element-query.hpp

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/*
  ELEMENT-QUERY.hpp  -  session sub-interface to query and retrieve elements
 
   Copyright (C)
     2010,            Hermann Vosseler <Ichthyostega@web.de>
 
 **Lumiera** is free software; you can redistribute it and/or modify it
 under the terms of the GNU General Public License as published by the
 Free Software Foundation; either version 2 of the License, or (at your
 option) any later version. See the file COPYING for further details.
 
*/
 
 
#ifndef STEAM_MOBJECT_SESSION_ELEMENT_QUERY_H
#define STEAM_MOBJECT_SESSION_ELEMENT_QUERY_H
 
 
#include "steam/mobject/placement.hpp"
#include "steam/mobject/mobject-ref.hpp"
#include "steam/mobject/session/specific-contents-query.hpp"
#include "steam/mobject/session/session-service-explore-scope.hpp"
#include "lib/nocopy.hpp"
 
#include <functional>
 
 
 
namespace steam {
namespace mobject {
namespace session {
  
  
  using std::function;
  
  
  namespace { // type matching helper
    template<class PRED>
    struct _PickRes;
    
    template<class MO>
    struct _PickRes<function<bool(Placement<MO> const&)> >
      {
        using Type = MO;
        using Result = MORef<MO>;
        using Iterator = ScopeQuery<MO>::iterator;
      };
    
    template<class MO>
    struct _PickRes<bool(&)(Placement<MO> const&)>
      {
        using Type = MO;
        using Result = MORef<MO>;
        using Iterator = ScopeQuery<MO>::iterator;
      };
    
    template<class MO>
    struct _PickRes<bool(*)(Placement<MO> const&)>
      {
        using Type = MO;
        using Result = MORef<MO>;
        using Iterator = ScopeQuery<MO>::iterator;
      };
  }
  
  
  
  
  class ElementQuery
    : util::NonCopyable
    {
      
    public:
      
      template<typename PRED>
      _PickRes<PRED>::Result
      pick (PRED const& searchPredicate)
        {
          using ResultRef = _PickRes<PRED>::Result;
          using Iterator = _PickRes<PRED>::Iterator;
          
          Iterator iter (pickAllSuitable ( SessionServiceExploreScope::getScopeRoot()
                                         , searchPredicate
                                         , SessionServiceExploreScope::getResolver()
                                         ));
          ResultRef found;
          if (iter)                 // in case there is an result
            found.activate(*iter); //  pick the first element found...
          return found;           //   or return an empty MObjectRef else
        }
      
    };
  
  
  
}}} // namespace steam::mobject::session
#endif