/* -*- 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 nsRefPtrHashtable_h__

#define nsRefPtrHashtable_h__

#include "nsBaseHashtable.h"

#include "nsHashKeys.h"

#include "nsAutoPtr.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 nsDataHashtable, nsClassHashtable

 */

template<class KeyClass, class PtrType>

class nsRefPtrHashtable

  : public nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*>

{

public:

  typedef typename KeyClass::KeyType KeyType;

  typedef PtrType* UserDataType;

  typedef nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*> base_type;

  nsRefPtrHashtable() {}

  explicit nsRefPtrHashtable(uint32_t aInitLength)

    : nsBaseHashtable<KeyClass, RefPtr<PtrType>, PtrType*>(aInitLength)

  {

  }

  /**

   * @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, UserDataType* aData) const;

  /**

   * @copydoc nsBaseHashtable::Get

   */

  already_AddRefed<PtrType> 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!

   */

  PtrType* GetWeak(KeyType aKey, bool* aFound = nullptr) const;

  // Overload Put, rather than overriding it.

  using base_type::Put;

  void Put(KeyType aKey, already_AddRefed<PtrType> aData);

  MOZ_MUST_USE bool Put(KeyType aKey, already_AddRefed<PtrType> 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, UserDataType* aData = nullptr);

};

template<typename K, typename T>

inline void

ImplCycleCollectionUnlink(nsRefPtrHashtable<K, T>& aField)

{

  aField.Clear();

}

template<typename K, typename T>

inline void

ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,

                            nsRefPtrHashtable<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);

  }

}

//

// nsRefPtrHashtable definitions

//

template<class KeyClass, class PtrType>

bool

nsRefPtrHashtable<KeyClass, PtrType>::Get(KeyType aKey,

                                          UserDataType* aRefPtr) const

{

  typename base_type::EntryType* ent = this->GetEntry(aKey);

  if (ent) {

    if (aRefPtr) {

      *aRefPtr = ent->mData;

      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<PtrType>

nsRefPtrHashtable<KeyClass, PtrType>::Get(KeyType aKey) const

{

  typename base_type::EntryType* ent = this->GetEntry(aKey);

  if (!ent) {

    return nullptr;

  }

  RefPtr<PtrType> copy = ent->mData;

  return copy.forget();

}

template<class KeyClass, class PtrType>

PtrType*

nsRefPtrHashtable<KeyClass, PtrType>::GetWeak(KeyType aKey, bool* aFound) const

{

  typename base_type::EntryType* ent = this->GetEntry(aKey);

  if (ent) {

    if (aFound) {

      *aFound = true;

    }

    return ent->mData;

  }

  // Key does not exist, return nullptr and set aFound to false

  if (aFound) {

    *aFound = false;

  }

  return nullptr;

}

template<class KeyClass, class PtrType>

void

nsRefPtrHashtable<KeyClass, PtrType>::Put(KeyType aKey,

                                          already_AddRefed<PtrType> aData)

{

  if (!Put(aKey, std::move(aData), mozilla::fallible)) {

    NS_ABORT_OOM(this->mTable.EntrySize() * this->mTable.EntryCount());

  }

}

template<class KeyClass, class PtrType>

bool

nsRefPtrHashtable<KeyClass, PtrType>::Put(KeyType aKey,

                                          already_AddRefed<PtrType> aData,

                                          const mozilla::fallible_t&)

{

  typename base_type::EntryType* ent = this->PutEntry(aKey, mozilla::fallible);

  if (!ent) {

    return false;

  }

  ent->mData = aData;

  return true;

}

template<class KeyClass, class PtrType>

bool

nsRefPtrHashtable<KeyClass, PtrType>::Remove(KeyType aKey,

                                             UserDataType* aRefPtr)

{

  typename base_type::EntryType* ent = this->GetEntry(aKey);

  if (ent) {

    if (aRefPtr) {

      ent->mData.forget(aRefPtr);

    }

    this->RemoveEntry(ent);

    return true;

  }

  if (aRefPtr) {

    *aRefPtr = nullptr;

  }

  return false;

}

#endif // nsRefPtrHashtable_h__