TFriendElement.cxx

Go to the documentation of this file.

// @(#)root/tree:$Id$
// Author: Rene Brun   07/04/2001

/*************************************************************************
 * Copyright (C) 1995-2001, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

/** \class TFriendElement
\ingroup tree

A TFriendElement TF describes a TTree object TF in a file.
When a TFriendElement TF is added to the the list of friends of an
existing TTree T, any variable from TF can be referenced in a query
to T.

To add a TFriendElement to an existing TTree T, do:
~~~ {.cpp}
    T.AddFriend("friendTreename","friendTreeFile");
~~~
See TTree::AddFriend for more information.
*/

#include "TFriendElement.h"
#include "TBuffer.h"
#include "TTree.h"
#include "TFile.h"
#include "TROOT.h"

ClassImp(TFriendElement);

////////////////////////////////////////////////////////////////////////////////
/// Default constructor for a friend element.

TFriendElement::TFriendElement() : TNamed()
{
   fFile       = 0;
   fTree       = 0;
   fOwnFile    = kFALSE;
   fParentTree = 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Create a friend element.
///
/// If treename is of the form "a=b", an alias called "a" is created for
/// treename = "b" by default the alias name is the name of the tree.

TFriendElement::TFriendElement(TTree *tree, const char *treename, const char *filename)
    :TNamed(treename,filename)
{
   fFile       = 0;
   fTree       = 0;
   fOwnFile    = kTRUE;
   fParentTree = tree;
   fTreeName   = treename;
   if (treename && strchr(treename,'=')) {
      char *temp = Compress(treename);
      char *equal = strchr(temp,'=');
      if (!equal) return;;
      *equal=0;
      fTreeName = equal+1;
      SetName(temp);
      delete [] temp;
   }

   Connect();
}

////////////////////////////////////////////////////////////////////////////////
/// Create a friend element.
///
/// If treename is of the form "a=b", an alias called "a" is created for
/// treename = "b" by default the alias name is the name of the tree.
/// The passed TFile is managed by the user (i.e. user must delete the TFile).

TFriendElement::TFriendElement(TTree *tree, const char *treename, TFile *file)
    :TNamed(treename,file?file->GetName():"")
{
   fFile       = file;
   fTree       = 0;
   fOwnFile    = kFALSE;
   fParentTree = tree;
   fTreeName   = treename;
   if (fParentTree && fParentTree->GetDirectory()
       && fParentTree->GetDirectory()->GetFile() == fFile) {
      // The friend and the TTree are in the same file, let's not record
      // the filename.
      SetTitle("");
   }
   if (treename && strchr(treename,'=')) {
      char *temp = Compress(treename);
      char *equal = strchr(temp,'=');
      if (!equal) return;;
      *equal=0;
      fTreeName = equal+1;
      SetName(temp);
      delete [] temp;
   }

   Connect();
}

////////////////////////////////////////////////////////////////////////////////
/// Create a friend element.

TFriendElement::TFriendElement(TTree *tree, TTree* friendtree, const char *alias)
   : TNamed(friendtree?friendtree->GetName():"",
            friendtree
            ? (   friendtree->GetDirectory()
                  ? (    friendtree->GetDirectory()->GetFile()
                         ? friendtree->GetDirectory()->GetFile()->GetName()
                         :  "")
                  : "")
            :  "")
{
   fTree       = friendtree;
   fTreeName   = "";
   fFile       = 0;
   fOwnFile    = kFALSE;
   fParentTree = tree;
   if (fTree) {
      fTreeName   = fTree->GetName();
      if (fTree->GetDirectory()) fFile = fTree->GetDirectory()->GetFile();
      if (fParentTree && fParentTree->GetDirectory()
          && fParentTree->GetDirectory()->GetFile() == fFile) {
         // The friend and the TTree are in the same file, let's not record
         // the filename.
         SetTitle("");
      }
   } else {
      MakeZombie(); // ROOT-7007
   }
   if (alias && strlen(alias)) {
      char *temp = Compress(alias);
      SetName(temp);
      delete [] temp;
   }

   // No need to Connect.
}

////////////////////////////////////////////////////////////////////////////////
/// Destructor.  Disconnect from the owning tree if needed.

TFriendElement::~TFriendElement()
{
   DisConnect();
}

////////////////////////////////////////////////////////////////////////////////
/// Connect file and return TTree.

TTree *TFriendElement::Connect()
{
   GetFile();
   auto treePtr = GetTree();
   if (!treePtr) MakeZombie(); // ROOT-7007
   return treePtr;
}

////////////////////////////////////////////////////////////////////////////////
/// DisConnect file and TTree.

TTree *TFriendElement::DisConnect()
{
   if (fOwnFile) delete fFile;
   fFile = 0;
   fTree = 0;
   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Return pointer to TFile containing this friend TTree.

TFile *TFriendElement::GetFile()
{
   if (fFile || IsZombie()) return fFile;

   if (strlen(GetTitle())) {
      TDirectory::TContext ctxt;
      fFile = TFile::Open(GetTitle());
      fOwnFile = kTRUE;
   } else {
      TDirectory *dir = fParentTree->GetDirectory();
      if (dir) {
         fFile = dir->GetFile();
         fOwnFile = kFALSE;
      }
   }
   if (fFile && fFile->IsZombie()) {
      MakeZombie();
      delete fFile;
      fFile = 0;
   }
   return fFile;
}

////////////////////////////////////////////////////////////////////////////////
/// Return pointer to friend TTree.

TTree *TFriendElement::GetTree()
{
   if (fTree) return fTree;

   if (GetFile()) {
      fFile->GetObject(GetTreeName(),fTree);
      if (fTree) return fTree;
   }

   // This could be a memory tree or chain
   fTree = dynamic_cast<TTree*>( gROOT->FindObject(GetTreeName()) );

   return fTree;
}

////////////////////////////////////////////////////////////////////////////////
/// List this friend element.

void TFriendElement::ls(Option_t *) const
{
   printf(" Friend Tree: %s in file: %s\n",GetName(),GetTitle());
}