CountedPtr.h

 
#pragma once

 
#if defined(CountedPtr_RECURSES)
#error Recursive header files inclusion detected in CountedPtr.h
#else // defined(CountedPtr_RECURSES)
#define CountedPtr_RECURSES
 
#if !defined CountedPtr_h
#define CountedPtr_h

// Inclusions
#include <iostream>
#include "DGtal/base/Common.h"
 
namespace DGtal
{
  template <typename T> class CountedPtrOrPtr;
  template <typename T> class CountedConstPtrOrConstPtr;

  // template class CountedPtr
  template <typename T>
  class CountedPtr
  {
  public:

    friend class CountedPtrOrPtr<T>;
    friend class CountedConstPtrOrConstPtr<T>;
 
    // ----------------------- Standard services ------------------------------
  public:
    struct Counter {
      Counter(T* p = 0, unsigned c = 1) : ptr(p), count(c) {}
      T*          ptr;
      unsigned    count;
    };
 

    explicit CountedPtr(T* p = 0) : myCounter(0)
    {
      if (p) myCounter = new Counter(p);
    }

    ~CountedPtr()
    {
      release();
    }

    CountedPtr(const CountedPtr& r) noexcept
    {
      acquire(r.myCounter);
    }

   CountedPtr& operator=(const CountedPtr& r)
    {
      if (this != &r)
        {
          release();
          acquire(r.myCounter);
        }
      return *this;
    }

    T& operator*()  const noexcept
    {
      return *myCounter->ptr;
    }

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

    T* get()        const noexcept
    {
      return myCounter ? myCounter->ptr : 0;
    }

    bool unique()   const noexcept
    {
      return (myCounter ? myCounter->count == 1 : true);
    }

    bool operator==( const T* other ) const
    {
      return get() == other;
    }

    bool operator!=( const T* other ) const
    {
      return get() != other;
    }

    unsigned int count() const
    {
      return myCounter->count;
    }

    inline T* drop()
    {
      ASSERT( isValid() );
      ASSERT( unique() );
      T* tmp = myCounter->ptr;
      delete myCounter;
      myCounter = 0;
      return tmp;
    }
private:
    void acquire(Counter* c) noexcept
    { // increment the count
        myCounter = c;
        if (c) ++c->count;
    }

    void release()
    { // decrement the count, delete if it is 0
        if (myCounter) {
            if (--myCounter->count == 0) {
                delete myCounter->ptr;
                delete myCounter;
            }
            myCounter = 0;
        }
    }
 
 
    // ----------------------- Interface --------------------------------------
  public:

    void selfDisplay ( std::ostream & out ) const;

    bool isValid() const;
 
    // ------------------------- Protected Data ------------------------------
  private:
    Counter* myCounter;
 
    // ------------------------- Private Data --------------------------------
  private:
 
    // ------------------------- Hidden services ------------------------------
  protected:
 
 
    // ------------------------- Internals ------------------------------------
  private:
 
  }; // end of class CountedPtr
 

  template <typename T>
  std::ostream&
  operator<< ( std::ostream & out, const CountedPtr<T> & object );
 
} // namespace DGtal
 

// Includes inline functions.
#include "DGtal/base/CountedPtr.ih"
 
//                                                                           //
 
#endif // !defined CountedPtr_h
 
#undef CountedPtr_RECURSES
#endif // else defined(CountedPtr_RECURSES)