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examples/SysLibs/FileStores/WritePermFS1/WritePermFS1.cpp

// Copyright (c) 2000-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// Example constructs and writes a network of objects to a permanent file store.
// Each object is then loaded back in, one at a time, its content displayed at the 
// console and then destroyed.
// The CClassR object is changed and stored back before it is destroyed 
// The order in which the objects are loaded from the store is different from the order
// in which they were initially created.
// The example creates an index of "top level" stream ids. The index is stored in its
// own stream and forms the root stream of the store. 
// The example:
// creates a permanent file store (replacing any existing permanent 
// file store of the same name)
// constructs a TExampleIndex object
// constructs a CClassP object, externalizes it in its own stream, 
// saves the stream id in the index and then destroys the 
// CClassP object
// constructs a CClassR object, externalizes it in its own stream, 
// saves the stream id in the index and then destroys the 
// CClassR object
// constructs a CClassABC container object containing a CClassA, 
// a CClassB and a CClassC object and then completes the construction
// of these contained objects.
// The CClassB object is externalized in its own stream. The CClassA, the streamid of the
// CClassB object and the CClassC object are externalized in a single
// stream and this streamid is saved into the index
// externalizes the TExampleIndex object in its own stream and makes
// this stream the root stream of the file store.
// closes the permanent file store.
// re-opens the permanent file store
// restores the TExampleIndex object from the root stream
// restores the CClassR object from its stream, displays the content,
// changes the content, replaces the stream and then destroys the object from
// memory
// restores the CClassR object for a second time from its stream, displays 
// the (updated) content and then destroys the object from memory again
// restores the CClassABC container object; in effect, this restores 
// its contained CClassA and CClassC objects and the stream id of its
// CClassB object. The CClassB object is not restored into memory until 
// it is needed. 
// displays the content of the CClassA, CClassB and CClassC objects; it is
// at this time that the CClassB object is restored into memory.
// restores the CClassP object from its stream and displays its contents
// and then destroys it
// (NB that the order in which the objects are restored is different to 
// the order in which their corresponding streams were created)
// closes the permanent file store.
// Notes:
// The file name and extension of the permanent file store is 
// "WritePermFS.dat"and will be created in "\epoc32ex\data\" on the system drive.
//

#include "WritePermFS1.h"

//***************************************************************
//
// Implementations
//
//***************************************************************


// The file name, extension and path for the file store
_LIT(KFullNameOfFileStore,"\\epoc32ex\\data\\WritePermFS.dat");

                                //  Do the example
LOCAL_C void doExampleL()
    {
                                // make sure directory exists
        fsSession.MkDirAll(KFullNameOfFileStore);
        doMakeL(KFullNameOfFileStore);
        doUseL(KFullNameOfFileStore);
        }
 

LOCAL_C void doMakeL(const TDesC& aName)
        {
                                // Create (replace, if it exists) the permanent file store
        TParse  filestorename;
        fsSession.Parse(aName,filestorename);
        CFileStore* store = CPermanentFileStore::ReplaceLC(fsSession,filestorename.FullName(),EFileWrite);

                                // Must say what kind of file store.
        store->SetTypeL(KPermanentFileStoreLayoutUid);

                                // Create a TExampleIndex object to hold the stream ids of all
                                // the component streams
        TExampleIndex theIndex;

                                // Construct the CClassP object, putting some data into it, 
                                // write it to its own stream and save the stream id in
                                // the index.
                                // Destroy the CClassP object after stream creation
        _LIT(KTxtDataForClassP,"Data for CClassP - PPPPP");
        CClassP* theP = CClassP::NewLC(KTxtDataForClassP,*store);
        theIndex.iPid = theP->StoreL();
        CleanupStack::PopAndDestroy();
        
                                // Construct the CClassR object, put some data into it, 
                                // write it to its own stream and save the stream id in
                                // the index.
                                // Destroy the CClassR object after stream creation
        _LIT(KTxtDataForClassR,"Data for the CClassR - RRRRR");
        CClassR* theR = CClassR::NewLC(KTxtDataForClassR,*store);
        theIndex.iRid = theR->StoreL();
        CleanupStack::PopAndDestroy();                                                  
                                
