1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/rdf/base/src/nsContainerEnumerator.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,262 @@
1.4 +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/*
1.10 +
1.11 + A simple cursor that enumerates the elements of an RDF container
1.12 + (RDF:Bag, RDF:Seq, or RDF:Alt).
1.13 +
1.14 + Caveats
1.15 + -------
1.16 +
1.17 + 1. This uses an implementation-specific detail to determine the
1.18 + index of the last element in the container; specifically, the RDF
1.19 + utilities maintain a counter attribute on the container that
1.20 + holds the numeric value of the next value that is to be
1.21 + assigned. So, this cursor will bust if you use it with a bag that
1.22 + hasn't been created using the RDF utility routines.
1.23 +
1.24 + */
1.25 +
1.26 +#include "nscore.h"
1.27 +#include "nsCOMPtr.h"
1.28 +#include "nsIRDFContainerUtils.h"
1.29 +#include "nsIRDFDataSource.h"
1.30 +#include "nsIRDFNode.h"
1.31 +#include "nsIRDFService.h"
1.32 +#include "nsIServiceManager.h"
1.33 +#include "nsRDFCID.h"
1.34 +#include "nsString.h"
1.35 +#include "nsXPIDLString.h"
1.36 +#include "prlog.h"
1.37 +#include "rdf.h"
1.38 +#include "rdfutil.h"
1.39 +
1.40 +////////////////////////////////////////////////////////////////////////
1.41 +
1.42 +class ContainerEnumeratorImpl : public nsISimpleEnumerator {
1.43 +private:
1.44 + // pseudo-constants
1.45 + static nsrefcnt gRefCnt;
1.46 + static nsIRDFResource* kRDF_nextVal;
1.47 + static nsIRDFContainerUtils* gRDFC;
1.48 +
1.49 + nsCOMPtr<nsIRDFDataSource> mDataSource;
1.50 + nsCOMPtr<nsIRDFResource> mContainer;
1.51 + nsCOMPtr<nsIRDFResource> mOrdinalProperty;
1.52 +
1.53 + nsCOMPtr<nsISimpleEnumerator> mCurrent;
1.54 + nsCOMPtr<nsIRDFNode> mResult;
1.55 + int32_t mNextIndex;
1.56 +
1.57 +public:
1.58 + ContainerEnumeratorImpl(nsIRDFDataSource* ds, nsIRDFResource* container);
1.59 + virtual ~ContainerEnumeratorImpl();
1.60 +
1.61 + nsresult Init();
1.62 +
1.63 + NS_DECL_ISUPPORTS
1.64 + NS_DECL_NSISIMPLEENUMERATOR
1.65 +};
1.66 +
1.67 +nsrefcnt ContainerEnumeratorImpl::gRefCnt;
1.68 +nsIRDFResource* ContainerEnumeratorImpl::kRDF_nextVal;
1.69 +nsIRDFContainerUtils* ContainerEnumeratorImpl::gRDFC;
1.70 +
1.71 +
1.72 +ContainerEnumeratorImpl::ContainerEnumeratorImpl(nsIRDFDataSource* aDataSource,
1.73 + nsIRDFResource* aContainer)
1.74 + : mDataSource(aDataSource),
1.75 + mContainer(aContainer),
1.76 + mNextIndex(1)
1.77 +{
1.78 +}
1.79 +
1.80 +nsresult
1.81 +ContainerEnumeratorImpl::Init()
1.82 +{
1.83 + if (gRefCnt++ == 0) {
1.84 + nsresult rv;
1.85 +
1.86 + NS_DEFINE_CID(kRDFServiceCID, NS_RDFSERVICE_CID);
1.87 + nsCOMPtr<nsIRDFService> rdf = do_GetService(kRDFServiceCID);
1.88 + NS_ASSERTION(rdf != nullptr, "unable to acquire resource manager");
1.89 + if (! rdf)
1.90 + return NS_ERROR_FAILURE;
1.91 +
1.92 + rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "nextVal"), &kRDF_nextVal);
1.93 + NS_ASSERTION(NS_SUCCEEDED(rv), "unable to get resource");
1.94 + if (NS_FAILED(rv)) return rv;
1.95 +
1.96 + NS_DEFINE_CID(kRDFContainerUtilsCID, NS_RDFCONTAINERUTILS_CID);
1.97 + rv = CallGetService(kRDFContainerUtilsCID, &gRDFC);
1.98 + if (NS_FAILED(rv)) return rv;
1.99 + }
1.100 +
1.101 + return NS_OK;
1.102 +}
1.103 +
1.104 +
1.105 +ContainerEnumeratorImpl::~ContainerEnumeratorImpl()
1.106 +{
1.107 + if (--gRefCnt == 0) {
1.108 + NS_IF_RELEASE(kRDF_nextVal);
1.109 + NS_IF_RELEASE(gRDFC);
1.110 + }
1.111 +}
1.112 +
1.113 +NS_IMPL_ISUPPORTS(ContainerEnumeratorImpl, nsISimpleEnumerator)
1.114 +
1.115 +
1.116 +NS_IMETHODIMP
1.117 +ContainerEnumeratorImpl::HasMoreElements(bool* aResult)
1.118 +{
1.119 + NS_PRECONDITION(aResult != nullptr, "null ptr");
1.120 + if (! aResult)
1.121 + return NS_ERROR_NULL_POINTER;
1.122 +
1.123 + nsresult rv;
1.124 +
1.125 + // If we've already queued up a next value, then we know there are more elements.
