TBranchBrowsable.cxx

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// @(#)root/tree:$Id: c5d87ada87b506444a9d0bc027d622273440b891 $
// Author: Axel Naumann   14/10/2004

/*************************************************************************
 * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

#include "TBranchBrowsable.h"
#include "TBranchElement.h"
#include "TBranchObject.h"
#include "TMethod.h"
#include "TBrowser.h"
#include "TTree.h"
#include "TLeafObject.h"
#include "TClonesArray.h"
#include "TVirtualPad.h"
#include "TClass.h"
#include "TBaseClass.h"
#include "TDataMember.h"
#include "TStreamerInfo.h"
#include "TStreamerElement.h"
#include "TVirtualCollectionProxy.h"
#include "TRef.h"
#include <algorithm>

ClassImp(TVirtualBranchBrowsable);

/** \class TVirtualBranchBrowsable

TVirtualBranchBrowsable is a base class (not really abstract, but useless
by itself) for helper objects that extend TBranch's browsing support.
Each registered derived class's generator method is called, which fills
all created helper objects into a list which can then be browsed.
For details of what these browser helper objects can do, see e.g.
TMethodBrowsable, which allows methods to show up in the TBrowser.

Only registered helper objects are created. By default, only
TMethodBrowsable, TNonSplitBrowsable, and TCollectionPropertyBrowsable
are registered (see RegisterDefaultGenerators). You can prevent any of
their objects to show up in the browser by unregistering the generator:
~~~ {.cpp}
    TMethodBrowsable::Unregister()
~~~
will stop creating browsable method helper objects from that call on.
Note that these helper objects are cached (in TBranch::fBrowsables);
already created (and thus cached) browsables will still appear in the
browser even after unregistering the corresponding generator.

You can implement your own browsable objects and thier generator; see
e.g. the simple TCollectionPropertyBrowsable. Note that you will have
to register your generator just like any other, and that you should
implement the following methods for your own class, mainly for
consistency reasons:
~~~ {.cpp}
    static void Register() {
      TVirtualBranchBrowsable::RegisterGenerator(GetBrowsables); }
    static void Unregister() {
      TVirtualBranchBrowsable::UnregisterGenerator(GetBrowsables); }
~~~
where GetBrowsables is a static member function of your class, that
creates the browsable helper objects, and has the signature
~~~ {.cpp}
    static Int_t GetBrowsables(TList& list, const TBranch* branch,
                               const TVirtualBranchBrowsable* parent=0);
~~~

It has to return the number of browsable helper objects for parent
(or, if NULL, for branch) which are added to the list.
*/

std::list<TVirtualBranchBrowsable::MethodCreateListOfBrowsables_t>
   TVirtualBranchBrowsable::fgGenerators;
Bool_t TVirtualBranchBrowsable::fgGeneratorsSet=kFALSE;

////////////////////////////////////////////////////////////////////////////////
/// Constructor setting all members according to parameters.

TVirtualBranchBrowsable::TVirtualBranchBrowsable(const TBranch* branch, TClass* type,
                                                 Bool_t typeIsPointer,
                                                 const TVirtualBranchBrowsable* parent /*=0*/):
fBranch(branch), fParent(parent), fLeaves(0), fClass(type), fTypeIsPointer(typeIsPointer)
{
   if (!fgGeneratorsSet) RegisterDefaultGenerators();
   if (!branch)
      Warning("TVirtualBranchBrowsable", "branch is NULL!");
}

////////////////////////////////////////////////////////////////////////////////
/// Destructor. Delete our leaves.

TVirtualBranchBrowsable::~TVirtualBranchBrowsable()
{
   delete fLeaves;
}

////////////////////////////////////////////////////////////////////////////////
/// Calls TTree::Draw on the method if return type is not a class;
/// otherwise expands returned object's "folder"

void TVirtualBranchBrowsable::Browse(TBrowser *b)
{
   if (!fClass
       || (fClass->GetCollectionProxy()
           && fClass->GetCollectionProxy()->GetType() > 0)) {
      TString name;
      GetScope(name);

      // If this is meant to be run on the collection
      // we need to "move" the "@" from branch.@member
      // to branch@.member
      name.ReplaceAll(".@","@.");
      name.ReplaceAll("->@","@->");

      TTree* tree=0;
      if (!fBranch) {
         Error("Browse", "branch not set - might access wrong tree!");
         return;
      } else tree=fBranch->GetTree();
      tree->Draw(name, "", b ? b->GetDrawOption() : "");
      if (gPad) gPad->Update();
   } else
      if (GetLeaves()) GetLeaves()->Browse(b);
}

////////////////////////////////////////////////////////////////////////////////
/// Askes all registered generators to fill their browsables into
/// the list. The browsables are generated for a given parent,
/// or (if 0), for a given branch. The branch is passed down to
/// leaves of TVirtualBranchBrowsable, too, as we need to access
/// the branch's TTree to be able to traw.

