RcHandle_T.h

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/*
 * Distributed under the OpenDDS License.
 * See: http://www.opendds.org/license.html
 */

#ifndef OPENDDS_DCPS_RCHANDLE_T_H
#define OPENDDS_DCPS_RCHANDLE_T_H

#include "dds/Versioned_Namespace.h"
#include "Definitions.h"
#include "unique_ptr.h"

OPENDDS_BEGIN_VERSIONED_NAMESPACE_DECL

namespace OpenDDS {
namespace DCPS {

struct inc_count {};
struct keep_count {};

/// Templated Reference counted handle to a pointer.
/// A non-DDS specific helper class.
template <typename T>
class RcHandle {
public:
  RcHandle()
    : ptr_(0)
  {
  }

  RcHandle(T* p, keep_count)
    : ptr_(p)
  {
  }

  template <typename U>
  RcHandle(unique_ptr<U> p)
    : ptr_(p.release())
  {
  }

  RcHandle(T* p, inc_count)
    : ptr_(p)
  {
    this->bump_up();
  }

  template <typename U>
  RcHandle(const RcHandle<U>& other)
    : ptr_(other.in())
  {
    this->bump_up();
  }

  RcHandle(const RcHandle& b)
    : ptr_(b.ptr_)
  {
    this->bump_up();
  }

  ~RcHandle()
  {
    this->bump_down();
  }

  void reset()
  {
    RcHandle tmp;
    swap(tmp);
  }

  template <typename U>
  void reset(T* p, U counting_strategy)
  {
    RcHandle tmp(p, counting_strategy);
    swap(tmp);
  }

  RcHandle& operator=(const RcHandle& b)
  {
    RcHandle tmp(b);
    swap(tmp);
    return *this;
  }

  template <class U>
  RcHandle& operator=(const RcHandle<U>& b)
  {
    RcHandle<T> tmp(b);
    swap(tmp);
    return *this;
  }

  template <typename U>
  RcHandle& operator=(unique_ptr<U> b)
  {
    RcHandle<T> tmp(b.release(), keep_count());
    swap(tmp);
    return *this;
  }

  void swap(RcHandle& rhs)
  {
    T* t = this->ptr_;
    this->ptr_ = rhs.ptr_;
    rhs.ptr_ = t;
  }

  T* operator->() const
  {
    OPENDDS_ASSERT(ptr_);
    return this->ptr_;
  }

  T& operator*() const
  {
    OPENDDS_ASSERT(ptr_);
    return *this->ptr_;
  }

  bool is_nil() const
  {
    return this->ptr_ == 0;
  }

  T* in() const
  {
    return this->ptr_;
  }

  T* get() const
  {
    return this->ptr_;
  }

  T*& inout()
  {
    return this->ptr_;
  }

  T*& out()
  {
    this->bump_down();
    return this->ptr_;
  }

  T* _retn()
  {
    T* retval = this->ptr_;
    this->ptr_ = 0;
    return retval;
  }

  operator bool() const
  {
    return in() != 0;
  }

  bool operator==(const RcHandle& rhs) const
  {
    return in() == rhs.in();
  }

  bool operator!=(const RcHandle& rhs) const
  {
    return in() != rhs.in();
  }

  bool operator < (const RcHandle& rhs) const
  {
    return in() < rhs.in();
  }

private:
  void bump_up()
  {
    if (ptr_ != 0) {
      ptr_->_add_ref();
    }
  }

  void bump_down()
  {
    if (ptr_ != 0) {
      ptr_->_remove_ref();
      ptr_ = 0;
    }
  }

  /// The actual "unsmart" pointer to the T object.
  T* ptr_;
};


template <typename T>
void swap(RcHandle<T>& lhs, RcHandle<T>& rhs)
{
  lhs.swap(rhs);
}

template <typename T, typename U>
RcHandle<T> static_rchandle_cast(const RcHandle<U>& h)
{
  return RcHandle<T>(static_cast<T*>(h.in()), inc_count());
}

template <typename T, typename U>
RcHandle<T> const_rchandle_cast(const RcHandle<U>& h)
{
  return RcHandle<T>(const_cast<T*>(h.in()), inc_count());
}

template <typename T, typename U>
RcHandle<T> dynamic_rchandle_cast(const RcHandle<U>& h)
{
  return RcHandle<T>(dynamic_cast<T*>(h.in()), inc_count());
}


template< class T >
class reference_wrapper{
public:
  // types
  typedef T type;

