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/gecko_api/include/nsRefPtrHashtable.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 *   Neil Rashbrook <neil@parkwaycc.co.uk>
 24 *
 25 * Alternatively, the contents of this file may be used under the terms of
 26 * either the GNU General Public License Version 2 or later (the "GPL"), or
 27 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 28 * in which case the provisions of the GPL or the LGPL are applicable instead
 29 * of those above. If you wish to allow use of your version of this file only
 30 * under the terms of either the GPL or the LGPL, and not to allow others to
 31 * use your version of this file under the terms of the MPL, indicate your
 32 * decision by deleting the provisions above and replace them with the notice
 33 * and other provisions required by the GPL or the LGPL. If you do not delete
 34 * the provisions above, a recipient may use your version of this file under
 35 * the terms of any one of the MPL, the GPL or the LGPL.
 36 *
 37 * ***** END LICENSE BLOCK ***** */
 38
 39#ifndef nsRefPtrHashtable_h__
 40#define nsRefPtrHashtable_h__
 41
 42#include "nsBaseHashtable.h"
 43#include "nsHashKeys.h"
 44#include "nsAutoPtr.h"
 45
 46/**
 47 * templated hashtable class maps keys to reference pointers.
 48 * See nsBaseHashtable for complete declaration.
 49 * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
 50 *   for a complete specification.
 51 * @param RefPtr the reference-type being wrapped
 52 * @see nsDataHashtable, nsClassHashtable
 53 */
 54template<class KeyClass, class RefPtr>
 55class nsRefPtrHashtable :
 56  public nsBaseHashtable< KeyClass, nsRefPtr<RefPtr> , RefPtr* >
 57{
 58public:
 59  typedef typename KeyClass::KeyType KeyType;
 60  typedef RefPtr* UserDataType;
 61
 62  /**
 63   * @copydoc nsBaseHashtable::Get
 64   * @param pData This is an XPCOM getter, so pData is already_addrefed.
 65   *   If the key doesn't exist, pData will be set to nsnull.
 66   */
 67  PRBool Get(KeyType aKey, UserDataType* pData) const;
 68
 69  /**
 70   * Gets a weak reference to the hashtable entry.
 71   * @param aFound If not nsnull, will be set to PR_TRUE if the entry is found,
 72   *               to PR_FALSE otherwise.
 73   * @return The entry, or nsnull if not found. Do not release this pointer!
 74   */
 75  RefPtr* GetWeak(KeyType aKey, PRBool* aFound = nsnull) const;
 76};
 77
 78/**
 79 * Thread-safe version of nsRefPtrHashtable
 80 * @param KeyClass a wrapper-class for the hashtable key, see nsHashKeys.h
 81 *   for a complete specification.
 82 * @param RefPtr the reference-type being wrapped
 83 */
 84template<class KeyClass, class RefPtr>
 85class nsRefPtrHashtableMT :
 86  public nsBaseHashtableMT< KeyClass, nsRefPtr<RefPtr> , RefPtr* >
 87{
 88public:
 89  typedef typename KeyClass::KeyType KeyType;
 90  typedef RefPtr* UserDataType;
 91
 92  /**
 93   * @copydoc nsBaseHashtable::Get
 94   * @param pData This is an XPCOM getter, so pData is already_addrefed.
 95   *   If the key doesn't exist, pData will be set to nsnull.
 96   */
 97  PRBool Get(KeyType aKey, UserDataType* pData) const;
 98
 99  // GetWeak does not make sense on a multi-threaded hashtable, where another
100  // thread may remove the entry (and hence release it) as soon as GetWeak
101  // returns
102};
103
104
105//
106// nsRefPtrHashtable definitions
107//
108
109template<class KeyClass, class RefPtr>
110PRBool
111nsRefPtrHashtable<KeyClass,RefPtr>::Get
112  (KeyType aKey, UserDataType* pRefPtr) const
113{
114  typename nsBaseHashtable<KeyClass, nsRefPtr<RefPtr>, RefPtr*>::EntryType* ent =
115    GetEntry(aKey);
116
117  if (ent)
118  {
119    if (pRefPtr)
120    {
121      *pRefPtr = ent->mData;
122
123      NS_IF_ADDREF(*pRefPtr);
124    }
125
126    return PR_TRUE;
127  }
128
129  // if the key doesn't exist, set *pRefPtr to null
130  // so that it is a valid XPCOM getter
131  if (pRefPtr)
132    *pRefPtr = nsnull;
133
134  return PR_FALSE;
135}
136
137template<class KeyClass, class RefPtr>
138RefPtr*
139nsRefPtrHashtable<KeyClass,RefPtr>::GetWeak
140  (KeyType aKey, PRBool* aFound) const
141{
142  typename nsBaseHashtable<KeyClass, nsRefPtr<RefPtr>, RefPtr*>::EntryType* ent =
143    GetEntry(aKey);
144
145  if (ent)
146  {
147    if (aFound)
148      *aFound = PR_TRUE;
149
150    return ent->mData;
151  }
152
153  // Key does not exist, return nsnull and set aFound to PR_FALSE
154  if (aFound)
155    *aFound = PR_FALSE;
156  return nsnull;
157}
158
159//
160// nsRefPtrHashtableMT definitions
161//
162
163template<class KeyClass, class RefPtr>
164PRBool
165nsRefPtrHashtableMT<KeyClass,RefPtr>::Get
166  (KeyType aKey, UserDataType* pRefPtr) const
167{
168  PR_Lock(this->mLock);
169
170  typename nsBaseHashtableMT<KeyClass, nsRefPtr<RefPtr>, RefPtr*>::EntryType* ent =
171    GetEntry(aKey);
172
173  if (ent)
174  {
175    if (pRefPtr)
176    {
177      *pRefPtr = ent->mData;
178
179      NS_IF_ADDREF(*pRefPtr);
180    }
181
182    PR_Unlock(this->mLock);
183
184    return PR_TRUE;
185  }
186
187  // if the key doesn't exist, set *pRefPtr to null
188  // so that it is a valid XPCOM getter
189  if (pRefPtr)
190    *pRefPtr = nsnull;
191
192  PR_Unlock(this->mLock);
193
194  return PR_FALSE;
195}
196
197#endif // nsRefPtrHashtable_h__