this method when you want to iterate through all
+   * items in the container, passing a functor along
+   * to call your code.
+   * If the deque is modified during ForEach, iteration will continue based on
+   * item indices; meaning that front operations may effectively skip over
+   * items or visit some items multiple times.
+   *
+   * @param   aFunctor object to call for each member
+   */
+  void ForEach(nsDequeFunctor<T>& aFunctor) const {
+    for (size_t i = 0; i < mSize; ++i) {
+      aFunctor(ObjectAt(i));
+    }
+  }
+
+  // If this deque is const, we can provide ConstDequeIterator's.
+  ConstDequeIterator begin() const { return ConstDequeIterator(*this, 0); }
+  ConstDequeIterator end() const { return ConstDequeIterator(*this, mSize); }
+
+  // If this deque is *not* const, we provide ConstIterator's that can handle
+  // deque size changes.
+  ConstIterator begin() { return ConstIterator(*this, 0); }
+  ConstIterator end() {
+    return ConstIterator(*this, ConstIterator::EndIteratorIndex);
+  }
+
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    size_t size = nsDequeBase::SizeOfExcludingThis(aMallocSizeOf);
+    if (mDeallocator) {
+      size += aMallocSizeOf(mDeallocator);
+    }
+    return size;
+  }
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+ protected:
+  nsDequeFunctor<T>* mDeallocator;
+
+ private:
+  /**
+   * Copy constructor (deleted)
+   *
+   * @param aOther another deque
+   */
+  nsDeque(const nsDeque& aOther) = delete;
+
+  /**
+   * Deque assignment operator (deleted)
+   *
+   * @param aOther another deque
+   * @return *this
+   */
+  nsDeque& operator=(const nsDeque& aOther) = delete;
+
+  void SetDeallocator(nsDequeFunctor<T>* aDeallocator) {
+    delete mDeallocator;
+    mDeallocator = aDeallocator;
+  }
+};
+
+/**
+ * Specialization of nsDeque for reference counted pointers.
+ *
+ * Provides builtin reference handling as part of Push/Peek/Pop
+ */
+template <typename T>
+class nsRefPtrDeque : private nsDeque<T> {
+  typedef mozilla::fallible_t fallible_t;
+
+  class RefPtrDeallocator : public nsDequeFunctor<T> {
+   public:
+    virtual void operator()(T* aObject) override {
+      RefPtr<T> releaseMe = dont_AddRef(aObject);
+    }
+  };
+
+ public:
+  using PointerType = RefPtr<T>;
+  using ConstDequeIterator =
+      mozilla::detail::ConstDequeIterator<nsRefPtrDeque<T>>;
+  using ConstIterator = mozilla::detail::ConstIterator<nsRefPtrDeque<T>>;
+
+  explicit nsRefPtrDeque() : nsDeque<T>(new RefPtrDeallocator()) {}
+
+  inline void PushFront(already_AddRefed<T> aItem) {
+    T* item = aItem.take();
+    nsDeque<T>::PushFront(item);
+  }
+
+  inline void PushFront(T* aItem) { PushFront(do_AddRef(aItem)); }
+
+  inline void Push(T* aItem) { Push(do_AddRef(aItem)); }
+
+  inline void Push(already_AddRefed<T> aItem) {
+    T* item = aItem.take();
+    nsDeque<T>::Push(item);
+  }
+
+  inline already_AddRefed<T> PopFront() {
+    return dont_AddRef(nsDeque<T>::PopFront());
+  }
+
+  inline already_AddRefed<T> Pop() { return dont_AddRef(nsDeque<T>::Pop()); }
+
+  inline T* PeekFront() const { return nsDeque<T>::PeekFront(); }
+
+  inline T* Peek() const { return nsDeque<T>::Peek(); }
+
+  inline T* ObjectAt(size_t aIndex) const {
+    return nsDeque<T>::ObjectAt(aIndex);
+  }
+
+  inline void Erase() { nsDeque<T>::Erase(); }
+
+  // If this deque is const, we can provide ConstDequeIterator's.
+  ConstDequeIterator begin() const { return ConstDequeIterator(*this, 0); }
+  ConstDequeIterator end() const {
+    return ConstDequeIterator(*this, GetSize());
+  }
+
+  // If this deque is *not* const, we provide ConstIterator's that can handle
+  // deque size changes.
+  ConstIterator begin() { return ConstIterator(*this, 0); }
+  ConstIterator end() {
+    return ConstIterator(*this, ConstIterator::EndIteratorIndex);
+  }
+
+  inline size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    return nsDeque<T>::SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  inline size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    return nsDeque<T>::SizeOfIncludingThis(aMallocSizeOf);
+  }
+
+  inline size_t GetSize() const { return nsDeque<T>::GetSize(); }
+
+  /**
+   * Call this method when you want to iterate through all
+   * items in the container, passing a functor along
+   * to call your code.
+   * If the deque is modified during ForEach, iteration will continue based on
+   * item indices; meaning that front operations may effectively skip over
+   * items or visit some items multiple times.
+   *
+   * @param   aFunctor object to call for each member
+   */
+  void ForEach(nsDequeFunctor<T>& aFunctor) const {
+    size_t size = GetSize();
+    for (size_t i = 0; i < size; ++i) {
+      aFunctor(ObjectAt(i));
+    }
+  }
+};
+
+#endif