Int_t TVirtualBranchBrowsable::FillListOfBrowsables(TList& li, const TBranch* branch,
   const TVirtualBranchBrowsable* parent /* =0 */)
{
   if (!fgGeneratorsSet) RegisterDefaultGenerators();
   std::list<MethodCreateListOfBrowsables_t>::iterator iGenerator;
   Int_t numCreated=0;
   for (iGenerator=fgGenerators.begin(); iGenerator!=fgGenerators.end(); iGenerator++)
      numCreated+=(*(*iGenerator))(li, branch, parent);
   return numCreated;
}

////////////////////////////////////////////////////////////////////////////////
/// Check whether the branch (or the parent) contains a collection.
/// If it does, set "contained" to the contained type (if we can
/// retrieve it) and return the TClass for the collection. Set
/// "contained" to the branch's (or parent's) contained object's
/// class for non-collections, returning 0.
///
/// Only one of "branch" or "parent" can ge given (depending on whether
/// we are creating browsable objects for a branch or for another
/// browsable object)

TClass* TVirtualBranchBrowsable::GetCollectionContainedType(const TBranch* branch,
                                                            const TVirtualBranchBrowsable* parent,
                                                            TClass* &contained)
{
   contained=0;
   TClass* type=0;
   if (parent)
      type=parent->GetClassType();
   else if (branch) {
      if (branch->IsA()==TBranchElement::Class()) {
         // could be a split TClonesArray
         TBranchElement* be=(TBranchElement*) branch;

         // this is the contained type - if !=0
         const char* clonesname=be->GetClonesName();
         if (clonesname && strlen(clonesname))
            contained=TClass::GetClass(clonesname);

         // check if we're in a sub-branch of this class
         // we can only find out asking the streamer given our ID
         TStreamerElement *element=0;
         if (be->GetID()>=0 && be->GetInfo()
            && (be->GetID() < be->GetInfo()->GetNelement())
            && be->GetInfo()->IsCompiled()
            && (element=be->GetInfo()->GetElement(be->GetID()))) {
            // if contained is set (i.e. GetClonesName was successful),
            // this element containes the container, otherwise it's the
            // contained
            if (contained)
               // we have all we need
               return element->GetClassPointer();
            else
               type=element->GetClassPointer();
         } else if (clonesname && strlen(clonesname)) {
            // we have a clones name, and the TCA is not split:
            contained=TClass::GetClass(clonesname);
            return TClass::GetClass(be->GetClassName());
         } else
            type=TClass::GetClass(be->GetClassName());
      } else if (branch->IsA()==TBranchObject::Class()) {
         // could be an unsplit TClonesArray
         TBranchObject* bo=(TBranchObject*)branch;
         const char* clonesname=bo->GetClassName();
         contained=0;
         if (!clonesname || !clonesname[0]) return 0;
         type=TClass::GetClass(clonesname);
      }
   } else {
      ::Warning("TVirtualBranchBrowsable::GetCollectionContainedType", "Neither branch nor parent given!");
      return 0;
   }

   if (!type) return 0;

   TBranch* branchNonCost=const_cast<TBranch*>(branch);
   if (type->InheritsFrom(TClonesArray::Class())
      && branch->IsA()==TBranchObject::Class()
      && branchNonCost->GetListOfLeaves()
      && branchNonCost->GetListOfLeaves()->GetEntriesFast()==1) {
      // load first entry of the branch. Yes, this is bad, and might have
      // unexpected side effects for the user, esp as already looking at
      // (and not just drawing) a branch triggeres it.
      // To prove just how ugly it is, we'll also have to const_cast the
      // branch...
      if (branch->GetReadEntry()==-1) branchNonCost->GetEntry(0);
      // now get element
      TLeafObject* lo = (TLeafObject*)branchNonCost->GetListOfLeaves()->First();
      if (lo) {
         TObject* objContainer = lo->GetObject();
         if (objContainer && objContainer->IsA()==TClonesArray::Class()) {
            contained = ((TClonesArray*)objContainer)->GetClass();
         }
      }
      return type;
   } else    if (type->InheritsFrom(TClonesArray::Class())
      && branch->IsA()==TBranchElement::Class()
      && branchNonCost->GetListOfLeaves()
      && branchNonCost->GetListOfLeaves()->GetEntriesFast()==1) {
      // load first entry of the branch. Yes, this is bad, and might have
      // unexpected side effects for the user, esp as already looking at
      // (and not just drawing) a branch triggeres it.
      // To prove just how ugly it is, we'll also have to const_cast the
      // branch...

