get_attributes.hpp

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//
// (c) Copyright 2015 DESY, Eugen Wintersberger <eugen.wintersberger@desy.de>
//
// This file is part of libpniio.
//
// libpniio 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.
//
// libpniio is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with libpniio.  If not, see <http://www.gnu.org/licenses/>.
// ===========================================================================
// Created on: Jul 31, 2015
//     Author: Eugen Wintersberger <eugen.wintersberger@desy.de>
//
#pragma once

#include <pni/core/types.hpp>
#include <pni/core/error.hpp>
#include "../nxobject.hpp"
#include "../nxobject_traits.hpp"


namespace pni{
namespace io{
namespace nx{

    template<
             typename CTYPE, 
             template<nximp_code> class PTYPE,
             nximp_code IMPID
           >
    CTYPE get_attributes(const PTYPE<IMPID> &parent)
    {
        typedef typename nxobject_trait<IMPID>::object_type object_type;
        typedef typename nxobject_trait<IMPID>::attribute_type attribute_type;
        typedef typename CTYPE::value_type value_type;

        static_assert(std::is_same<value_type,object_type>::value || 
                      std::is_same<value_type,attribute_type>::value,
                      "The containers value_type must be either an attribute"
                      " or an object type!");
        
        CTYPE attributes;

        std::copy(parent.attributes.begin(),parent.attributes.end(),
                  std::back_inserter(attributes));

        return attributes;
    }


    //------------------------------------------------------------------------
    template<
             typename CTYPE,
             typename GTYPE,
             typename FTYPE,
             typename ATYPE,
             typename LTYPE
            > 
    class get_attributes_visitor : public boost::static_visitor<CTYPE>
    {
        public:
            using result_type = CTYPE;
            using group_type = GTYPE;
            using field_type = FTYPE;
            using attribute_type = ATYPE;
            using link_type = LTYPE;
      
            //---------------------------------------------------------------------
            result_type operator()(const group_type &g) const
            {
                return get_attributes<result_type>(g);
            }

            //---------------------------------------------------------------------
            result_type operator()(const field_type &f) const
            {
                return get_attributes<result_type>(f);
            }

            //---------------------------------------------------------------------
            result_type operator()(const attribute_type &) const
            {
                using namespace pni::core;
                throw type_error(EXCEPTION_RECORD,
                        "Attributes cannot have attributes by themself!");
                return result_type();
            }

            //----------------------------------------------------------------
            result_type operator()(const link_type &) const
            {
                using namespace pni::core;
                throw type_error(EXCEPTION_RECORD,
                        "Instances of link do not have attributes!");
                return result_type();
            }
    };

    template<
             typename CTYPE,
             typename GTYPE,
             typename FTYPE,
             typename ATYPE,
             typename LTYPE
            > 
    CTYPE get_attributes(const nxobject<GTYPE,FTYPE,ATYPE,LTYPE> &parent)
    {
        using visitor_type = get_attributes_visitor<CTYPE,GTYPE,FTYPE,ATYPE,LTYPE>;
        return boost::apply_visitor(visitor_type(),parent);
    }

//end of namespace 
}
}
}