gecko-dev/xpcom/glue/nsCategoryCache.h

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/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is a cache for services in a category.
*
* The Initial Developer of the Original Code is
* Christian Biesinger <cbiesinger@web.de>.
* Portions created by the Initial Developer are Copyright (C) 2005
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef nsCategoryCache_h_
#define nsCategoryCache_h_
#include "nsICategoryManager.h"
#include "nsIObserver.h"
#include "nsISimpleEnumerator.h"
#include "nsISupportsPrimitives.h"
#include "nsServiceManagerUtils.h"
#include "nsAutoPtr.h"
#include "nsCOMArray.h"
#include "nsDataHashtable.h"
#include "nsXPCOM.h"
class NS_NO_VTABLE nsCategoryListener {
protected:
// no virtual destructor (people shouldn't delete through an
// nsCategoryListener pointer)
~nsCategoryListener() {}
public:
virtual void EntryAdded(const nsCString& aValue) = 0;
virtual void EntryRemoved(const nsCString& aValue) = 0;
virtual void CategoryCleared() = 0;
};
class NS_COM_GLUE nsCategoryObserver : public nsIObserver {
public:
nsCategoryObserver(const char* aCategory,
nsCategoryListener* aCategoryListener);
~nsCategoryObserver();
void ListenerDied();
NS_DECL_ISUPPORTS
NS_DECL_NSIOBSERVER
private:
NS_HIDDEN_(void) RemoveObservers();
nsDataHashtable<nsCStringHashKey, nsCString> mHash;
nsCategoryListener* mListener;
nsCString mCategory;
};
/**
* This is a helper class that caches services that are registered in a certain
* category. The intended usage is that a service stores a variable of type
* nsCategoryCache<nsIFoo> in a member variable, where nsIFoo is the interface
* that these services should implement. The constructor of this class should
* then get the name of the category.
*/
template<class T>
class nsCategoryCache : protected nsCategoryListener {
public:
explicit nsCategoryCache(const char* aCategory);
~nsCategoryCache() { if (mObserver) mObserver->ListenerDied(); }
const nsCOMArray<T>& GetEntries() {
// Lazy initialization, so that services in this category can't
// cause reentrant getService (bug 386376)
if (!mObserver)
mObserver = new nsCategoryObserver(mCategoryName.get(), this);
return mEntries;
}
protected:
virtual void EntryAdded(const nsCString& aValue);
virtual void EntryRemoved(const nsCString& aValue);
virtual void CategoryCleared();
private:
friend class CategoryObserver;
// Not to be implemented
nsCategoryCache(const nsCategoryCache<T>&);
nsCString mCategoryName;
nsCOMArray<T> mEntries;
nsRefPtr<nsCategoryObserver> mObserver;
};
// -----------------------------------
// Implementation
template<class T>
nsCategoryCache<T>::nsCategoryCache(const char* aCategory)
: mCategoryName(aCategory)
{
}
template<class T>
void nsCategoryCache<T>::EntryAdded(const nsCString& aValue) {
nsCOMPtr<T> catEntry = do_GetService(aValue.get());
if (catEntry)
mEntries.AppendObject(catEntry);
}
template<class T>
void nsCategoryCache<T>::EntryRemoved(const nsCString& aValue) {
nsCOMPtr<T> catEntry = do_GetService(aValue.get());
if (catEntry)
mEntries.RemoveObject(catEntry);
}
template<class T>
void nsCategoryCache<T>::CategoryCleared() {
mEntries.Clear();
}
#endif