TFileIter

class TFileIter : public TListIter

    private:

      virtual TIterator& operator=(const TIterator&)

    protected:

          void Initialize()
         TKey* NextEventKey(UInt_t eventNumber = UInt_t(-1), UInt_t runNumber = UInt_t(-1), const char* name = "*")
      TObject* ReadObj(const TKey* key) const
          void RestoreFileScope()
          void SaveFileScope()

    public:

                           TFileIter(const char* name, Option_t* option, const char* ftitle, Int_t compress = 1, Int_t netopt = 0)
                           TFileIter(TFile* file = 0)
                           TFileIter(const TFileIter&)
                   virtual ~TFileIter()
            static TClass* Class()
                     Int_t CurrentCursorPosition() const
                     TKey* GetCurrentKey() const
        static const char* GetDefaultMapFileName() const
        static const char* GetForeignFileSystemKey() const
               const char* GetKeyName() const
        static const char* GetLocalFileNameKey() const
          virtual TObject* GetObject() const
                     Int_t GetObjlen() const
        static const char* GetResourceName() const
      virtual const TFile* GetTFile() const
           virtual TClass* IsA() const
            static TString MapName(const char* name, const char* localSystemKey = "0", const char* mountedFileSystemKey = "0")
          virtual TObject* Next()
          virtual TObject* Next(Int_t nSkip)
          virtual TObject* NextEventGet(UInt_t eventNumber = UInt_t(-1), UInt_t runNumber = UInt_t(-1), const char* name = "*")
             virtual Int_t NextEventPut(TObject* obj, UInt_t eventNum, UInt_t runNumber, const char* name = "0")
                     char* operator const char*() const
                    TFile* operator const TFile*() const
                       int operator int() const
                       int operator!=(const char* name) const
                  TObject* operator()(Int_t nSkip)
                  TObject* operator()()
                  TObject* operator*() const
                TFileIter& operator++()
                TFileIter& operator+=(Int_t shift)
                TFileIter& operator--()
                TFileIter& operator-=(Int_t shift)
                TFileIter& operator=(Int_t cursorPosition)
                TFileIter& operator=(const char* keyNameToFind)
                       int operator==(const char* name) const
              virtual void Reset()
              virtual void Rewind()
                      void SetCursorPosition(Int_t cursorPosition)
                      void SetCursorPosition(const char* keyNameToFind)
              virtual void ShowMembers(TMemberInspector& insp, char* parent)
          virtual TObject* SkipObjects(Int_t nSkip = 1)
              virtual void Streamer(TBuffer& b)
                      void StreamerNVirtual(TBuffer& b)
             virtual Int_t TotalKeys() const

Data Members

    private:

           TFile* fFileBackUp       ! temporary data-members
      TDirectory* fDirectoryBackUp  ! to save/restore TFile/TDirectory global scope

    protected:

       TFile* fRootFile        Tfile to be iterated over
      TString fEventName       current key name
       UInt_t fRunNumber       current "run number"
       UInt_t fEventNumber     current "event number"
        Int_t fCursorPosition  the position of the current key in the sorted TKey list
       Bool_t fOwnTFile        Bit whether this classs creates TFile on its own to delete

Class Description

                                                                       
 Class to iterate (read / write ) the events written to TFile.         
 The event is supposed to assign an unique ID in form of               
                                                                       
  TKey <event Id> ::= eventName "." run_number "." event_number        
                                                                       
 and stored as the TKey name of the object written                     
                                                                       
        ///////        //////////      ////////        ///////     

 void TestFileIter(){
 // This macros tests the various methods of TFileIter class.
   gSystem->Load("libTable");

   //First create simple ROOT file
   TDataSet *ds = new TDataSet("event");
   TObject *nextObject = 0;
   TRandom run;
   TRandom event;
   {
     TFileIter outSet("test.root","RECREATE");
     UInt_t totalEvent = 10;
     UInt_t runNumber  = 20010301;
     Int_t i=0;
     Int_t j=0;
     for (;j < 10;j++) {
       for (i = 1;i<totalEvent;i++) {
         outSet.NextEventPut(ds,UInt_t(i),UInt_t(runNumber+j+10*run.Rndm()-5));
       }
     }
   }
   printf(" ----------------------> TFile has been created <--------------------n");
   TFile *f = new TFile("test.root");
   TFileIter readObj(f);
   // the number of the object available directly from "MyDataSet.root"
   Int_t size = readObj.TotalKeys();
   printf(" The total number of the objects: %dn",size);