1.126 + if (mResult) {
1.127 + *aResult = true;
1.128 + return NS_OK;
1.129 + }
1.130 +
1.131 + // Otherwise, we need to grovel
1.132 +
1.133 + // Figure out the upper bound so we'll know when we're done. Since it's
1.134 + // possible that we're targeting a composite datasource, we'll need to
1.135 + // "GetTargets()" and take the maximum value of "nextVal" to know the
1.136 + // upper bound.
1.137 + //
1.138 + // Remember that since nextVal is the next index that we'd assign
1.139 + // to an element in a container, it's *one more* than count of
1.140 + // elements in the container.
1.141 + int32_t max = 0;
1.142 +
1.143 + nsCOMPtr<nsISimpleEnumerator> targets;
1.144 + rv = mDataSource->GetTargets(mContainer, kRDF_nextVal, true, getter_AddRefs(targets));
1.145 + if (NS_FAILED(rv)) return rv;
1.146 +
1.147 + while (1) {
1.148 + bool hasmore;
1.149 + targets->HasMoreElements(&hasmore);
1.150 + if (! hasmore)
1.151 + break;
1.152 +
1.153 + nsCOMPtr<nsISupports> isupports;
1.154 + targets->GetNext(getter_AddRefs(isupports));
1.155 +
1.156 + nsCOMPtr<nsIRDFLiteral> nextValLiteral = do_QueryInterface(isupports);
1.157 + if (! nextValLiteral)
1.158 + continue;
1.159 +
1.160 + const char16_t *nextValStr;
1.161 + nextValLiteral->GetValueConst(&nextValStr);
1.162 +
1.163 + nsresult err;
1.164 + int32_t nextVal = nsAutoString(nextValStr).ToInteger(&err);
1.165 +
1.166 + if (nextVal > max)
1.167 + max = nextVal;
1.168 + }
1.169 +
1.170 + // Now pre-fetch our next value into mResult.
1.171 + while (mCurrent || mNextIndex < max) {
1.172 +
1.173 + // If mCurrent has been depleted, then conjure up a new one
1.174 + if (! mCurrent) {
1.175 + rv = gRDFC->IndexToOrdinalResource(mNextIndex, getter_AddRefs(mOrdinalProperty));
1.176 + if (NS_FAILED(rv)) return rv;
1.177 +
1.178 + rv = mDataSource->GetTargets(mContainer, mOrdinalProperty, true, getter_AddRefs(mCurrent));
1.179 + if (NS_FAILED(rv)) return rv;
1.180 +
1.181 + ++mNextIndex;
1.182 + }
1.183 +
1.184 + if (mCurrent) {
1.185 + bool hasMore;
1.186 + rv = mCurrent->HasMoreElements(&hasMore);
1.187 + if (NS_FAILED(rv)) return rv;
1.188 +
1.189 + // Is the current enumerator depleted? If so, iterate to
1.190 + // the next index.
1.191 + if (! hasMore) {
1.192 + mCurrent = nullptr;
1.193 + continue;
1.194 + }
1.195 +
1.196 + // "Peek" ahead and pull out the next target.
1.197 + nsCOMPtr<nsISupports> result;
1.198 + rv = mCurrent->GetNext(getter_AddRefs(result));
1.199 + if (NS_FAILED(rv)) return rv;
1.200 +
1.201 + mResult = do_QueryInterface(result, &rv);
1.202 + if (NS_FAILED(rv)) return rv;
1.203 +
1.204 + *aResult = true;
1.205 + return NS_OK;
1.206 + }
1.207 + }
1.208 +
1.209 + // If we get here, we ran out of elements. The cursor is empty.
1.210 + *aResult = false;
1.211 + return NS_OK;
1.212 +}
1.213 +
1.214 +
1.215 +NS_IMETHODIMP
1.216 +ContainerEnumeratorImpl::GetNext(nsISupports** aResult)
1.217 +{
1.218 + nsresult rv;
1.219 +
1.220 + bool hasMore;
1.221 + rv = HasMoreElements(&hasMore);
1.222 + if (NS_FAILED(rv)) return rv;
1.223 +
1.224 + if (! hasMore)
1.225 + return NS_ERROR_UNEXPECTED;
1.226 +
1.227 + NS_ADDREF(*aResult = mResult);
1.228 + mResult = nullptr;
1.229 +
1.230 + return NS_OK;
1.231 +}
1.232 +
1.233 +
1.234 +////////////////////////////////////////////////////////////////////////
1.235 +
1.236 +nsresult
1.237 +NS_NewContainerEnumerator(nsIRDFDataSource* aDataSource,
1.238 + nsIRDFResource* aContainer,
1.239 + nsISimpleEnumerator** aResult)
1.240 +{
1.241 + NS_PRECONDITION(aDataSource != nullptr, "null ptr");
1.242 + if (! aDataSource)
1.243 + return NS_ERROR_NULL_POINTER;
1.244 +
1.245 + NS_PRECONDITION(aContainer != nullptr, "null ptr");
1.246 + if (! aContainer)
1.247 + return NS_ERROR_NULL_POINTER;
1.248 +
1.249 + NS_PRECONDITION(aResult != nullptr, "null ptr");
1.250 + if (! aResult)
1.251 + return NS_ERROR_NULL_POINTER;
1.252 +
1.253 + ContainerEnumeratorImpl* result = new ContainerEnumeratorImpl(aDataSource, aContainer);
1.254 + if (! result)
1.255 + return NS_ERROR_OUT_OF_MEMORY;
1.256 +
1.257 + NS_ADDREF(result);
1.258 +
1.259 + nsresult rv = result->Init();
1.260 + if (NS_FAILED(rv))
1.261 + NS_RELEASE(result);
1.262 +
1.263 + *aResult = result;
1.264 + return rv;
1.265 +}
