safeptr.hpp

/************************************************************************
*
* Copyright 2011 Jakob Leben (jakob.leben@gmail.com)
*
* This file is part of SuperCollider Qt GUI.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program.  If not, see <http://www.gnu.org/licenses/>.
*
************************************************************************/

#ifndef QC_SAFE_PTR_H
#define QC_SAFE_PTR_H

#include "Common.h"

#include <QApplication>
#include <QAtomicPointer>
#include <QAtomicInt>
#include <QMutex>

namespace QtCollider {

template<typename T> class SafePtr
{
public:
  SafePtr() : d(0) {}

  SafePtr( const SafePtr & other )
  : d ( other.d )
  {
    ref();
  }

  SafePtr( T* ptr )
  : d ( new Data( ptr ) )
  {}

  SafePtr & operator= ( const SafePtr & other ) {
    deref();
    d = other.d;
    ref();
    return *this;
  }

  ~SafePtr() {
    deref();
  }

  T * operator-> () const { return d->ptr.load(); }

  T & operator* () const { return *d->ptr.load(); }

  operator T* () const { return (d ? d->ptr.load() : 0); }

  T *ptr() const { return (d ? d->ptr.load() : 0); }

  void *id() const { return (void*) d; } // useful for checking internal pointer identity

  void invalidate() { qcDebugMsg(2,"SafePtr: invalidating"); if(d) d->ptr = 0; }

private:
  struct Data {
    Data ( T * ptr_ ) : ptr(ptr_), refCount(1) {}
    QAtomicPointer<T> ptr;
    QAtomicInt refCount;
  };

  void ref() {
    if( d ) {
      d->refCount.ref();
      qcDebugMsg(2,QString("SafePtr: +refcount = %1").arg(d->refCount.load()));
    }
  }
  void deref() {
    if( d ) {
      bool ref = d->refCount.deref();
      qcDebugMsg(2,QString("SafePtr: -refcount = %1").arg(d->refCount.load()));
      if( !ref ) {
        qcDebugMsg(2,"SafePtr: unreferenced!");
        delete d;
      }
    }
  }

  Data *d;
};

} // namespace QtCollider

#endif