value_rule.hpp

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//
// (c) Copyright 2013 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: May 6, 2013
//     Author: Eugen Wintersberger <eugen.wintersberger@desy.de>
//
//

#pragma once

#include <pni/core/types.hpp>
#include <pni/core/type_erasures.hpp>
#include <boost/variant.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>

#include "spirit_rules.hpp"
#include "complex_rule.hpp"

namespace pni{
namespace io{

   
    template<typename ITERT>
    struct value_rule : boost::spirit::qi::grammar<ITERT,pni::core::value()>
    {
        //--------------------------------------------------------------------
        // definition of internal classes used by the value_rule
        //--------------------------------------------------------------------
        class value_constructor_visitor : 
            public boost::static_visitor<pni::core::value>
        {
            public:
                pni::core::value operator()(const pni::core::int64 &v) const
                {
                    return pni::core::value(v);
                }
                
                pni::core::value operator()(const pni::core::complex64 &v) const
                {
                    return pni::core::value(v);
                }

                pni::core::value operator()(const pni::core::float64 &v) const
                {
                    return pni::core::value(v);
                }
        };

        //--------------------------------------------------------------------
        struct value_constructor
        {
            template<typename Sig> struct result
            {
                typedef pni::core::value type;
            };

            //-----------------------------------------------------------------
            template<typename Arg> 
            pni::core::value operator()(Arg const &n) const
            {
                return boost::apply_visitor(value_constructor_visitor(),n);
            }

        };

        //--------------------------------------------------------------------
        // here starts the implementation of the rule
        //--------------------------------------------------------------------
        typename boost::mpl::at<
                                spirit_rules,
                                pni::core::int64
                               >::type   integer_rule_;

        typename boost::mpl::at<
                                spirit_rules,
                                pni::core::float64
                               >::type float_rule_;

        complex_rule<ITERT,pni::core::complex64> complex_rule_;
        boost::spirit::qi::rule<ITERT,pni::core::value()> value_;
        boost::spirit::qi::rule<ITERT>               sign_rule;
        boost::spirit::qi::rule<ITERT>               float_signs;
        boost::phoenix::function<value_constructor> construct_value;

        //--------------------------------------------------------------------
        value_rule() : value_rule::base_type(value_)
        {
            //using namespace pni::core;
            using namespace boost::spirit::qi;
            //using namespace boost::fusion;
            using namespace boost::phoenix;
            using boost::spirit::qi::_1;

            sign_rule = char_('+')|char_('-');
            float_signs = char_('.')|char_('e');

            value_ = ((integer_rule_ >> !(float_signs|sign_rule))
                      | 
                      (float_rule_ >> !(sign_rule))
                      | 
                      complex_rule_)[_val = construct_value(_1)];
        }
    };

//end of namespace
}
}