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tRef.h

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/******************************************************************************/
/*                                                                            */
/* POLiTe - Persistent Object Library Test                                    */
/*                                        Ph.D. Thesis by Mgr. Michal Kopecky */
/*                                                                            */
/* Charles University Prague                                                  */
/*                                                                            */
/******************************************************************************/
/*                                                                            */
/* File name: ...                                                             */
/* Module: ......                                                             */
/*                                                                            */
/******************************************************************************/

#ifndef __T_REF_H__
#define __T_REF_H__

template<class T> class Ref;

// Parent Header(s)
#include <cRefBase.h>

// Other POLiTe Header(s)
#include <cObjectBuffer.h>

template<class T> class Ref : public RefBase
{
#ifdef POLITE_TEST_FRIEND
        friend POLITE_TEST_FRIEND;
#endif // POLITE_TEST_FRIEND

public:
        T *operator ->()
        //Returns the pointer to the pointed object
        //which will be read from the database, if the object
        //is not present in memory yet.
        {
                if (*this == DBNULL)
                        throw ObjLibException_NotFound();
                return IsPersistent() ? (T *)ObjectCache.GetReferencedObject(*this) : (T *)_Object();
        };

        T &operator *()
        //Returns the pointed object
        //which will be read from the database, if the object
        //is not present in memory yet.
        {
                if (*this == DBNULL)
                        throw ObjLibException_NotFound();
                return IsPersistent() ? *(T *)ObjectCache.GetReferencedObject(*this) : *(T *)_Object();
        };

        Ref(): RefBase() {};

        Ref(const RefBase &Dbp): RefBase(Dbp) {};

        Ref(const Object * const DbObj): RefBase(DbObj) {};

        Ref(
                class Connection *aConnection,
                class ProtoBase *aPrototype,
                char *aSelectKeyValues,
                unsigned short aStrategies
                )
                : RefBase(aConnection, aPrototype, aSelectKeyValues, aStrategies) {};

        Ref(
                class Connection *aConnection,
                const long anOid
                )
                : RefBase(aConnection, anOid, Class[T::ClassName()]) {};

        Ref(
                class Connection *aConnection,
                const QueRefProto &aQuery
                )
                : RefBase()
        {
                // use temporary query result to find firts object matching the query
                Result<T> *r = (Result<T> *)(Class[T::ClassName()]->ExecuteQuery(aQuery,aConnection,1,new Result<T>));
                *this = ++(*r);
                if (((*r)!=DBNULL) && (++(*r)!=DBNULL))
                        // there is more than one object that match the condition
                        *this = DBNULL;
                delete r;
        };

        Ref(
                class Connection *aConnection,
                const char *aQuery
                )
                : RefBase()
        {
                // use temporary query result to find firts object matching the query
                Result<T> *r = (Result<T> *)(Class[T::ClassName()]->ExecuteQuery(Query(aQuery),aConnection,1,new Result<T>));
                *this = ++(*r);
                if (((*r)!=DBNULL) && (++(*r)!=DBNULL))
                        // there is more than one object that match the condition
                        *this = DBNULL;
                delete r;
        };

        Ref<T> &operator = (const RefBase &Dbp)
        {
                return (Ref<T> &)this->RefBase::operator = (Dbp);
        };

        Ref<T> &operator = (const T *Ptr)
        {
                return (Ref<T> &)this->RefBase::operator = (Ptr->Address());
        };
};

#endif //__T_REF_H__

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