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/gecko_api/include/nsInterfaceHashtable.h

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  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/
  9 *
 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
 28 * of those above. If you wish to allow use of your version of this file only
 29 * under the terms of either the GPL or the LGPL, and not to allow others to
 30 * use your version of this file under the terms of the MPL, indicate your
 31 * decision by deleting the provisions above and replace them with the notice
 32 * and other provisions required by the GPL or the LGPL. If you do not delete
 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 */
 53template<class KeyClass,class Interface>
 54class nsInterfaceHashtable :
 55  public nsBaseHashtable< KeyClass, nsCOMPtr<Interface> , Interface* >
 56{
 57public:
 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) 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 */
 83template<class KeyClass,class Interface>
 84class nsInterfaceHashtableMT :
 85  public nsBaseHashtableMT< KeyClass, nsCOMPtr<Interface> , Interface* >
 86{
 87public:
 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) 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
108template<class KeyClass,class Interface>
109PRBool
110nsInterfaceHashtable<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
136template<class KeyClass,class Interface>
137Interface*
138nsInterfaceHashtable<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
162template<class KeyClass,class Interface>
163PRBool
164nsInterfaceHashtableMT<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__