Adding upstream version 115.7.0esr.upstream/115.7.0esr

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

1 files changed, 966 insertions, 0 deletions

diff --git a/xpcom/ds/nsTHashtable.h b/xpcom/ds/nsTHashtable.h
new file mode 100644
index 0000000000..d4a385551f
--- /dev/null
+++ b/xpcom/ds/nsTHashtable.h
@@ -0,0 +1,966 @@
+/* -*- 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/. */
+
+// See the comment at the top of mfbt/HashTable.h for a comparison between
+// PLDHashTable and mozilla::HashTable.
+
+#ifndef nsTHashtable_h__
+#define nsTHashtable_h__
+
+#include <iterator>
+#include <new>
+#include <type_traits>
+#include <utility>
+
+#include "PLDHashTable.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/OperatorNewExtensions.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/fallible.h"
+#include "nsPointerHashKeys.h"
+#include "nsTArrayForwardDeclare.h"
+
+template <class EntryType>
+class nsTHashtable;
+
+namespace detail {
+class nsTHashtableIteratorBase {
+ public:
+  using EndIteratorTag = PLDHashTable::Iterator::EndIteratorTag;
+
+  nsTHashtableIteratorBase(nsTHashtableIteratorBase&& aOther) = default;
+
+  nsTHashtableIteratorBase& operator=(nsTHashtableIteratorBase&& aOther) {
+    // User-defined because the move assignment operator is deleted in
+    // PLDHashtable::Iterator.
+    return operator=(static_cast<const nsTHashtableIteratorBase&>(aOther));
+  }
+
+  nsTHashtableIteratorBase(const nsTHashtableIteratorBase& aOther)
+      : mIterator{aOther.mIterator.Clone()} {}
+  nsTHashtableIteratorBase& operator=(const nsTHashtableIteratorBase& aOther) {
+    // Since PLDHashTable::Iterator has no assignment operator, we destroy and
+    // recreate mIterator.
+    mIterator.~Iterator();
+    new (&mIterator) PLDHashTable::Iterator(aOther.mIterator.Clone());
+    return *this;
+  }
+
+  explicit nsTHashtableIteratorBase(PLDHashTable::Iterator aFrom)
+      : mIterator{std::move(aFrom)} {}
+
+  explicit nsTHashtableIteratorBase(const PLDHashTable& aTable)
+      : mIterator{&const_cast<PLDHashTable&>(aTable)} {}
+
+  nsTHashtableIteratorBase(const PLDHashTable& aTable, EndIteratorTag aTag)
+      : mIterator{&const_cast<PLDHashTable&>(aTable), aTag} {}
+
+  bool operator==(const nsTHashtableIteratorBase& aRhs) const {
+    return mIterator == aRhs.mIterator;
+  }
+  bool operator!=(const nsTHashtableIteratorBase& aRhs) const {
+    return !(*this == aRhs);
+  }
+
+ protected:
+  PLDHashTable::Iterator mIterator;
+};
+
+// STL-style iterators to allow the use in range-based for loops, e.g.
+template <typename T>
+class nsTHashtableEntryIterator : public nsTHashtableIteratorBase {
+  friend class nsTHashtable<std::remove_const_t<T>>;
+
+ public:
+  using iterator_category = std::forward_iterator_tag;
+  using value_type = T;
+  using difference_type = int32_t;
+  using pointer = value_type*;
+  using reference = value_type&;
+
+  using iterator_type = nsTHashtableEntryIterator;
+  using const_iterator_type = nsTHashtableEntryIterator<const T>;
+
+  using nsTHashtableIteratorBase::nsTHashtableIteratorBase;
+
+  value_type* operator->() const {
+    return static_cast<value_type*>(mIterator.Get());
+  }
+  value_type& operator*() const {
+    return *static_cast<value_type*>(mIterator.Get());
+  }
+
+  iterator_type& operator++() {
+    mIterator.Next();
+    return *this;
+  }
+  iterator_type operator++(int) {
+    iterator_type it = *this;
+    ++*this;
+    return it;
+  }
+
+  operator const_iterator_type() const {
+    return const_iterator_type{mIterator.Clone()};
+  }
+};
+
+template <typename EntryType>
+class nsTHashtableKeyIterator : public nsTHashtableIteratorBase {
+  friend class nsTHashtable<EntryType>;
+
+ public:
+  using iterator_category = std::forward_iterator_tag;
+  using value_type = const std::decay_t<typename EntryType::KeyType>;
+  using difference_type = int32_t;
+  using pointer = value_type*;
