1
2#if !defined(BOOST_PP_IS_ITERATING)
3
4///// header body
5
6#ifndef BOOST_MPL_INHERIT_HPP_INCLUDED
7#define BOOST_MPL_INHERIT_HPP_INCLUDED
8
9// Copyright Aleksey Gurtovoy 2001-2004
10//
11// Distributed under the Boost Software License, Version 1.0.
12// (See accompanying file LICENSE_1_0.txt or copy at
13// http://www.boost.org/LICENSE_1_0.txt)
14//
15// See http://www.boost.org/libs/mpl for documentation.
16
17// $Id$
18// $Date$
19// $Revision$
20
21#if !defined(BOOST_MPL_PREPROCESSING_MODE)
22# include <boost/mpl/empty_base.hpp>
23# include <boost/mpl/aux_/na_spec.hpp>
24# include <boost/mpl/aux_/lambda_support.hpp>
25#endif
26
27#include <boost/mpl/aux_/config/use_preprocessed.hpp>
28
29#if !defined(BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS) \
30 && !defined(BOOST_MPL_PREPROCESSING_MODE)
31
32# define BOOST_MPL_PREPROCESSED_HEADER inherit.hpp
33# include <boost/mpl/aux_/include_preprocessed.hpp>
34
35#else
36
37# include <boost/mpl/limits/arity.hpp>
38# include <boost/mpl/aux_/preprocessor/params.hpp>
39# include <boost/mpl/aux_/preprocessor/default_params.hpp>
40# include <boost/mpl/aux_/preprocessor/enum.hpp>
41# include <boost/mpl/aux_/config/ctps.hpp>
42# include <boost/mpl/aux_/config/dtp.hpp>
43
44# include <boost/preprocessor/iterate.hpp>
45# include <boost/preprocessor/dec.hpp>
46# include <boost/preprocessor/cat.hpp>
47
48namespace boost { namespace mpl {
49
50// 'inherit<T1,T2,..,Tn>' metafunction; returns an unspecified class type
51// produced by public derivation from all metafunction's parameters
52// (T1,T2,..,Tn), except the parameters of 'empty_base' class type;
53// regardless the position and number of 'empty_base' parameters in the
54// metafunction's argument list, derivation from them is always a no-op;
55// for instance:
56// inherit<her>::type == her
57// inherit<her,my>::type == struct unspecified : her, my {};
58// inherit<empty_base,her>::type == her
59// inherit<empty_base,her,empty_base,empty_base>::type == her
60// inherit<her,empty_base,my>::type == struct unspecified : her, my {};
61// inherit<empty_base,empty_base>::type == empty_base
62
63#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
64
65template<
66 typename BOOST_MPL_AUX_NA_PARAM(T1)
67 , typename BOOST_MPL_AUX_NA_PARAM(T2)
68 >
69struct inherit2
70 : T1, T2
71{
72 typedef inherit2 type;
73 BOOST_MPL_AUX_LAMBDA_SUPPORT(2, inherit2, (T1,T2))
74};
75
76template< typename T1 >
77struct inherit2<T1,empty_base>
78{
79 typedef T1 type;
80 BOOST_MPL_AUX_LAMBDA_SUPPORT_SPEC(2, inherit2, (T1,empty_base))
81};
82
83template< typename T2 >
84struct inherit2<empty_base,T2>
85{
86 typedef T2 type;
87 BOOST_MPL_AUX_LAMBDA_SUPPORT_SPEC(2, inherit2, (empty_base,T2))
88};
89
90// needed to disambiguate the previous two in case when both
91// T1 and T2 == empty_base
92template<>
93struct inherit2<empty_base,empty_base>
94{
95 typedef empty_base type;
96 BOOST_MPL_AUX_LAMBDA_SUPPORT_SPEC(2, inherit2, (empty_base,empty_base))
