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examples/SysLibs/Streams/WriteToEmbedded/WriteToEmbedded.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 uses an embedded store.
// This example uses a permanent file store. It constructs a CMainClass object
// which has a CClassABC object as a component. The CClassABC object itself
// has other components and its structure is the same as found in the
// WriteToMany example.
// Here, the CClassABC component object network is stored in an embedded store.
// The example:
// creates a permanent file store
// constructs a CMainClass object. This results in the construction
// of a CClassABC objet network which is stored in its own embedded
// store (within the main store). 
// stores the CMainClass object in its own stream in the main store
// and makes that stream the root stream.
// closes the store and deletes the CMainClass object from memory
// re-opens the permanent file store
// restores the CMainClass object and opens the embedded store. As the 
// the contained CClassABC object itself has components which are only 
// loaded in when needed, then the embedded store is kept open.
// Displays the content of the CClassA, CClassB and CClassC objects.
// Deletes the CClassABC object from CMainClass and deletes its representation
// from the permanent file store. Note that knowledge of the detailed
// structure of the CClassABC object network is not needed. 
// Attempts to redisplay the content of the CClassA, CClassB and CClassC 
// objects; this should fail as they have been deleted.
// closes the store and deletes the CMainClass object from memory.
// Notes:
// The file name and extension of the direct file store is "WriteToEmbedded.dat".
// and will be created in the "\data\" folder of the writable drive.
//

#include "WriteToEmbedded.h"
//***************************************************************
//
// Implementations
//***************************************************************

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

                                //  Do the example
LOCAL_C void doExampleL()
    {
                            // make sure directory exists
        fsSession.MkDirAll(KFullNameOfFileStore);
        doMakeAndStoreL(KFullNameOfFileStore);
        doDeleteComponentL(KFullNameOfFileStore);
        }
 
LOCAL_C void doMakeAndStoreL(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);
        
                                // Construct a main object and its component
                                // CClassABC object; the CClassABC component object
                                // and its components are stored in an embedded store
                                // within the main store.  
        CMainClass* theMain = CMainClass::NewLC(*store);

                                // Store the CMainClass object in its own stream 
                                // in the top level store
        TStreamId theId = theMain->StoreL();

                                // Set this stream id as the root stream
        store->SetRootL(theId);

                                // Commit theses changes to the top level store
        store->CommitL();

                                // Destroy:
                                //              the CMainClass object,
                                //              the permanent file store object (closes the file)
        CleanupStack::PopAndDestroy(2); 
        }

LOCAL_C void doDeleteComponentL(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 main object
        CMainClass* theMain = CMainClass::NewLC(*store,store->Root());
        
                                // Show the content of the classes contained by CClassABC,
                                // loading as needed
        CClassABC* abc = theMain->PtrAbc();
        
        _LIT(KTxtClassAContent,"CClassA content ...");
        _LIT(KTxtClassBContent,"CClassB content ...");
        _LIT(KTxtClassCContent,"CClassC content ...");
        _LIT(KTxtClassABCDeleted,"CClassABC component deleted");

        if (abc)
                {
                doShow(KTxtClassAContent,*abc->PtrA());
                doShow(KTxtClassBContent,*abc->PtrBL());                                        
                doShow(KTxtClassCContent,*abc->PtrC());
                }
        else
                doShow(KTxtClassABCDeleted);
                
                                // remove the CClassABC component from CMainClass and
                                // and remove its representation from the store
        theMain->RemoveAbcL();

                                // Try and show the contents again; the pointer
                                // abc should now be NULL
        abc = theMain->PtrAbc();
        if (abc)
                {
                doShow(KTxtClassAContent,*abc->PtrA());
                doShow(KTxtClassBContent,*abc->PtrBL());                                        
                doShow(KTxtClassCContent,*abc->PtrC());
                }
        else
                doShow(KTxtClassABCDeleted);

                                // Destroy:
                                //              the CMainClass object, 
                                //      the permanent file store object (closes the file) 
        CleanupStack::PopAndDestroy(2);
        }

_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& aComment)
        {
        console->Printf(KTxtNewLine);
        console->Printf(aComment);
        console->Printf(KTxtNewLine);
        }
        
