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DbIter.h

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//====================================================================
//      dbIter definition
//--------------------------------------------------------------------
//
//      Package    : DbCnv/DbSvc ( The LHCb Offline System)
//
//  Description: Generic persistable object iterator
//
//      Author     : M.Frank
//  History    :
// +---------+----------------------------------------------+---------
// |    Date |                 Comment                      | Who     
// +---------+----------------------------------------------+---------
// | 11/07/99| Initial version                              | MF
// +---------+----------------------------------------------+---------
//====================================================================
#ifndef DBCNV_DBOBJECTITER_H
#define DBCNV_DBOBJECTITER_H

// Framework include files
#include "GaudiDb/DbObject.h"
#include "GaudiDb/DbHandle.h"
#include "GaudiDb/IOODataBase.h"
#include "DbContainer.h"

template <class T> class dbIter  {
  dbHandle<DbContainer>      m_container;
  dbHandle<T>                m_object;
  IDbCursor*                 m_cursor;
  void releaseCursor()    {
    if ( m_cursor )   {
      m_cursor->release();
      m_cursor = 0;
    }
  }
public:
  dbIter() {
    m_cursor = 0;
  }
  virtual ~dbIter() {
    releaseCursor();
  }
  DbResult scan(const dbHandle<DbContainer>& cntH)    {
    releaseCursor();
    m_object = dbHandle<T> (cntH.type());
    m_container = cntH;
    if ( m_container.isValid() )   {
      m_cursor = m_container.makeCursor();
    }
    return ( 0 == m_cursor ) ? DbOOMs::DbError : DbOOMs::DbSuccess;
  }
  DbResult next()   {
    if ( m_cursor )   {
      dbHandle<DbObject> objH(m_object.type());
      if ( DbOOMs::DbSuccess == m_cursor->next(m_container, objH) )    {
        if ( objH.isValid() )   {
          m_object = objH;
          return DbOOMs::DbSuccess;
        }
      }
    }
    return DbOOMs::DbError;
  }
  dbHandle<T>& operator->()    {
    return m_object;
  }
  bool operator==(const dbIter<T>& iter)   const     {
    return m_object.operator->() == iter.m_object.operator->();
  }
};

template <> class dbIter<DbObject>  {
  dbHandle<DbContainer>      m_container;
  dbHandle<DbObject>         m_object;
  IDbCursor*                 m_cursor;
  void releaseCursor()    {
    if ( m_cursor )   {
      m_cursor->release();
      m_cursor = 0;
    }
  }
public:
  dbIter() {
    m_cursor = 0;
  }
  virtual ~dbIter() {
    releaseCursor();
  }
  DbResult scan(const dbHandle<DbContainer>& cntH)    {
    releaseCursor();
    m_object = dbHandle<DbObject> (cntH.type());
    m_container = cntH;
    if ( m_container.isValid() )   {
      m_cursor = m_container.makeCursor();
    }
    return ( 0 == m_cursor ) ? DbOOMs::DbError : DbOOMs::DbSuccess;
  }
  DbResult next()   {
    if ( m_cursor )   {
      if ( DbOOMs::DbSuccess == m_cursor->next(m_container, m_object) )    {
        if ( m_object.isValid() )   {
          return DbOOMs::DbSuccess;
        }
      }
    }
    return DbOOMs::DbError;
  }
  dbHandle<DbObject>& operator->()    {
    return m_object;
  }
  bool operator==(const dbIter<DbObject>& iter)   const     {
    return m_object.operator->() == iter.m_object.operator->();
  }
};
#endif // DBCNV_DBOBJECTITER_H

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