interpreter/preprocessor/faust-0.9.47mr3/architecture/osclib/faust/src/lib/smartpointer.h

   1 /*
   2
   3   Copyright (C) 2011 Grame
   4
   5   This library is free software; you can redistribute it and/or
   6   modify it under the terms of the GNU Lesser General Public
   7   License as published by the Free Software Foundation; either
   8   version 2.1 of the License, or (at your option) any later version.
   9
  10   This library is distributed in the hope that it will be useful,
  11   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13   Lesser General Public License for more details.
  14
  15   You should have received a copy of the GNU Lesser General Public
  16   License along with this library; if not, write to the Free Software
  17   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  18
  19   Grame Research Laboratory, 9 rue du Garet, 69001 Lyon - France
  20   research@grame.fr
  21
  22 */
  23
  24 #ifndef __smartpointer__
  25 #define __smartpointer__
  26
  27 #include <cassert>
  28
  29 namespace oscfaust
  30 {
  31
  32 /*!
  33 \brief the base class for smart pointers implementation
  34
  35         Any object that want to support smart pointers should
  36         inherit from the smartable class which provides reference counting
  37         and automatic delete when the reference count drops to zero.
  38 */
  39 class smartable {
  40         private:
  41                 unsigned        refCount;
  42         public:
  43                 //! gives the reference count of the object
  44                 unsigned refs() const         { return refCount; }
  45                 //! addReference increments the ref count and checks for refCount overflow
  46                 void addReference()           { refCount++; assert(refCount != 0); }
  47                 //! removeReference delete the object when refCount is zero
  48                 void removeReference()            { if (--refCount == 0) delete this; }
  49
  50         protected:
  51                 smartable() : refCount(0) {}
  52                 smartable(const smartable&): refCount(0) {}
  53                 //! destructor checks for non-zero refCount
  54                 virtual ~smartable()    { assert (refCount == 0); }
  55                 smartable& operator=(const smartable&) { return *this; }
  56 };
  57
  58 /*!
  59 \brief the smart pointer implementation
  60
  61         A smart pointer is in charge of maintaining the objects reference count
  62         by the way of pointers operators overloading. It supports class
  63         inheritance and conversion whenever possible.
  64 \n      Instances of the SMARTP class are supposed to use \e smartable types (or at least
  65         objects that implements the \e addReference and \e removeReference
  66         methods in a consistent way).
  67 */
  68 template<class T> class SMARTP {
  69         private:
  70                 //! the actual pointer to the class
  71                 T* fSmartPtr;
  72
  73         public:
  74                 //! an empty constructor - points to null
  75                 SMARTP()        : fSmartPtr(0) {}
  76                 //! build a smart pointer from a class pointer
  77                 SMARTP(T* rawptr) : fSmartPtr(rawptr)              { if (fSmartPtr) fSmartPtr->addReference(); }
  78                 //! build a smart pointer from an convertible class reference
  79                 template<class T2>
  80                 SMARTP(const SMARTP<T2>& ptr) : fSmartPtr((T*)ptr) { if (fSmartPtr) fSmartPtr->addReference(); }
  81                 //! build a smart pointer from another smart pointer reference
  82                 SMARTP(const SMARTP& ptr) : fSmartPtr((T*)ptr)     { if (fSmartPtr) fSmartPtr->addReference(); }
  83
  84                 //! the smart pointer destructor: simply removes one reference count
  85                 ~SMARTP()  { if (fSmartPtr) fSmartPtr->removeReference(); }
  86
  87                 //! cast operator to retrieve the actual class pointer
  88                 operator T*() const  { return fSmartPtr;        }
  89
  90                 //! '*' operator to access the actual class pointer
  91                 T& operator*() const {
  92                         // checks for null dereference
  93                         assert (fSmartPtr != 0);
  94                         return *fSmartPtr;
  95                 }
  96
  97                 //! operator -> overloading to access the actual class pointer
  98                 T* operator->() const   {
  99                         // checks for null dereference
 100                         assert (fSmartPtr != 0);
 101                         return fSmartPtr;
 102                 }
 103
 104                 //! operator = that moves the actual class pointer
 105                 template <class T2>
 106                 SMARTP& operator=(T2 p1_)       { *this=(T*)p1_; return *this; }
 107
 108                 //! operator = that moves the actual class pointer
 109                 SMARTP& operator=(T* p_)        {
 110                         // check first that pointers differ
 111                         if (fSmartPtr != p_) {
 112                                 // increments the ref count of the new pointer if not null
 113                                 if (p_ != 0) p_->addReference();
 114                                 // decrements the ref count of the old pointer if not null
 115                                 if (fSmartPtr != 0) fSmartPtr->removeReference();
 116                                 // and finally stores the new actual pointer
 117                                 fSmartPtr = p_;
 118                         }
 119                         return *this;
 120                 }
 121                 //! operator < to support SMARTP map with Visual C++
 122                 bool operator<(const SMARTP<T>& p_)     const                     { return fSmartPtr < ((T *) p_); }
 123                 //! operator = to support inherited class reference
 124                 SMARTP& operator=(const SMARTP<T>& p_)                { return operator=((T *) p_); }
 125                 //! dynamic cast support
 126                 template<class T2> SMARTP& cast(T2* p_)               { return operator=(dynamic_cast<T*>(p_)); }
 127                 //! dynamic cast support
 128                 template<class T2> SMARTP& cast(const SMARTP<T2>& p_) { return operator=(dynamic_cast<T*>(p_)); }
 129 };
 130
 131 }
 132
 133 #endif