WeakRef.h

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/*CXXR $Id: WeakRef.h 1348 2013-02-25 17:49:03Z arr $
 *CXXR
 *CXXR This file is part of CXXR, a project to refactor the R interpreter
 *CXXR into C++.  It may consist in whole or in part of program code and
 *CXXR documentation taken from the R project itself, incorporated into
 *CXXR CXXR (and possibly MODIFIED) under the terms of the GNU General Public
 *CXXR Licence.
 *CXXR 
 *CXXR CXXR is Copyright (C) 2008-13 Andrew R. Runnalls, subject to such other
 *CXXR copyrights and copyright restrictions as may be stated below.
 *CXXR 
 *CXXR CXXR is not part of the R project, and bugs and other issues should
 *CXXR not be reported via r-bugs or other R project channels; instead refer
 *CXXR to the CXXR website.
 *CXXR */

/*
 *  R : A Computer Language for Statistical Data Analysis
 *  Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 *  Copyright (C) 1999-2006   The R Development Core Team.
 *  Andrew Runnalls (C) 2007
 *
 *  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 2.1 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, a copy is available at
 *  http://www.r-project.org/Licenses/
 */

#ifndef WEAKREF_HPP
#define WEAKREF_HPP

#include "CXXR/RObject.h"

#ifdef __cplusplus
extern "C" {
#endif

    /* Finalization interface */
    typedef void (*R_CFinalizer_t)(SEXP);
    void R_RegisterFinalizer(SEXP s, SEXP fun);
    void R_RegisterCFinalizer(SEXP s, R_CFinalizer_t fun);
    void R_RegisterFinalizerEx(SEXP s, SEXP fun, Rboolean onexit);
    void R_RegisterCFinalizerEx(SEXP s, R_CFinalizer_t fun, Rboolean onexit);

    /* Weak reference interface */
    SEXP R_MakeWeakRef(SEXP key, SEXP val, SEXP fin, Rboolean onexit);
    SEXP R_MakeWeakRefC(SEXP key, SEXP val, R_CFinalizer_t fin,
                        Rboolean onexit);
    void R_RunExitFinalizers(void);
    SEXP R_WeakRefKey(SEXP w);
    SEXP R_WeakRefValue(SEXP w);

#ifdef __cplusplus
}  // extern "C"

#include <list>
#include "CXXR/Allocator.hpp"
#include "CXXR/FunctionBase.h"

namespace CXXR {
    class WeakRef : public RObject {
    public:
        WeakRef(RObject* key, RObject* value, FunctionBase* R_finalizer = 0,
                bool finalize_on_exit = false);

        WeakRef(RObject* key, RObject* value, R_CFinalizer_t C_finalizer,
                bool finalize_on_exit = false);

        ~WeakRef();

        static bool check();

        RObject* key() const {return m_key;}

        static void runExitFinalizers();

        static bool runFinalizers();

        RObject* value() const {return m_value;}

        // Virtual functions of RObject:
        unsigned int packGPBits() const;
        void unpackGPBits(unsigned int gpbits);
    protected:
        // Virtual function of GCNode:
        void detachReferents();
    private:
        typedef std::list<WeakRef*, Allocator<WeakRef*> > WRList;
        static WRList* s_live;
        static WRList* s_f10n_pending;  // Finalization pending
        static WRList* s_tombstone;

        static int s_count;  // Count of references in existence (for
                             // debugging)

        GCEdge<> m_key;
        GCEdge<> m_value;
        GCEdge<FunctionBase> m_Rfinalizer;
        GCEdge<> m_self;  // Each WeakRef refers to itself, to stop
                          // WeakRef nodes being deleted by gclite().
        R_CFinalizer_t m_Cfinalizer;
        WRList::iterator m_lit;
        bool m_ready_to_finalize;
        bool m_finalize_on_exit;

        // Clean up static data members:
        static void cleanup();

        void finalize();

        // Initialize the static data members:
        static void initialize();

        static void markThru();

        // Tombstone the node:
        void tombstone();

        // Transfer the WeakRef from list 'from' to list 'to':
        void transfer(WRList* from, WRList* to)
        {
            to->splice(to->end(), *from, m_lit);
        }

        // Return pointer to the list (s_live, s_f10n_pending or
        // s_tombstone) on which - according to its internal data -
        // the object currently should be listed (and quite possibly
        // is listed).
        WRList* wrList() const;

        friend class GCNode;
        friend class SchwarzCounter<WeakRef>;
    };
}  // namespace CXXR

namespace {
    CXXR::SchwarzCounter<CXXR::WeakRef> weakref_schwarz_ctr;
}

#endif /* __cplusplus */

#endif /* WEAKREF_HPP */