countedPtr.h

#ifndef _H_INCLUDE_COUNTED_PTR
#define _H_INCLUDE_COUNTED_PTR

#include <memory>

/**
 * this is a reference counting smartpointer
 * do not use this for arrays, use CountedArrayPtr
 */
template <typename T> 
class CountedPtr {
private:
    T * ptr;
    long * count;

public:
    explicit CountedPtr(T * p = 0)
        : ptr(p), count(new long(1)) {
    }

    CountedPtr(const CountedPtr<T> & p) throw()
        : ptr(p.ptr), count(p.count) {
        ++*count;
    }

    ~CountedPtr() throw() {
        dispose();
    }

    CountedPtr<T>& operator= (const CountedPtr<T> & p) throw() {
        if (this != &p) {
            dispose();
            ptr = p.ptr;
            count = p.count;
            ++*count;
        }
        return *this;
    }

    bool isNull() const throw() {
        return ptr == 0;
    }

    T& operator*() const throw() {
        return *ptr;
    }

    T* operator->() const throw() {
        return ptr;
    }

    T* get() const throw() {
        return ptr;
    }

private:
    void dispose() {
        if (--*count == 0) {
            delete count;
            delete ptr;
            ptr = 0;
            count = 0;
        }
    }
};


/**
 * this is a reference counting smartpointer for arrays
 */
template <typename T> 
class CountedArrayPtr {
private:
    T * ptr;
    long * count;

public:
    explicit CountedArrayPtr(T * p = 0)
        : ptr(p), count(new long(1)) {
    }

    CountedArrayPtr(const CountedArrayPtr<T> & p) throw()
        : ptr(p.ptr), count(p.count) {
        ++*count;
    }

    ~CountedArrayPtr() throw() {
        dispose();
    }

    CountedArrayPtr<T>& operator= (const CountedArrayPtr<T>& p) throw() {
        if (this != &p) {
            dispose();
            ptr = p.ptr;
            count = p.count;
            ++*count;
        }
        return *this;
    }

    T& operator[](int index) const throw() {
        return ptr[index];
    }

    T* get() const throw() {
        return ptr;
    }

private:
    void dispose() {
        if (--*count == 0) {
            delete count;
            delete [] ptr;
            ptr = 0;
        }
    }
};

template<typename _Tp>
    class auto_arr
    {
    private:
      _Tp* _M_ptr;
      
    public:
      /// The pointed-to type.
      typedef _Tp element_type;
      
      /**
       *  @brief  An %auto_ptr is usually constructed from a raw pointer.
       *  @param  p  A pointer (defaults to NULL).
       *
       *  This object now @e owns the object pointed to by @a p.
       */
      explicit
      auto_arr(element_type* __p = 0) throw() : _M_ptr(__p) { }

      /**
       *  @brief  An %auto_ptr can be constructed from another %auto_ptr.
       *  @param  a  Another %auto_ptr of the same type.
       *
       *  This object now @e owns the object previously owned by @a a,
       *  which has given up ownsership.
       */
      auto_arr(auto_arr& __a) throw() : _M_ptr(__a.release()) { }

      /**
       *  @brief  An %auto_ptr can be constructed from another %auto_ptr.
       *  @param  a  Another %auto_ptr of a different but related type.
       *
       *  A pointer-to-Tp1 must be convertible to a
       *  pointer-to-Tp/element_type.
       *
       *  This object now @e owns the object previously owned by @a a,
       *  which has given up ownsership.
       */
      template<typename _Tp1>
        auto_arr(auto_arr<_Tp1>& __a) throw() : _M_ptr(__a.release()) { }

      /**
       *  @brief  %auto_ptr assignment operator.
       *  @param  a  Another %auto_ptr of the same type.
       *
       *  This object now @e owns the object previously owned by @a a,
       *  which has given up ownsership.  The object that this one @e
       *  used to own and track has been deleted.
       */
      auto_arr&
      operator=(auto_arr& __a) throw()
      {
	reset(__a.release());
	return *this;
      }

