#ifndef BOOST_MPL_INDEX_IF_HPP_INCLUDED

 #define BOOST_MPL_INDEX_IF_HPP_INCLUDED

 // Copyright Eric Friedman 2003

 //

 // 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)

 //

 // See http://www.boost.org/libs/mpl for documentation.

 // $Source: /cvsroot/boost/boost/boost/mpl/index_if.hpp,v $

 // $Date: 2004/09/02 15:40:41 $

 // $Revision: 1.7 $

 #include <boost/mpl/aux_/find_if_pred.hpp>

 #include <boost/mpl/begin_end.hpp>

 #include <boost/mpl/if.hpp>

 #include <boost/mpl/int.hpp>

 #include <boost/mpl/iter_fold_if.hpp>

 #include <boost/mpl/next.hpp>

 #include <boost/mpl/void.hpp>

 #include <boost/mpl/aux_/na_spec.hpp>

 #include <boost/mpl/aux_/lambda_support.hpp>

 #include <boost/type_traits/is_same.hpp>

 namespace boost { namespace mpl {

 template<

       typename BOOST_MPL_AUX_NA_PARAM(Sequence)

     , typename BOOST_MPL_AUX_NA_PARAM(Predicate)

     >

 struct index_if

 {

     typedef typename iter_fold_if<

           Sequence

         , int_<0>

         , next<>

         , aux::find_if_pred<Predicate>

         >::type result_;

     typedef typename end<Sequence>::type not_found_;

     typedef typename first<result_>::type result_index_;

     typedef typename second<result_>::type result_iterator_;

     typedef typename if_<

           is_same< result_iterator_,not_found_ >

         , void_

         , result_index_

         >::type type;

     BOOST_MPL_AUX_LAMBDA_SUPPORT(2,index_if,(Sequence,Predicate))

 };

 BOOST_MPL_AUX_NA_SPEC(2, index_if)

 }}

 #endif // BOOST_MPL_INDEX_IF_HPP_INCLUDED