97};
98
99#else
100
101namespace aux {
102
103template< bool C1, bool C2 >
104struct inherit2_impl
105{
106 template< typename Derived, typename T1, typename T2 > struct result_
107 : T1, T2
108 {
109 typedef Derived type_;
110 };
111};
112
113template<>
114struct inherit2_impl<false,true>
115{
116 template< typename Derived, typename T1, typename T2 > struct result_
117 : T1
118 {
119 typedef T1 type_;
120 };
121};
122
123template<>
124struct inherit2_impl<true,false>
125{
126 template< typename Derived, typename T1, typename T2 > struct result_
127 : T2
128 {
129 typedef T2 type_;
130 };
131};
132
133template<>
134struct inherit2_impl<true,true>
135{
136 template< typename Derived, typename T1, typename T2 > struct result_
137 {
138 typedef T1 type_;
139 };
140};
141
142} // namespace aux
143
144template<
145 typename BOOST_MPL_AUX_NA_PARAM(T1)
146 , typename BOOST_MPL_AUX_NA_PARAM(T2)
147 >
148struct inherit2
149 : aux::inherit2_impl<
150 is_empty_base<T1>::value
151 , is_empty_base<T2>::value
152 >::template result_< inherit2<T1,T2>,T1,T2 >
153{
154 typedef typename inherit2::type_ type;
155 BOOST_MPL_AUX_LAMBDA_SUPPORT(2, inherit2, (T1,T2))
156};
157
158#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
159
160BOOST_MPL_AUX_NA_SPEC(2, inherit2)
161
162#define BOOST_PP_ITERATION_PARAMS_1 \
163 (3,(3, BOOST_MPL_LIMIT_METAFUNCTION_ARITY, <boost/mpl/inherit.hpp>))
164#include BOOST_PP_ITERATE()
165
166}}
167
168#endif // BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS
169#endif // BOOST_MPL_INHERIT_HPP_INCLUDED
170
171///// iteration
172
173#else
174#define n_ BOOST_PP_FRAME_ITERATION(1)
175
176template<
177 BOOST_MPL_PP_DEFAULT_PARAMS(n_, typename T, na)
178 >
179struct BOOST_PP_CAT(inherit,n_)
180 : inherit2<
181 typename BOOST_PP_CAT(inherit,BOOST_PP_DEC(n_))<
182 BOOST_MPL_PP_PARAMS(BOOST_PP_DEC(n_), T)
183 >::type
184 , BOOST_PP_CAT(T,n_)
185 >
186{
187 BOOST_MPL_AUX_LAMBDA_SUPPORT(
188 n_
189 , BOOST_PP_CAT(inherit,n_)
190 , (BOOST_MPL_PP_PARAMS(n_, T))
191 )
192};
193
194BOOST_MPL_AUX_NA_SPEC(n_, BOOST_PP_CAT(inherit,n_))
195
196#if n_ == BOOST_MPL_LIMIT_METAFUNCTION_ARITY
197/// primary template
198template<
199 BOOST_MPL_PP_DEFAULT_PARAMS(n_, typename T, empty_base)
200 >
201struct inherit
202 : BOOST_PP_CAT(inherit,n_)<BOOST_MPL_PP_PARAMS(n_, T)>
203{
204};
205
206// 'na' specialization
207template<>
208struct inherit< BOOST_MPL_PP_ENUM(5, na) >
209{
210 template<
211#if !defined(BOOST_MPL_CFG_NO_DEFAULT_PARAMETERS_IN_NESTED_TEMPLATES)
212 BOOST_MPL_PP_DEFAULT_PARAMS(n_, typename T, empty_base)
213#else
214 BOOST_MPL_PP_PARAMS(n_, typename T)
215#endif
216 >
217 struct apply
218 : inherit< BOOST_MPL_PP_PARAMS(n_, T) >
219 {
220 };
221};
222
223BOOST_MPL_AUX_NA_SPEC_LAMBDA(n_, inherit)
224BOOST_MPL_AUX_NA_SPEC_ARITY(n_, inherit)
225BOOST_MPL_AUX_NA_SPEC_TEMPLATE_ARITY(n_, n_, inherit)
226#endif
227
228#undef n_
229#endif // BOOST_PP_IS_ITERATING
230

source code of include/boost/mpl/inherit.hpp