LCOV - code coverage report
Current view: directory - rdf/base/src - nsContainerEnumerator.cpp (source / functions) Found Hit Coverage
Test: app.info Lines: 93 84 90.3 %
Date: 2012-06-02 Functions: 10 10 100.0 %

       1                 : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
       2                 : /* ***** BEGIN LICENSE BLOCK *****
       3                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       4                 :  *
       5                 :  * The contents of this file are subject to the Mozilla Public License Version
       6                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       7                 :  * the License. You may obtain a copy of the License at
       8                 :  * http://www.mozilla.org/MPL/
       9                 :  *
      10                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      11                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      12                 :  * for the specific language governing rights and limitations under the
      13                 :  * License.
      14                 :  *
      15                 :  * The Original Code is mozilla.org code.
      16                 :  *
      17                 :  * The Initial Developer of the Original Code is
      18                 :  * Netscape Communications Corporation.
      19                 :  * Portions created by the Initial Developer are Copyright (C) 1998
      20                 :  * the Initial Developer. All Rights Reserved.
      21                 :  *
      22                 :  * Contributor(s):
      23                 :  *   Pierre Phaneuf <pp@ludusdesign.com>
      24                 :  *
      25                 :  * Alternatively, the contents of this file may be used under the terms of
      26                 :  * either of the GNU General Public License Version 2 or later (the "GPL"),
      27                 :  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      28                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      29                 :  * of those above. If you wish to allow use of your version of this file only
      30                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      31                 :  * use your version of this file under the terms of the MPL, indicate your
      32                 :  * decision by deleting the provisions above and replace them with the notice
      33                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      34                 :  * the provisions above, a recipient may use your version of this file under
      35                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      36                 :  *
      37                 :  * ***** END LICENSE BLOCK ***** */
      38                 : 
      39                 : /*
      40                 : 
      41                 :   A simple cursor that enumerates the elements of an RDF container
      42                 :   (RDF:Bag, RDF:Seq, or RDF:Alt).
      43                 : 
      44                 :   Caveats
      45                 :   -------
      46                 : 
      47                 :   1. This uses an implementation-specific detail to determine the
      48                 :      index of the last element in the container; specifically, the RDF
      49                 :      utilities maintain a counter attribute on the container that
      50                 :      holds the numeric value of the next value that is to be
      51                 :      assigned. So, this cursor will bust if you use it with a bag that
      52                 :      hasn't been created using the RDF utility routines.
      53                 : 
      54                 :  */
      55                 : 
      56                 : #include "nscore.h"
      57                 : #include "nsCOMPtr.h"
      58                 : #include "nsIRDFContainerUtils.h"
      59                 : #include "nsIRDFDataSource.h"
      60                 : #include "nsIRDFNode.h"
      61                 : #include "nsIRDFService.h"
      62                 : #include "nsIServiceManager.h"
      63                 : #include "nsRDFCID.h"
      64                 : #include "nsString.h"
      65                 : #include "nsXPIDLString.h"
      66                 : #include "prlog.h"
      67                 : #include "rdf.h"
      68                 : #include "rdfutil.h"
      69                 : 
      70                 : ////////////////////////////////////////////////////////////////////////
      71                 : 
      72                 : static NS_DEFINE_CID(kRDFServiceCID,        NS_RDFSERVICE_CID);
      73                 : static NS_DEFINE_CID(kRDFContainerUtilsCID, NS_RDFCONTAINERUTILS_CID);
      74                 : 
      75                 : ////////////////////////////////////////////////////////////////////////
      76                 : 
      77                 : class ContainerEnumeratorImpl : public nsISimpleEnumerator {
      78                 : private:
      79                 :     // pseudo-constants
      80                 :     static nsrefcnt              gRefCnt;
      81                 :     static nsIRDFResource*       kRDF_nextVal;
      82                 :     static nsIRDFContainerUtils* gRDFC;
      83                 : 
      84                 :     nsCOMPtr<nsIRDFDataSource>      mDataSource;
      85                 :     nsCOMPtr<nsIRDFResource>        mContainer;
      86                 :     nsCOMPtr<nsIRDFResource>        mOrdinalProperty;
      87                 : 
      88                 :     nsCOMPtr<nsISimpleEnumerator>   mCurrent;
      89                 :     nsCOMPtr<nsIRDFNode>            mResult;
      90                 :     PRInt32 mNextIndex;
      91                 : 
      92                 : public:
      93                 :     ContainerEnumeratorImpl(nsIRDFDataSource* ds, nsIRDFResource* container);