  // construct/copy/destroy
  reference_wrapper(T& ref): _ptr(&ref) {}
  // access
  operator T& () const { return *_ptr; }
  T& get() const { return *_ptr; }

private:
  T* _ptr;
};

template <typename T>
reference_wrapper<T> ref(T& r)
{
  return reference_wrapper<T>(r);
}

template <typename T>
T const& unwrap_reference(T const& t)
{
  return t;
}

template <typename T>
T& unwrap_reference(reference_wrapper<T> const& t)
{
  return t.get();
}


template <typename T>
RcHandle<T> make_rch()
{
  return RcHandle<T>(new T(), keep_count());
}

template <typename T, typename U>
RcHandle<T> make_rch(U const& u)
{
  return RcHandle<T>(new T(unwrap_reference(u)), keep_count());
}

template <typename T, typename U0, typename U1>
RcHandle<T> make_rch(U0 const& u0, U1 const& u1)
{
  return RcHandle<T>(new T(unwrap_reference(u0), unwrap_reference(u1)), keep_count());
}

template <typename T, typename U0, typename U1, typename U2>
RcHandle<T> make_rch(U0 const& u0, U1 const& u1, U2 const& u2)
{
  return RcHandle<T>(new T(unwrap_reference(u0), unwrap_reference(u1), unwrap_reference(u2)), keep_count());
}

template <typename T, typename U0, typename U1, typename U2, typename U3>
RcHandle<T> make_rch(U0 const& u0, U1 const& u1, U2 const& u2, U3 const& u3)
{
  return RcHandle<T>(new T(unwrap_reference(u0), unwrap_reference(u1), unwrap_reference(u2), unwrap_reference(u3)), keep_count());
}

template <typename T, typename U0, typename U1, typename U2, typename U3, typename U4>
RcHandle<T> make_rch(U0 const& u0, U1 const& u1, U2 const& u2, U3 const& u3, U4 const& u4)
{
  return RcHandle<T>(new T(unwrap_reference(u0), unwrap_reference(u1), unwrap_reference(u2), unwrap_reference(u3), unwrap_reference(u4)), keep_count());
}

template <typename T, typename U0, typename U1, typename U2, typename U3, typename U4, typename U5>
RcHandle<T> make_rch(U0 const& u0, U1 const& u1, U2 const& u2, U3 const& u3, U4 const& u4, U5 const& u5)
{
  return RcHandle<T>(new T(unwrap_reference(u0), unwrap_reference(u1), unwrap_reference(u2), unwrap_reference(u3), unwrap_reference(u4), unwrap_reference(u5)), keep_count());
}

template <typename T, typename U0, typename U1, typename U2, typename U3, typename U4, typename U5, typename U6>
RcHandle<T> make_rch(U0 const& u0, U1 const& u1, U2 const& u2, U3 const& u3, U4 const& u4, U5 const& u5, U6 const& u6)
{
  return RcHandle<T>(new T(unwrap_reference(u0), unwrap_reference(u1), unwrap_reference(u2), unwrap_reference(u3), unwrap_reference(u4), unwrap_reference(u5), unwrap_reference(u6)), keep_count());
}

template <typename T, typename U0, typename U1, typename U2, typename U3, typename U4, typename U5, typename U6, typename U7>
RcHandle<T> make_rch(U0 const& u0, U1 const& u1, U2 const& u2, U3 const& u3, U4 const& u4, U5 const& u5, U6 const& u6, U7 const& u7)
{
  return RcHandle<T>(new T(unwrap_reference(u0), unwrap_reference(u1), unwrap_reference(u2), unwrap_reference(u3), unwrap_reference(u4), unwrap_reference(u5), unwrap_reference(u6), unwrap_reference(u7)), keep_count());
}

template<typename T>
RcHandle<T> rchandle_from(T* pointer)
{
  OPENDDS_ASSERT(pointer == 0 || pointer->ref_count() > 0);
  return RcHandle<T>(pointer, inc_count());
}


} // namespace DCPS
} // namespace OpenDDS

OPENDDS_END_VERSIONED_NAMESPACE_DECL

#endif  /* OPENDDS_RCHANDLE_T_H */