// -- Boost Lambda Library -------------------------------------------------

 // Copyright (C) 1999, 2000 Jaakko Järvi (jaakko.jarvi@cs.utu.fi)

 //

 // 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)

 //

 // For more information, see www.boost.org

 // --------------------------------------------------

 #ifndef BOOST_LAMBDA_ARITY_CODE_HPP

 #define BOOST_LAMBDA_ARITY_CODE_HPP

 #include "boost/type_traits/cv_traits.hpp"

 #include "boost/type_traits/transform_traits.hpp"

 namespace boost { 

 namespace lambda {

 // These constants state, whether a lambda_functor instantiation results from 

 // an expression which contains no placeholders (NONE), 

 // only free1 placeholders (FIRST), 

 // free2 placeholders and maybe free1 placeholders (SECOND),

 // free3 and maybe free1 and free2 placeholders (THIRD),

 // freeE placeholders and maybe free1 and free2  (EXCEPTION).

 // RETHROW means, that a rethrow expression is used somewhere in the lambda_functor.

 enum { NONE             = 0x00, // Notice we are using bits as flags here.

        FIRST            = 0x01, 

        SECOND           = 0x02, 

        THIRD            = 0x04, 

        EXCEPTION        = 0x08, 

        RETHROW          = 0x10};

 template<class T>

 struct get_tuple_arity;

 namespace detail {

 template <class T> struct get_arity_;

 } // end detail;

 template <class T> struct get_arity {

   BOOST_STATIC_CONSTANT(int, value = detail::get_arity_<typename boost::remove_cv<typename boost::remove_reference<T>::type>::type>::value);

 };

 namespace detail {

 template<class T>

 struct get_arity_ {

   BOOST_STATIC_CONSTANT(int, value = 0);

 };

 template<class T>

 struct get_arity_<lambda_functor<T> > {

   BOOST_STATIC_CONSTANT(int, value = get_arity<T>::value);

 };

 template<class Action, class Args>

 struct get_arity_<lambda_functor_base<Action, Args> > {

   BOOST_STATIC_CONSTANT(int, value = get_tuple_arity<Args>::value);

 };

 template<int I>

 struct get_arity_<placeholder<I> > {

   BOOST_STATIC_CONSTANT(int, value = I);

 };

 } // detail 

 template<class T>

 struct get_tuple_arity {

   BOOST_STATIC_CONSTANT(int, value = get_arity<typename T::head_type>::value | get_tuple_arity<typename T::tail_type>::value);

 };

 template<>

 struct get_tuple_arity<null_type> {

   BOOST_STATIC_CONSTANT(int, value = 0);

 };

   // Does T have placeholder<I> as it's subexpression?

 template<class T, int I>

 struct has_placeholder {

   BOOST_STATIC_CONSTANT(bool, value = (get_arity<T>::value & I) != 0);

 }; 

 template<int I, int J>

 struct includes_placeholder {

   BOOST_STATIC_CONSTANT(bool, value = (J & I) != 0);

 };

 template<int I, int J>

 struct lacks_placeholder {

   BOOST_STATIC_CONSTANT(bool, value = ((J & I) == 0));

 };

 } // namespace lambda

 } // namespace boost

 #endif