1 files changed, 115 insertions, 0 deletions
diff --git a/xpcom/ds/nsClassHashtable.h b/xpcom/ds/nsClassHashtable.h
new file mode 100644
index 0000000000..a1a2384f7e
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+++ b/xpcom/ds/nsClassHashtable.h
@@ -0,0 +1,115 @@
+/* -*- 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 nsClassHashtable_h__
+#define nsClassHashtable_h__
+
+#include <utility>
+
+#include "mozilla/UniquePtr.h"
+#include "nsBaseHashtable.h"
+#include "nsHashKeys.h"
+
+/**
+ * Helper class that provides methods to wrap and unwrap the UserDataType.
+ */
+template <class T>
+class nsUniquePtrConverter {
+ public:
+  using UserDataType = T*;
+  using DataType = mozilla::UniquePtr<T>;
+
+  static UserDataType Unwrap(DataType& src) { return src.get(); }
+  static DataType Wrap(UserDataType&& src) { return DataType(std::move(src)); }
+  static DataType Wrap(const UserDataType& src) { return DataType(src); }
+};
+
+/**
+ * templated hashtable class maps keys to C++ object pointers.
+ * See nsBaseHashtable for complete declaration.
+ * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
+ *   for a complete specification.
+ * @param Class the class-type being wrapped
+ * @see nsInterfaceHashtable, nsClassHashtable
+ */
+template <class KeyClass, class T>
+class nsClassHashtable : public nsBaseHashtable<KeyClass, mozilla::UniquePtr<T>,
+                                                T*, nsUniquePtrConverter<T>> {
+ public:
+  typedef typename KeyClass::KeyType KeyType;
+  typedef T* UserDataType;
+  typedef nsBaseHashtable<KeyClass, mozilla::UniquePtr<T>, T*,
+                          nsUniquePtrConverter<T>>
+      base_type;
+
+  using base_type::IsEmpty;
+  using base_type::Remove;
+
+  nsClassHashtable() = default;
+  explicit nsClassHashtable(uint32_t aInitLength) : base_type(aInitLength) {}
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @param aData if the key doesn't exist, pData will be set to nullptr.
+   */
+  bool Get(KeyType aKey, UserDataType* aData) const;
+
+  /**
+   * @copydoc nsBaseHashtable::Get
+   * @returns nullptr if the key is not present.
+   */
+  [[nodiscard]] UserDataType Get(KeyType aKey) const;
+};
+
+template <typename K, typename T>
+inline void ImplCycleCollectionUnlink(nsClassHashtable<K, T>& aField) {
+  aField.Clear();
+}
+
+template <typename K, typename T>
+inline void ImplCycleCollectionTraverse(
+    nsCycleCollectionTraversalCallback& aCallback,
+    const nsClassHashtable<K, T>& aField, const char* aName,
+    uint32_t aFlags = 0) {
+  for (auto iter = aField.ConstIter(); !iter.Done(); iter.Next()) {
+    ImplCycleCollectionTraverse(aCallback, *iter.UserData(), aName, aFlags);
+  }
+}
+
+//
+// nsClassHashtable definitions
+//
+
+template <class KeyClass, class T>
+bool nsClassHashtable<KeyClass, T>::Get(KeyType aKey, T** aRetVal) const {
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+
+  if (ent) {
+    if (aRetVal) {
+      *aRetVal = ent->GetData().get();
+    }
+
+    return true;
+  }
+
+  if (aRetVal) {
+    *aRetVal = nullptr;
+  }
+
+  return false;
+}
+
+template <class KeyClass, class T>
+T* nsClassHashtable<KeyClass, T>::Get(KeyType aKey) const {
+  typename base_type::EntryType* ent = this->GetEntry(aKey);
+  if (!ent) {
+    return nullptr;
+  }
+
+  return ent->GetData().get();
+}
+
+#endif  // nsClassHashtable_h__