      //if (branch->GetReadEntry()==-1) branchNonCost->GetEntry(0);
      // now get element
      //TLeafObject* lo=(TLeafElement*)branchNonCost->GetListOfLeaves()->First();
      //TObject* objContainer=(TObject*)((TBranchElement*)branch)->GetValuePointer();

      //if (objContainer && objContainer->IsA()==TClonesArray::Class())
      //   contained=((TClonesArray*)objContainer)->GetClass();

      // Currently we can peer into the nested TClonesArray, we need
      // to update TBranchElement::GetValuePointer.
      return type;
   } else if (type->InheritsFrom(TCollection::Class())) {
      // some other container, and we don't know what the contained type is
      return type;
   } else if (type->GetCollectionProxy()) {
      contained=type->GetCollectionProxy()->GetValueClass();
      return type;
   } else if (type->InheritsFrom(TRef::Class()))
      // we don't do TRefs, so return contained and container as 0
      return 0;
   else contained=type;
   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Return list of leaves. If not set up yet we'll create them.

TList* TVirtualBranchBrowsable::GetLeaves() const
{
   if (!fLeaves) {
      TList* leaves=new TList();
      leaves->SetOwner();
      FillListOfBrowsables(*leaves, GetBranch(), this);
      const_cast<TVirtualBranchBrowsable*>(this)->fLeaves=leaves;
   }
   return fLeaves;
}

////////////////////////////////////////////////////////////////////////////////
/// returns the list of registered generator methods

std::list<TVirtualBranchBrowsable::MethodCreateListOfBrowsables_t>& TVirtualBranchBrowsable::GetRegisteredGenerators()
{
   return fgGenerators;
}

////////////////////////////////////////////////////////////////////////////////
/// Returns the full name for TTree::Draw to draw *this.
/// Recursively appends, starting at the top TBranch,
/// all method / object names with proper reference operators (->, .)
/// depending on fTypeIsPointer.

void TVirtualBranchBrowsable::GetScope(TString & scope) const
{
   if (fParent)
      fParent->GetScope(scope);
   else {
      scope=fBranch->GetName();
      Ssiz_t pos = scope.First('[');
      if (pos != kNPOS) {
         scope.Remove(pos);
      }
      if (!scope.EndsWith(".")) scope+=".";
      const TBranch* mother=fBranch;
      while (mother != mother->GetMother() && (mother=mother->GetMother())) {
         TString nameMother(mother->GetName());
         if (!nameMother.EndsWith(".")) {
            scope.Prepend(".");
            scope.Prepend(nameMother);
         } else {
            if (mother != mother->GetMother()) {
               // If the mother is the top level mother
               // and its ends ends with a ., the name is already
               // embedded!
               scope.Prepend(nameMother);
            }
         }
      }
   }
   if (GetName() && GetName()[0]=='.')
      scope+=(GetName()+1);
   else
      scope+=GetName();
   if (fClass && !scope.EndsWith(".")) { // otherwise we're a leaf, and no delimiter is appended
      if (fTypeIsPointer)
         scope+="->";
      else scope+=".";
   }
}

////////////////////////////////////////////////////////////////////////////////
/// Adds the default generators. The user can remove any of them as follows:
///
///     TMethodBrowsable::Unregister();
///
/// which will cause the browser not to show any methods.

void TVirtualBranchBrowsable::RegisterDefaultGenerators()
{
   if (fgGeneratorsSet) return;
   // can't call RegisterGenerator - would be recusive infite loop
   fgGenerators.push_back(&TMethodBrowsable::GetBrowsables);
   fgGenerators.push_back(&TNonSplitBrowsable::GetBrowsables);
   fgGenerators.push_back(&TCollectionPropertyBrowsable::GetBrowsables);
   fgGeneratorsSet=kTRUE;
}

////////////////////////////////////////////////////////////////////////////////
/// Adds a generator to be called when browsing branches.
/// Called by the Register method, which should be implemented
/// for all derived classes (see e.g. TMethodBrowsable::Register())

void TVirtualBranchBrowsable::RegisterGenerator(MethodCreateListOfBrowsables_t generator)
{
   if (!fgGeneratorsSet) RegisterDefaultGenerators();
   // make sure we're not adding another copy
   fgGenerators.remove(generator);
   fgGenerators.push_back(generator);
}

////////////////////////////////////////////////////////////////////////////////
/// Removes a generator from the list of generators to be called when
/// browsing branches. The user can remove any of the generators as follows:
///
///     TMethodBrowsable::Unregister();
///
/// which will cause the browser not to show any methods.

void TVirtualBranchBrowsable::UnregisterGenerator(MethodCreateListOfBrowsables_t generator)
{
   if (!fgGeneratorsSet) RegisterDefaultGenerators();
   fgGenerators.remove(generator);
}

ClassImp(TMethodBrowsable);

