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CdbBdbNTupleConversionImpl.hh

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#ifndef CDBBDBTABLE_NTUPLE_CONVERSION_IMPL_HH
#define CDBBDBTABLE_NTUPLE_CONVERSION_IMPL_HH

// File and Version Information:
//      $Id: CdbBdbNTupleConversionImpl.hh,v 1.3 2004/04/02 07:48:56 gapon Exp $

#include "BdbCond/BdbObject.hh"

#include "CdbBase/CdbCPtr.hh"

#include "CdbTable/CdbNTuple.hh"

#include <string>

/// The generic implementation of the conversion facility
/**
  * IMPLEMENTATION NOTE:
  *
  *   The current implementation of this factory will support only predefined
  *   "primitive types" of elements. A mechanizm of expened support for arbitrary
  *   (or user defined) types of elements will be added later.
  *
  * USAGE NOTES:
  *
  *   Users are discouraged to use this API directly as its interface or
  *   implementation is likely to change. Another reason not to use this
  *   class is its "heavy" template interface.
  *
  *   The current package has a number of "fron-end" classes with more stable
  *   and much simple API.
  */
template < class        T,
           unsigned int NCOL,
           class        ELEMENT_CONVERSION_RULES >
class CdbBdbNTupleConversionImpl {

public:

  /// Convert a persistent object to the transient form
  /**
    * If successuful, the method would initialize the smart pointer to point
    * onto a newely created transient table (of unspecified here actual implentation)
    * filled with data and metadata copied from the specified persistent table.
    *
    * If any kind of error will happen then the transient pointer is guaranteed
    * to stay intact.
    *
    * REQUIREMENTS:
    *
    * (1) The persistent table must have the same actual type and configurations
    *     (number of columns) as the transient one.
    *
    * (2) The corresponding vortual tables for the persistnt class must be
    *     properly loaded.
    *
    * (3) The type of elements of a persistent typle would be derived from
    *     the type converter policy supplied (or default) as a template parameter
    *     of the class.
    *
    * (4) Should the transient and persistent types of elements be different
    *     the corresponding conversion must exist and be provided through
    *     the supplied (or default) converter policy.
    */
    static CdbStatus to_transient( CdbCPtr< CdbNTuple< T, NCOL > >& thePtr,
                                   const ooRef(BdbObject)&          thePersRef );

  /// Convert a persistent object to the transient form (regular pointer version)

    static CdbStatus to_transient( CdbNTuple< T, NCOL >*&  thePtr,
                                   const ooRef(BdbObject)& thePersRef );

  /// Convert a transient object to the persistent form
  /**
    * If successuful, the method would initialize the persistent  reference to point
    * onto a newely created persistent table (of unspecified here actual implentation)
    * filled with data and metadata copied from the specified transient table.
    *
    * If any kind of error will happen then the persistent pointer is guaranteed
    * to stay intact.
    *
    * REQUIREMENTS:
    *
    * (1) The persistent table must have the same actual type and configurations
    *     (number of columns) as the transient one.
    *
    * (2) The corresponding vortual tables for the persistnt class must be
    *     properly loaded.
    *
    * (3) The type of elements of a persistent typle would be derived from
    *     the type converter policy supplied (or default) as a template parameter
    *     of the class.
    *
    * (4) Should the transient and persistent types of elements be different
    *     the corresponding conversion must exist and be provided through
    *     the supplied (or default) converter policy.
    */
    static CdbStatus to_persistent( ooRef(BdbObject)&                      thePersRef,
                                    const CdbCPtr< CdbNTuple< T, NCOL > >& thePtr,
                                    const BdbRefAny&                       theHintRef );
};

/// The (partialy) specialize version of the conversion facility for strings
/**
  * This specialization is only meant to be used for n-tuples of strings.
  */
template < unsigned int NCOL,
           class        ELEMENT_CONVERSION_RULES >
class CdbBdbNTupleConversionImpl< std::string,
                                  NCOL,
                                  ELEMENT_CONVERSION_RULES > {

public:

  /// Convert a persistent object to the transient form
  /**
    * @see CdbBdbNTupleConversionImpl::to_transient()
    */
    static CdbStatus to_transient( CdbCPtr< CdbNTuple< std::string, NCOL > >& thePtr,
                                   const ooRef(BdbObject)&                    thePersRef );

  /// Convert a persistent object to the transient form (regular pointer version)

    static CdbStatus to_transient( CdbNTuple< std::string, NCOL >*& thePtr,
                                   const ooRef(BdbObject)&          thePersRef );

  /// Convert a transient object to the persistent form
  /**
    * @see CdbBdbNTupleConversionImpl::to_transient()
    */
    static CdbStatus to_persistent( ooRef(BdbObject)&                                thePersRef,
                                    const CdbCPtr< CdbNTuple< std::string, NCOL > >& thePtr,
                                    const BdbRefAny&                                 theHintRef );
};

#ifdef     BABAR_COMP_INST
#include "CdbBdbTable/CdbBdbNTupleConversionImpl.cc"
#endif  // BABAR_COMP_INST

#endif // CDBBDBTABLE_NTUPLE_CONVERSION_IMPL_HH

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