Chris@16: /*==============================================================================
Chris@16:     Copyright (c) 2010 Thomas Heller
Chris@16:     Copyright (c) 2010 Eric Niebler
Chris@16: 
Chris@16:     Distributed under the Boost Software License, Version 1.0. (See accompanying
Chris@16:     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: ==============================================================================*/
Chris@16: #ifndef BOOST_PHOENIX_CORE_ARITY_HPP
Chris@16: #define BOOST_PHOENIX_CORE_ARITY_HPP
Chris@16: 
Chris@16: #include <boost/phoenix/core/limits.hpp>
Chris@16: #include <boost/is_placeholder.hpp>
Chris@16: #include <boost/mpl/max.hpp>
Chris@16: #include <boost/mpl/int.hpp>
Chris@16: #include <boost/phoenix/core/meta_grammar.hpp>
Chris@16: #include <boost/phoenix/core/terminal_fwd.hpp>
Chris@16: #include <boost/phoenix/support/vector.hpp>
Chris@16: #include <boost/proto/matches.hpp>
Chris@16: #include <boost/proto/transform/fold.hpp>
Chris@16: 
Chris@16: namespace boost { namespace phoenix
Chris@16: {
Chris@16:     /////////////////////////////////////////////////////////////////////////////
Chris@16:     //
Chris@16:     //  Calculate the arity of an expression using proto transforms
Chris@16:     //
Chris@16:     /////////////////////////////////////////////////////////////////////////////
Chris@16:     
Chris@16:     struct arity;
Chris@16: 
Chris@16:     namespace result_of
Chris@16:     {
Chris@16:         template <typename Expr>
Chris@16:         struct arity
Chris@16:             : mpl::int_<
Chris@16:                 evaluator::impl<
Chris@16:                     Expr const&
Chris@16:                   , vector2<
Chris@16:                         mpl::int_<0>
Chris@16:                       , boost::phoenix::arity
Chris@16:                     >&
Chris@16:                   , proto::empty_env
Chris@16:                 >::result_type::value
Chris@16:             >
Chris@16:         {};
Chris@16:     }
Chris@16: 
Chris@16:     struct arity
Chris@16:     {
Chris@16:         template <typename Rule, typename Dummy = void>
Chris@16:         struct when
Chris@16:             : proto::fold<
Chris@16:                 proto::_
Chris@16:               , mpl::int_<0>
Chris@16:               , proto::make<mpl::max<
Chris@16:                     proto::_state
Chris@16:                   , proto::call<
Chris@16:                         evaluator(
Chris@16:                             proto::_
Chris@16:                           , proto::call<
Chris@16:                                 functional::context(_env, _actions)
Chris@16:                             >
Chris@16:                         )
Chris@16:                     >
Chris@16:                 >()>
Chris@16:             >
Chris@16:         {};
Chris@16:     };
Chris@16: 
Chris@16:     template <typename Dummy>
Chris@16:     struct arity::when<rule::argument, Dummy>
Chris@16:         : proto::make<is_placeholder<proto::_value>()>
Chris@16:     {};
Chris@16:     
Chris@16:     template <typename Dummy>
Chris@16:     struct arity::when<rule::custom_terminal, Dummy>
Chris@16:         : proto::make<mpl::int_<0>()>
Chris@16:     {};
Chris@16:     
Chris@16:     template <typename Dummy>
Chris@16:     struct arity::when<rule::terminal, Dummy>
Chris@16:         : proto::make<mpl::int_<0>()>
Chris@16:     {};
Chris@16: }}
Chris@16: 
Chris@16: #endif