                                // Construct the container object for CClassA,CClassB and CClassC.
                                // Complete the construction of the contained CClassA, CClassB
                                // and CClassC objects.
                                //  
                                // Write out this object network and save the top level stream id
                                // in the index.
                                // Destroy this object network after stream creation
        _LIT(KTxtDataForClassA,"Data for the CClassA - AAAAA");
        _LIT(KTxtDataForClassB,"Data for the CClassB - BBBBB");
        _LIT(KTxtDataForClassC,"Data for the CClassC - CCCCC");

        CClassABC* theABC = CClassABC::NewLC(*store);
        theABC->ConstructAL(KTxtDataForClassA,-1,2);
        theABC->ConstructB(KTxtDataForClassB,-3,4,5.6);
        theABC->ConstructC(KTxtDataForClassC);
        theIndex.iABCid = theABC->StoreL();
        CleanupStack::PopAndDestroy();                                                  

                                // Now write the index itself to its own stream ...
        TStreamId id  = theIndex.StoreL(*store);

                                // ... and make this stream the root stream
        store->SetRootL(id);

                                // Now commit all changes to the store
        store->CommitL();
                        
                                // Destroy the permanent file store object (closes the file)
        CleanupStack::PopAndDestroy();  
        }


LOCAL_C void doUseL(const TDesC& aName)
        {
                                // Open the permanent file store
        TParse  filestorename;
        fsSession.Parse(aName,filestorename);
        CFileStore* store = CPermanentFileStore::OpenLC(fsSession,filestorename.FullName(),EFileRead|EFileWrite);

                                // Restore the index of streamids so that we can access (restore)
                                // all the other objects. The index is found in the root stream 
        TExampleIndex theIndex;
        theIndex.RestoreL(*store,store->Root());
                                
                                // Restore the CClassR object, display the content, make a change and
                                // update the stream to reflect the changed content.
                                // If updating the stream succeeds, commit the changes to the store
                                // otherwise attempt to revert the store to its state at the last
                                // commit point.
                                // Destroy the CClassR object.
        CClassR* theR;

        _LIT(KTxtClassRContent,"CClassR content ...");
        _LIT(KTxtNewForClassR,"New data for the CClassR +++++++");

        theR = CClassR::NewLC(*store,theIndex.iRid);
        doShow(KTxtClassRContent,*theR);
        theR->ChangeDataL(KTxtNewForClassR);
        CleanupStack::PopAndDestroy();
                                
                                // Restore the CClassR object again, display the content and
                                // then destroy it
        _LIT(KTxtUpadtedClassR,"Updated CClassR content ...");

        theR = CClassR::NewLC(*store,theIndex.iRid);
        doShow(KTxtUpadtedClassR,*theR);
        CleanupStack::PopAndDestroy();

                                // Restore the CClassABC and display content of all contained objects.
                                // Note that the loading of the CClassB object is deferred until it 
                                // is needed.
                                // Destroy the CClassABC 
        _LIT(KTxtShowClassA,"CClassA content ...");
        _LIT(KTxtShowClassB,"CClassB content ...");
        _LIT(KTxtShowClassC,"CClassC content ...");

        CClassABC* theABC = CClassABC::NewLC(*store,theIndex.iABCid);
        doShow(KTxtShowClassA,*theABC->PtrA());
        doShow(KTxtShowClassB,*theABC->PtrBL());// CClassB object is loaded at this point
        doShow(KTxtShowClassC,*theABC->PtrC()); 
        CleanupStack::PopAndDestroy();

                                // Restore the CClassP object, display the content and
                                // then destroy it;
        _LIT(KTxtShowClassP,"CClassP content ...");

        CClassP* theP = CClassP::NewLC(*store,theIndex.iPid);
        doShow(KTxtShowClassP,*theP);
        CleanupStack::PopAndDestroy();