      /**
       *  @brief  %auto_ptr assignment operator.
       *  @param  a  Another %auto_ptr of a different but related type.
       *
       *  A pointer-to-Tp1 must be convertible to a pointer-to-Tp/element_type.
       *
       *  This object now @e owns the object previously owned by @a a,
       *  which has given up ownsership.  The object that this one @e
       *  used to own and track has been deleted.
       */
      template<typename _Tp1>
        auto_arr&
        operator=(auto_arr<_Tp1>& __a) throw()
        {
	  reset(__a.release());
	  return *this;
	}

      /**
       *  When the %auto_ptr goes out of scope, the object it owns is
       *  deleted.  If it no longer owns anything (i.e., @c get() is
       *  @c NULL), then this has no effect.
       *
       *  @if maint
       *  The C++ standard says there is supposed to be an empty throw
       *  specification here, but omitting it is standard conforming.  Its
       *  presence can be detected only if _Tp::~_Tp() throws, but this is
       *  prohibited.  [17.4.3.6]/2
       *  @end maint
       */
      ~auto_arr() { delete [] _M_ptr; }
      
      /**
       *  @brief  Smart pointer dereferencing.
       *
       *  If this %auto_ptr no longer owns anything, then this
       *  operation will crash.  (For a smart pointer, "no longer owns
       *  anything" is the same as being a null pointer, and you know
       *  what happens when you dereference one of those...)
       */
      element_type&
      operator*() const throw() 
      {
	_GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
	return *_M_ptr; 
      }
      
      /**
       *  @brief  Smart pointer dereferencing.
       *
       *  This returns the pointer itself, which the language then will
       *  automatically cause to be dereferenced.
       */
      element_type*
      operator->() const throw() 
      {
	_GLIBCXX_DEBUG_ASSERT(_M_ptr != 0);
	return _M_ptr; 
      }
      
      /**
       *  @brief  Bypassing the smart pointer.
       *  @return  The raw pointer being managed.
       *
       *  You can get a copy of the pointer that this object owns, for
       *  situations such as passing to a function which only accepts
       *  a raw pointer.
       *
       *  @note  This %auto_ptr still owns the memory.
       */
      element_type*
      get() const throw() { return _M_ptr; }
      
      /**
       *  @brief  Bypassing the smart pointer.
       *  @return  The raw pointer being managed.
       *
       *  You can get a copy of the pointer that this object owns, for
       *  situations such as passing to a function which only accepts
       *  a raw pointer.
       *
       *  @note  This %auto_ptr no longer owns the memory.  When this object
       *  goes out of scope, nothing will happen.
       */
      element_type*
      release() throw()
      {
	element_type* __tmp = _M_ptr;
	_M_ptr = 0;
	return __tmp;
      }
      
      /**
       *  @brief  Forcibly deletes the managed object.
       *  @param  p  A pointer (defaults to NULL).
       *
       *  This object now @e owns the object pointed to by @a p.  The
       *  previous object has been deleted.
       */
      void
      reset(element_type* __p = 0) throw()
      {
	if (__p != _M_ptr)
	  {
	    delete [] _M_ptr;
	    _M_ptr = __p;
	  }
      }
      
      /** @{
       *  @brief  Automatic conversions
       *
       *  These operations convert an %auto_ptr into and from an auto_ptr_ref
       *  automatically as needed.  This allows constructs such as
       *  @code
       *    auto_ptr<Derived>  func_returning_auto_ptr(.....);
       *    ...
       *    auto_ptr<Base> ptr = func_returning_auto_ptr(.....);
       *  @endcode
       */
      auto_arr(std::auto_ptr_ref<element_type> __ref) throw()
      : _M_ptr(__ref._M_ptr) { }
      
      auto_arr&
      operator=(std::auto_ptr_ref<element_type> __ref) throw()
      {
	if (__ref._M_ptr != this->get())
	  {
	    delete [] _M_ptr;
	    _M_ptr = __ref._M_ptr;
	  }
	return *this;
      }
      
      template<typename _Tp1>
        operator std::auto_ptr_ref<_Tp1>() throw()
        { return std::auto_ptr_ref<_Tp1>(this->release()); }

      template<typename _Tp1>
        operator auto_arr<_Tp1>() throw()
        { return auto_arr<_Tp1>(this->release()); }
      /** @}  */
  };

#endif