////////////////////////////////////////////////////////////////////////////////
/// \class TMethodBrowsable
///
/// This helper object allows the browsing of methods of objects stored in
/// branches. They will be depicted by a leaf (or a branch, in case the method
/// returns an object) with a red exclamation mark. Only a subset of all
/// methods will be shown in the browser (see IsMethodBrowsable for the
/// criteria a method has to satisfy).
///
/// Obviously, methods are only available if the library is loaded which
/// contains the dictionary for the class to be browsed!
///
/// If a branch contains a collection, TMethodBrowsable tries to find out
/// what the contained element is (it will only create methods for the
/// contained elements, but never for the collection). If it fails to extract
/// the type of the contained elements, or if there is no guarantee that the
/// type has any other common denominator than TObject (e.g. in the case of
/// a TObjArray, which can hold any object deriving from TObject) no methods
/// will be added.

////////////////////////////////////////////////////////////////////////////////
/// Constructor.
/// Links a TBranchElement to a TMethod, allowing the TBrowser to
/// browse simple methods.
///
/// The c'tor sets the name for a method "Class::Method(params) const"
/// to "Method(params)", title to TMethod::GetPrototype

TMethodBrowsable::TMethodBrowsable(const TBranch* branch, TMethod* m,
                                   const TVirtualBranchBrowsable* parent /* =0 */):
   TVirtualBranchBrowsable(branch, 0, kFALSE, parent), fMethod(m)
{
   TString name(m->GetName());
   name+="()";
   if (name.EndsWith(" const")) name.Remove(name.Length()-6);
   SetName(name);

   name=m->GetPrototype();
   if (m->GetCommentString() && strlen(m->GetCommentString()))
      name.Append(" // ").Append(m->GetCommentString());
   SetTitle(name);

   TString plainReturnType(m->GetReturnTypeName());
   if (plainReturnType.EndsWith("*")) {
      SetTypeIsPointer();
      plainReturnType.Remove(plainReturnType.Length()-1);
      plainReturnType.Strip();
      if(plainReturnType.BeginsWith("const")) {
         plainReturnType.Remove(0,5);
         plainReturnType.Strip();
      }
   }
   SetType(TClass::GetClass(plainReturnType));
}

////////////////////////////////////////////////////////////////////////////////
/// Given a class, this methods fills list with TMethodBrowsables
/// for the class and its base classes, and returns the number of
/// added elements. If called from a TBranch::Browse overload, "branch"
/// should be set to the calling TBranch, otherwise "parent" should
/// be set to the TVirtualBranchBrowsable being browsed, and branch
/// should be the branch of the parent.

void TMethodBrowsable::GetBrowsableMethodsForClass(TClass* cl, TList& li)
{
   if (!cl) return;
   TList allClasses;
   allClasses.Add(cl);

   if (cl->IsLoaded()) {
      for(TObjLink* lnk=allClasses.FirstLink();
          lnk; lnk=lnk->Next()) {
         cl=(TClass*)lnk->GetObject();
         TList* bases=cl->GetListOfBases();
         TBaseClass* base;
         TIter iB(bases);
         while ((base=(TBaseClass*)iB())) {
            TClass* bc=base->GetClassPointer();
            if (bc) allClasses.Add(bc);
         }
      }
   } else {
      TVirtualStreamerInfo *info = cl->GetStreamerInfo();
      for(int el = 0; el < info->GetElements()->GetEntries(); ++el) {
         TStreamerElement *element = (TStreamerElement *)info->GetElements()->UncheckedAt(el);
         if (element->IsBase()) {
            TClass *bc = element->GetClassPointer();
            if (bc) allClasses.Add(bc);
         }
      }
   }

   TList allMethods;
   TIter iC(&allClasses);
   while ((cl=(TClass*)iC())) {
      TList* methods=cl->GetListOfMethods();
      if (!methods) continue;
      TMethod* method=0;
      TIter iM(methods);
      while ((method=(TMethod*)iM()))
         if (method && !allMethods.FindObject(method->GetName()))
            allMethods.Add(method);
   }

   TIter iM(&allMethods);
   TMethod* m=0;
   while ((m=(TMethod*)iM())) {
      if (TMethodBrowsable::IsMethodBrowsable(m)) {
         li.Add(m);
      }
   }
}

////////////////////////////////////////////////////////////////////////////////
/// This methods fills list with TMethodBrowsables
/// for the branch's or parent's class and its base classes, and returns
/// the number of added elements. If called from a TBranch::Browse
/// overload, "branch" should be set to the calling TBranch, otherwise
/// "parent" should be set to the TVirtualBranchBrowsable being browsed.