                                // Destroy the permanent file store object (closes the file) 
        CleanupStack::PopAndDestroy();
        } 

_LIT(KTxtNewLine,"\n");
_LIT(KFormatType1,"\n%S, ");
_LIT(KFormatType2,"%d, ");
_LIT(KFormatType3,"%u  ");
_LIT(KFormatType4,"%u, ");
_LIT(KFormatType5,"%f  ");
                                                                        
LOCAL_C void doShow(const TDesC& aHeading,const CClassA& anA)
        {
        console->Printf(KTxtNewLine);
        console->Printf(aHeading);
        console->Printf(KFormatType1,anA.iVarBuf);
        console->Printf(KFormatType2,anA.iIntValue);
        console->Printf(KFormatType3,anA.iUintValue);
        console->Printf(KTxtNewLine);
        }


LOCAL_C void doShow(const TDesC& aHeading,const CClassB& aB)
        {
        console->Printf(KTxtNewLine);
        console->Printf(aHeading);
        console->Printf(KFormatType1,&aB.iFixBuf);
        console->Printf(KFormatType2,aB.iIntValue);
        console->Printf(KFormatType4,aB.iUintValue);
        console->Printf(KFormatType5,aB.iRealValue);
        console->Printf(KTxtNewLine);
        }


LOCAL_C void doShow(const TDesC& aHeading,const CClassC& aC)
        {
        console->Printf(KTxtNewLine);
        console->Printf(aHeading);
        console->Printf(KFormatType1,&aC.iFixBuf);
        console->Printf(KTxtNewLine);
        }

LOCAL_C void doShow(const TDesC& aHeading,const CClassP& aP)
        {
        console->Printf(KTxtNewLine);
        console->Printf(aHeading);
        console->Printf(KFormatType1,&aP.iFixBuf);
        console->Printf(KTxtNewLine);
        }

LOCAL_C void doShow(const TDesC& aHeading,const CClassR& aR)
        {
        console->Printf(KTxtNewLine);
        console->Printf(aHeading);
        console->Printf(KFormatType1,&aR.iFixBuf);
        console->Printf(KTxtNewLine);
        }

//***************************************************************
//
// CClassABC Implementation
//
//***************************************************************
CClassABC::CClassABC(CStreamStore& aStore)
        : iStore(aStore)
        {}

CClassABC::CClassABC(CStreamStore& aStore,TStreamId anId)
        : iStore(aStore), iId(anId)
        {}

CClassABC* CClassABC::NewLC(CStreamStore& aStore)
        {
        CClassABC* self = new (ELeave) CClassABC(aStore);
        CleanupStack::PushL(self);
        self->ConstructL();
        return self;
        }

CClassABC* CClassABC::NewLC(CStreamStore& aStore, TStreamId anId)
        {                                                                                                                       
        CClassABC* self = new (ELeave) CClassABC(aStore,anId);
        CleanupStack::PushL(self);
        self->RestoreL();
        return self;
        }
                
void CClassABC::ConstructL()
        {
        iA = CClassA::NewL();
        iB = CClassB::NewL();// assigns CClassB* to TSwizzle<CClassB>. Uses TSwizzle operator=(T*)
        iC = CClassC::NewL();
        }

void CClassABC::ConstructAL(const TDesC& aData,TInt anInt,TUint aUint)
        {
        iA->iVarBuf    = aData.AllocL();        
        iA->iIntValue  = anInt;
        iA->iUintValue = aUint;
        }
                        
void CClassABC::ConstructB(const TDesC& aData,TInt anInt,TUint aUint,TReal aReal)
        {
        iB->iFixBuf    = aData;
        iB->iIntValue  = anInt; 
        iB->iUintValue = aUint;
        iB->iRealValue = aReal;
        }
                        
void CClassABC::ConstructC(const TDesC& aData)
        {
        iC->iFixBuf = aData;
        }