+  using reference = value_type&;
+
+  using iterator_type = nsTHashtableKeyIterator;
+  using const_iterator_type = nsTHashtableKeyIterator;
+
+  using nsTHashtableIteratorBase::nsTHashtableIteratorBase;
+
+  value_type* operator->() const {
+    return &static_cast<const EntryType*>(mIterator.Get())->GetKey();
+  }
+  decltype(auto) operator*() const {
+    return static_cast<const EntryType*>(mIterator.Get())->GetKey();
+  }
+
+  iterator_type& operator++() {
+    mIterator.Next();
+    return *this;
+  }
+  iterator_type operator++(int) {
+    iterator_type it = *this;
+    ++*this;
+    return it;
+  }
+};
+
+template <typename EntryType>
+class nsTHashtableKeyRange {
+ public:
+  using IteratorType = nsTHashtableKeyIterator<EntryType>;
+  using iterator = IteratorType;
+
+  explicit nsTHashtableKeyRange(const PLDHashTable& aHashtable)
+      : mHashtable{aHashtable} {}
+
+  auto begin() const { return IteratorType{mHashtable}; }
+  auto end() const {
+    return IteratorType{mHashtable, typename IteratorType::EndIteratorTag{}};
+  }
+  auto cbegin() const { return begin(); }
+  auto cend() const { return end(); }
+
+  uint32_t Count() const { return mHashtable.EntryCount(); }
+
+ private:
+  const PLDHashTable& mHashtable;
+};
+
+template <typename EntryType>
+auto RangeSize(const ::detail::nsTHashtableKeyRange<EntryType>& aRange) {
+  return aRange.Count();
+}
+
+}  // namespace detail
+
+/**
+ * a base class for templated hashtables.
+ *
+ * Clients will rarely need to use this class directly. Check the derived
+ * classes first, to see if they will meet your needs.
+ *
+ * @param EntryType  the templated entry-type class that is managed by the
+ *   hashtable. <code>EntryType</code> must extend the following declaration,
+ *   and <strong>must not declare any virtual functions or derive from classes
+ *   with virtual functions.</strong>  Any vtable pointer would break the
+ *   PLDHashTable code.
+ *<pre>   class EntryType : public PLDHashEntryHdr
+ *   {
+ *   public: or friend nsTHashtable<EntryType>;
+ *     // KeyType is what we use when Get()ing or Put()ing this entry
+ *     // this should either be a simple datatype (uint32_t, nsISupports*) or
+ *     // a const reference (const nsAString&)
+ *     typedef something KeyType;
+ *     // KeyTypePointer is the pointer-version of KeyType, because
+ *     // PLDHashTable.h requires keys to cast to <code>const void*</code>
+ *     typedef const something* KeyTypePointer;
+ *
+ *     EntryType(KeyTypePointer aKey);
+ *
+ *     // A copy or C++11 Move constructor must be defined, even if
+ *     // AllowMemMove() == true, otherwise you will cause link errors.
+ *     EntryType(const EntryType& aEnt);  // Either this...
+ *     EntryType(EntryType&& aEnt);       // ...or this
+ *
+ *     // the destructor must be defined... or you will cause link errors!
+ *     ~EntryType();
+ *
+ *     // KeyEquals(): does this entry match this key?
+ *     bool KeyEquals(KeyTypePointer aKey) const;
+ *
+ *     // KeyToPointer(): Convert KeyType to KeyTypePointer
+ *     static KeyTypePointer KeyToPointer(KeyType aKey);
+ *
+ *     // HashKey(): calculate the hash number
+ *     static PLDHashNumber HashKey(KeyTypePointer aKey);
+ *
+ *     // ALLOW_MEMMOVE can we move this class with memmove(), or do we have
+ *     // to use the copy constructor?
+ *     enum { ALLOW_MEMMOVE = true/false };
+ *   }</pre>
+ *
+ * @see nsInterfaceHashtable
+ * @see nsClassHashtable
+ * @see nsTHashMap
+ * @author "Benjamin Smedberg <bsmedberg@covad.net>"
+ */
+
+template <class EntryType>
+class MOZ_NEEDS_NO_VTABLE_TYPE nsTHashtable {
+  typedef mozilla::fallible_t fallible_t;
+  static_assert(std::is_pointer_v<typename EntryType::KeyTypePointer>,
+                "KeyTypePointer should be a pointer");
+
+ public:
+  // Separate constructors instead of default aInitLength parameter since
+  // otherwise the default no-arg constructor isn't found.
