/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: NPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Netscape 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/NPL/
 *
 * 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 mozilla.org code.
 *
 * The Initial Developer of the Original Code is 
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Pierre Phaneuf <pp@ludusdesign.com>
 *
 * 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 NPL, 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 NPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/*

  An empty enumerator.

 */

#include "nsIEnumerator.h"

////////////////////////////////////////////////////////////////////////

class EmptyEnumeratorImpl : public nsISimpleEnumerator
{
public:
    EmptyEnumeratorImpl(void) {};
    virtual ~EmptyEnumeratorImpl(void) {};

    // nsISupports interface
    NS_IMETHOD_(nsrefcnt) AddRef(void) {
        return 2;
    }

    NS_IMETHOD_(nsrefcnt) Release(void) {
        return 1;
    }

    NS_IMETHOD QueryInterface(REFNSIID iid, void** result) {
        if (! result)
            return NS_ERROR_NULL_POINTER;

        if (iid.Equals(NS_GET_IID(nsISimpleEnumerator)) ||
            iid.Equals(NS_GET_IID(nsISupports))) {
            *result = (nsISimpleEnumerator*) this;
            NS_ADDREF(this);
            return NS_OK;
        }
        return NS_NOINTERFACE;
    }

    // nsISimpleEnumerator
    NS_IMETHOD HasMoreElements(PRBool* aResult) {
        *aResult = PR_FALSE;
        return NS_OK;
    }

    NS_IMETHOD GetNext(nsISupports** aResult) {
        return NS_ERROR_UNEXPECTED;
    }
};

extern "C" NS_COM nsresult
NS_NewEmptyEnumerator(nsISimpleEnumerator** aResult)
{
    static EmptyEnumeratorImpl gEmptyEnumerator;
    *aResult = &gEmptyEnumerator;
    return NS_OK;
}