boost_1_45_0/boost/spirit/home/support/context.hpp

/*=============================================================================
    Copyright (c) 2001-2010 Joel de Guzman

    Distributed under the Boost Software License, Version 1.0. (See accompanying
    file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
==============================================================================*/
#if !defined(BOOST_SPIRIT_CONTEXT_OCTOBER_31_2008_0654PM)
#define BOOST_SPIRIT_CONTEXT_OCTOBER_31_2008_0654PM

#if defined(_MSC_VER)
#pragma once
#endif

#include <boost/preprocessor/repetition/repeat_from_to.hpp>
#include <boost/spirit/home/support/nonterminal/expand_arg.hpp>
#include <boost/spirit/home/support/assert_msg.hpp>
#include <boost/spirit/home/phoenix/core/actor.hpp>
#include <boost/spirit/home/phoenix/core/argument.hpp>
#include <boost/fusion/include/at.hpp>
#include <boost/fusion/include/size.hpp>
#include <boost/fusion/include/as_list.hpp>
#include <boost/fusion/include/transform.hpp>
#include <boost/mpl/size.hpp>
#include <boost/mpl/at.hpp>

#if !defined(SPIRIT_ATTRIBUTES_LIMIT)
# define SPIRIT_ATTRIBUTES_LIMIT PHOENIX_LIMIT
#endif

#define SPIRIT_DECLARE_ATTRIBUTE(z, n, data)                                    \
    phoenix::actor<attribute<n> > const                                         \
        BOOST_PP_CAT(_r, n) = attribute<n>();

#define SPIRIT_USING_ATTRIBUTE(z, n, data) using spirit::BOOST_PP_CAT(_r, n);

namespace boost { namespace spirit
{
    template <typename Attributes, typename Locals>
    struct context
    {
        typedef Attributes attributes_type;
        typedef Locals locals_type;

        context(typename Attributes::car_type attribute)
          : attributes(attribute, fusion::nil()), locals() {}

        template <typename Args, typename Context>
        context(
            typename Attributes::car_type attribute
          , Args const& args
          , Context& caller_context
        ) : attributes(
                attribute
              , fusion::as_list(
                    fusion::transform(
                        args
                      , detail::expand_arg<Context>(caller_context)
                    )
                )
            )
          , locals() {}

        context(Attributes const& attributes)
          : attributes(attributes), locals() {}

        Attributes attributes;  // The attributes
        Locals locals;          // Local variables
    };

    template <typename Context>
    struct attributes_of
    {
        typedef typename Context::attributes_type type;
    };

    template <typename Context>
    struct attributes_of<Context const>
    {
        typedef typename Context::attributes_type const type;
    };

    template <typename Context>
    struct locals_of
    {
        typedef typename Context::locals_type type;
    };

    template <typename Context>
    struct locals_of<Context const>
    {
        typedef typename Context::locals_type const type;
    };

    template <int N>
    struct attribute
    {
        typedef mpl::true_ no_nullary;

        template <typename Env>
        struct result
        {
            typedef typename
                attributes_of<typename
                    mpl::at_c<typename Env::args_type, 1>::type
                >::type
            attributes_type;

            typedef typename
                fusion::result_of::size<attributes_type>::type
            attributes_size;

            // report invalid argument not found (N is out of bounds)
            BOOST_SPIRIT_ASSERT_MSG(
                (N < attributes_size::value),
                index_is_out_of_bounds, ());

            typedef typename
                fusion::result_of::at_c<attributes_type, N>::type
            type;
        };

        template <typename Env>
        typename result<Env>::type
        eval(Env const& env) const
        {
            return fusion::at_c<N>((fusion::at_c<1>(env.args())).attributes);
        }
    };

    template <int N>
    struct local_variable
    {
        typedef mpl::true_ no_nullary;

        template <typename Env>
        struct result
        {
            typedef typename
                locals_of<typename
                    mpl::at_c<typename Env::args_type, 1>::type
                >::type
            locals_type;

            typedef typename
                fusion::result_of::size<locals_type>::type
            locals_size;

            // report invalid argument not found (N is out of bounds)
            BOOST_SPIRIT_ASSERT_MSG(
                (N < locals_size::value),
                index_is_out_of_bounds, ());

            typedef typename
                fusion::result_of::at_c<locals_type, N>::type
            type;
        };

        template <typename Env>
        typename result<Env>::type
        eval(Env const& env) const
        {
            return get_arg<N>((fusion::at_c<1>(env.args())).locals);
        }
    };

    // _val refers to the 'return' value of a rule (same as _r0)
    // _r1, _r2, ... refer to the rule arguments
    phoenix::actor<attribute<0> > const _val = attribute<0>();
    phoenix::actor<attribute<0> > const _r0 = attribute<0>();
    phoenix::actor<attribute<1> > const _r1 = attribute<1>();
    phoenix::actor<attribute<2> > const _r2 = attribute<2>();

    //  Bring in the rest of the attributes (_r4 .. _rN+1), using PP
    BOOST_PP_REPEAT_FROM_TO(
        3, SPIRIT_ATTRIBUTES_LIMIT, SPIRIT_DECLARE_ATTRIBUTE, _)

    // _a, _b, ... refer to the local variables of a rule
    phoenix::actor<local_variable<0> > const _a = local_variable<0>();
    phoenix::actor<local_variable<1> > const _b = local_variable<1>();
    phoenix::actor<local_variable<2> > const _c = local_variable<2>();
    phoenix::actor<local_variable<3> > const _d = local_variable<3>();
    phoenix::actor<local_variable<4> > const _e = local_variable<4>();
    phoenix::actor<local_variable<5> > const _f = local_variable<5>();
    phoenix::actor<local_variable<6> > const _g = local_variable<6>();
    phoenix::actor<local_variable<7> > const _h = local_variable<7>();
    phoenix::actor<local_variable<8> > const _i = local_variable<8>();
    phoenix::actor<local_variable<9> > const _j = local_variable<9>();

    // You can bring these in with the using directive
    // without worrying about bringing in too much.
    namespace labels
    {
        BOOST_PP_REPEAT(SPIRIT_ARGUMENTS_LIMIT, SPIRIT_USING_ARGUMENT, _)
        BOOST_PP_REPEAT(SPIRIT_ATTRIBUTES_LIMIT, SPIRIT_USING_ATTRIBUTE, _)
        using spirit::_val;
        using spirit::_a;
        using spirit::_b;
        using spirit::_c;
        using spirit::_d;
        using spirit::_e;
        using spirit::_f;
        using spirit::_g;
        using spirit::_h;
        using spirit::_i;
        using spirit::_j;
    }
}}

#endif