+  nsTHashtable()
+      : mTable(Ops(), sizeof(EntryType), PLDHashTable::kDefaultInitialLength) {}
+  explicit nsTHashtable(uint32_t aInitLength)
+      : mTable(Ops(), sizeof(EntryType), aInitLength) {}
+
+  /**
+   * destructor, cleans up and deallocates
+   */
+  ~nsTHashtable() = default;
+
+  nsTHashtable(nsTHashtable<EntryType>&& aOther);
+  nsTHashtable<EntryType>& operator=(nsTHashtable<EntryType>&& aOther);
+
+  nsTHashtable(const nsTHashtable<EntryType>&) = delete;
+  nsTHashtable& operator=(const nsTHashtable<EntryType>&) = delete;
+
+  /**
+   * Return the generation number for the table. This increments whenever
+   * the table data items are moved.
+   */
+  uint32_t GetGeneration() const { return mTable.Generation(); }
+
+  /**
+   * KeyType is typedef'ed for ease of use.
+   */
+  typedef typename EntryType::KeyType KeyType;
+
+  /**
+   * KeyTypePointer is typedef'ed for ease of use.
+   */
+  typedef typename EntryType::KeyTypePointer KeyTypePointer;
+
+  /**
+   * Return the number of entries in the table.
+   * @return    number of entries
+   */
+  uint32_t Count() const { return mTable.EntryCount(); }
+
+  /**
+   * Return true if the hashtable is empty.
+   */
+  bool IsEmpty() const { return Count() == 0; }
+
+  /**
+   * Get the entry associated with a key.
+   * @param     aKey the key to retrieve
+   * @return    pointer to the entry class, if the key exists; nullptr if the
+   *            key doesn't exist
+   */
+  EntryType* GetEntry(KeyType aKey) const {
+    return static_cast<EntryType*>(
+        mTable.Search(EntryType::KeyToPointer(aKey)));
+  }
+
+  /**
+   * Return true if an entry for the given key exists, false otherwise.
+   * @param     aKey the key to retrieve
+   * @return    true if the key exists, false if the key doesn't exist
+   */
+  bool Contains(KeyType aKey) const { return !!GetEntry(aKey); }
+
+  /**
+   * Infallibly get the entry associated with a key, or create a new entry,
+   * @param     aKey the key to retrieve
+   * @return    pointer to the entry retrieved; never nullptr
+   */
+  EntryType* PutEntry(KeyType aKey) {
+    // Infallible WithEntryHandle.
+    return WithEntryHandle(
+        aKey, [](auto entryHandle) { return entryHandle.OrInsert(); });
+  }
+
+  /**
+   * Fallibly get the entry associated with a key, or create a new entry,
+   * @param     aKey the key to retrieve
+   * @return    pointer to the entry retrieved; nullptr only if memory can't
+   *            be allocated
+   */
+  [[nodiscard]] EntryType* PutEntry(KeyType aKey, const fallible_t& aFallible) {
+    return WithEntryHandle(aKey, aFallible, [](auto maybeEntryHandle) {
+      return maybeEntryHandle ? maybeEntryHandle->OrInsert() : nullptr;
+    });
+  }
+
+  /**
+   * Get the entry associated with a key, or create a new entry using infallible
+   * allocation and insert that.
+   * @param     aKey the key to retrieve
+   * @param     aEntry will be assigned (if non-null) to the entry that was
+   * found or created
+   * @return    true if a new entry was created, or false if an existing entry
+   *            was found
+   */
+  [[nodiscard]] bool EnsureInserted(KeyType aKey,
+                                    EntryType** aEntry = nullptr) {
+    auto oldCount = Count();
+    EntryType* entry = PutEntry(aKey);
+    if (aEntry) {
+      *aEntry = entry;
+    }
+    return oldCount != Count();
+  }
+
+  /**
+   * Remove the entry associated with a key.
+   * @param     aKey of the entry to remove
+   */
+  void RemoveEntry(KeyType aKey) {
+    mTable.Remove(EntryType::KeyToPointer(aKey));
+  }
+
+  /**
+   * Lookup the entry associated with aKey and remove it if found, otherwise
+   * do nothing.
+   * @param     aKey of the entry to remove
+   * @return    true if an entry was found and removed, or false if no entry
+   *            was found for aKey
+   */
+  bool EnsureRemoved(KeyType aKey) {
+    auto* entry = GetEntry(aKey);
+    if (entry) {
+      RemoveEntry(entry);
+      return true;
+    }
+    return false;
+  }
+
+  /**
+   * Remove the entry associated with a key.
