1 files changed, 245 insertions, 0 deletions
diff --git a/xpcom/ds/nsRefCountedHashtable.h b/xpcom/ds/nsRefCountedHashtable.h
new file mode 100644
index 0000000000..e3a0456a09
--- /dev/null
+++ b/xpcom/ds/nsRefCountedHashtable.h
@@ -0,0 +1,245 @@
+/* -*- 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/. */
+
+#ifndef XPCOM_DS_NSREFCOUNTEDHASHTABLE_H_
+#define XPCOM_DS_NSREFCOUNTEDHASHTABLE_H_
+
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+
+/**
+ * templated hashtable class maps keys to reference pointers.
+ * See nsBaseHashtable for complete declaration.
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param PtrType the reference-type being wrapped
+ * @see nsClassHashtable, nsTHashMap
+ */
+template <class KeyClass, class PtrType>
+class nsRefCountedHashtable
+    : public nsBaseHashtable<
+          KeyClass, PtrType,
+          typename mozilla::detail::SmartPtrTraits<PtrType>::RawPointerType> {
+ public:
+  using KeyType = typename KeyClass::KeyType;
+  using SmartPtrTraits = mozilla::detail::SmartPtrTraits<PtrType>;
+  using PointeeType = typename SmartPtrTraits::PointeeType;
+  using RawPointerType = typename SmartPtrTraits::RawPointerType;
+  using base_type = nsBaseHashtable<KeyClass, PtrType, RawPointerType>;
+
+  using base_type::base_type;
+
+  static_assert(SmartPtrTraits::IsRefCounted);
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @param aData This is an XPCOM getter, so aData is already_addrefed.
+   *   If the key doesn't exist, *aData will be set to nullptr.
+   */
+  bool Get(KeyType aKey, RawPointerType* aData) const;
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   */
+  [[nodiscard]] already_AddRefed<PointeeType> Get(KeyType aKey) const;
+
+  /**
+   * Gets a weak reference to the hashtable entry.
+   * @param aFound If not nullptr, will be set to true if the entry is found,
+   *               to false otherwise.
+   * @return The entry, or nullptr if not found. Do not release this pointer!
+   */
+  [[nodiscard]] RawPointerType GetWeak(KeyType aKey,
+                                       bool* aFound = nullptr) const;
+
+  using base_type::InsertOrUpdate;
+
+  template <typename U,
+            typename = std::enable_if_t<std::is_base_of_v<PointeeType, U>>>
+  void InsertOrUpdate(
+      KeyType aKey,
+      typename SmartPtrTraits::template OtherSmartPtrType<U>&& aData);
+
+  template <typename U,
+            typename = std::enable_if_t<std::is_base_of_v<PointeeType, U>>>
+  [[nodiscard]] bool InsertOrUpdate(
+      KeyType aKey,
+      typename SmartPtrTraits::template OtherSmartPtrType<U>&& aData,
+      const mozilla::fallible_t&);
+
+  template <typename U,
+            typename = std::enable_if_t<std::is_base_of_v<PointeeType, U>>>
+  void InsertOrUpdate(KeyType aKey, already_AddRefed<U>&& aData);
+
+  template <typename U,
+            typename = std::enable_if_t<std::is_base_of_v<PointeeType, U>>>
+  [[nodiscard]] bool InsertOrUpdate(KeyType aKey, already_AddRefed<U>&& aData,
+                                    const mozilla::fallible_t&);
+
+  /**
+   * Remove the entry associated with aKey (if any), optionally _moving_ its
+   * current value into *aData, thereby avoiding calls to AddRef and Release.
+   * Return true if found.
+   * @param aKey the key to remove from the hashtable
+   * @param aData where to move the value (if non-null).  If an entry is not
+   *              found it will be set to nullptr.
