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 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
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 * 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 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):
 *
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 * either of 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
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#include "nsAdapterEnumerator.h"

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


nsAdapterEnumerator::nsAdapterEnumerator(nsIEnumerator* aEnum)
    : mEnum(aEnum), mCurrent(0), mStarted(PR_FALSE)
{
    NS_ADDREF(mEnum);
}


nsAdapterEnumerator::~nsAdapterEnumerator()
{
    NS_RELEASE(mEnum);
    NS_IF_RELEASE(mCurrent);
}


NS_IMPL_ISUPPORTS1(nsAdapterEnumerator, nsISimpleEnumerator)

NS_IMETHODIMP
nsAdapterEnumerator::HasMoreElements(PRBool* aResult)
{
    nsresult rv;

    if (mCurrent) {
        *aResult = PR_TRUE;
        return NS_OK;
    }

    if (! mStarted) {
        mStarted = PR_TRUE;
        rv = mEnum->First();
        if (rv == NS_OK) {
            mEnum->CurrentItem(&mCurrent);
            *aResult = PR_TRUE;
        }
        else {
            *aResult = PR_FALSE;
        }
    }
    else {
        *aResult = PR_FALSE;

        rv = mEnum->IsDone();
        if (rv != NS_OK) {
            // We're not done. Advance to the next one.
            rv = mEnum->Next();
            if (rv == NS_OK) {
                mEnum->CurrentItem(&mCurrent);
                *aResult = PR_TRUE;
            }
        }
    }
    return NS_OK;
}


NS_IMETHODIMP
nsAdapterEnumerator::GetNext(nsISupports** aResult)
{
    nsresult rv;

    PRBool hasMore;
    rv = HasMoreElements(&hasMore);
    if (NS_FAILED(rv)) return rv;

    if (! hasMore)
        return NS_ERROR_UNEXPECTED;

    // No need to addref, we "transfer" the ownership to the caller.
    *aResult = mCurrent;
    mCurrent = 0;
    return NS_OK;
}