xpcom/ds/nsPointerHashKeys.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Definitions for nsPtrHashKey<T> and nsVoidPtrHashKey.  */
   8
   9 #ifndef nsPointerHashKeys_h
  10 #define nsPointerHashKeys_h
  11
  12 #include "nscore.h"
  13
  14 #include "mozilla/Attributes.h"
  15 #include "mozilla/HashFunctions.h"
  16
  17 #include "PLDHashTable.h"
  18
  19 /**
  20  * hashkey wrapper using T* KeyType
  21  *
  22  * @see nsTHashtable::EntryType for specification
  23  */
  24 template <class T>
  25 class nsPtrHashKey : public PLDHashEntryHdr {
  26  public:
  27   using KeyType = T*;
  28   using KeyTypePointer = const T*;
  29
  30   explicit nsPtrHashKey(const T* aKey) : mKey(const_cast<T*>(aKey)) {}
  31   nsPtrHashKey(nsPtrHashKey&& aToMove) = default;
  32   ~nsPtrHashKey() = default;
  33
  34   KeyType GetKey() const { return mKey; }
  35   bool KeyEquals(KeyTypePointer aKey) const { return aKey == mKey; }
  36
  37   static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
  38   static PLDHashNumber HashKey(KeyTypePointer aKey) {
  39     return mozilla::HashGeneric(aKey);
  40   }
  41   enum { ALLOW_MEMMOVE = true };
  42
  43  protected:
  44   T* MOZ_NON_OWNING_REF mKey;
  45 };
  46
  47 using nsVoidPtrHashKey = nsPtrHashKey<const void>;
  48
  49 #endif  // nsPointerHashKeys_h