   //-----------------------------------------------------------------------
   // Loop over all objects, read them in to memory one by one

   printf(" -- > Loop over all objects, read them in to memory one by one < -- n");
   for( readObj = 0; int(readObj) < size; ++readObj){
       nextObject = *readObj;
       printf(" %d bytes of the object "%s" of class "%s" written with TKey "%s"  has been read from filen"
                ,readObj.GetObjlen()
                ,nextObject->GetName()
                ,nextObject->IsA()->GetName()
                ,(const char *)readObj
             );
       delete nextObject;
  }
 //-----------------------------------------------------------------------
 //  Now loop over all objects in inverse order
  printf(" -- > Now loop over all objects in inverse order < -- n");
  for( readObj = size-1; (int)readObj >= 0; --readObj)
  {
       nextObject = *readObj;
       if (nextObject) {
          printf(" Object "%s" of class "%s" written with TKey "%s"  has been read from filen"
                 ,nextObject->GetName()
                 , nextObject->IsA()->GetName()
                 ,(const char *)readObj
                );
         delete nextObject;
      } else {
        printf("Error reading file by indexn");
      }
  }
 //-----------------------------------------------------------------------
 // Loop over the objects starting from the object with the key name "event.02.01"
   printf(" -- > Loop over the objects starting from the object with the key name "event.02.01" < -- n");
   for( readObj = "event.02.01"; (const char *)readObj != 0; ++readObj){
       nextObject = *readObj;
       printf(" Object "%s" of class "%s" written with Tkey "%s"  has been read from filen"
               , nextObject->GetName()
               , nextObject->IsA()->GetName()
               , (const char *)readObj
             );
       delete nextObject;
   }

   printf(" -- > Loop over the objects starting from the 86-th object" < -- n");
   for( readObj = (const char *)(readObj = 86); (const char *)readObj != 0; ++readObj){
       nextObject = *readObj;
       printf(" Object "%s" of class "%s" written with Tkey "%s"  has been read from filen"
               , nextObject->GetName()
               , nextObject->IsA()->GetName()
               , (const char *)readObj
             );
       delete nextObject;
   }

 }
-----------------------------------------------------------------------

__________________________________________________________________________

 Open ROOT TFile by the name provided;
 This TFile is to be deleted by the TFileIter alone

 Copy stor can be used with the "read only" files only.

 return the pointer to the current TKey

 return the name of the current TKey

 read the object from TFile defined by the current TKey

 ATTENTION:  memory leak danger !!!
 ---------
 This method does create a new object and it is the end-user
 code responsibility to take care about the object returned
 to avoid memeory leak.

 Returns the uncompressed length of the current object

 The total number of the TKey keys in this current TFile
 Usually this means the total number of different objects
 thos can be read separately with one "read" operation

 return the pointer to the object defined by next TKey
 This method is not recommended. It was done for the sake
 of the compatibility with TListIter

 Reset the status of the iterator

 Find the key by the name provided

 Returns the pointer to the nSkip object from the current one
 nSkip = 0; the state of the iterator is not changed

 nSkip > 0; iterator skips nSkip objects in the container.
            the direction of the iteration is
            sign(nSkip)*kIterForward

 reads, creates and returns the object by TKey name that matches
 the "name" ."runNumber" ." eventNumber" schema
 Attention: This method does create a new TObject and it is the user
 code responsibility to take care (delete) this object to avoid
 memory leak.

 Create a special TKey name with obj provided and write it out.

 --------------------------------------------------------------------------------------
 MapName(const char *name, const char *localSystemKey,const char *mountedFileSystemKey)
 --------------------------------------------------------------------------------------
 Substitute the logical name with the real one if any
 1. add a line into system.rootrc or ~/.rootrc or ./.rootrc

  TFileIter.ForeignFileMap  mapFile // the name of the file
 to map the local name
 to the global file service

  If this line is omitted then TFileIter class seeks for
  the default mapping file in the current directory "io.config"

Inline Functions

          TIterator& operator=(const TIterator&)
                void RestoreFileScope()
                void SaveFileScope()
               Int_t CurrentCursorPosition() const
        const TFile* GetTFile() const
         const char* GetResourceName() const
         const char* GetDefaultMapFileName() const
         const char* GetLocalFileNameKey() const
         const char* GetForeignFileSystemKey() const
                void SetCursorPosition(const char* keyNameToFind)
          TFileIter& operator=(Int_t cursorPosition)
          TFileIter& operator=(const char* keyNameToFind)
          TFileIter& operator+=(Int_t shift)
          TFileIter& operator-=(Int_t shift)
          TFileIter& operator++()
          TFileIter& operator--()
            TObject* operator*() const
               char* operator const char*() const
              TFile* operator const TFile*() const
                 int operator int() const
                 int operator==(const char* name) const
                 int operator!=(const char* name) const
            TObject* Next(Int_t nSkip)
                void Rewind()
            TObject* operator()(Int_t nSkip)
            TObject* operator()()
             TClass* Class()
             TClass* IsA() const
                void ShowMembers(TMemberInspector& insp, char* parent)
                void Streamer(TBuffer& b)
                void StreamerNVirtual(TBuffer& b)