                        // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
                        // Destructor deletes the CClassB object only if it is in memory.
                        // The IsPtr() function can be used to determine whether the 
                        // CClassB object is memory. 
                        // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
CClassABC::~CClassABC()
        {
        delete iA;
        delete iC;
        if (iB.IsPtr())
                delete iB.AsPtr(); // can also "delete iB;" makes implicit call to "operator T*()"
        }

        
                                // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
                                // Stores the CClassB object in its own stream and
                                // then stores:
                                //              the CClassA object,
                                //              the streamid of the CClassB object,
                                //              the CClassC object
                                // in a separate stream.
                                // Returns the streamid of this last stream
                                // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
TStreamId CClassABC::StoreL()
        {
                                // Construct the output stream which is intended
                                // to hold the CClassB object only.
        RStoreWriteStream outstream;
        TStreamId idForB = outstream.CreateLC(iStore);
                                // Stream out the CClassB object.
                                // Note that the right hand side returns a reference
                                // to CClassB
        outstream  << *iB; 
                                // Commit changes to the stream
        outstream.CommitL();
                                // Cleanup the stream object
        CleanupStack::PopAndDestroy();  
                                // Now construct the output stream which is intended
                                // to hold:
                                //              the CClassA object,
                                //              the streamid of the CClassB object,
                                //              the CClassC object
        TStreamId id = outstream.CreateLC(iStore);
                                // Write out the CClassA object.
        outstream  << *iA; 
                                // Write out the stream id of the CClassB object
        outstream  << idForB;
                                // Write out the CClassC object.
        outstream  << *iC;
                                // Commit changes to the stream
        outstream.CommitL();
                                // Cleanup the stream object,
        CleanupStack::PopAndDestroy();  
                                // Return this stream id
        return id;
        }

                                
const CClassA* CClassABC::PtrA()
        {
        return iA;      // Return a pointer to the contained CClassA object
        }

                                
const CClassB* CClassABC::PtrBL()
        {
        if (iB.IsId())          // If the contained CClassB object is not in memory, it must
                RestoreBL();    // be loaded in before a pointer can be returned to the caller
        return iB.AsPtr();
        }

                                
const CClassC* CClassABC::PtrC()
        {
        return iC;      //Returns a pointer to the contained CClassC object
        }
                                
                                // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
                                // Restores the CClassA and CClassC objects and the streamid for the
                                // CClassB object.
                                // The swizzle for the CClassB object is constructed from the
                                // streamid but the CClassB object itself is NOT restored at 
                                // this time.
                                // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
void CClassABC::RestoreL()
        {
                                // Construct the input stream.
        RStoreReadStream instream;
        instream.OpenLC(iStore,iId);
                                // Construct a CClassA object and restore from the stream
        iA = CClassA::NewL();
        instream >> *iA;
                                // Construct the swizzle for the CClassB object. This
                                // stream contains the id of the stream which 
                                // actually contains the full CClassB object. The loading of
                                // the CClassB object into memory is deferred until later.
                                // The resulting swizzle represents the CClassB object as 
                                // a streamid 
        instream >> iB;
                                // Construct a CClassC object and restrore from the stream
        iC = CClassC::NewL();
        instream >> *iC;
                                // Cleanup the stream object
        CleanupStack::PopAndDestroy();
        }


                                // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
                                // Loads the CClassB object into memory and changes the swizzle's
                                // representation from "streamid" to "pointer".
                                // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 
void CClassABC::RestoreBL()
        {
                                // Construct the input stream. Assumes we have the correct store (this
                                // emphasizes the need to ensure that the store remain open)
        RStoreReadStream instream;
        instream.OpenLC(iStore,iB.AsId());
                                // Construct a CClassB object and restore from the stream. The 
                                // assignment: CClassB* to TSwizzle<CClassB> changes the
                                // swizzle's representation of the CClassB object 
                                // from "streamid" to "pointer"
        CClassB* ptrB = CClassB::NewLC();
        instream >> *ptrB;
        CleanupStack::Pop();
        iB = ptrB;
                                // Cleanup the stream object                    
        CleanupStack::PopAndDestroy();
        }       