Int_t TMethodBrowsable::GetBrowsables(TList& li, const TBranch* branch,
                                      const TVirtualBranchBrowsable* parent /*=0*/)
{
   TClass* cl;
   // we don't care about collections, so only use the TClass argument,
   // and not the return value
   GetCollectionContainedType(branch, parent, cl);
   if (!cl) return 0;

   TList listMethods;
   GetBrowsableMethodsForClass(cl, listMethods);
   TMethod* method=0;
   TIter iMethods(&listMethods);
   while ((method=(TMethod*)iMethods())) {
      li.Add(new TMethodBrowsable(branch, method, parent));
   }
   return listMethods.GetSize();
}

////////////////////////////////////////////////////////////////////////////////
/// A TMethod is browsable if it is const, public and not pure virtual,
/// if does not have any parameter without default value, and if it has
/// a (non-void) return value.
/// A method called *, Get*, or get* will not be browsable if there is a
/// persistent data member called f*, _*, or m*, as data member access is
/// faster than method access. Examples: if one of fX, _X, or mX is a
/// persistent data member, the methods GetX(), getX(), and X() will not
/// be browsable.

Bool_t TMethodBrowsable::IsMethodBrowsable(const TMethod* m)
{
   if (m->GetNargs()-m->GetNargsOpt()==0
       && (m->Property() & kIsConstant
           & ~kIsPrivate & ~kIsProtected & ~kIsPureVirtual )
       && m->GetReturnTypeName()
       && strcmp("void",m->GetReturnTypeName())
       && !strstr(m->GetName(),"DeclFile")
       && !strstr(m->GetName(),"ImplFile")
       && strcmp(m->GetName(),"IsA")
       && strcmp(m->GetName(),"Class")
       && strcmp(m->GetName(),"CanBypassStreamer")
       && strcmp(m->GetName(),"Class_Name")
       && strcmp(m->GetName(),"ClassName")
       && strcmp(m->GetName(),"Clone")
       && strcmp(m->GetName(),"DrawClone")
       && strcmp(m->GetName(),"GetName")
       && strcmp(m->GetName(),"GetDrawOption")
       && strcmp(m->GetName(),"GetIconName")
       && strcmp(m->GetName(),"GetOption")
       && strcmp(m->GetName(),"GetTitle")
       && strcmp(m->GetName(),"GetUniqueID")
       && strcmp(m->GetName(),"Hash")
       && strcmp(m->GetName(),"IsFolder")
       && strcmp(m->GetName(),"IsOnHeap")
       && strcmp(m->GetName(),"IsSortable")
       && strcmp(m->GetName(),"IsZombie")) {

      // look for matching data member
      TClass* cl=m->GetClass();
      if (!cl) return kTRUE;
      TList* members=cl->GetListOfDataMembers();
      if (!members) return kTRUE;
      const char* baseName=m->GetName();
      if (!strncmp(m->GetName(), "Get", 3) ||
          !strncmp(m->GetName(), "get", 3))
         baseName+=3;
      if (!baseName[0]) return kTRUE;

      TObject* mem=0;
      const char* arrMemberNames[3]={"f%s","_%s","m%s"};
      for (Int_t i=0; !mem && i<3; i++)
         mem=members->FindObject(TString::Format(arrMemberNames[i],baseName));
      return (!mem ||! ((TDataMember*)mem)->IsPersistent());
   };
   return kFALSE;
}

////////////////////////////////////////////////////////////////////////////////
/// Wrapper for the registration method. Needed against MSVC, which
/// assigned different addr to the same method, depending on what
/// translation unit you're in...

void TMethodBrowsable::Register()
{
   TVirtualBranchBrowsable::RegisterGenerator(GetBrowsables);
}

////////////////////////////////////////////////////////////////////////////////
/// Wrapper for the registration method. Needed against MSVC, which
/// assigned different addr to the same method, depending on what
/// translation unit you're in...

void TMethodBrowsable::Unregister()
{
   TVirtualBranchBrowsable::UnregisterGenerator(GetBrowsables);
}

ClassImp(TNonSplitBrowsable);

////////////////////////////////////////////////////////////////////////////////
/// \class TNonSplitBrowsable
///
/// Allows a TBrowser to browse non-split branches as if they were split. The
/// generator extracts the necessary information from the streamer info in
/// memory (which does not have to be the same as the one on file, in case
/// a library was loaded containing the dictionary for this type), i.e. it
/// also works without loading the class's library.
///
/// Just as with TMethodBrowsables, if the generator finds a collection it
/// only takes the contained objects into account, not the collections. If
/// it identifies a collection, but cannot extract the contained type, or the
/// contained type can be anything deriving from a TObject (like for TObjArray)
/// or is not limited at all, no browser helper objects are created.

////////////////////////////////////////////////////////////////////////////////
/// Constructor. Creates a TNonSplitBrowsable from a TStreamerElement, containing branch
/// and (if applicable) parent TVirtualBranchBrowsable.

