RetroZilla/xpcom/ds/nsEmptyEnumerator.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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 * for the specific language governing rights and limitations under the
 * License.
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 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
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 * Portions created by the Initial Developer are Copyright (C) 1998
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 * Contributor(s):
 *   L. David Baron <dbaron@dbaron.org>
 *   Pierre Phaneuf <pp@ludusdesign.com>
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/*

  An empty enumerator.

 */

#include "nsEmptyEnumerator.h"

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

MOZ_DECL_CTOR_COUNTER(EmptyEnumeratorImpl)

EmptyEnumeratorImpl::EmptyEnumeratorImpl(void)
{
    MOZ_COUNT_CTOR(EmptyEnumeratorImpl);
}

EmptyEnumeratorImpl::~EmptyEnumeratorImpl(void)
{
    MOZ_COUNT_DTOR(EmptyEnumeratorImpl);
}

// nsISupports interface
NS_IMETHODIMP_(nsrefcnt) EmptyEnumeratorImpl::AddRef(void)
{
    return 2;
}

NS_IMETHODIMP_(nsrefcnt) EmptyEnumeratorImpl::Release(void)
{
    return 1;
}

NS_IMPL_QUERY_INTERFACE1(EmptyEnumeratorImpl, nsISimpleEnumerator)


// nsISimpleEnumerator interface
NS_IMETHODIMP EmptyEnumeratorImpl::HasMoreElements(PRBool* aResult)
{
    *aResult = PR_FALSE;
    return NS_OK;
}

NS_IMETHODIMP EmptyEnumeratorImpl::HasMore(PRBool* aResult)
{
    *aResult = PR_FALSE;
    return NS_OK;
}

NS_IMETHODIMP EmptyEnumeratorImpl::GetNext(nsISupports** aResult)
{
    return NS_ERROR_UNEXPECTED;
}

NS_IMETHODIMP EmptyEnumeratorImpl::GetNext(nsACString& aResult)
{
    return NS_ERROR_UNEXPECTED;
}

NS_IMETHODIMP EmptyEnumeratorImpl::GetNext(nsAString& aResult)
{
    return NS_ERROR_UNEXPECTED;
}

static EmptyEnumeratorImpl* gEmptyEnumerator = nsnull;

extern "C" NS_COM nsresult
NS_NewEmptyEnumerator(nsISimpleEnumerator** aResult)
{
    nsresult rv = NS_OK;
    if (!gEmptyEnumerator) {
        gEmptyEnumerator = new EmptyEnumeratorImpl();
        if (!gEmptyEnumerator)
            rv = NS_ERROR_OUT_OF_MEMORY;
    }
    *aResult = gEmptyEnumerator;
    return rv;
}

/* static */ void
EmptyEnumeratorImpl::Shutdown()
{
    delete gEmptyEnumerator;
    gEmptyEnumerator = nsnull;
}