//***************************************************************
//
// CClassA Implementation
//
//***************************************************************
CClassA* CClassA::NewL()
        {
        CClassA* self = CClassA::NewLC();
        CleanupStack::Pop();
        return self;
        }

CClassA* CClassA::NewLC()
        {
        CClassA* self = new (ELeave) CClassA;
        CleanupStack::PushL(self);
        return self;
        }

CClassA::~CClassA()
        {
        delete iVarBuf;
        }

void CClassA::ExternalizeL(RWriteStream& aStream) const
        {
        aStream.WriteInt32L(iVarBuf->Des().MaxLength());
        aStream << *iVarBuf;
        aStream.WriteInt32L(iIntValue);
        aStream.WriteUint32L(iUintValue);
        }  
 
void CClassA::InternalizeL(RReadStream& aStream)
        {
        TInt maxlen;
        maxlen     = aStream.ReadInt32L();
        iVarBuf    = HBufC::NewL(aStream,maxlen);
        iIntValue  = aStream.ReadInt32L();
        iUintValue = aStream.ReadUint32L();
        }  
                

//***************************************************************
//
// CClassB Implementation
//
//***************************************************************
CClassB* CClassB::NewLC()
        {
        CClassB* self = new (ELeave) CClassB;
        CleanupStack::PushL(self);
        return self;
        }

CClassB* CClassB::NewL()        
        {
        CClassB* self = CClassB::NewLC();
        CleanupStack::Pop();    
        return self;
        }

void CClassB::ExternalizeL(RWriteStream& aStream) const
        {
        aStream << iFixBuf;
        aStream.WriteInt32L(iIntValue);
        aStream.WriteUint32L(iUintValue);
        aStream.WriteReal64L(iRealValue);
        }  
 
void CClassB::InternalizeL(RReadStream& aStream)
        {
        aStream >> iFixBuf;
        iIntValue  = aStream.ReadInt32L();
        iUintValue = aStream.ReadUint32L();
        iRealValue = aStream.ReadReal64L();
        }  

//***************************************************************
//
// CClassC Implementation
//
//***************************************************************
CClassC* CClassC::NewL()
        {
        CClassC* self = CClassC::NewLC();
        CleanupStack::Pop();
        return self;
        }

CClassC* CClassC::NewLC()
        {
        CClassC* self = new (ELeave) CClassC;
        CleanupStack::PushL(self);
        return self;
        }

void CClassC::ExternalizeL(RWriteStream& aStream) const
        {
        aStream << iFixBuf;
        }  
 
void CClassC::InternalizeL(RReadStream& aStream)
        {
        aStream >> iFixBuf;
        }  

//***************************************************************
//
// CClassP Implementation
//
//***************************************************************
CClassP::CClassP(CStreamStore& aStore)
        : iStore(aStore)
        {}

CClassP::CClassP(CStreamStore& aStore,TStreamId anId)
        : iStore(aStore), iId(anId)
        {}

CClassP* CClassP::NewLC(const TDesC& aData,CStreamStore& aStore)
        {
        CClassP* self = new (ELeave) CClassP(aStore);
        CleanupStack::PushL(self);
        self->Construct(aData);
        return self;
        }

CClassP* CClassP::NewLC(CStreamStore& aStore, TStreamId anId)
        {
        CClassP* self = new (ELeave) CClassP(aStore,anId);
        CleanupStack::PushL(self);
        self->RestoreL();
        return self;
        }

void CClassP::Construct(const TDesC& aData)
        {
        iFixBuf = aData;
        }

void CClassP::RestoreL()
        {
        RStoreReadStream instream;
        instream.OpenLC(iStore,iId);
        InternalizeL(instream);                 // or we can say instream >> *this;
        CleanupStack::PopAndDestroy();  
        }

