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lightning-sunbird  0.9+nobinonly
nsAdapterEnumerator.cpp
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00001 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
00002 /* ***** BEGIN LICENSE BLOCK *****
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00010  * Software distributed under the License is distributed on an "AS IS" basis,
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00015  * The Original Code is mozilla.org code.
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00017  * The Initial Developer of the Original Code is
00018  * Netscape Communications Corporation.
00019  * Portions created by the Initial Developer are Copyright (C) 1998
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00022  * Contributor(s):
00023  *
00024  * Alternatively, the contents of this file may be used under the terms of
00025  * either of the GNU General Public License Version 2 or later (the "GPL"),
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00036  * ***** END LICENSE BLOCK ***** */
00037 
00038 #include "nsAdapterEnumerator.h"
00039 
00041 
00042 
00043 nsAdapterEnumerator::nsAdapterEnumerator(nsIEnumerator* aEnum)
00044     : mEnum(aEnum), mCurrent(0), mStarted(PR_FALSE)
00045 {
00046     NS_ADDREF(mEnum);
00047 }
00048 
00049 
00050 nsAdapterEnumerator::~nsAdapterEnumerator()
00051 {
00052     NS_RELEASE(mEnum);
00053     NS_IF_RELEASE(mCurrent);
00054 }
00055 
00056 
00057 NS_IMPL_ISUPPORTS1(nsAdapterEnumerator, nsISimpleEnumerator)
00058 
00059 NS_IMETHODIMP
00060 nsAdapterEnumerator::HasMoreElements(PRBool* aResult)
00061 {
00062     nsresult rv;
00063 
00064     if (mCurrent) {
00065         *aResult = PR_TRUE;
00066         return NS_OK;
00067     }
00068 
00069     if (! mStarted) {
00070         mStarted = PR_TRUE;
00071         rv = mEnum->First();
00072         if (rv == NS_OK) {
00073             mEnum->CurrentItem(&mCurrent);
00074             *aResult = PR_TRUE;
00075         }
00076         else {
00077             *aResult = PR_FALSE;
00078         }
00079     }
00080     else {
00081         *aResult = PR_FALSE;
00082 
00083         rv = mEnum->IsDone();
00084         if (rv != NS_OK) {
00085             // We're not done. Advance to the next one.
00086             rv = mEnum->Next();
00087             if (rv == NS_OK) {
00088                 mEnum->CurrentItem(&mCurrent);
00089                 *aResult = PR_TRUE;
00090             }
00091         }
00092     }
00093     return NS_OK;
00094 }
00095 
00096 
00097 NS_IMETHODIMP
00098 nsAdapterEnumerator::GetNext(nsISupports** aResult)
00099 {
00100     nsresult rv;
00101 
00102     PRBool hasMore;
00103     rv = HasMoreElements(&hasMore);
00104     if (NS_FAILED(rv)) return rv;
00105 
00106     if (! hasMore)
00107         return NS_ERROR_UNEXPECTED;
00108 
00109     // No need to addref, we "transfer" the ownership to the caller.
00110     *aResult = mCurrent;
00111     mCurrent = 0;
00112     return NS_OK;
00113 }
00114