      94                 :     virtual ~ContainerEnumeratorImpl();
      95                 : 
      96                 :     nsresult Init();
      97                 : 
      98                 :     NS_DECL_ISUPPORTS
      99                 :     NS_DECL_NSISIMPLEENUMERATOR
     100                 : };
     101                 : 
     102                 : nsrefcnt              ContainerEnumeratorImpl::gRefCnt;
     103                 : nsIRDFResource*       ContainerEnumeratorImpl::kRDF_nextVal;
     104                 : nsIRDFContainerUtils* ContainerEnumeratorImpl::gRDFC;
     105                 : 
     106                 : 
     107             291 : ContainerEnumeratorImpl::ContainerEnumeratorImpl(nsIRDFDataSource* aDataSource,
     108                 :                                                  nsIRDFResource* aContainer)
     109                 :     : mDataSource(aDataSource),
     110                 :       mContainer(aContainer),
     111             291 :       mNextIndex(1)
     112                 : {
     113             291 : }
     114                 : 
     115                 : nsresult
     116             291 : ContainerEnumeratorImpl::Init()
     117                 : {
     118             291 :     if (gRefCnt++ == 0) {
     119                 :         nsresult rv;
     120             520 :         nsCOMPtr<nsIRDFService> rdf = do_GetService(kRDFServiceCID);
     121             260 :         NS_ASSERTION(rdf != nsnull, "unable to acquire resource manager");
     122             260 :         if (! rdf)
     123               0 :             return NS_ERROR_FAILURE;
     124                 : 
     125             260 :         rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "nextVal"), &kRDF_nextVal);
     126             260 :         NS_ASSERTION(NS_SUCCEEDED(rv), "unable to get resource");
     127             260 :         if (NS_FAILED(rv)) return rv;
     128                 : 
     129             260 :         rv = CallGetService(kRDFContainerUtilsCID, &gRDFC);
     130             260 :         if (NS_FAILED(rv)) return rv;
     131                 :     }
     132                 : 
     133             291 :     return NS_OK;
     134                 : }
     135                 : 
     136                 : 
     137             873 : ContainerEnumeratorImpl::~ContainerEnumeratorImpl()
     138                 : {
     139             291 :     if (--gRefCnt == 0) {
     140             260 :         NS_IF_RELEASE(kRDF_nextVal);
     141             260 :         NS_IF_RELEASE(gRDFC);
     142                 :     }
     143            1164 : }
     144                 : 
     145            4067 : NS_IMPL_ISUPPORTS1(ContainerEnumeratorImpl, nsISimpleEnumerator)
     146                 : 
     147                 : 
     148                 : NS_IMETHODIMP
     149            1207 : ContainerEnumeratorImpl::HasMoreElements(bool* aResult)
     150                 : {
     151            1207 :     NS_PRECONDITION(aResult != nsnull, "null ptr");
     152            1207 :     if (! aResult)
     153               0 :         return NS_ERROR_NULL_POINTER;
     154                 : 
     155                 :     nsresult rv;
     156                 : 
     157                 :     // If we've already queued up a next value, then we know there are more elements.
     158            1207 :     if (mResult) {
     159             458 :         *aResult = true;
     160             458 :         return NS_OK;
     161                 :     }
     162                 : 
     163                 :     // Otherwise, we need to grovel
     164                 : 
     165                 :     // Figure out the upper bound so we'll know when we're done. Since it's
     166                 :     // possible that we're targeting a composite datasource, we'll need to
     167                 :     // "GetTargets()" and take the maximum value of "nextVal" to know the
     168                 :     // upper bound.
     169                 :     //
     170                 :     // Remember that since nextVal is the next index that we'd assign
     171                 :     // to an element in a container, it's *one more* than count of
     172                 :     // elements in the container.
     173             749 :     PRInt32 max = 0;
     174                 : 
     175            1498 :     nsCOMPtr<nsISimpleEnumerator> targets;
     176             749 :     rv = mDataSource->GetTargets(mContainer, kRDF_nextVal, true, getter_AddRefs(targets));
     177             749 :     if (NS_FAILED(rv)) return rv;
     178                 : 
     179             749 :     while (1) {
     180                 :         bool hasmore;
     181            1498 :         targets->HasMoreElements(&hasmore);
     182            1498 :         if (! hasmore)
     183                 :             break;
     184                 : 
     185            1498 :         nsCOMPtr<nsISupports> isupports;
     186             749 :         targets->GetNext(getter_AddRefs(isupports));
     187                 : 
     188            1498 :         nsCOMPtr<nsIRDFLiteral> nextValLiteral = do_QueryInterface(isupports);
     189             749 :         if (! nextValLiteral)
     190               0 :              continue;
     191                 : 
     192                 :          const PRUnichar *nextValStr;
     193             749 :          nextValLiteral->GetValueConst(&nextValStr);
     194                 :                  
     195                 :          PRInt32 err;
     196             749 :          PRInt32 nextVal = nsAutoString(nextValStr).ToInteger(&err);
     197                 : 
     198             749 :          if (nextVal > max)
     199             749 :              max = nextVal;
     200                 :     }
     201                 : 
     202                 :     // Now pre-fetch our next value into mResult.