TNonSplitBrowsable::TNonSplitBrowsable(const TStreamerElement* element, const TBranch* branch,
                                       const TVirtualBranchBrowsable* parent /* =0 */):
   TVirtualBranchBrowsable(branch, element->GetClassPointer(),
   element->IsaPointer(), parent)
{
   SetNameTitle(element->GetName(), element->GetTitle());
}

////////////////////////////////////////////////////////////////////////////////
/// Given either a branch "branch" or a "parent" TVirtualBranchBrowsable, we fill
/// "list" with objects of type TNonSplitBrowsable which represent the members
/// of class "cl" (and its base classes' members).

Int_t TNonSplitBrowsable::GetBrowsables(TList& li, const TBranch* branch,
                                        const TVirtualBranchBrowsable* parent /* =0 */)
{
   // branch has to be unsplit, i.e. without sub-branches
   if (parent==0
       && (branch==0 ||
           (const_cast<TBranch*>(branch)->GetListOfBranches()
            && const_cast<TBranch*>(branch)->GetListOfBranches()->GetEntries()!=0)
           )
       ) {
      return 0;
   }
   // we only expand our own parents
   //if (parent && parent->IsA()!=TNonSplitBrowsable::Class()) return 0;

   TClass* clContained=0;
   GetCollectionContainedType(branch, parent, clContained);
   TVirtualStreamerInfo* streamerInfo= clContained?clContained->GetStreamerInfo():0;
   if (!streamerInfo
      || !streamerInfo->GetElements()
      || !streamerInfo->GetElements()->GetSize())  return 0;

   if (!branch && parent) branch=parent->GetBranch();

   // we simply add all of our and the bases' members into one big list
   TList myStreamerElementsToCheck;
   myStreamerElementsToCheck.AddAll(streamerInfo->GetElements());

   Int_t numAdded=0;
   TStreamerElement* streamerElement=0;
   for (TObjLink *link = myStreamerElementsToCheck.FirstLink();
        link;
        link = link->Next() ) {
      streamerElement = (TStreamerElement*)link->GetObject();
      if (streamerElement->IsBase()) {
         // this is a base class place holder
         // continue with the base class's streamer info
         TClass* base=streamerElement->GetClassPointer();
         if (!base || !base->GetStreamerInfo()) continue;

         // add all of the base class's streamer elements
         // (which in turn can be a base, which will be
         // unfolded in a later iteration) to the list
         TObjArray* baseElements=base->GetStreamerInfo()->GetElements();
         if (!baseElements) continue;
         TIter iBaseSE(baseElements);
         TStreamerElement* baseSE=0;
         while ((baseSE=(TStreamerElement*)iBaseSE()))
            // we should probably check whether we're replacing something here...
            myStreamerElementsToCheck.Add(baseSE);
      } else if (!strcmp(streamerElement->GetName(),"This")
         && !strcmp(clContained->GetName(), streamerElement->GetTypeName())) {
         // this is a collection of the real elements.
         // So get the class ptr for these elements...
         TClass* clElements=streamerElement->GetClassPointer();
         TVirtualCollectionProxy* collProxy=clElements?clElements->GetCollectionProxy():0;
         clElements=collProxy?collProxy->GetValueClass():0;
         if (!clElements) continue;

         // now loop over the class's streamer elements
         streamerInfo = clElements->GetStreamerInfo();
         if (streamerInfo) {
            TIter iElem(streamerInfo->GetElements());
            TStreamerElement* elem=0;
            while ((elem=(TStreamerElement*)iElem())) {
               TNonSplitBrowsable* nsb=new TNonSplitBrowsable(elem, branch, parent);
               li.Add(nsb);
               numAdded++;
            }
         } else {
            ::Error("TNonSplitBrowsable::GetBrowsables",
                    "Missing the StreamerInfo for the class \"%s\" for the branch \"%s\" in the TTree \"%s\".",
                    clElements->GetName(), branch->GetName(), branch->GetTree()->GetName());
         }
      } else {
         // we have a basic streamer element
         TNonSplitBrowsable* nsb=new TNonSplitBrowsable(streamerElement, branch, parent);
         li.Add(nsb);
         numAdded++;
      }
   }
   return numAdded;
}

////////////////////////////////////////////////////////////////////////////////
/// Wrapper for the registration method. Needed against MSVC, which
/// assigned different addr to the same method, depending on what
/// translation unit you're in...

void TNonSplitBrowsable::Register()
{
   TVirtualBranchBrowsable::RegisterGenerator(GetBrowsables);
}

////////////////////////////////////////////////////////////////////////////////
/// Wrapper for the registration method. Needed against MSVC, which
/// assigned different addr to the same method, depending on what
/// translation unit you're in...

void TNonSplitBrowsable::Unregister()
{
   TVirtualBranchBrowsable::UnregisterGenerator(GetBrowsables);
}

ClassImp(TCollectionPropertyBrowsable);

////////////////////////////////////////////////////////////////////////////////
/// \class TCollectionPropertyBrowsable
///
/// A tiny browser helper object (and its generator) for adding a virtual
/// (as in "not actually part of the class", not in C++ virtual) "@size()"
/// method to a collection. For all collections that derive from
/// TCollection, or have a TVirtualCollectionProxy associated with them,
/// a leaf is created that allows access to the number of elements in the
/// collection. For TClonesArrays and types with an associated
/// TVirtualCollectionProxy, this forwards to TTreeFormula's
/// "@branch.size()" functionality. For all other collections, a method call
/// to the appropriate collection's member function is executed when drawing.
///
/// These objects are of course only created for elements containing a
/// collection; the generator has no effect on any other elements.

