1
2#ifndef BOOST_MPL_MAP_AUX_AT_IMPL_HPP_INCLUDED
3#define BOOST_MPL_MAP_AUX_AT_IMPL_HPP_INCLUDED
4
5// Copyright Aleksey Gurtovoy 2003-2004
6// Copyright David Abrahams 2003-2004
7//
8// Distributed under the Boost Software License, Version 1.0.
9// (See accompanying file LICENSE_1_0.txt or copy at
10// http://www.boost.org/LICENSE_1_0.txt)
11//
12// See http://www.boost.org/libs/mpl for documentation.
13
14// $Id$
15// $Date$
16// $Revision$
17
18#include <boost/mpl/at_fwd.hpp>
19#include <boost/mpl/long.hpp>
20#include <boost/mpl/map/aux_/tag.hpp>
21#include <boost/mpl/aux_/order_impl.hpp>
22#include <boost/mpl/aux_/overload_names.hpp>
23#include <boost/mpl/aux_/type_wrapper.hpp>
24#include <boost/mpl/aux_/ptr_to_ref.hpp>
25#include <boost/mpl/aux_/static_cast.hpp>
26#include <boost/mpl/aux_/config/typeof.hpp>
27#include <boost/mpl/aux_/config/ctps.hpp>
28
29#if !defined(BOOST_MPL_CFG_TYPEOF_BASED_SEQUENCES)
30# include <boost/mpl/eval_if.hpp>
31# include <boost/mpl/pair.hpp>
32# include <boost/mpl/void.hpp>
33# include <boost/mpl/aux_/config/static_constant.hpp>
34#endif
35
36namespace boost { namespace mpl {
37
38#if defined(BOOST_MPL_CFG_TYPEOF_BASED_SEQUENCES)
39
40template< typename Map, typename Key >
41struct m_at
42{
43 typedef aux::type_wrapper<Key> key_;
44 typedef __typeof__( BOOST_MPL_AUX_OVERLOAD_CALL_VALUE_BY_KEY(
45 Map
46 , BOOST_MPL_AUX_STATIC_CAST(key_*, 0)
47 ) ) type;
48};
49
50template<>
51struct at_impl< aux::map_tag >
52{
53 template< typename Map, typename Key > struct apply
54 : aux::wrapped_type< typename m_at<
55 Map
56 , Key
57 >::type >
58 {
59 };
60};
61
62// agurt 31/jan/04: two-step implementation for the sake of GCC 3.x
63template< typename Map, long order >
64struct item_by_order_impl
65{
66 typedef __typeof__( BOOST_MPL_AUX_OVERLOAD_CALL_ITEM_BY_ORDER(
67 Map
68 , BOOST_MPL_AUX_STATIC_CAST(long_<order>*, 0)
69 ) ) type;
70};
71
72template< typename Map, long order >
73struct item_by_order
74 : aux::wrapped_type<
75 typename item_by_order_impl<Map,order>::type
76 >
77{
78};
79
80#else // BOOST_MPL_CFG_TYPEOF_BASED_SEQUENCES
81
82# if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
83
84template< typename Map, long n > struct m_at
85{
86 typedef void_ type;
87};
88
89# else
90
91template< long n > struct m_at_impl
92{
93 template< typename Map > struct result_
94 {
95 typedef void_ type;
96 };
97};
98
99template< typename Map, long n > struct m_at
100{
101 typedef typename m_at_impl<n>::result_<Map>::type type;
102};
103
104# endif
105
106
107template<>
108struct at_impl< aux::map_tag >
109{
110 template< typename Map, typename Key > struct apply
111 {
112 typedef typename m_at< Map, (x_order_impl<Map,Key>::value - 2) >::type item_;
113 typedef typename eval_if<
114 is_void_<item_>
115 , void_
116 , second<item_>
117 >::type type;
118 };
119};
120
121template< typename Map, long order > struct is_item_masked
122{
123 BOOST_STATIC_CONSTANT(bool, value =
124 sizeof( BOOST_MPL_AUX_OVERLOAD_CALL_IS_MASKED(
125 Map
126 , BOOST_MPL_AUX_STATIC_CAST(long_<order>*, 0)
127 ) ) == sizeof(aux::yes_tag)
128 );
129};
130
131template< typename Map, long order > struct item_by_order
132{
133 typedef typename eval_if_c<
134 is_item_masked<Map,order>::value
135 , void_
136 , m_at<Map,(order - 2)>
137 >::type type;
138};
139
140#endif
141
142}}
143
144#endif // BOOST_MPL_SET_AUX_AT_IMPL_HPP_INCLUDED
145

source code of include/boost/mpl/map/aux_/at_impl.hpp