include/AD/memory/ptr.h

   1 //////////////////////////////////////////////////////////////////////////////
   2 // NOTICE:
   3 //
   4 // ADLib, Prop and their related set of tools and documentation are in the
   5 // public domain.   The author(s) of this software reserve no copyrights on
   6 // the source code and any code generated using the tools.  You are encouraged
   7 // to use ADLib and Prop to develop software, in both academic and commercial
   8 // settings, and are free to incorporate any part of ADLib and Prop into
   9 // your programs.
  10 //
  11 // Although you are under no obligation to do so, we strongly recommend that
  12 // you give away all software developed using our tools.
  13 //
  14 // We also ask that credit be given to us when ADLib and/or Prop are used in
  15 // your programs, and that this notice be preserved intact in all the source
  16 // code.
  17 //
  18 // This software is still under development and we welcome any suggestions
  19 // and help from the users.
  20 //
  21 // Allen Leung
  22 // 1994
  23 //////////////////////////////////////////////////////////////////////////////
  24
  25 #ifndef reference_counting_pointers_h
  26 #define reference_counting_pointers_h
  27
  28 #include <AD/generic/generic.h>
  29 #include <AD/memory/ref.h>
  30
  31 //
  32 // Ptr<Obj> handled the reference counting of class |Obj|
  33 //
  34
  35 template <class Obj>
  36    class Ptr {
  37    protected:
  38        Obj * obj;
  39
  40    public:
  41        Ptr(Obj * ob) : obj(ob) {}
  42        Ptr(Ptr& r) : obj(r.obj) { if (obj) obj->reference_count++; }
  43       ~Ptr() { if (obj && --obj->reference_count == 0) delete obj; }
  44
  45        void operator = (Ptr& r)
  46           { if (r.obj) r.obj->reference_count++;
  47             if (obj && --obj->reference_count == 0) delete obj;
  48             obj = r.obj;
  49           }
  50        Obj * operator -> () { return obj; }
  51    };
  52
  53 #endif