/gecko_api/include/nsCategoryCache.h

  1/* ***** BEGIN LICENSE BLOCK *****
  2 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  3 *
  4 * The contents of this file are subject to the Mozilla Public License Version
  5 * 1.1 (the "License"); you may not use this file except in compliance with
  6 * the License. You may obtain a copy of the License at
  7 * http://www.mozilla.org/MPL/
  8 *
  9 * Software distributed under the License is distributed on an "AS IS" basis,
 10 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 11 * for the specific language governing rights and limitations under the
 12 * License.
 13 *
 14 * The Original Code is a cache for services in a category.
 15 *
 16 * The Initial Developer of the Original Code is
 17 * Christian Biesinger <cbiesinger@web.de>.
 18 * Portions created by the Initial Developer are Copyright (C) 2005
 19 * the Initial Developer. All Rights Reserved.
 20 *
 21 * Contributor(s):
 22 *
 23 * Alternatively, the contents of this file may be used under the terms of
 24 * either the GNU General Public License Version 2 or later (the "GPL"), or
 25 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 26 * in which case the provisions of the GPL or the LGPL are applicable instead
 27 * of those above. If you wish to allow use of your version of this file only
 28 * under the terms of either the GPL or the LGPL, and not to allow others to
 29 * use your version of this file under the terms of the MPL, indicate your
 30 * decision by deleting the provisions above and replace them with the notice
 31 * and other provisions required by the GPL or the LGPL. If you do not delete
 32 * the provisions above, a recipient may use your version of this file under
 33 * the terms of any one of the MPL, the GPL or the LGPL.
 34 *
 35 * ***** END LICENSE BLOCK ***** */
 36
 37#ifndef nsCategoryCache_h_
 38#define nsCategoryCache_h_
 39
 40#include "nsICategoryManager.h"
 41#include "nsIObserver.h"
 42#include "nsISimpleEnumerator.h"
 43#include "nsISupportsPrimitives.h"
 44
 45#include "nsServiceManagerUtils.h"
 46
 47#include "nsAutoPtr.h"
 48#include "nsCOMArray.h"
 49#include "nsDataHashtable.h"
 50
 51#include "nsXPCOM.h"
 52
 53class NS_NO_VTABLE nsCategoryListener {
 54  protected:
 55    // no virtual destructor (people shouldn't delete through an
 56    // nsCategoryListener pointer)
 57    ~nsCategoryListener() {}
 58
 59  public:
 60    virtual void EntryAdded(const nsCString& aValue) = 0;
 61    virtual void EntryRemoved(const nsCString& aValue) = 0;
 62    virtual void CategoryCleared() = 0;
 63};
 64
 65class NS_COM_GLUE nsCategoryObserver : public nsIObserver {
 66  public:
 67    nsCategoryObserver(const char* aCategory,
 68                       nsCategoryListener* aCategoryListener);
 69    ~nsCategoryObserver();
 70
 71    void ListenerDied();
 72
 73    NS_DECL_ISUPPORTS
 74    NS_DECL_NSIOBSERVER
 75  private:
 76    nsDataHashtable<nsCStringHashKey, nsCString> mHash;
 77    nsCategoryListener*                          mListener;
 78    nsCString                                    mCategory;
 79};
 80
 81/**
 82 * This is a helper class that caches services that are registered in a certain
 83 * category. The intended usage is that a service stores a variable of type
 84 * nsCategoryCache<nsIFoo> in a member variable, where nsIFoo is the interface
 85 * that these services should implement. The constructor of this class should
 86 * then get the name of the category.
 87 */
 88template<class T>
 89class nsCategoryCache : protected nsCategoryListener {
 90  public:
 91    explicit nsCategoryCache(const char* aCategory);
 92    ~nsCategoryCache() { if (mObserver) mObserver->ListenerDied(); }
 93
 94    const nsCOMArray<T>& GetEntries() {
 95      // Lazy initialization, so that services in this category can't
 96      // cause reentrant getService (bug 386376)
 97      if (!mObserver)
 98        mObserver = new nsCategoryObserver(mCategoryName.get(), this);
 99      return mEntries;
100    }
101  protected:
102    virtual void EntryAdded(const nsCString& aValue);
103    virtual void EntryRemoved(const nsCString& aValue);
104    virtual void CategoryCleared();
105  private:
106    friend class CategoryObserver;
107
108    // Not to be implemented
109    nsCategoryCache(const nsCategoryCache<T>&);
110
111    nsCString mCategoryName;
112    nsCOMArray<T> mEntries;
113    nsRefPtr<nsCategoryObserver> mObserver;
114};
115
116// -----------------------------------
117// Implementation
118
119template<class T>
120nsCategoryCache<T>::nsCategoryCache(const char* aCategory)
121: mCategoryName(aCategory)
122{
123}
124
125template<class T>
126void nsCategoryCache<T>::EntryAdded(const nsCString& aValue) {
127  nsCOMPtr<T> catEntry = do_GetService(aValue.get());
128  if (catEntry)
129    mEntries.AppendObject(catEntry);
130}
131
132template<class T>
133void nsCategoryCache<T>::EntryRemoved(const nsCString& aValue) {
134  nsCOMPtr<T> catEntry = do_GetService(aValue.get());
135  if (catEntry)
136    mEntries.RemoveObject(catEntry);
137}
138
139template<class T>
140void nsCategoryCache<T>::CategoryCleared() {
141  mEntries.Clear();
142}
143
144#endif