vrpn_MainloopObject.h

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/** @file
    @brief Header
 
    @date 2011
 
    @author
    Ryan Pavlik
    <rpavlik@iastate.edu> and <abiryan@ryand.net>
    http://academic.cleardefinition.com/
    Iowa State University Virtual Reality Applications Center
    Human-Computer Interaction Graduate Program
*/
 
//          Copyright Iowa State University 2011.
// Distributed under the Boost Software License, Version 1.0.
//    (See accompanying file LICENSE_1_0.txt or copy at
//          http://www.boost.org/LICENSE_1_0.txt)
 
#ifndef INCLUDED_vrpn_MainloopObject_h_GUID_38f638e4_40e0_4c6d_bebc_21c463794b88
#define INCLUDED_vrpn_MainloopObject_h_GUID_38f638e4_40e0_4c6d_bebc_21c463794b88
 
// Internal Includes
#include "vrpn_Connection.h"
 
// Library/third-party includes
// - none
 
// Standard includes
#include <stdexcept>
 
#ifdef VRPN_MAINLOOPOBJECT_VERBOSE
#include <iostream>
#define VRPN_MAINLOOPOBJECT_MSG(_x)                                            \
    std::cout << __FILE__ << ":" << __LINE__ << ": " << _x << std::endl;
#else
#define VRPN_MAINLOOPOBJECT_MSG(_x)
#endif
 
class VRPN_API vrpn_Connection;
 
/// An interface for all VRPN objects that have a "mainloop" method.
/// Not instantiated directly: use vrpn_MainloopObject::wrap() to create one
class vrpn_MainloopObject {
public:
    /// Exception thrown when trying to wrap a NULL pointer.
 struct CannotWrapNullPointerIntoMainloopObject : public std::logic_error {
 CannotWrapNullPointerIntoMainloopObject()
            : std::logic_error(
 "Cannot wrap a null pointer into a vrpn_MainloopObject!")
        {
        }
    };
 
    /// Destructor
 virtual ~vrpn_MainloopObject() {}
 
    /// The mainloop function: the primary thing we look for in a VRPN object
 virtual void mainloop() = 0;
 
    /// Checks the connectionPtr() for the VRPN object to make sure it is not
    /// NULL.
 virtual bool broken() = 0;
 
    /// Templated wrapping function
 template <class T> static vrpn_MainloopObject *wrap(T o);
 
    /// Templated wrapping function that can encourage the
    /// wrapper to not destroy the wrapped object at destruction
 template <class T> static vrpn_MainloopObject *wrap(T o, bool owner);
 
protected:
    /// Internal function to return a typeless pointer of the contained
    /// object, for comparison purposes.
 virtual void *_returnContained() const = 0;
 vrpn_MainloopObject() {}
 friend bool operator==(vrpn_MainloopObject const &lhs,
 vrpn_MainloopObject const &rhs);
 friend bool operator!=(vrpn_MainloopObject const &lhs,
 vrpn_MainloopObject const &rhs);
};
 
/// @name Comparison operators
/// @relates vrpn_MainloopObject
/// @{
inline bool operator==(vrpn_MainloopObject const &lhs,
 vrpn_MainloopObject const &rhs)
{
 return lhs._returnContained() == rhs._returnContained();
}
 
inline bool operator!=(vrpn_MainloopObject const &lhs,
 vrpn_MainloopObject const &rhs)
{
 return lhs._returnContained() == rhs._returnContained();
}
/// @}
 
/// Namespace enclosing internal implementation details
namespace detail {
 template <class T> class TypedMainloopObject;
 
    /// Template class for holding generic VRPN objects with
    /// type information.
 template <class T>
 class TypedMainloopObject<T *> : public vrpn_MainloopObject {
 public:
 TypedMainloopObject(T *o, bool do_delete = true)
            : _instance(o)
            , _do_delete(do_delete)
        {
 if (!o) {
 throw vrpn_MainloopObject::
                    CannotWrapNullPointerIntoMainloopObject();
            }
            VRPN_MAINLOOPOBJECT_MSG("Wrapping vrpn object " << o)
        }
 virtual ~TypedMainloopObject()
        {
 if (_do_delete) {
 try {
 delete _instance;
                } catch (...) {
                  fprintf(stderr, "TypedMainloopObject::~TypedMainloopObject: delete failed\n");
 return;
                }
                VRPN_MAINLOOPOBJECT_MSG("Deleted contained vrpn object "
                                        << _instance)
            }
 else {
                VRPN_MAINLOOPOBJECT_MSG("NOT deleting contained vrpn object "
                                        << _instance)
            }
        }
 
 virtual void mainloop() { _instance->mainloop(); }
 
 virtual bool broken() { return (_instance->connectionPtr() == NULL); }
 
 protected:
 virtual void *_returnContained() const { return _instance; }
        T *_instance;
 bool _do_delete;
    };
 
    /// Specialization for connections, since they're reference-counted.
 template <>
 class TypedMainloopObject<vrpn_Connection *> : public vrpn_MainloopObject {
 public:
 TypedMainloopObject(vrpn_Connection *o)
            : _instance(o)
        {
 if (!o) {
 throw vrpn_MainloopObject::
                    CannotWrapNullPointerIntoMainloopObject();
            }
            VRPN_MAINLOOPOBJECT_MSG("Wrapping vrpn connection " << o)
        }
 virtual ~TypedMainloopObject()
        {
            VRPN_MAINLOOPOBJECT_MSG("Unreferencing contained vrpn connection "
                                    << _instance)
            _instance->removeReference();
        }
 
 virtual void mainloop() { _instance->mainloop(); }
 
 virtual bool broken() { return (!_instance->doing_okay()); }
 
 protected:
 virtual void *_returnContained() const { return _instance; }
 vrpn_Connection *_instance;
    };
 
} // end of namespace detail
 
template <class T> inline vrpn_MainloopObject *vrpn_MainloopObject::wrap(T o)
{
 vrpn_MainloopObject *ret = NULL;
 try {
    ret = new detail::TypedMainloopObject<T>(o);
  } catch (...) {}
 return ret;
}
 
template <class T>
inline vrpn_MainloopObject *vrpn_MainloopObject::wrap(T o, bool owner)
{
 vrpn_MainloopObject *ret = NULL;
 try {
    ret = new detail::TypedMainloopObject<T>(o, owner);
  } catch (...) { }
 return ret;
}
 
#endif // INCLUDED_vrpn_MainloopObject_h_GUID_38f638e4_40e0_4c6d_bebc_21c463794b88