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);
        }

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

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

CMainClass::CMainClass(CStreamStore& aStore)
        : iStore(aStore)
        {}

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

_LIT(KTxtMainData,"Main data");
_LIT(KTxtClassAData,"Data for the CClassA - AAAAA");
_LIT(KTxtClassBData,"Data for the CClassB - BBBBB");
_LIT(KTxtClassCData,"Data for the CClassC - CCCCC");

void CMainClass::ConstructL()
        {
        iSomeData = KTxtMainData;
                                // create the stream to contain the embedded store
        RStoreWriteStream childStream;
                                // we need to keep track of this stream id
        iEmbeddedStoreId = childStream.CreateLC(iStore);
                                // construct the embedded store
        CPersistentStore* embeddedStore = CEmbeddedStore::NewLC(childStream);
                                // construct the CClassABC and its containees. Note that
                                // the store it uses is the embedded store.
        iAbc = CClassABC::NewL(*embeddedStore); 
        iAbc->ConstructAL(KTxtClassAData,-1,2);
        iAbc->ConstructB(KTxtClassBData,-3,4,5.6);
        iAbc->ConstructC(KTxtClassCData);
                                // store the CClassABC and its containees in the
                                // embedded store ...
        TStreamId idForAbc = iAbc->StoreL();
                                // ... and set this stream id as the root 
                                // stream of the embedded store
        embeddedStore->SetRootL(idForAbc);      
                                // Commit changes to the embedded store
        embeddedStore->CommitL();
                                // Commit changes to the stream containing the 
                                // embedded store.
        childStream.CommitL();
                                // Destroy the embedded store object
                                // Cleanup the stream containing the emmbedded store 
        CleanupStack::PopAndDestroy(2);
        }

CMainClass::~CMainClass()
        {
        delete iEmbeddedStore;
        iChildStream.Release(); //stream cleanup
        delete iAbc;
        }

TStreamId CMainClass::StoreL()
        {
        RStoreWriteStream stream;
        TStreamId id = stream.CreateLC(iStore);
        ExternalizeL(stream);
        stream.CommitL();
        CleanupStack::PopAndDestroy();
        return id;
        }
        
void CMainClass::ExternalizeL(RWriteStream& aStream)
        {
        aStream << iSomeData; 
        aStream << iEmbeddedStoreId;
        }

void CMainClass::RestoreL()
        {
        RStoreReadStream stream;
        stream.OpenLC(iStore,iId);
                                // restore the CMainClass object
        InternalizeL(stream);
                                // clean up the stream
        CleanupStack::PopAndDestroy();
                                // open stream containing the embedded store
                                // (and keep it open)
        if (iEmbeddedStoreId != KNullStreamId)
                {
                iChildStream.OpenL(iStore,iEmbeddedStoreId);
                                // construct the embedded store 
                                // (and keep it open)
                iEmbeddedStore = CEmbeddedStore::FromL(iChildStream);
                                // restore the CClassABC object network from the
                                // embedded store. Note that not all of CClassABC's
                                // containees are loaded in, hence the need to keep
                                // the embedded store open 
                iAbc = CClassABC::NewL(*iEmbeddedStore,iEmbeddedStore->Root());
                }
        }

void CMainClass::InternalizeL(RReadStream& aStream)
        {
        aStream >> iSomeData; 
        aStream >> iEmbeddedStoreId;
        }

CClassABC* CMainClass::PtrAbc()
        {
        return iAbc;
        }

void CMainClass::RemoveAbcL()
        {
                                // Remove the CClassABC component from memory an
                                // from the store. 
                                // To remove the CClassABC representation from the 
                                // store, just delete the stream containing the
                                // embedded store which contains the representation of
                                // the CClassABC object network.
        if (!iAbc)
                return;
        delete iAbc;
        iAbc = NULL;
                                // close the embedded store
        delete iEmbeddedStore;
        iEmbeddedStore = NULL;
                                // cleanup the stream (this is in the top 
                                // level store) containing the embedded store
        iChildStream.Release();
                                // delete the stream from the top level store ...
        iStore.DeleteL(iEmbeddedStoreId);
                                // ... and commit these changes to the top
                                // level store
        iStore.CommitL();                       
        iEmbeddedStoreId = KNullStreamId;
        }

//***************************************************************
//
// 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::NewL(CStreamStore& aStore)
        {
        CClassABC* self = CClassABC::NewLC(aStore);
        CleanupStack::Pop();
        return self;
        }

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

CClassABC* CClassABC::NewL(CStreamStore& aStore, TStreamId anId)
        {
        CClassABC* self = CClassABC::NewLC(aStore,anId);
        CleanupStack::Pop();
        return self;
        }
                
void CClassABC::ConstructL()
        {
        iA = CClassA::NewL();
        iB = CClassB::NewL();
        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;
        }  

---

Copyright ©2010 Nokia Corporation and/or its subsidiary(-ies).
All rights reserved. Unless otherwise stated, these materials are provided under the terms of the Eclipse Public License v1.0.