mirror of
https://github.com/classilla/tenfourfox.git
synced 2024-09-11 02:56:06 +00:00
264 lines
7.3 KiB
C++
264 lines
7.3 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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A simple cursor that enumerates the elements of an RDF container
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(RDF:Bag, RDF:Seq, or RDF:Alt).
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Caveats
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-------
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1. This uses an implementation-specific detail to determine the
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index of the last element in the container; specifically, the RDF
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utilities maintain a counter attribute on the container that
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holds the numeric value of the next value that is to be
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assigned. So, this cursor will bust if you use it with a bag that
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hasn't been created using the RDF utility routines.
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*/
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#include "nscore.h"
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#include "nsCOMPtr.h"
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#include "nsIRDFContainerUtils.h"
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#include "nsIRDFDataSource.h"
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#include "nsIRDFNode.h"
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#include "nsIRDFService.h"
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#include "nsIServiceManager.h"
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#include "nsRDFCID.h"
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#include "nsString.h"
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#include "nsXPIDLString.h"
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#include "mozilla/Logging.h"
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#include "rdf.h"
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#include "rdfutil.h"
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////////////////////////////////////////////////////////////////////////
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class ContainerEnumeratorImpl : public nsISimpleEnumerator {
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private:
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// pseudo-constants
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static nsrefcnt gRefCnt;
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static nsIRDFResource* kRDF_nextVal;
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static nsIRDFContainerUtils* gRDFC;
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nsCOMPtr<nsIRDFDataSource> mDataSource;
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nsCOMPtr<nsIRDFResource> mContainer;
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nsCOMPtr<nsIRDFResource> mOrdinalProperty;
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nsCOMPtr<nsISimpleEnumerator> mCurrent;
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nsCOMPtr<nsIRDFNode> mResult;
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int32_t mNextIndex;
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virtual ~ContainerEnumeratorImpl();
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public:
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ContainerEnumeratorImpl(nsIRDFDataSource* ds, nsIRDFResource* container);
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nsresult Init();
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NS_DECL_ISUPPORTS
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NS_DECL_NSISIMPLEENUMERATOR
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};
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nsrefcnt ContainerEnumeratorImpl::gRefCnt;
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nsIRDFResource* ContainerEnumeratorImpl::kRDF_nextVal;
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nsIRDFContainerUtils* ContainerEnumeratorImpl::gRDFC;
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ContainerEnumeratorImpl::ContainerEnumeratorImpl(nsIRDFDataSource* aDataSource,
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nsIRDFResource* aContainer)
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: mDataSource(aDataSource),
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mContainer(aContainer),
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mNextIndex(1)
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{
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}
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nsresult
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ContainerEnumeratorImpl::Init()
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{
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if (gRefCnt++ == 0) {
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nsresult rv;
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NS_DEFINE_CID(kRDFServiceCID, NS_RDFSERVICE_CID);
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nsCOMPtr<nsIRDFService> rdf = do_GetService(kRDFServiceCID);
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NS_ASSERTION(rdf != nullptr, "unable to acquire resource manager");
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if (! rdf)
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return NS_ERROR_FAILURE;
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rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "nextVal"), &kRDF_nextVal);
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NS_ASSERTION(NS_SUCCEEDED(rv), "unable to get resource");
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if (NS_FAILED(rv)) return rv;
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NS_DEFINE_CID(kRDFContainerUtilsCID, NS_RDFCONTAINERUTILS_CID);
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rv = CallGetService(kRDFContainerUtilsCID, &gRDFC);
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if (NS_FAILED(rv)) return rv;
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}
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return NS_OK;
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}
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ContainerEnumeratorImpl::~ContainerEnumeratorImpl()
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{
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if (--gRefCnt == 0) {
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NS_IF_RELEASE(kRDF_nextVal);
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NS_IF_RELEASE(gRDFC);
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}
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}
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NS_IMPL_ISUPPORTS(ContainerEnumeratorImpl, nsISimpleEnumerator)
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NS_IMETHODIMP
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ContainerEnumeratorImpl::HasMoreElements(bool* aResult)
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{
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NS_PRECONDITION(aResult != nullptr, "null ptr");
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if (! aResult)
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return NS_ERROR_NULL_POINTER;
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nsresult rv;
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// If we've already queued up a next value, then we know there are more elements.