+   * @return true if an entry for aKey was found (and removed)
+   */
+  inline bool Remove(KeyType aKey, RawPointerType* aData = nullptr);
+
+  nsRefCountedHashtable Clone() const {
+    return this->template CloneAs<nsRefCountedHashtable>();
+  }
+};
+
+template <typename K, typename T>
+inline void ImplCycleCollectionUnlink(nsRefCountedHashtable<K, T>& aField) {
+  aField.Clear();
+}
+
+template <typename K, typename T>
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& aCallback,
+    nsRefCountedHashtable<K, T>& aField, const char* aName,
+    uint32_t aFlags = 0) {
+  for (auto iter = aField.ConstIter(); !iter.Done(); iter.Next()) {
+    CycleCollectionNoteChild(aCallback, iter.UserData(), aName, aFlags);
+  }
+}
+
+//
+// nsRefCountedHashtable definitions
+//
+
+template <class KeyClass, class PtrType>
+bool nsRefCountedHashtable<KeyClass, PtrType>::Get(
+    KeyType aKey, RawPointerType* aRefPtr) const {
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aRefPtr) {
+      *aRefPtr = ent->GetData();
+
+      NS_IF_ADDREF(*aRefPtr);
+    }
+
+    return true;
+  }
+
+  // if the key doesn't exist, set *aRefPtr to null
+  // so that it is a valid XPCOM getter
+  if (aRefPtr) {
+    *aRefPtr = nullptr;
+  }
+
+  return false;
+}
+
+template <class KeyClass, class PtrType>
+already_AddRefed<typename nsRefCountedHashtable<KeyClass, PtrType>::PointeeType>
+nsRefCountedHashtable<KeyClass, PtrType>::Get(KeyType aKey) const {
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+  if (!ent) {
+    return nullptr;
+  }
+
+  PtrType copy = ent->GetData();
+  return copy.forget();
+}
+
+template <class KeyClass, class PtrType>
+typename nsRefCountedHashtable<KeyClass, PtrType>::RawPointerType
+nsRefCountedHashtable<KeyClass, PtrType>::GetWeak(KeyType aKey,
+                                                  bool* aFound) const {
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aFound) {
+      *aFound = true;
+    }
+
+    return ent->GetData();
+  }
+
+  // Key does not exist, return nullptr and set aFound to false
+  if (aFound) {
+    *aFound = false;
+  }
+
+  return nullptr;
+}
+
+template <class KeyClass, class PtrType>
+template <typename U, typename>
+void nsRefCountedHashtable<KeyClass, PtrType>::InsertOrUpdate(
+    KeyType aKey,
+    typename SmartPtrTraits::template OtherSmartPtrType<U>&& aData) {
+  if (!InsertOrUpdate(aKey, std::move(aData), mozilla::fallible)) {
+    NS_ABORT_OOM(this->mTable.EntrySize() * this->mTable.EntryCount());
+  }
+}
+
+template <class KeyClass, class PtrType>
+template <typename U, typename>
+bool nsRefCountedHashtable<KeyClass, PtrType>::InsertOrUpdate(
+    KeyType aKey,
+    typename SmartPtrTraits::template OtherSmartPtrType<U>&& aData,
+    const mozilla::fallible_t&) {
+  typename base_type::EntryType* ent = this->PutEntry(aKey, mozilla::fallible);
+
+  if (!ent) {
+    return false;
+  }
+
+  ent->SetData(std::move(aData));
+
+  return true;
+}
+
+template <class KeyClass, class PtrType>
+template <typename U, typename>
+void nsRefCountedHashtable<KeyClass, PtrType>::InsertOrUpdate(
+    KeyType aKey, already_AddRefed<U>&& aData) {
+  if (!InsertOrUpdate(aKey, std::move(aData), mozilla::fallible)) {
+    NS_ABORT_OOM(this->mTable.EntrySize() * this->mTable.EntryCount());
+  }
+}
+
+template <class KeyClass, class PtrType>
+template <typename U, typename>
+bool nsRefCountedHashtable<KeyClass, PtrType>::InsertOrUpdate(
+    KeyType aKey, already_AddRefed<U>&& aData, const mozilla::fallible_t&) {
+  typename base_type::EntryType* ent = this->PutEntry(aKey, mozilla::fallible);
+
+  if (!ent) {
+    return false;
+  }
+
+  ent->SetData(std::move(aData));
+
+  return true;
+}
+
+template <class KeyClass, class PtrType>
+bool nsRefCountedHashtable<KeyClass, PtrType>::Remove(KeyType aKey,
+                                                      RawPointerType* aRefPtr) {
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aRefPtr) {
+      ent->GetModifiableData()->forget(aRefPtr);
+    }
+    this->RemoveEntry(ent);
+    return true;
+  }
+
+  if (aRefPtr) {
+    *aRefPtr = nullptr;
+  }
+  return false;
+}
+
+#endif  // XPCOM_DS_NSREFCOUNTEDHASHTABLE_H_