include/GaudiKernel/IEvtSelector.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 #ifndef GAUDIKERNEL_IEVTSELECTOR_H
0012 #define GAUDIKERNEL_IEVTSELECTOR_H 1
0013
0014 // Include files
0015 #include "GaudiKernel/IInterface.h"
0016 #include "GaudiKernel/IOpaqueAddress.h"
0017 #include "GaudiKernel/StatusCode.h"
0018 #include <string>
0019
0020 /** @class IEvtSelector IEvtSelector.h GaudiKernel/IEvtSelector.h
0021
0022     The Event Selector Interface. The EventSelector component is able
0023     to produce a list of event  given a set of stream specifications.
0024
0025     @author C. Cioffi
0026     @date   14/11/2003
0027 */
0028 class GAUDI_API IEvtSelector : virtual public IInterface {
0029 public:
0030   /// InterfaceID
0031   DeclareInterfaceID( IEvtSelector, 2, 0 );
0032
0033   class Context {
0034   public:
0035     virtual ~Context()               = default;
0036     virtual void* identifier() const = 0;
0037   };
0038
0039   /**Create and return a context object that will
0040      keep track of the state of selection.
0041
0042      @param c Reference of a pointer to a Context object.
0043   */
0044   virtual StatusCode createContext( Context*& c ) const = 0;
0045
0046   /**Fetch the next event or the first event if it will be use soon
0047      after the creation of the context.
0048      It will return StatusCode::FAILURE if there have been problem in the fetching or it
0049      has been reached the end of the list of events.
0050
0051      @param c Reference to the Context object.
0052   */
0053   virtual StatusCode next( Context& c ) const = 0;
0054
0055   /**Same of next(const Context&) plus the possibility to jump the next n-1 events.
0056
0057      @param c Reference to the Context object.
0058      @param jump The event to jump to from the current event.
0059   */
0060   virtual StatusCode next( Context& c, int jump ) const = 0;
0061
0062   /**Fetch the previous event.
0063      It will return StatusCode::FAILURE if there have been problem in the fetching or it
0064      has been reached the begin of the list of events.
0065
0066      @param c Reference to the Context object.
0067    */
0068   virtual StatusCode previous( Context& c ) const = 0;
0069
0070   /**Same of previous(Context& c) the possibility to jump the previous n-1 events.
0071
0072      @param c Reference to the Context object.
0073      @param jump The event to jump to from the current event.
0074    */
0075   virtual StatusCode previous( Context& c, int jump ) const = 0;
0076
0077   /** Access last item in the iteration
0078    * @param refContext [IN/OUT] Reference to the Context object.
0079    */
0080   virtual StatusCode last( Context& refContext ) const = 0;
0081
0082   /** Will set the state of the context in a way that the next event read
0083    * is the first of the list.
0084    *
0085    * @param c Reference to the Context object.
0086    */
0087   virtual StatusCode rewind( Context& c ) const = 0;
0088
0089   /** Create an IOpaqueAddress object from the event fetched.
0090    *
0091    * @param c Reference to the Context object.
0092    * @param iop Refernce pointer to a IOpaqueAddress object
0093    *
0094    */
0095   virtual StatusCode createAddress( const Context& c, IOpaqueAddress*& iop ) const = 0;
0096
0097   /** Release the Context object.
0098    *
0099    * @param c Reference pointer to the Context object.
0100    */
0101   virtual StatusCode releaseContext( Context*& ) const = 0;
0102
0103   /** Will set a new criteria for the selection of the next list of events and will change
0104    * the state of the context in a way to point to the new list.
0105    *
0106    * @param cr The new criteria string.
0107    * @param c Reference pointer to the Context object.
0108    */
0109   virtual StatusCode resetCriteria( const std::string& cr, Context& c ) const = 0;
0110 };
0111
0112 #endif // GAUDIKERNEL_IEVTSELECTOR_H