TStreamId CClassP::StoreL()
        {
        RStoreWriteStream outstream;
        TStreamId id = outstream.CreateLC(iStore);
        ExternalizeL(outstream);                // or we can say outstream << *this;
        outstream.CommitL();
        CleanupStack::PopAndDestroy();  
        return id;
        }

void CClassP::ExternalizeL(RWriteStream& aStream) const
        {
        aStream << iFixBuf;
        }  
 
void CClassP::InternalizeL(RReadStream& aStream)
        {
        aStream >> iFixBuf;
        }  


//***************************************************************
//
// CClassR Implementation
//
//***************************************************************
CClassR::CClassR(CStreamStore& aStore)
        : iStore(aStore)
        {}

CClassR::CClassR(CStreamStore& aStore,TStreamId anId)
        : iStore(aStore), iId(anId)
        {}

CClassR* CClassR::NewLC(const TDesC& aData,CStreamStore& aStore)
        {
        CClassR* self = new (ELeave) CClassR(aStore);
        CleanupStack::PushL(self);
        self->Construct(aData);
        return self;
        }

CClassR* CClassR::NewLC(CStreamStore& aStore, TStreamId anId)
        {
        CClassR* self = new (ELeave) CClassR(aStore,anId);
        CleanupStack::PushL(self);
        self->RestoreL();
        return self;
        }

void CClassR::Construct(const TDesC& aData)
        {
        iFixBuf = aData;
        }

_LIT(KTxtFailedMsg,"Failed to update CClassR stream\n");

void CClassR::ChangeDataL(const TDesC& aData)
        {
        iFixBuf = aData;
        TRAPD(error,UpdateStoreL());
        if (error!=KErrNone)
                {
                iStore.Revert();
                console->Printf(KTxtFailedMsg);
                User::Leave(error);
                }
        }
                
void CClassR::RestoreL()
        {
        RStoreReadStream instream;
        instream.OpenLC(iStore,iId);
        InternalizeL(instream);                 // or we can say instream >> *this;
        CleanupStack::PopAndDestroy();  
        }

TStreamId CClassR::StoreL()
        {
        RStoreWriteStream outstream;
        TStreamId id = outstream.CreateLC(iStore);
        ExternalizeL(outstream);                // or we can say outstream << *this;
        outstream.CommitL();
        CleanupStack::PopAndDestroy();  
        return id;
        }

void CClassR::UpdateStoreL()
        {
        RStoreWriteStream outstream;
        outstream.ReplaceLC(iStore,iId);
        ExternalizeL(outstream);                // or we can say outstream << *this;
        outstream.CommitL();
        CleanupStack::PopAndDestroy();
        iStore.CommitL();// commit the changes to the store
        }

void CClassR::ExternalizeL(RWriteStream& aStream) const
        {
        aStream << iFixBuf;
        }  
 
void CClassR::InternalizeL(RReadStream& aStream)
        {
        aStream >> iFixBuf;
        }  

//***************************************************************
//
// TExampleIndex Implementation
//
//***************************************************************

TStreamId TExampleIndex::StoreL(CStreamStore& aStore)
        {
        RStoreWriteStream outstream;
        TStreamId id = outstream.CreateLC(aStore);
        ExternalizeL(outstream);                // or we can say outstream << *this;
        outstream.CommitL();
        CleanupStack::PopAndDestroy();  
        return id;
        }

void TExampleIndex::RestoreL(CStreamStore& aStore, TStreamId anId)
        {
        RStoreReadStream instream;
        instream.OpenLC(aStore,anId);
        InternalizeL(instream);
        CleanupStack::PopAndDestroy();  
        }

void TExampleIndex::ExternalizeL(RWriteStream& aStream) const
        {
        aStream << iPid;
        aStream << iRid;
        aStream << iABCid;
        }  

void TExampleIndex::InternalizeL(RReadStream& aStream)
        {
        aStream >> iPid;
        aStream >> iRid;
        aStream >> iABCid;
        }  

---

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All rights reserved. Unless otherwise stated, these materials are provided under the terms of the Eclipse Public License v1.0.