rc_ptr.h

//
// Copyright (c) 2014 Limit Point Systems, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

// Interface for class rc_ptr

#ifndef RC_PTR_H
#define RC_PTR_H

#ifndef SHEAF_DLL_SPEC_H
#include "SheafSystem/sheaf_dll_spec.h"
#endif

#ifndef SHEAF_H
#include "SheafSystem/sheaf.h"
#endif

namespace sheaf
{
  
template<typename T>
class rc_ptr
{

  // The following set of arcane definitions allow an rc_ptr
  // to behave as one expects a pointer to in comparisons.
  // See A. Alexandrescu "Modern C++ Design", Ch 7, section 8.

  inline friend bool operator==(const rc_ptr& lhs, const T* rhs)
  {
    return lhs._target == rhs;
  };

  inline friend bool operator==(const T* lhs, const rc_ptr& rhs)
  {
    return lhs == rhs._target;
  };

  inline friend bool operator!=(const rc_ptr& lhs, const T* rhs)
  {
    return lhs._target != rhs;
  };

  inline friend bool operator!=(const T* lhs, const rc_ptr& rhs)
  {
    return lhs != rhs._target;
  };

  template <typename U>
  inline friend bool operator==(const rc_ptr& lhs, const U* rhs)
  {
    return lhs._target == rhs;
  };

  template <typename U>
  inline friend bool operator==(const U* lhs, const rc_ptr& rhs)
  {
    return lhs == rhs._target;
  };

  template <typename U>
  inline friend bool operator!=(const rc_ptr& lhs, const U* rhs)
  {
    return lhs._target != rhs;
  };

  template <typename U>
  inline friend bool operator!=(const U* lhs, const rc_ptr& rhs)
  {
    return lhs != rhs._target;
  };

  // The next two defintions are convenient for stating contracts.

  inline friend bool same_target(const rc_ptr<T>& xp1, const rc_ptr<T>& xp2)
  {
    return xp1._target == xp2._target;
  };

  inline friend size_type target_ref_ct(const rc_ptr<T>& xp)
  {
    return xp != 0 ? xp->ref_ct() : 0;
  };

public:

  rc_ptr(T* xtarget = 0);

  rc_ptr(const rc_ptr& xother);

  ~rc_ptr();

  bool operator!() const;

  template <typename U>
  bool operator==(const rc_ptr<U>& xother) const;

  template <typename U>
  bool operator!=(const rc_ptr<U>& xother) const;

  rc_ptr& operator=(const rc_ptr& xother);

  rc_ptr& operator=(T* xtarget);

  T* operator->() const;

  T& operator*() const;

private:

  T* _target;

};


// ===========================================================
// NON-MEMBER FUNCTIONS
// ===========================================================
 
} // namespace sheaf

#endif // ifndef RC_PTR_H