xpcom/glue/nsInterfaceHashtable.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
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  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is C++ hashtable templates.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * Benjamin Smedberg.
  19  * Portions created by the Initial Developer are Copyright (C) 2002
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *
  24  * Alternatively, the contents of this file may be used under the terms of
  25  * either the GNU General Public License Version 2 or later (the "GPL"), or
  26  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  27  * in which case the provisions of the GPL or the LGPL are applicable instead
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  33  * the provisions above, a recipient may use your version of this file under
  34  * the terms of any one of the MPL, the GPL or the LGPL.
  35  *
  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifndef nsInterfaceHashtable_h__
  39 #define nsInterfaceHashtable_h__
  40
  41 #include "nsBaseHashtable.h"
  42 #include "nsHashKeys.h"
  43 #include "nsCOMPtr.h"
  44
  45 /**
  46  * templated hashtable class maps keys to interface pointers.
  47  * See nsBaseHashtable for complete declaration.
  48  * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
  49  *   for a complete specification.
  50  * @param Interface the interface-type being wrapped
  51  * @see nsDataHashtable, nsClassHashtable
  52  */
  53 template<class KeyClass,class Interface>
  54 class nsInterfaceHashtable :
  55   public nsBaseHashtable< KeyClass, nsCOMPtr<Interface> , Interface* >
  56 {
  57 public:
  58   typedef typename KeyClass::KeyType KeyType;
  59   typedef Interface* UserDataType;
  60
  61   /**
  62    * @copydoc nsBaseHashtable::Get
  63    * @param pData This is an XPCOM getter, so pData is already_addrefed.
  64    *   If the key doesn't exist, pData will be set to nsnull.
  65    */
  66   PRBool Get(KeyType aKey, UserDataType* pData NS_OUTPARAM) const;
  67
  68   /**
  69    * Gets a weak reference to the hashtable entry.
  70    * @param aFound If not nsnull, will be set to PR_TRUE if the entry is found,
  71    *               to PR_FALSE otherwise.
  72    * @return The entry, or nsnull if not found. Do not release this pointer!
  73    */
  74   Interface* GetWeak(KeyType aKey, PRBool* aFound = nsnull) const;
  75 };
  76
  77 /**
  78  * Thread-safe version of nsInterfaceHashtable
  79  * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
  80  *   for a complete specification.
  81  * @param Interface the interface-type being wrapped
  82  */
  83 template<class KeyClass,class Interface>
  84 class nsInterfaceHashtableMT :
  85   public nsBaseHashtableMT< KeyClass, nsCOMPtr<Interface> , Interface* >
  86 {
  87 public:
  88   typedef typename KeyClass::KeyType KeyType;
  89   typedef Interface* UserDataType;
  90
  91   /**
  92    * @copydoc nsBaseHashtable::Get
  93    * @param pData This is an XPCOM getter, so pData is already_addrefed.
  94    *   If the key doesn't exist, pData will be set to nsnull.
  95    */
  96   PRBool Get(KeyType aKey, UserDataType* pData NS_OUTPARAM) const;
  97
  98   // GetWeak does not make sense on a multi-threaded hashtable, where another
  99   // thread may remove the entry (and hence release it) as soon as GetWeak
 100   // returns
 101 };
 102
 103
 104 //
 105 // nsInterfaceHashtable definitions
 106 //
 107
 108 template<class KeyClass,class Interface>
 109 PRBool
 110 nsInterfaceHashtable<KeyClass,Interface>::Get
 111   (KeyType aKey, UserDataType* pInterface) const
 112 {
 113   typename nsBaseHashtable<KeyClass, nsCOMPtr<Interface>, Interface*>::EntryType* ent =
 114     GetEntry(aKey);
 115
 116   if (ent)
 117   {
 118     if (pInterface)
 119     {
 120       *pInterface = ent->mData;
 121
 122       NS_IF_ADDREF(*pInterface);
 123     }
 124
 125     return PR_TRUE;
 126   }
 127
 128   // if the key doesn't exist, set *pInterface to null
 129   // so that it is a valid XPCOM getter
 130   if (pInterface)
 131     *pInterface = nsnull;
 132
 133   return PR_FALSE;
 134 }
 135
 136 template<class KeyClass,class Interface>
 137 Interface*
 138 nsInterfaceHashtable<KeyClass,Interface>::GetWeak
 139   (KeyType aKey, PRBool* aFound) const
 140 {
 141   typename nsBaseHashtable<KeyClass, nsCOMPtr<Interface>, Interface*>::EntryType* ent =
 142     GetEntry(aKey);
 143
 144   if (ent)
 145   {
 146     if (aFound)
 147       *aFound = PR_TRUE;
 148
 149     return ent->mData;
 150   }
 151
 152   // Key does not exist, return nsnull and set aFound to PR_FALSE
 153   if (aFound)
 154     *aFound = PR_FALSE;
 155   return nsnull;
 156 }
 157
 158 //
 159 // nsInterfaceHashtableMT definitions
 160 //
 161
 162 template<class KeyClass,class Interface>
 163 PRBool
 164 nsInterfaceHashtableMT<KeyClass,Interface>::Get
 165   (KeyType aKey, UserDataType* pInterface) const
 166 {
 167   PR_Lock(this->mLock);
 168
 169   typename nsBaseHashtableMT<KeyClass, nsCOMPtr<Interface>, Interface*>::EntryType* ent =
 170     GetEntry(aKey);
 171
 172   if (ent)
 173   {
 174     if (pInterface)
 175     {
 176       *pInterface = ent->mData;
 177
 178       NS_IF_ADDREF(*pInterface);
 179     }
 180
 181     PR_Unlock(this->mLock);
 182
 183     return PR_TRUE;
 184   }
 185
 186   // if the key doesn't exist, set *pInterface to null
 187   // so that it is a valid XPCOM getter
 188   if (pInterface)
 189     *pInterface = nsnull;
 190
 191   PR_Unlock(this->mLock);
 192
 193   return PR_FALSE;
 194 }
 195
 196 #endif // nsInterfaceHashtable_h__