2 #ifndef BOOST_MPL_AUX_PUSH_FRONT_IMPL_HPP_INCLUDED
3 #define BOOST_MPL_AUX_PUSH_FRONT_IMPL_HPP_INCLUDED
5 // Copyright Aleksey Gurtovoy 2000-2008
7 // Distributed under the Boost Software License, Version 1.0.
8 // (See accompanying file LICENSE_1_0.txt or copy at
9 // http://www.boost.org/LICENSE_1_0.txt)
11 // See http://www.boost.org/libs/mpl for documentation.
13 // $Id: push_front_impl.hpp 55679 2009-08-20 07:50:16Z agurtovoy $
14 // $Date: 2009-08-20 03:50:16 -0400 (Thu, 20 Aug 2009) $
17 #include <boost/mpl/push_front_fwd.hpp>
18 #include <boost/mpl/assert.hpp>
19 #include <boost/mpl/aux_/has_type.hpp>
20 #include <boost/mpl/aux_/traits_lambda_spec.hpp>
21 #include <boost/mpl/aux_/config/forwarding.hpp>
22 #include <boost/mpl/aux_/config/static_constant.hpp>
24 #include <boost/type_traits/is_same.hpp>
26 namespace boost { namespace mpl {
28 struct has_push_front_arg {};
30 // agurt 05/feb/04: no default implementation; the stub definition is needed
31 // to enable the default 'has_push_front' implementation below
33 template< typename Tag >
34 struct push_front_impl
36 template< typename Sequence, typename T > struct apply
38 // should be instantiated only in the context of 'has_push_front_impl';
39 // if you've got an assert here, you are requesting a 'push_front'
40 // specialization that doesn't exist.
42 ( boost::is_same< T, has_push_front_arg >::value )
43 , REQUESTED_PUSH_FRONT_SPECIALIZATION_FOR_SEQUENCE_DOES_NOT_EXIST
49 template< typename Tag >
50 struct has_push_front_impl
52 template< typename Seq > struct apply
53 #if !defined(BOOST_MPL_CFG_NO_NESTED_FORWARDING)
54 : aux::has_type< push_front< Seq, has_push_front_arg > >
58 typedef aux::has_type< push_front< Seq, has_push_front_arg > > type;
59 BOOST_STATIC_CONSTANT(bool, value =
60 (aux::has_type< push_front< Seq, has_push_front_arg > >::value)
66 BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(2, push_front_impl)
67 BOOST_MPL_ALGORITM_TRAITS_LAMBDA_SPEC(1, has_push_front_impl)
71 #endif // BOOST_MPL_AUX_PUSH_FRONT_IMPL_HPP_INCLUDED