+   * @param aEntry   the entry-pointer to remove (obtained from GetEntry)
+   */
+  void RemoveEntry(EntryType* aEntry) { mTable.RemoveEntry(aEntry); }
+
+  /**
+   * Remove the entry associated with a key, but don't resize the hashtable.
+   * This is a low-level method, and is not recommended unless you know what
+   * you're doing. If you use it, please add a comment explaining why you
+   * didn't use RemoveEntry().
+   * @param aEntry   the entry-pointer to remove (obtained from GetEntry)
+   */
+  void RawRemoveEntry(EntryType* aEntry) { mTable.RawRemove(aEntry); }
+
+ protected:
+  class EntryHandle {
+   public:
+    EntryHandle(EntryHandle&& aOther) = default;
+    ~EntryHandle() = default;
+
+    EntryHandle(const EntryHandle&) = delete;
+    EntryHandle& operator=(const EntryHandle&) = delete;
+    EntryHandle& operator=(const EntryHandle&&) = delete;
+
+    KeyType Key() const { return mKey; }
+
+    bool HasEntry() const { return mEntryHandle.HasEntry(); }
+
+    explicit operator bool() const { return mEntryHandle.operator bool(); }
+
+    EntryType* Entry() { return static_cast<EntryType*>(mEntryHandle.Entry()); }
+
+    void Insert() { InsertInternal(); }
+
+    EntryType* OrInsert() {
+      if (!HasEntry()) {
+        Insert();
+      }
+      return Entry();
+    }
+
+    void Remove() { mEntryHandle.Remove(); }
+
+    void OrRemove() { mEntryHandle.OrRemove(); }
+
+   protected:
+    template <typename... Args>
+    void InsertInternal(Args&&... aArgs) {
+      MOZ_RELEASE_ASSERT(!HasEntry());
+      mEntryHandle.Insert([&](PLDHashEntryHdr* entry) {
+        new (mozilla::KnownNotNull, entry) EntryType(
+            EntryType::KeyToPointer(mKey), std::forward<Args>(aArgs)...);
+      });
+    }
+
+   private:
+    friend class nsTHashtable;
+
+    EntryHandle(KeyType aKey, PLDHashTable::EntryHandle&& aEntryHandle)
+        : mKey(aKey), mEntryHandle(std::move(aEntryHandle)) {}
+
+    KeyType mKey;
+    PLDHashTable::EntryHandle mEntryHandle;
+  };
+
+  template <class F>
+  auto WithEntryHandle(KeyType aKey, F&& aFunc)
+      -> std::invoke_result_t<F, EntryHandle&&> {
+    return this->mTable.WithEntryHandle(
+        EntryType::KeyToPointer(aKey),
+        [&aKey, &aFunc](auto entryHandle) -> decltype(auto) {
+          return std::forward<F>(aFunc)(
+              EntryHandle{aKey, std::move(entryHandle)});
+        });
+  }
+
+  template <class F>
+  auto WithEntryHandle(KeyType aKey, const mozilla::fallible_t& aFallible,
+                       F&& aFunc)
+      -> std::invoke_result_t<F, mozilla::Maybe<EntryHandle>&&> {
+    return this->mTable.WithEntryHandle(
+        EntryType::KeyToPointer(aKey), aFallible,
+        [&aKey, &aFunc](auto maybeEntryHandle) {
+          return std::forward<F>(aFunc)(
+              maybeEntryHandle
+                  ? mozilla::Some(EntryHandle{aKey, maybeEntryHandle.extract()})
+                  : mozilla::Nothing());
+        });
+  }
+
+ public:
+  class ConstIterator {
+   public:
+    explicit ConstIterator(nsTHashtable* aTable)
+        : mBaseIterator(&aTable->mTable) {}
+    ~ConstIterator() = default;
+
+    KeyType Key() const { return Get()->GetKey(); }
+
+    const EntryType* Get() const {
+      return static_cast<const EntryType*>(mBaseIterator.Get());
+    }
+
+    bool Done() const { return mBaseIterator.Done(); }
+    void Next() { mBaseIterator.Next(); }
+
+    ConstIterator() = delete;
+    ConstIterator(const ConstIterator&) = delete;
+    ConstIterator(ConstIterator&& aOther) = delete;
+    ConstIterator& operator=(const ConstIterator&) = delete;
+    ConstIterator& operator=(ConstIterator&&) = delete;
+
+   protected:
+    PLDHashTable::Iterator mBaseIterator;
+  };
+
+  // This is an iterator that also allows entry removal. Example usage:
+  //
+  //   for (auto iter = table.Iter(); !iter.Done(); iter.Next()) {
+  //     Entry* entry = iter.Get();
+  //     // ... do stuff with |entry| ...
