source: src/Patterns/Singleton_impl.hpp@ 48ab70a

/*
 * Singleton_impl.hpp
 *
 *  Created on: Mar 10, 2010
 *      Author: crueger
 */

#ifndef SINGLETON_IMPL_HPP_
#define SINGLETON_IMPL_HPP_

#include "Patterns/Singleton.hpp"

/****** Static instance Variables of the template *******/

template <class T,bool _may_create>
typename Singleton<T,_may_create>::ptr_t Singleton<T,_may_create>::theInstance(0);

template <class T,bool _may_create>
boost::recursive_mutex Singleton<T,_may_create>::instanceLock;

/****** templates singleton creation and destruction functions ******/

template <class T,bool _may_create>
T& Singleton<T,_may_create>::getInstance(){
  // boost supports RAII-Style locking, so we don't need to unlock
  boost::recursive_mutex::scoped_lock guard(instanceLock);
  if(!theInstance.get()) {
    theInstance.reset(creator::make());
  }
  return *theInstance;
}

template <class T,bool _may_create>
T* Singleton<T,_may_create>::getPointer(){
  // boost supports RAII-Style locking, so we don't need to unlock
  boost::recursive_mutex::scoped_lock guard(instanceLock);
  if(!theInstance.get()) {
    theInstance.reset(creator::make());
  }
  return theInstance.get();

}

template <class T,bool _may_create>
void Singleton<T,_may_create>::purgeInstance(){
  // boost supports RAII-Style locking, so we don't need to unlock
  boost::recursive_mutex::scoped_lock guard(instanceLock);
  theInstance.reset();
}

template <class T,bool _may_create>
T& Singleton<T,_may_create>::resetInstance(){
  ptr_t oldInstance;
  {
    // boost supports RAII-Style locking, so we don't need to unlock
    boost::recursive_mutex::scoped_lock guard(instanceLock);

    oldInstance = theInstance;
    theInstance.reset(creator::make());
    // oldworld does not need protection any more,
    // since we should have the only reference

    // worldLock handles access to the pointer,
    // not to the object
  } // scope-end releases the lock

  // oldInstance goes out of scope at the End of this function. The carried object will then be destroyed by the auto_ptr
  return *theInstance;
}


template <class T,bool _may_create>
void Singleton<T,_may_create>::setInstance(T* newInstance){
  assert(!theInstance.get() && "Trying to set the instance of an already created singleton");
  boost::recursive_mutex::scoped_lock guard(instanceLock);
  theInstance.reset(newInstance);
}

template<class T, bool _may_create>
Singleton<T,_may_create>::Singleton(){/* empty */}

// private copy constructor to avoid unintended copying
template <class T, bool _may_create>
Singleton<T,_may_create>::Singleton(const Singleton<T,_may_create>&){
  assert(0 && "Copy constructor of singleton template called");
}

/**
 * This define allows simple instantiation of the necessary singleton functions
 * at a chosen place.
 */
#define CONSTRUCT_SINGLETON(name) \
    template name& Singleton< name , name::may_create >::getInstance(); \
    template name* Singleton< name , name::may_create >::getPointer();  \
    template void  Singleton< name , name::may_create >::purgeInstance(); \
    template name& Singleton< name , name::may_create >::resetInstance(); \
    template void  Singleton< name , name::may_create >::setInstance( name* );

/************ Internal Pointer Wrapper to allow automatic purging *************/

template <class T,bool _may_create>
Singleton<T,_may_create>::ptr_t::ptr_t() :
content(0){};

template <class T,bool _may_create>
Singleton<T,_may_create>::ptr_t::ptr_t(T* _content) :
content(_content){};

template <class T,bool _may_create>
Singleton<T,_may_create>::ptr_t:: ~ptr_t()
{delete content;};

template <class T,bool _may_create>
T& Singleton<T,_may_create>::ptr_t::operator*()
{return *content;};

template <class T,bool _may_create>
T* Singleton<T,_may_create>::ptr_t::get()
{return content;};

template <class T,bool _may_create>
void Singleton<T,_may_create>::ptr_t::reset(T* _content){
  delete content;
  content = _content;
}

template <class T,bool _may_create>
void Singleton<T,_may_create>::ptr_t::reset()
{reset(0);}

template <class T,bool _may_create>
typename Singleton<T,_may_create>::ptr_t& Singleton<T,_may_create>::ptr_t::operator=(const typename Singleton<T,_may_create>::ptr_t& rhs){
  if(&rhs!=this){
    delete content;
    content = rhs.content;
    rhs.content = 0;
  }
  return *this;
}


#endif /* SINGLETON_IMPL_HPP_ */