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if (mResult) {
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*aResult = true;
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return NS_OK;
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}
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// Otherwise, we need to grovel
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// Figure out the upper bound so we'll know when we're done. Since it's
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// possible that we're targeting a composite datasource, we'll need to
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// "GetTargets()" and take the maximum value of "nextVal" to know the
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// upper bound.
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//
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// Remember that since nextVal is the next index that we'd assign
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// to an element in a container, it's *one more* than count of
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// elements in the container.
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int32_t max = 0;
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nsCOMPtr<nsISimpleEnumerator> targets;
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rv = mDataSource->GetTargets(mContainer, kRDF_nextVal, true, getter_AddRefs(targets));
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if (NS_FAILED(rv)) return rv;
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while (1) {
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bool hasmore;
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targets->HasMoreElements(&hasmore);
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if (! hasmore)
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break;
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nsCOMPtr<nsISupports> isupports;
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targets->GetNext(getter_AddRefs(isupports));
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nsCOMPtr<nsIRDFLiteral> nextValLiteral = do_QueryInterface(isupports);
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if (! nextValLiteral)
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continue;
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const char16_t *nextValStr;
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nextValLiteral->GetValueConst(&nextValStr);
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nsresult err;
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int32_t nextVal = nsAutoString(nextValStr).ToInteger(&err);
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if (nextVal > max)
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max = nextVal;
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}
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// Now pre-fetch our next value into mResult.
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while (mCurrent || mNextIndex < max) {
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// If mCurrent has been depleted, then conjure up a new one
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if (! mCurrent) {
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rv = gRDFC->IndexToOrdinalResource(mNextIndex, getter_AddRefs(mOrdinalProperty));
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if (NS_FAILED(rv)) return rv;
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rv = mDataSource->GetTargets(mContainer, mOrdinalProperty, true, getter_AddRefs(mCurrent));
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if (NS_FAILED(rv)) return rv;
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++mNextIndex;
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}
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if (mCurrent) {
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bool hasMore;
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rv = mCurrent->HasMoreElements(&hasMore);
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if (NS_FAILED(rv)) return rv;
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// Is the current enumerator depleted? If so, iterate to
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// the next index.
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if (! hasMore) {
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mCurrent = nullptr;
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continue;
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}
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// "Peek" ahead and pull out the next target.
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nsCOMPtr<nsISupports> result;
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rv = mCurrent->GetNext(getter_AddRefs(result));
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if (NS_FAILED(rv)) return rv;
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mResult = do_QueryInterface(result, &rv);
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if (NS_FAILED(rv)) return rv;
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*aResult = true;
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return NS_OK;
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}
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}
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// If we get here, we ran out of elements. The cursor is empty.
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*aResult = false;
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return NS_OK;
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}
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NS_IMETHODIMP
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ContainerEnumeratorImpl::GetNext(nsISupports** aResult)
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{
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nsresult rv;
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bool hasMore;
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rv = HasMoreElements(&hasMore);
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if (NS_FAILED(rv)) return rv;
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if (! hasMore)
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return NS_ERROR_UNEXPECTED;
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NS_ADDREF(*aResult = mResult);
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mResult = nullptr;
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return NS_OK;
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}
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////////////////////////////////////////////////////////////////////////
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nsresult
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NS_NewContainerEnumerator(nsIRDFDataSource* aDataSource,
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nsIRDFResource* aContainer,
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nsISimpleEnumerator** aResult)
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{
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NS_PRECONDITION(aDataSource != nullptr, "null ptr");
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if (! aDataSource)
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return NS_ERROR_NULL_POINTER;
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NS_PRECONDITION(aContainer != nullptr, "null ptr");
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if (! aContainer)
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return NS_ERROR_NULL_POINTER;
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NS_PRECONDITION(aResult != nullptr, "null ptr");
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if (! aResult)
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return NS_ERROR_NULL_POINTER;
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ContainerEnumeratorImpl* result = new ContainerEnumeratorImpl(aDataSource, aContainer);
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if (! result)
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return NS_ERROR_OUT_OF_MEMORY;
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NS_ADDREF(result);
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nsresult rv = result->Init();
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if (NS_FAILED(rv))
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NS_RELEASE(result);
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*aResult = result;
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return rv;
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}
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