////////////////////////////////////////////////////////////////////////////////
/// Browses a TCollectionPropertyBrowsable. The only difference to
/// the generic TVirtualBranchBrowsable::Browse is our fDraw

void TCollectionPropertyBrowsable::Browse(TBrowser *b)
{
   GetBranch()->GetTree()->Draw(GetDraw(), "", b ? b->GetDrawOption() : "");
   if (gPad) gPad->Update();
}

////////////////////////////////////////////////////////////////////////////////
/// If the element to browse (given by either parent of branch) contains
/// a collection (TClonesArray or something for which a TVirtualCollectionProxy
/// exists), we will add some special objects to the browser. For now there is
/// just one object "@size", returning the size of the collection (as in
/// std::list::size(), or TClonesArray::GetEntries()).
/// The objects we create are simply used to forward strings (like "@size") to
/// TTreeFormula via our Browse method. These strings are stored in fName.

Int_t TCollectionPropertyBrowsable::GetBrowsables(TList& li, const TBranch* branch,
                                                  const TVirtualBranchBrowsable* parent /* =0 */)
{
   TClass* clContained=0;
   TClass* clCollection=GetCollectionContainedType(branch, parent, clContained);
   if (!clCollection || !clContained) return 0;

   // Build the fDraw string. Start with our scope.
   TString scope;
   if (parent) {
      parent->GetScope(scope);
      branch=parent->GetBranch();
   } else if (branch){
      scope=branch->GetName();
      scope+=".";
      const TBranch* mother=branch;
      while (mother != mother->GetMother() && (mother=mother->GetMother())) {
         TString nameMother(mother->GetName());
         if (!nameMother.EndsWith(".")) {
            scope.Prepend(".");
            scope.Prepend(nameMother);
         } else {
            if (mother != mother->GetMother()) {
               // If the mother is the top level mother
               // and its ends ends with a ., the name is already
               // embedded!
               scope.Prepend(nameMother);
            }
         }
      }
   } else {
      ::Warning("TCollectionPropertyBrowsable::GetBrowsables", "Neither branch nor parent is set!");
      return 0;
   }

   // remove trailing delimiters
   if (scope.EndsWith(".")) scope.Remove(scope.Length()-1, 1);
   else if (scope.EndsWith("->")) scope.Remove(scope.Length()-2, 2);

   // now prepend "@" to the last element of the scope,
   // to access the collection and not its containees
   Ssiz_t lastDot=scope.Last('.');
   Ssiz_t lastArrow=scope.Last('>'); // assuming there's no branch name containing ">"...
   Ssiz_t lastPart=lastDot;
   if (lastPart==kNPOS || (lastArrow!=kNPOS && lastPart<lastArrow))
      lastPart=lastArrow;
   if (lastPart==kNPOS) lastPart=0;
   else lastPart++;

   TString size_title("size of ");
   size_title += clCollection->GetName();
   if (clContained) {
      size_title += " of ";
      size_title += clContained->GetName();
   }

   if (clCollection->GetCollectionProxy() || clCollection==TClonesArray::Class()) {
   // the collection is one for which TTree::Draw supports @coll.size()

      TCollectionPropertyBrowsable* cpb;
      if ( clCollection->GetCollectionProxy() &&
           ( (clCollection->GetCollectionProxy()->GetValueClass()==0)
           ||(clCollection->GetCollectionProxy()->GetValueClass()->GetCollectionProxy()!=0
              && clCollection->GetCollectionProxy()->GetValueClass()->GetCollectionProxy()->GetValueClass()==0)
            )) {
         // If the contained type is not a class, we need an explitcit handle to get to the data.
         cpb = new TCollectionPropertyBrowsable("values", "values in the container",
                                                scope, branch, parent);
         li.Add(cpb);
      }
      scope.Insert(lastPart, "@");
      cpb = new TCollectionPropertyBrowsable("@size", size_title,
                                            scope+".size()", branch, parent);
      li.Add(cpb);
      return 1;
   } // if a collection proxy or TClonesArray
   else if (clCollection->InheritsFrom(TCollection::Class())) {
      // generic TCollection - we'll build size() ourselves, by mapping
      // it to the proper member function of the collection
      if (clCollection->InheritsFrom(TObjArray::Class()))
         scope+="@.GetEntries()";
      else scope+="@.GetSize()";
      TCollectionPropertyBrowsable* cpb=
         new TCollectionPropertyBrowsable("@size", size_title, scope, branch, parent);
      li.Add(cpb);
      return 1;
   }
   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Wrapper for the registration method. Needed against MSVC, which
/// assigned different addr to the same method, depending on what
/// translation unit you're in...

