vector/aux_/at.hpp

0001
0002 #ifndef BOOST_MPL_VECTOR_AUX_AT_HPP_INCLUDED
0003 #define BOOST_MPL_VECTOR_AUX_AT_HPP_INCLUDED
0004
0005 // Copyright Aleksey Gurtovoy 2000-2004
0006 //
0007 // Distributed under the Boost Software License, Version 1.0.
0008 // (See accompanying file LICENSE_1_0.txt or copy at
0009 // http://www.boost.org/LICENSE_1_0.txt)
0010 //
0011 // See http://www.boost.org/libs/mpl for documentation.
0012
0013 // $Id$
0014 // $Date$
0015 // $Revision$
0016
0017 #include <boost/mpl/at_fwd.hpp>
0018 #include <boost/mpl/vector/aux_/tag.hpp>
0019 #include <boost/mpl/long.hpp>
0020 #include <boost/mpl/void.hpp>
0021 #include <boost/mpl/aux_/nttp_decl.hpp>
0022 #include <boost/mpl/aux_/type_wrapper.hpp>
0023 #include <boost/mpl/aux_/value_wknd.hpp>
0024 #include <boost/mpl/aux_/config/typeof.hpp>
0025 #include <boost/mpl/aux_/config/ctps.hpp>
0026
0027 namespace boost { namespace mpl {
0028
0029 #if defined(BOOST_MPL_CFG_TYPEOF_BASED_SEQUENCES)
0030
0031 template< typename Vector, long n_ >
0032 struct v_at_impl
0033 {
0034     typedef long_< (Vector::lower_bound_::value + n_) > index_;
0035     typedef __typeof__( Vector::item_(index_()) ) type;
0036 };
0037
0038
0039 template< typename Vector, long n_ >
0040 struct v_at
0041     : aux::wrapped_type< typename v_at_impl<Vector,n_>::type >
0042 {
0043 };
0044
0045 template<>
0046 struct at_impl< aux::vector_tag >
0047 {
0048     template< typename Vector, typename N > struct apply
0049         : v_at<
0050               Vector
0051             , BOOST_MPL_AUX_VALUE_WKND(N)::value
0052             >
0053     {
0054     };
0055 };
0056
0057 #else
0058
0059 #   if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION) \
0060     && !defined(BOOST_MPL_CFG_NO_NONTYPE_TEMPLATE_PARTIAL_SPEC)
0061
0062 template< typename Vector, BOOST_MPL_AUX_NTTP_DECL(long, n_) > struct v_at;
0063
0064 template< BOOST_MPL_AUX_NTTP_DECL(long, n_) >
0065 struct at_impl< aux::vector_tag<n_> >
0066 {
0067     template< typename Vector, typename N > struct apply
0068 #if !defined(BOOST_BORLANDC)
0069         : v_at<
0070               Vector
0071             , BOOST_MPL_AUX_VALUE_WKND(N)::value
0072             >
0073     {
0074 #else
0075     {
0076         typedef typename v_at<
0077               Vector
0078             , BOOST_MPL_AUX_VALUE_WKND(N)::value
0079             >::type type;
0080 #endif
0081     };
0082 };
0083
0084 #   else
0085
0086 namespace aux {
0087
0088 template< BOOST_MPL_AUX_NTTP_DECL(long, n_) > struct v_at_impl
0089 {
0090     template< typename V > struct result_;
0091 };
0092
0093 // to work around ETI, etc.
0094 template<> struct v_at_impl<-1>
0095 {
0096     template< typename V > struct result_
0097     {
0098         typedef void_ type;
0099     };
0100 };
0101
0102 } // namespace aux
0103
0104 template< typename T, BOOST_MPL_AUX_NTTP_DECL(long, n_) >
0105 struct v_at
0106     : aux::v_at_impl<n_>::template result_<T>
0107 {
0108 };
0109
0110 #   endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
0111
0112 #endif // BOOST_MPL_CFG_TYPEOF_BASED_SEQUENCES
0113
0114 }}
0115
0116 #endif // BOOST_MPL_VECTOR_AUX_AT_HPP_INCLUDED