library: libTable #include "TFileIter.h"

# TFileIter

class description - source file - inheritance tree (.pdf)

## class TFileIter : public TListIter

| Inheritance Chart:

`TIterator`

<-

`TListIter`

<-

`TFileIter`

        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: %d\n",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 file\n"
                    ,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 file\n"
                     ,nextObject->GetName()
                     , nextObject->IsA()->GetName()
                     ,(const char *)readObj
                    );
             delete nextObject;
          } else {
            printf("Error reading file by index\n");
          }
      }
     //-----------------------------------------------------------------------
     // 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 file\n"
                   , 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 file\n"
                   , nextObject->GetName()
                   , nextObject->IsA()->GetName()
                   , (const char *)readObj
                 );
           delete nextObject;
       }

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

TFileIter(TFile *file) : fRootFile(file), fEventName("event"), fRunNumber(UInt_t(-1)),fEventNumber(UInt_t(-1)), fCursorPosition(-1), fOwnTFile(kFALSE)

    __________________________________________________________________________

TFileIter(const char *name, Option_t *option, const char *ftitle , Int_t compress, Int_t /*netopt*/) : fRootFile (0)

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

TFileIter(const TFileIter &dst) : TListIter() ,fRootFile(dst.fRootFile) ,fEventName(dst.fEventName), fRunNumber(dst.fRunNumber) ,fEventNumber(dst.fRunNumber), fCursorPosition(-1), fOwnTFile(dst.fOwnTFile)

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

~TFileIter()

void Initialize()

TKey* GetCurrentKey() const

     return the pointer to the current TKey

const char* GetKeyName() const

     return the name of the current TKey

TObject* GetObject() const

     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.

Int_t GetObjlen() const

     Returns the uncompressed length of the current object

Int_t TotalKeys() const

     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

TObject* Next(Int_t nSkip)

     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

void Reset()

     Reset the status of the iterator

void SetCursorPosition(const char *keyNameToFind)

     Find the key by the name provided

TObject* SkipObjects(Int_t nSkip)

     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

TKey* NextEventKey(UInt_t eventNumber, UInt_t runNumber, const char *name)

TObject* NextEventGet(UInt_t eventNumber, UInt_t runNumber, const char *name)

     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.

TObject* ReadObj(const TKey *key) const

Int_t NextEventPut(TObject *obj, UInt_t eventNum, UInt_t runNumber , const char *name)

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

TString MapName(const char *name, const char *localSystemKey,const char *mountedFileSystemKey)

     --------------------------------------------------------------------------------------
     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)

Author: Valery Fine(fine@bnl.gov) 01/03/2001
Last update: root/table:$Name: $:$Id: TFileIter.cxx,v 1.4 2004/02/13 14:27:00 rdm Exp $
Copyright (C) 1995-2004, Rene Brun and Fons Rademakers. *