void TCollectionPropertyBrowsable::Register()
{
   TVirtualBranchBrowsable::RegisterGenerator(GetBrowsables);
}

////////////////////////////////////////////////////////////////////////////////
/// Wrapper for the registration method. Needed against MSVC, which
/// assigned different addr to the same method, depending on what
/// translation unit you're in...

void TCollectionPropertyBrowsable::Unregister()
{
   TVirtualBranchBrowsable::UnregisterGenerator(GetBrowsables);
}

ClassImp(TCollectionMethodBrowsable);

////////////////////////////////////////////////////////////////////////////////
/// \class TCollectionMethodBrowsable
///
/// TCollectionMethodBrowsable extends TCollectionPropertyBrowsable by showing
/// all methods of the collection itself. If none are available - e.g. for STL
/// classes like std::list, a TVirtualBranchBrowsable object is reated instead.
/// The methods' names will have a "@" prepended, to distinguish them from the
/// contained elements' methods.
///
/// This browser helper object is not part of the default list of registered
/// generators (see TVirtualBranchBrowsable::RegisterDefaultGenerators()).
/// If you want to use it, you should call
///   TCollectionMethodBrowsable::Register();
/// As it extends the functionality of TVirtualBranchBrowsable, one might want
/// to unregister the generator of the "@size()" method by calling
///   TCollectionPropertyBrowsable::Unregister();

////////////////////////////////////////////////////////////////////////////////
/// Contructor, see TMethodBrowsable's constructor.
/// Prepends "@" to the name to make this method work on the container.

TCollectionMethodBrowsable::TCollectionMethodBrowsable(const TBranch* branch, TMethod* m,
                                                       const TVirtualBranchBrowsable* parent /*=0*/):
TMethodBrowsable(branch, m, parent)
{
   SetName(TString("@")+GetName());
}

////////////////////////////////////////////////////////////////////////////////
/// This methods fills list with TMethodBrowsables
/// for the branch's or parent's collection class and its base classes,
/// and returns the number of added elements. If called from a TBranch::Browse
/// overload, "branch" should be set to the calling TBranch, otherwise
/// "parent" should be set to the TVirtualBranchBrowsable being browsed.

Int_t TCollectionMethodBrowsable::GetBrowsables(TList& li, const TBranch* branch,
                                                const TVirtualBranchBrowsable* parent /*=0*/)
{
   TClass* clContained=0;
   // we don't care about the contained class, but only about the collections,
   TClass* clContainer=GetCollectionContainedType(branch, parent, clContained);
   if (!clContainer || !clContained) return 0;

   TList listMethods;
   GetBrowsableMethodsForClass(clContainer, listMethods);
   TMethod* method=0;
   TIter iMethods(&listMethods);
   while ((method=(TMethod*)iMethods()))
      li.Add(new TCollectionMethodBrowsable(branch, method, parent));

   // if we have no methods, and if the class has a collection proxy, just add
   // the corresponding TCollectionPropertyBrowsable instead.
   // But only do that if TCollectionPropertyBrowsable is not generatated anyway
   // - we don't need two of them.
   if (!listMethods.GetSize() && clContainer->GetCollectionProxy()) {
      std::list<MethodCreateListOfBrowsables_t>& listGenerators=GetRegisteredGenerators();
      std::list<MethodCreateListOfBrowsables_t>::iterator iIsRegistered
         = std::find(listGenerators.begin(), listGenerators.end(), &TCollectionPropertyBrowsable::GetBrowsables);
      if (iIsRegistered==listGenerators.end()) {
         TCollectionPropertyBrowsable::GetBrowsables(li, branch, parent);
         return 1;
      }
   }
   return listMethods.GetSize();
}

////////////////////////////////////////////////////////////////////////////////
/// Wrapper for the registration method. Needed against MSVC, which
/// assigned different addr to the same method, depending on what
/// translation unit you're in...

void TCollectionMethodBrowsable::Register()
{
   TVirtualBranchBrowsable::RegisterGenerator(GetBrowsables);
}

////////////////////////////////////////////////////////////////////////////////
/// Wrapper for the registration method. Needed against MSVC, which
/// assigned different addr to the same method, depending on what
/// translation unit you're in...

void TCollectionMethodBrowsable::Unregister()
{
   TVirtualBranchBrowsable::UnregisterGenerator(GetBrowsables);
}