+  //     // ... possibly call iter.Remove() once ...
+  //   }
+  //
+  class Iterator final : public ConstIterator {
+   public:
+    using ConstIterator::ConstIterator;
+
+    using ConstIterator::Get;
+
+    EntryType* Get() const {
+      return static_cast<EntryType*>(this->mBaseIterator.Get());
+    }
+
+    void Remove() { this->mBaseIterator.Remove(); }
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  ConstIterator ConstIter() const {
+    return ConstIterator(const_cast<nsTHashtable*>(this));
+  }
+
+  using const_iterator = ::detail::nsTHashtableEntryIterator<const EntryType>;
+  using iterator = ::detail::nsTHashtableEntryIterator<EntryType>;
+
+  iterator begin() { return iterator{mTable}; }
+  const_iterator begin() const { return const_iterator{mTable}; }
+  const_iterator cbegin() const { return begin(); }
+  iterator end() {
+    return iterator{mTable, typename iterator::EndIteratorTag{}};
+  }
+  const_iterator end() const {
+    return const_iterator{mTable, typename const_iterator::EndIteratorTag{}};
+  }
+  const_iterator cend() const { return end(); }
+
+  void Remove(const_iterator& aIter) { aIter.mIterator.Remove(); }
+
+  /**
+   * Return a range of the keys (of KeyType). Note this range iterates over the
+   * keys in place, so modifications to the nsTHashtable invalidate the range
+   * while it's iterated, except when calling Remove() with a key iterator
+   * derived from that range.
+   */
+  auto Keys() const {
+    return ::detail::nsTHashtableKeyRange<EntryType>{mTable};
+  }
+
+  /**
+   * Remove an entry from a key range, specified via a key iterator, e.g.
+   *
+   * for (auto it = hash.Keys().begin(), end = hash.Keys().end();
+   *      it != end; * ++it) {
+   *   if (*it > 42) { hash.Remove(it); }
+   * }
+   */
+  void Remove(::detail::nsTHashtableKeyIterator<EntryType>& aIter) {
+    aIter.mIterator.Remove();
+  }
+
+  /**
+   * Remove all entries, return hashtable to "pristine" state. It's
+   * conceptually the same as calling the destructor and then re-calling the
+   * constructor.
+   */
+  void Clear() { mTable.Clear(); }
+
+  /**
+   * Measure the size of the table's entry storage. Does *not* measure anything
+   * hanging off table entries; hence the "Shallow" prefix. To measure that,
+   * either use SizeOfExcludingThis() or iterate manually over the entries,
+   * calling SizeOfExcludingThis() on each one.
+   *
+   * @param     aMallocSizeOf the function used to measure heap-allocated blocks
+   * @return    the measured shallow size of the table
+   */
+  size_t ShallowSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    return mTable.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Like ShallowSizeOfExcludingThis, but includes sizeof(*this).
+   */
+  size_t ShallowSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    return aMallocSizeOf(this) + ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * This is a "deep" measurement of the table. To use it, |EntryType| must
+   * define SizeOfExcludingThis, and that method will be called on all live
+   * entries.
+   */
+  size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    size_t n = ShallowSizeOfExcludingThis(aMallocSizeOf);
+    for (auto iter = ConstIter(); !iter.Done(); iter.Next()) {
+      n += (*iter.Get()).SizeOfExcludingThis(aMallocSizeOf);
+    }
+    return n;
+  }
+
+  /**
+   * Like SizeOfExcludingThis, but includes sizeof(*this).
+   */
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);
+  }
+
+  /**
+   * Swap the elements in this hashtable with the elements in aOther.
+   */
+  void SwapElements(nsTHashtable<EntryType>& aOther) {
+    MOZ_ASSERT_IF(this->mTable.Ops() && aOther.mTable.Ops(),
+                  this->mTable.Ops() == aOther.mTable.Ops());
+    std::swap(this->mTable, aOther.mTable);
+  }
+
+  /**
+   * Mark the table as constant after initialization.
+   *
+   * This will prevent assertions when a read-only hash is accessed on multiple
+   * threads without synchronization.