     203            1956 :     while (mCurrent || mNextIndex < max) {
     204                 : 
     205                 :         // If mCurrent has been depleted, then conjure up a new one
     206             916 :         if (! mCurrent) {
     207             458 :             rv = gRDFC->IndexToOrdinalResource(mNextIndex, getter_AddRefs(mOrdinalProperty));
     208             458 :             if (NS_FAILED(rv)) return rv;
     209                 : 
     210             458 :             rv = mDataSource->GetTargets(mContainer, mOrdinalProperty, true, getter_AddRefs(mCurrent));
     211             458 :             if (NS_FAILED(rv)) return rv;
     212                 : 
     213             458 :             ++mNextIndex;
     214                 :         }
     215                 : 
     216             916 :         if (mCurrent) {
     217                 :             bool hasMore;
     218             916 :             rv = mCurrent->HasMoreElements(&hasMore);
     219             916 :             if (NS_FAILED(rv)) return rv;
     220                 : 
     221                 :             // Is the current enumerator depleted? If so, iterate to
     222                 :             // the next index.
     223             916 :             if (! hasMore) {
     224             458 :                 mCurrent = nsnull;
     225             458 :                 continue;
     226                 :             }
     227                 : 
     228                 :             // "Peek" ahead and pull out the next target.
     229             916 :             nsCOMPtr<nsISupports> result;
     230             458 :             rv = mCurrent->GetNext(getter_AddRefs(result));
     231             458 :             if (NS_FAILED(rv)) return rv;
     232                 : 
     233             458 :             mResult = do_QueryInterface(result, &rv);
     234             458 :             if (NS_FAILED(rv)) return rv;
     235                 : 
     236             458 :             *aResult = true;
     237             458 :             return NS_OK;
     238                 :         }
     239                 :     }
     240                 : 
     241                 :     // If we get here, we ran out of elements. The cursor is empty.
     242             291 :     *aResult = false;
     243             291 :     return NS_OK;
     244                 : }
     245                 : 
     246                 : 
     247                 : NS_IMETHODIMP
     248             458 : ContainerEnumeratorImpl::GetNext(nsISupports** aResult)
     249                 : {
     250                 :     nsresult rv;
     251                 : 
     252                 :     bool hasMore;
     253             458 :     rv = HasMoreElements(&hasMore);
     254             458 :     if (NS_FAILED(rv)) return rv;
     255                 : 
     256             458 :     if (! hasMore)
     257               0 :         return NS_ERROR_UNEXPECTED;
     258                 : 
     259             458 :     NS_ADDREF(*aResult = mResult);
     260             458 :     mResult = nsnull;
     261                 : 
     262             458 :     return NS_OK;
     263                 : }
     264                 : 
     265                 : 
     266                 : ////////////////////////////////////////////////////////////////////////
     267                 : 
     268                 : nsresult
     269             291 : NS_NewContainerEnumerator(nsIRDFDataSource* aDataSource,
     270                 :                           nsIRDFResource* aContainer,
     271                 :                           nsISimpleEnumerator** aResult)
     272                 : {
     273             291 :     NS_PRECONDITION(aDataSource != nsnull, "null ptr");
     274             291 :     if (! aDataSource)
     275               0 :         return NS_ERROR_NULL_POINTER;
     276                 : 
     277             291 :     NS_PRECONDITION(aContainer != nsnull, "null ptr");
     278             291 :     if (! aContainer)
     279               0 :         return NS_ERROR_NULL_POINTER;
     280                 : 
     281             291 :     NS_PRECONDITION(aResult != nsnull, "null ptr");
     282             291 :     if (! aResult)
     283               0 :         return NS_ERROR_NULL_POINTER;
     284                 : 
     285             291 :     ContainerEnumeratorImpl* result = new ContainerEnumeratorImpl(aDataSource, aContainer);
     286             291 :     if (! result)
     287               0 :         return NS_ERROR_OUT_OF_MEMORY;
     288                 : 
     289             291 :     NS_ADDREF(result);
     290                 : 
     291             291 :     nsresult rv = result->Init();
     292             291 :     if (NS_FAILED(rv))
     293               0 :         NS_RELEASE(result);
     294                 : 
     295             291 :     *aResult = result;
     296             291 :     return rv;
     297                 : }

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