gecko-dev/xpcom/ds/nsEnumeratorUtils.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.
 *
 * 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
 * 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"),
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#include "nsEnumeratorUtils.h"


nsArrayEnumerator::nsArrayEnumerator(nsISupportsArray* aValueArray)
    : mValueArray(aValueArray),
      mIndex(0)
{
    NS_IF_ADDREF(mValueArray);
}

nsArrayEnumerator::~nsArrayEnumerator(void)
{
    NS_IF_RELEASE(mValueArray);
}

NS_IMPL_ISUPPORTS1(nsArrayEnumerator, nsISimpleEnumerator)

NS_IMETHODIMP
nsArrayEnumerator::HasMoreElements(PRBool* aResult)
{
    NS_PRECONDITION(aResult != 0, "null ptr");
    if (! aResult)
        return NS_ERROR_NULL_POINTER;

    if (!mValueArray) {
        *aResult = PR_FALSE;
        return NS_OK;
    }

    PRUint32 cnt;
    nsresult rv = mValueArray->Count(&cnt);
    if (NS_FAILED(rv)) return rv;
    *aResult = (mIndex < (PRInt32) cnt);
    return NS_OK;
}

NS_IMETHODIMP
nsArrayEnumerator::GetNext(nsISupports** aResult)
{
    NS_PRECONDITION(aResult != 0, "null ptr");
    if (! aResult)
        return NS_ERROR_NULL_POINTER;

    if (!mValueArray) {
        *aResult = nsnull;
        return NS_OK;
    }

    PRUint32 cnt;
    nsresult rv = mValueArray->Count(&cnt);
    if (NS_FAILED(rv)) return rv;
    if (mIndex >= (PRInt32) cnt)
        return NS_ERROR_UNEXPECTED;

    *aResult = mValueArray->ElementAt(mIndex++);
    return NS_OK;
}

extern NS_COM nsresult
NS_NewArrayEnumerator(nsISimpleEnumerator* *result,
                      nsISupportsArray* array)
{
    nsArrayEnumerator* enumer = new nsArrayEnumerator(array);
    if (enumer == nsnull)
        return NS_ERROR_OUT_OF_MEMORY;
    *result = enumer; 
    NS_ADDREF(*result);
    return NS_OK;
}

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

nsSingletonEnumerator::nsSingletonEnumerator(nsISupports* aValue)
    : mValue(aValue)
{
    NS_IF_ADDREF(mValue);
    mConsumed = (mValue ? PR_FALSE : PR_TRUE);
}

nsSingletonEnumerator::~nsSingletonEnumerator()
{
    NS_IF_RELEASE(mValue);
}

NS_IMPL_ISUPPORTS1(nsSingletonEnumerator, nsISimpleEnumerator)

NS_IMETHODIMP
nsSingletonEnumerator::HasMoreElements(PRBool* aResult)
{
    NS_PRECONDITION(aResult != 0, "null ptr");
    if (! aResult)
        return NS_ERROR_NULL_POINTER;

    *aResult = !mConsumed;
    return NS_OK;
}


NS_IMETHODIMP
nsSingletonEnumerator::GetNext(nsISupports** aResult)
{
    NS_PRECONDITION(aResult != 0, "null ptr");
    if (! aResult)
        return NS_ERROR_NULL_POINTER;

    if (mConsumed)
        return NS_ERROR_UNEXPECTED;

    mConsumed = PR_TRUE;

    *aResult = mValue;
    NS_ADDREF(*aResult);
    return NS_OK;
}

extern "C" NS_COM nsresult
NS_NewSingletonEnumerator(nsISimpleEnumerator* *result,
                          nsISupports* singleton)
{
    nsSingletonEnumerator* enumer = new nsSingletonEnumerator(singleton);
    if (enumer == nsnull)
        return NS_ERROR_OUT_OF_MEMORY;
    *result = enumer; 
    NS_ADDREF(*result);
    return NS_OK;
}

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

nsUnionEnumerator::nsUnionEnumerator(nsISimpleEnumerator* firstEnumerator,
                                     nsISimpleEnumerator* secondEnumerator)
    : mFirstEnumerator(firstEnumerator),
      mSecondEnumerator(secondEnumerator),
      mConsumed(PR_FALSE), mAtSecond(PR_FALSE)
{
}

nsUnionEnumerator::~nsUnionEnumerator()
{
}

NS_IMPL_ISUPPORTS1(nsUnionEnumerator, nsISimpleEnumerator)

NS_IMETHODIMP
nsUnionEnumerator::HasMoreElements(PRBool* aResult)
{
    NS_PRECONDITION(aResult != 0, "null ptr");
    if (! aResult)
        return NS_ERROR_NULL_POINTER;

    nsresult rv;

    if (mConsumed) {
        *aResult = PR_FALSE;
        return NS_OK;
    }

    if (! mAtSecond) {
        rv = mFirstEnumerator->HasMoreElements(aResult);
        if (NS_FAILED(rv)) return rv;

        if (*aResult)
            return NS_OK;

        mAtSecond = PR_TRUE;
    }

    rv = mSecondEnumerator->HasMoreElements(aResult);
    if (NS_FAILED(rv)) return rv;

    if (*aResult)
        return NS_OK;

    *aResult = PR_FALSE;
    mConsumed = PR_TRUE;
    return NS_OK;
}

NS_IMETHODIMP
nsUnionEnumerator::GetNext(nsISupports** aResult)
{
    NS_PRECONDITION(aResult != 0, "null ptr");
    if (! aResult)
        return NS_ERROR_NULL_POINTER;

    if (mConsumed)
        return NS_ERROR_UNEXPECTED;

    if (! mAtSecond)
        return mFirstEnumerator->GetNext(aResult);

    return mSecondEnumerator->GetNext(aResult);
}

extern "C" NS_COM nsresult
NS_NewUnionEnumerator(nsISimpleEnumerator* *result,
                      nsISimpleEnumerator* firstEnumerator,
                      nsISimpleEnumerator* secondEnumerator)
{
    *result = nsnull;
    if (! firstEnumerator) {
        *result = secondEnumerator;
    } else if (! secondEnumerator) {
        *result = firstEnumerator;
    } else {
        nsUnionEnumerator* enumer = new nsUnionEnumerator(firstEnumerator, secondEnumerator);
        if (enumer == nsnull)
            return NS_ERROR_OUT_OF_MEMORY;
        *result = enumer; 
    }
    NS_ADDREF(*result);
    return NS_OK;
}


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