+   */
+  void MarkImmutable() { mTable.MarkImmutable(); }
+
+ protected:
+  PLDHashTable mTable;
+
+  static PLDHashNumber s_HashKey(const void* aKey);
+
+  static bool s_MatchEntry(const PLDHashEntryHdr* aEntry, const void* aKey);
+
+  static void s_CopyEntry(PLDHashTable* aTable, const PLDHashEntryHdr* aFrom,
+                          PLDHashEntryHdr* aTo);
+
+  static void s_ClearEntry(PLDHashTable* aTable, PLDHashEntryHdr* aEntry);
+
+ private:
+  // copy constructor, not implemented
+  nsTHashtable(nsTHashtable<EntryType>& aToCopy) = delete;
+
+  /**
+   * Gets the table's ops.
+   */
+  static const PLDHashTableOps* Ops();
+
+  // assignment operator, not implemented
+  nsTHashtable<EntryType>& operator=(nsTHashtable<EntryType>& aToEqual) =
+      delete;
+};
+
+namespace mozilla {
+namespace detail {
+
+// Like PLDHashTable::MoveEntryStub, but specialized for fixed N (i.e. the size
+// of the entries in the hashtable).  Saves a memory read to figure out the size
+// from the table and gives the compiler the opportunity to inline the memcpy.
+//
+// We define this outside of nsTHashtable so only one copy exists for every N,
+// rather than separate copies for every EntryType used with nsTHashtable.
+template <size_t N>
+static void FixedSizeEntryMover(PLDHashTable*, const PLDHashEntryHdr* aFrom,
+                                PLDHashEntryHdr* aTo) {
+  memcpy(aTo, aFrom, N);
+}
+
+}  // namespace detail
+}  // namespace mozilla
+
+//
+// template definitions
+//
+
+template <class EntryType>
+nsTHashtable<EntryType>::nsTHashtable(nsTHashtable<EntryType>&& aOther)
+    : mTable(std::move(aOther.mTable)) {}
+
+template <class EntryType>
+nsTHashtable<EntryType>& nsTHashtable<EntryType>::operator=(
+    nsTHashtable<EntryType>&& aOther) {
+  mTable = std::move(aOther.mTable);
+  return *this;
+}
+
+template <class EntryType>
+/* static */ const PLDHashTableOps* nsTHashtable<EntryType>::Ops() {
+  // If this variable is a global variable, we get strange start-up failures on
+  // WindowsCrtPatch.h (see bug 1166598 comment 20). But putting it inside a
+  // function avoids that problem.
+  static const PLDHashTableOps sOps = {
+      s_HashKey, s_MatchEntry,
+      EntryType::ALLOW_MEMMOVE
+          ? mozilla::detail::FixedSizeEntryMover<sizeof(EntryType)>
+          : s_CopyEntry,
+      // Simplify hashtable clearing in case our entries are trivially
+      // destructible.
+      std::is_trivially_destructible_v<EntryType> ? nullptr : s_ClearEntry,
+      // We don't use a generic initEntry hook because we want to allow
+      // initialization of data members defined in derived classes directly
+      // in the entry constructor (for example when a member can't be default
+      // constructed).
+      nullptr};
+  return &sOps;
+}
+
+// static definitions
+
+template <class EntryType>
+PLDHashNumber nsTHashtable<EntryType>::s_HashKey(const void* aKey) {
+  return EntryType::HashKey(static_cast<KeyTypePointer>(aKey));
+}
+
+template <class EntryType>
+bool nsTHashtable<EntryType>::s_MatchEntry(const PLDHashEntryHdr* aEntry,
+                                           const void* aKey) {
+  return (static_cast<const EntryType*>(aEntry))
+      ->KeyEquals(static_cast<KeyTypePointer>(aKey));
+}
+
+template <class EntryType>
+void nsTHashtable<EntryType>::s_CopyEntry(PLDHashTable* aTable,
+                                          const PLDHashEntryHdr* aFrom,
+                                          PLDHashEntryHdr* aTo) {
+  auto* fromEntry = const_cast<std::remove_const_t<EntryType>*>(
+      static_cast<const EntryType*>(aFrom));
+
+  new (mozilla::KnownNotNull, aTo) EntryType(std::move(*fromEntry));
+
+  fromEntry->~EntryType();
+}
+
+template <class EntryType>
+void nsTHashtable<EntryType>::s_ClearEntry(PLDHashTable* aTable,
+                                           PLDHashEntryHdr* aEntry) {
+  static_cast<EntryType*>(aEntry)->~EntryType();
+}
+
+class nsCycleCollectionTraversalCallback;
+
+template <class EntryType>
+inline void ImplCycleCollectionUnlink(nsTHashtable<EntryType>& aField) {
+  aField.Clear();
+}
+
+template <class EntryType>
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& aCallback,
+    nsTHashtable<EntryType>& aField, const char* aName, uint32_t aFlags = 0) {
+  for (auto iter = aField.Iter(); !iter.Done(); iter.Next()) {
+    EntryType* entry = iter.Get();
+    ImplCycleCollectionTraverse(aCallback, *entry, aName, aFlags);
+  }
+}
+
+/**
+ * For nsTHashtable with pointer entries, we can have a template specialization
+ * that layers a typed T* interface on top of a common implementation that
+ * works internally with void pointers.  This arrangement saves code size and
+ * might slightly improve performance as well.
