include/GaudiKernel/SmartDataPtr.h

0001 /***********************************************************************************\
0002 * (c) Copyright 1998-2019 CERN for the benefit of the LHCb and ATLAS collaborations *
0003 *                                                                                   *
0004 * This software is distributed under the terms of the Apache version 2 licence,     *
0005 * copied verbatim in the file "LICENSE".                                            *
0006 *                                                                                   *
0007 * In applying this licence, CERN does not waive the privileges and immunities       *
0008 * granted to it by virtue of its status as an Intergovernmental Organization        *
0009 * or submit itself to any jurisdiction.                                             *
0010 \***********************************************************************************/
0011 //  ====================================================================
0012 //  SmartDataPtr.h
0013 //  --------------------------------------------------------------------
0014 //
0015 //  Package    : GaudiKernel ( The LHCb Offline System)
0016 //
0017 //  Description: Implementation of a smart pointer class to access
0018 //               easily (and efficiently) data stores.
0019 //
0020 //  Author     : M.Frank
0021 //  ====================================================================
0022 #ifndef GAUDIKERNEL_SMARTDATAPTR_H
0023 #define GAUDIKERNEL_SMARTDATAPTR_H 1
0024
0025 // Framework include files
0026 #include "GaudiKernel/DataObject.h"
0027 #include "GaudiKernel/SmartDataStorePtr.h"
0028
0029 /** A small class used to access easily (and efficiently) data items
0030     residing in data stores.
0031
0032       The class constructors take several arguments neccessary to be passed
0033     tyo the data services in order to automatically load objects in case
0034     they are not yet loaded. This is achieved through a smart pointer
0035     mechanism i.e. by overloading the operator->() at dereferencing time
0036     the the object will be requested from the store.
0037
0038       The SmartDataPtr is meant to be "short living". It only makes
0039     sense to keep an object instance within e.g. the scope of one method.
0040     "long living" instances do not make sense and in the contrary
0041     would be harmful, because the information passed during construction
0042     to would be invalid and returned object pointers would actually
0043     point to hyperspace.
0044
0045       The intrinsic functionality, wether the object will be retrieved or
0046     loaded from the data store is defined by the LOADER::.
0047
0048
0049     Base Class:
0050     SmartDataStorePtr
0051
0052     @author  M.Frank
0053     @version 1.0
0054 */
0055
0056 template <class TYPE>
0057 class SmartDataPtr : public SmartDataStorePtr<TYPE, SmartDataObjectPtr::ObjectLoader> {
0058 public:
0059 /// unhides assignment operator of base class
0060 #if !defined( __ICC ) && !defined( __COVERITY__ )
0061   // icc and Coverity do not like this line, they fail with
0062   // SmartDataPtr.h(147): internal error: assertion failed: add_symbol_to_overload_list:
0063   //   symbol not in symbol header list (shared/edgcpfe/symbol_tbl.c, line 4804)
0064   using SmartDataStorePtr<TYPE, SmartDataObjectPtr::ObjectLoader>::operator=;
0065 #endif
0066   /** Standard constructor: Construct an SmartDataPtr instance which is
0067                             able to connect to a DataObject instance
0068                             which is identified by its parent object and
0069                             the path relative to the parent.
0070       @param  pService      Pointer to the data service interface which
0071                             should be used to load the object.
0072       @param  fullPath      Full path leading to the data object.
0073   */
0074   SmartDataPtr( IDataProviderSvc* pService, std::string fullPath )
0075       : SmartDataStorePtr<TYPE, SmartDataObjectPtr::ObjectLoader>( pService, nullptr, std::move( fullPath ) ) {}
0076
0077   /** Standard constructor: Construct an SmartDataPtr instance which is
0078                             able to connect to a DataObject instance
0079                             which is identified by its directory entry.
0080                             *** FASTEST ACCESS TO THE DATA STORE ***
0081       @param  pService      Pointer to the data service interface which
0082                             should be used to load the object.
0083       @param  pDirectory    Pointer to the data directory entry.
0084   */
0085   SmartDataPtr( IDataProviderSvc* pService, IRegistry* pDirectory )
0086       : SmartDataStorePtr<TYPE, SmartDataObjectPtr::ObjectLoader>( pService, pDirectory, "" ) {}
0087
0088   /** Standard constructor: Construct an SmartDataPtr instance which is
0089                             able to connect to a DataObject instance
0090                             which is identified by its parent object and
0091                             the path relative to the parent.
0092                             The path is meant to address only ONE level,
0093                             multiple path layers are invalid.
0094       @param  pService      Pointer to the data service interface which
0095                             should be used to load the object.
0096       @param  pObject       Pointer to the parent object.
0097       @param  path          Path to the data object relative to the parent object.
0098   */
0099   SmartDataPtr( IDataProviderSvc* pService, DataObject* pObject, std::string path )
0100       : SmartDataStorePtr<TYPE, SmartDataObjectPtr::ObjectLoader>( pService, nullptr, std::move( path ) ) {
0101     if ( pObject ) this->m_pRegistry = pObject->registry();
0102   }
0103
0104   /** Standard constructor: Construct an SmartDataPtr instance which is
0105                             able to connect to a DataObject instance
0106                             which is identified by its parent object and
0107                             the path relative to the parent.
0108                             The path is meant to address only ONE level,
0109                             multiple path layers are invalid.
0110       @param  refObject     Smart Pointer to the parent object.
0111       @param  pDirectory    Pointer to the data directory entry.
0112   */
0113   SmartDataPtr( SmartDataObjectPtr& refObject, IRegistry* pDirectory )
0114       : SmartDataStorePtr<TYPE, SmartDataObjectPtr::ObjectLoader>( refObject.service(), pDirectory, "" ) {}
0115
0116   /** Standard constructor: Construct an SmartDataPtr instance which is
0117                             able to connect to a DataObject instance
0118                             which is identified by its parent object and
0119                             the path relative to the parent.
0120                             The path is meant to address only ONE level,
0121                             multiple path layers are invalid.
0122       @param  refObject     Smart Pointer to the parent object.
0123       @param  path          Path to the data object relative to the parent object.
0124   */
0125   SmartDataPtr( SmartDataObjectPtr& refObject, std::string path )
0126       : SmartDataStorePtr<TYPE, SmartDataObjectPtr::ObjectLoader>( refObject.service(), refObject.directory(),
0127                                                                    std::move( path ) ) {}
0128
0129   /** Copy constructor: Construct an copy of a SmartDataPtr instance.
0130       @param  copy          Copy Smart Pointer to object.
0131   */
0132   SmartDataPtr( const SmartDataObjectPtr& copy ) : SmartDataStorePtr<TYPE, SmartDataObjectPtr::ObjectLoader>( copy ) {}
0133
0134   /** Standard destructor
0135    */
0136   virtual ~SmartDataPtr() = default;
0137
0138   /// Automatic conversion to data type
0139   template <class OTHER>
0140   SmartDataPtr& operator=( OTHER* pObj ) {
0141     this->m_pObject = dynamic_cast<TYPE*>( pObj );
0142     return *this;
0143   }
0144
0145   /// Automatic conversion to data type
0146   template <class OTHER>
0147   SmartDataPtr& operator=( const OTHER* pObj ) {
0148     this->m_pObject = dynamic_cast<TYPE*>( const_cast<OTHER*>( pObj ) );
0149     return *this;
0150   }
0151 };
0152
0153 #endif // GAUDIKERNEL_SMARTDATAPTR_H