ceph/src/boost/libs/phoenix/include/boost/phoenix/core/arity.hpp

   1 /*==============================================================================
   2     Copyright (c) 2010 Thomas Heller
   3     Copyright (c) 2010 Eric Niebler
   4
   5     Distributed under the Boost Software License, Version 1.0. (See accompanying
   6     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7 ==============================================================================*/
   8 #ifndef BOOST_PHOENIX_CORE_ARITY_HPP
   9 #define BOOST_PHOENIX_CORE_ARITY_HPP
  10
  11 #include <boost/phoenix/core/limits.hpp>
  12 #include <boost/is_placeholder.hpp>
  13 #include <boost/mpl/max.hpp>
  14 #include <boost/mpl/int.hpp>
  15 #include <boost/phoenix/core/meta_grammar.hpp>
  16 #include <boost/phoenix/core/terminal_fwd.hpp>
  17 #include <boost/phoenix/support/vector.hpp>
  18 #include <boost/proto/matches.hpp>
  19 #include <boost/proto/transform/fold.hpp>
  20
  21 namespace boost { namespace phoenix
  22 {
  23     /////////////////////////////////////////////////////////////////////////////
  24     //
  25     //  Calculate the arity of an expression using proto transforms
  26     //
  27     /////////////////////////////////////////////////////////////////////////////
  28
  29     struct arity;
  30
  31     namespace result_of
  32     {
  33         template <typename Expr>
  34         struct arity
  35             : mpl::int_<
  36                 evaluator::impl<
  37                     Expr const&
  38                   , vector2<
  39                         mpl::int_<0>
  40                       , boost::phoenix::arity
  41                     >&
  42                   , proto::empty_env
  43                 >::result_type::value
  44             >
  45         {};
  46     }
  47
  48     struct arity
  49     {
  50         template <typename Rule, typename Dummy = void>
  51         struct when
  52             : proto::fold<
  53                 proto::_
  54               , mpl::int_<0>
  55               , proto::make<mpl::max<
  56                     proto::_state
  57                   , proto::call<
  58                         evaluator(
  59                             proto::_
  60                           , proto::call<
  61                                 functional::context(_env, _actions)
  62                             >
  63                         )
  64                     >
  65                 >()>
  66             >
  67         {};
  68     };
  69
  70     template <typename Dummy>
  71     struct arity::when<rule::argument, Dummy>
  72         : proto::make<is_placeholder<proto::_value>()>
  73     {};
  74
  75     template <typename Dummy>
  76     struct arity::when<rule::custom_terminal, Dummy>
  77         : proto::make<mpl::int_<0>()>
  78     {};
  79
  80     template <typename Dummy>
  81     struct arity::when<rule::terminal, Dummy>
  82         : proto::make<mpl::int_<0>()>
  83     {};
  84 }}
  85
  86 #endif