+ */
+
+/**
+ * We need a separate entry type class for the inheritance structure of the
+ * nsTHashtable specialization below; nsVoidPtrHashKey is simply typedefed to a
+ * specialization of nsPtrHashKey, and the formulation:
+ *
+ * class nsTHashtable<nsPtrHashKey<T>> :
+ *   protected nsTHashtable<nsPtrHashKey<const void>
+ *
+ * is not going to turn out very well, since we'd wind up with an nsTHashtable
+ * instantiation that is its own base class.
+ */
+namespace detail {
+
+class VoidPtrHashKey : public nsPtrHashKey<const void> {
+  typedef nsPtrHashKey<const void> Base;
+
+ public:
+  explicit VoidPtrHashKey(const void* aKey) : Base(aKey) {}
+};
+
+}  // namespace detail
+
+/**
+ * See the main nsTHashtable documentation for descriptions of this class's
+ * methods.
+ */
+template <typename T>
+class nsTHashtable<nsPtrHashKey<T>>
+    : protected nsTHashtable<::detail::VoidPtrHashKey> {
+  typedef nsTHashtable<::detail::VoidPtrHashKey> Base;
+  typedef nsPtrHashKey<T> EntryType;
+
+  // We play games with reinterpret_cast'ing between these two classes, so
+  // try to ensure that playing said games is reasonable.
+  static_assert(sizeof(nsPtrHashKey<T>) == sizeof(::detail::VoidPtrHashKey),
+                "hash keys must be the same size");
+
+  nsTHashtable(const nsTHashtable& aOther) = delete;
+  nsTHashtable& operator=(const nsTHashtable& aOther) = delete;
+
+ public:
+  nsTHashtable() = default;
+  explicit nsTHashtable(uint32_t aInitLength) : Base(aInitLength) {}
+
+  ~nsTHashtable() = default;
+
+  nsTHashtable(nsTHashtable&&) = default;
+
+  using Base::Clear;
+  using Base::Count;
+  using Base::GetGeneration;
+  using Base::IsEmpty;
+
+  using Base::MarkImmutable;
+  using Base::ShallowSizeOfExcludingThis;
+  using Base::ShallowSizeOfIncludingThis;
+
+  /* Wrapper functions */
+  EntryType* GetEntry(T* aKey) const {
+    return reinterpret_cast<EntryType*>(Base::GetEntry(aKey));
+  }
+
+  bool Contains(T* aKey) const { return Base::Contains(aKey); }
+
+  EntryType* PutEntry(T* aKey) {
+    return reinterpret_cast<EntryType*>(Base::PutEntry(aKey));
+  }
+
+  [[nodiscard]] EntryType* PutEntry(T* aKey,
+                                    const mozilla::fallible_t& aFallible) {
+    return reinterpret_cast<EntryType*>(Base::PutEntry(aKey, aFallible));
+  }
+
+  [[nodiscard]] bool EnsureInserted(T* aKey, EntryType** aEntry = nullptr) {
+    return Base::EnsureInserted(
+        aKey, reinterpret_cast<::detail::VoidPtrHashKey**>(aEntry));
+  }
+
+  void RemoveEntry(T* aKey) { Base::RemoveEntry(aKey); }
+
+  bool EnsureRemoved(T* aKey) { return Base::EnsureRemoved(aKey); }
+
+  void RemoveEntry(EntryType* aEntry) {
+    Base::RemoveEntry(reinterpret_cast<::detail::VoidPtrHashKey*>(aEntry));
+  }
+
+  void RawRemoveEntry(EntryType* aEntry) {
+    Base::RawRemoveEntry(reinterpret_cast<::detail::VoidPtrHashKey*>(aEntry));
+  }
+
+ protected:
+  class EntryHandle : protected Base::EntryHandle {
+   public:
+    using Base = nsTHashtable::Base::EntryHandle;
+
+    EntryHandle(EntryHandle&& aOther) = default;
+    ~EntryHandle() = default;
+
+    EntryHandle(const EntryHandle&) = delete;
+    EntryHandle& operator=(const EntryHandle&) = delete;
+    EntryHandle& operator=(const EntryHandle&&) = delete;
+
+    using Base::Key;
+
+    using Base::HasEntry;
+
