conn.h

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#pragma once

/*+
________________________________________________________________________

 (C) dGB Beheer B.V.; (LICENSE) http://opendtect.org/OpendTect_license.txt
 Author:        A.H.Bril
 Date:          21-10-1995
 Contents:      Connections with data providers (Streams, databases)
________________________________________________________________________

-*/


#include "generalmod.h"
#include "dbkey.h"
class IOObj;
class StreamConn;

#define mCloseRollBack true


mExpClass(General) Conn
{
public:

    virtual             ~Conn()                 { close(); }
    virtual void        close(bool failed=false) {}
    inline void         rollback()              { close( mCloseRollBack ); }

    virtual bool        isBad() const           = 0;
    virtual const char* creationMessage() const { return 0; }

    virtual const char* connType() const        = 0;
    virtual bool        forRead() const         = 0;
    virtual bool        forWrite() const        { return !forRead(); }

    virtual StreamConn* getStream()             { return 0; }
    inline bool         isStream() const
                        { return const_cast<Conn*>(this)->getStream(); }

    inline Conn*        conn()                  { return gtConn(); }
    inline const Conn*  conn() const            { return gtConn(); }

    const DBKey&        linkedTo() const        { return ioobjid_; }
    void                setLinkedTo( const DBKey& id ) { ioobjid_ = id; }

                        // to fill 'forread' variables
    static const bool   Read;   // true
    static const bool   Write;  // false

protected:

                        Conn()                  {}

    DBKey               ioobjid_;

    virtual Conn*       gtConn() const  { return const_cast<Conn*>(this); }

};


mExpClass(General) XConn  : public Conn
{

    friend class        IOX;

public:

                        XConn() : conn_(0), mine_(true) {}
                        ~XConn()        { if ( mine_ ) delete conn_; }

    virtual bool        isBad() const
                        { return conn_ ? conn_->isBad() : true; }
    virtual const char* creationMessage() const
                        { return conn_ ? conn_->creationMessage() : 0; }
    virtual bool        forRead() const
                        { return conn_ && conn_->forRead(); }
    virtual bool        forWrite() const
                        { return conn_ && conn_->forWrite(); }
    virtual void        close( bool failed=false )
                        { if ( conn_ ) conn_->close(failed); }
    virtual StreamConn* getStream()
                        { return conn_ ? conn_->getStream() : 0; }

    void                setConn( Conn* c, bool becomesmine=true )
                        { if ( mine_ ) delete conn_;
                          conn_ = c; mine_ = becomesmine; }

    const char*         connType() const        { return sType(); }
    static const char*  sType();

protected:

    Conn*               conn_;
    bool                mine_;

    Conn*               gtConn() const  { return const_cast<Conn*>(conn_); }

};