TGlobal.h

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// @(#)root/meta:$Id$
// Author: Rene Brun   13/11/95

/*************************************************************************
 * 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.             *
 *************************************************************************/

#ifndef ROOT_TGlobal
#define ROOT_TGlobal


//////////////////////////////////////////////////////////////////////////
//                                                                      //
// TGlobal                                                              //
//                                                                      //
// Global variables class (global variables are obtained from CINT).    //
//                                                                      //
//////////////////////////////////////////////////////////////////////////

#include "TDictionary.h"

#include <functional>

class TGlobal : public TDictionary {

private:
   DataMemberInfo_t  *fInfo;      //!pointer to CINT data member info

public:
   TGlobal(DataMemberInfo_t *info = nullptr);
   TGlobal (const TGlobal &);
   TGlobal &operator=(const TGlobal &);

   virtual       ~TGlobal();
   virtual Int_t  GetArrayDim() const;
   virtual DeclId_t GetDeclId() const;
   virtual Int_t  GetMaxIndex(Int_t dim) const;
   virtual void  *GetAddress() const;
   virtual const char *GetTypeName() const;
   virtual const char *GetFullTypeName() const;
   virtual Bool_t IsValid();
   virtual Long_t Property() const;
   virtual bool   Update(DataMemberInfo_t *info);

   ClassDef(TGlobal,2)  //Global variable class
};

// Class to map the "funcky" globals and be able to add them to the list of globals.
class TGlobalMappedFunction : public TGlobal {
public:
   typedef void *(*GlobalFunc_t)();
   typedef std::function<void *()> GlobalFunctor_t;

   TGlobalMappedFunction(const char *name, const char *type, GlobalFunc_t funcPtr);

   virtual ~TGlobalMappedFunction() = default;
   Int_t GetArrayDim() const override { return 0; }
   DeclId_t GetDeclId() const override { return (DeclId_t)(fFuncPtr); } // Used as DeclId because of uniqueness
   Int_t GetMaxIndex(Int_t /*dim*/) const override { return -1; }
   void *GetAddress() const override { return !fFunctor ? (*fFuncPtr)() : fFunctor(); }
   const char *GetTypeName() const override { return GetTitle(); }
   const char *GetFullTypeName() const override { return GetTitle(); }
   Long_t Property() const override { return 0; }
   bool Update(DataMemberInfo_t * /*info*/) override { return false; }

   static void Add(TGlobalMappedFunction *gmf);

   template <typename GlobFunc>
   static void MakeFunctor(const char *name, const char *type, GlobFunc &func)
   {
      auto glob = new TGlobalMappedFunction(name, type, (GlobalFunc_t)((void *)&func));
      glob->fFunctor = [&func] {
         auto &res = func();
         return (void *)(&res);
      };
      Add(glob);
   }

   template <typename GlobFunc>
   static void MakeFunctor(const char *name, const char *type, GlobFunc &func, GlobalFunctor_t functor)
   {
      auto glob = new TGlobalMappedFunction(name, type, (GlobalFunc_t)((void *)&func));
      glob->fFunctor = functor;
      Add(glob);
   }

private:
   GlobalFunc_t fFuncPtr{nullptr}; // Function to call to get the address

   GlobalFunctor_t fFunctor; // functor which correctly returns pointer

   TGlobalMappedFunction &operator=(const TGlobal &) = delete;
   // Some of the special ones are created before the list is create e.g gFile
   // We need to buffer them.
   static TList &GetEarlyRegisteredGlobals();

   friend class TROOT;
};

#endif