garbagecoll.h

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// -*- mode: c++; indent-tabs-mode: nil; c-basic-offset: 4; coding: iso-8859-1; -*-


/*
ACT-CV - Machine Vision for Cognitive Modeling
Copyright (c) 2008 Marc Halbruegge

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, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#ifndef __GARBAGECOLL_H
#define __GARBAGECOLL_H


class ReferenceCount {
    int numReferences; 
public:
    ReferenceCount() : numReferences(0) {};
    virtual ~ReferenceCount(){};
    void IncRefCount() {
        ++numReferences;
    };
    void DecRefCount() {
        if (--numReferences == 0) delete this;
    }
};


template< class _t >
class GCPointer {
    typedef _t reference_type;
    _t *ref;
public:
    GCPointer(_t *newRef = nullptr) {
        ref=newRef;
        if (ref) ref->IncRefCount();
    }
    ~GCPointer() {
        if (ref) ref->DecRefCount();
    }
    GCPointer(const GCPointer &gcp) {
        ref=gcp.ref;
        if (ref) ref->IncRefCount();
    }
    GCPointer& operator=(const GCPointer &gcp) {
        _t *old_ref = ref;
        ref=gcp.ref;
        if (ref) ref->IncRefCount();
        if (old_ref) old_ref->DecRefCount();
        return *this;
    }
    GCPointer& operator=(_t *newRef) {
        _t *old_ref = ref;
        ref=newRef;
        if (ref) ref->IncRefCount();
        if (old_ref) old_ref->DecRefCount();
        return *this;
    }
    _t& operator * () const {
        return *ref;
    }
    _t* operator -> () const {
        return ref;
    }
    operator bool() const {
        return ref != nullptr;
    }
};

template<class _t>
class GCPLess {
public:
    bool operator () (const GCPointer<_t> &x, const GCPointer<_t> &y) const {
        return (*x) < (*y);
    }
};

#endif