// -*- C++ -*-

//=============================================================================
/**
 * @file Servant_var.h
 *
 * $Id: Servant_var.h 92387 2010-10-28 07:46:18Z johnnyw $
 *
 * @author Jody Hagins <jody@atdesk.com>
 * @author Carlos O'Ryan <coryan@atdesk.com>
 */
//=============================================================================

#ifndef TAO_PORTABLESERVER_SERVANT_VAR_H
#define TAO_PORTABLESERVER_SERVANT_VAR_H
#include /**/ "ace/pre.h"
#include "ace/config-all.h"

#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */

#include "tao/orbconf.h"

TAO_BEGIN_VERSIONED_NAMESPACE_DECL

namespace PortableServer
{
  /**
   * @class Servant_var
   *
   * @brief Provides a type safe counted reference to servants.
   *
   * @author Jody Hagins
   *
   * @todo Life would be much easier if _add_ref() and _remove_ref() had
   *       throw specs of "throw ()", that can be hidden in static
   *       methods though.
   */
  template<class T>
  class Servant_var
  {
  public:
    typedef T servant_type;

    /// Constructor.  Assumes ownership of @c p.
    Servant_var (T * p = 0);

    /// Copy constructor.  Adds reference to @c rhs.
    Servant_var (Servant_var<T> const & rhs);

    /// Assignment operator.  Adds reference to @c rhs.
    Servant_var<T> & operator= (Servant_var<T> const & rhs);

    /// Destructor.  Removes a reference from the underlying object,
    /// possibly destroying it.
    /**
     * This destructor doesn't throw exceptions.
     */
    ~Servant_var (void) /* throw () */;

    /// Assignment operator.  Assumes ownership of @c p.
    Servant_var<T> & operator= (T * p);

    /// Smart pointer operator-> provides access to the underlying object.
    T * operator->() const;

    /// Dereference the underlying object.
    T const & operator*() const;

    /// Dereference the underlying object.
    T & operator*();

    /// Return a void pointer to the underlying object.  This allows
    /// it to be used in conditional code and tested against 0.
    operator void const * () const;

    /// As an IN parameter.
    T * in() const;

    /// As an INOUT parameter.
    T *& inout();

    /// As an OUT parameter.
    T *& out();

    /// Return a pointer to the underlying object, and this counted
    /// reference will no longer own the object.
    T * _retn();

    /// Increment the reference count and return the servant.
    /**
     * It is safe to pass in a null pointer, the pointer is simply
     * returned in that case.
     *
     * @todo We might want to catch all (potential) exceptions in
     *       _add_ref().
     *
     * @todo It might be useful to add a _release() method that handles
     *       any potential exceptions...
     */
    static T * _duplicate (T *);

    /// Swap the contents of a Servant_var<T> with another
    /// Servant_var<T>
    /**
     * Non-throwing swap operation.
     * Often used to implement strong exception safety.
     */
    void swap (Servant_var<T> & rhs) /* throw () */;

  private:
    T * ptr_;
  };

  /// Compare two Servant_vars for equivalence.
  template <class X, class Y>
  bool operator==(Servant_var<X> const & x, Servant_var<Y> const & y);

  /// Compare two Servant_vars for non-equivalence.
  template <class X, class Y>
  bool operator!=(Servant_var<X> const & x, Servant_var<Y> const & y);

} // namespace PortableServer

TAO_END_VERSIONED_NAMESPACE_DECL

#if defined (__ACE_INLINE__)
# include "tao/PortableServer/Servant_var.inl"
#endif /* __ACE_INLINE__ */

#if defined (ACE_TEMPLATES_REQUIRE_SOURCE)
#include "tao/PortableServer/Servant_var.cpp"
#endif /* ACE_TEMPLATES_REQUIRE_SOURCE */

#if defined (ACE_TEMPLATES_REQUIRE_PRAGMA)
#pragma implementation ("tao/PortableServer/Servant_var.cpp")
#endif

#include /**/ "ace/post.h"
#endif  /* TAO_PORTABLESERVER_SERVANT_VAR_H */