+    using Base::operator bool;
+
+    EntryType* Entry() { return reinterpret_cast<EntryType*>(Base::Entry()); }
+
+    using Base::Insert;
+
+    EntryType* OrInsert() {
+      if (!HasEntry()) {
+        Insert();
+      }
+      return Entry();
+    }
+
+    using Base::Remove;
+
+    using Base::OrRemove;
+
+   private:
+    friend class nsTHashtable;
+
+    explicit EntryHandle(Base&& aBase) : Base(std::move(aBase)) {}
+  };
+
+  template <class F>
+  auto WithEntryHandle(KeyType aKey, F aFunc)
+      -> std::invoke_result_t<F, EntryHandle&&> {
+    return Base::WithEntryHandle(aKey, [&aFunc](auto entryHandle) {
+      return aFunc(EntryHandle{std::move(entryHandle)});
+    });
+  }
+
+  template <class F>
+  auto WithEntryHandle(KeyType aKey, const mozilla::fallible_t& aFallible,
+                       F aFunc)
+      -> std::invoke_result_t<F, mozilla::Maybe<EntryHandle>&&> {
+    return Base::WithEntryHandle(
+        aKey, aFallible, [&aFunc](auto maybeEntryHandle) {
+          return aFunc(maybeEntryHandle ? mozilla::Some(EntryHandle{
+                                              maybeEntryHandle.extract()})
+                                        : mozilla::Nothing());
+        });
+  }
+
+ public:
+  class ConstIterator {
+   public:
+    explicit ConstIterator(nsTHashtable* aTable)
+        : mBaseIterator(&aTable->mTable) {}
+    ~ConstIterator() = default;
+
+    KeyType Key() const { return Get()->GetKey(); }
+
+    const EntryType* Get() const {
+      return static_cast<const EntryType*>(mBaseIterator.Get());
+    }
+
+    bool Done() const { return mBaseIterator.Done(); }
+    void Next() { mBaseIterator.Next(); }
+
+    ConstIterator() = delete;
+    ConstIterator(const ConstIterator&) = delete;
+    ConstIterator(ConstIterator&& aOther) = delete;
+    ConstIterator& operator=(const ConstIterator&) = delete;
+    ConstIterator& operator=(ConstIterator&&) = delete;
+
+   protected:
+    PLDHashTable::Iterator mBaseIterator;
+  };
+
+  class Iterator final : public ConstIterator {
+   public:
+    using ConstIterator::ConstIterator;
+
+    using ConstIterator::Get;
+
+    EntryType* Get() const {
+      return static_cast<EntryType*>(this->mBaseIterator.Get());
+    }
+
+    void Remove() { this->mBaseIterator.Remove(); }
+  };
+
+  Iterator Iter() { return Iterator(this); }
+
+  ConstIterator ConstIter() const {
+    return ConstIterator(const_cast<nsTHashtable*>(this));
+  }
+
+  using const_iterator = ::detail::nsTHashtableEntryIterator<const EntryType>;
+  using iterator = ::detail::nsTHashtableEntryIterator<EntryType>;
+
+  iterator begin() { return iterator{mTable}; }
+  const_iterator begin() const { return const_iterator{mTable}; }
+  const_iterator cbegin() const { return begin(); }
+  iterator end() {
+    return iterator{mTable, typename iterator::EndIteratorTag{}};
+  }
+  const_iterator end() const {
+    return const_iterator{mTable, typename const_iterator::EndIteratorTag{}};
+  }
+  const_iterator cend() const { return end(); }
+
+  auto Keys() const {
+    return ::detail::nsTHashtableKeyRange<nsPtrHashKey<T>>{mTable};
+  }
+
+  void Remove(::detail::nsTHashtableKeyIterator<EntryType>& aIter) {
+    aIter.mIterator.Remove();
+  }
+
+  void SwapElements(nsTHashtable& aOther) { Base::SwapElements(aOther); }
+};
+
+#endif  // nsTHashtable_h__