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Jeff Thompson86b6d642013-10-17 15:01:56 -07001// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
2// (C) Copyright 2003-2007 Jonathan Turkanis
3// Distributed under the Boost Software License, Version 1.0. (See accompanying
4// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
5
6// See http://www.boost.org/libs/iostreams for documentation.
7
8// Contains the metafunction select, which mimics the effect of a chain of
9// nested mpl if_'s.
10//
11// -----------------------------------------------------------------------------
12//
13// Usage:
14//
15// typedef typename select<
16// case1, type1,
17// case2, type2,
18// ...
19// true_, typen
20// >::type selection;
21//
22// Here case1, case2, ... are models of MPL::IntegralConstant with value type
23// bool, and n <= 12.
24
25#ifndef NDNBOOST_IOSTREAMS_SELECT_HPP_INCLUDED
26#define NDNBOOST_IOSTREAMS_SELECT_HPP_INCLUDED
27
28#if defined(_MSC_VER) && (_MSC_VER >= 1020)
29# pragma once
30#endif
31
32#include <ndnboost/type_traits/is_base_and_derived.hpp>
33#include <ndnboost/mpl/eval_if.hpp>
34#include <ndnboost/mpl/identity.hpp>
35#include <ndnboost/mpl/if.hpp>
36#include <ndnboost/mpl/void.hpp>
37
38namespace ndnboost { namespace iostreams {
39
40typedef mpl::true_ else_;
41
42template< typename Case1 = mpl::true_,
43 typename Type1 = mpl::void_,
44 typename Case2 = mpl::true_,
45 typename Type2 = mpl::void_,
46 typename Case3 = mpl::true_,
47 typename Type3 = mpl::void_,
48 typename Case4 = mpl::true_,
49 typename Type4 = mpl::void_,
50 typename Case5 = mpl::true_,
51 typename Type5 = mpl::void_,
52 typename Case6 = mpl::true_,
53 typename Type6 = mpl::void_,
54 typename Case7 = mpl::true_,
55 typename Type7 = mpl::void_,
56 typename Case8 = mpl::true_,
57 typename Type8 = mpl::void_,
58 typename Case9 = mpl::true_,
59 typename Type9 = mpl::void_,
60 typename Case10 = mpl::true_,
61 typename Type10 = mpl::void_,
62 typename Case11 = mpl::true_,
63 typename Type11 = mpl::void_,
64 typename Case12 = mpl::true_,
65 typename Type12 = mpl::void_ >
66struct select {
67 typedef typename
68 mpl::eval_if<
69 Case1, mpl::identity<Type1>, mpl::eval_if<
70 Case2, mpl::identity<Type2>, mpl::eval_if<
71 Case3, mpl::identity<Type3>, mpl::eval_if<
72 Case4, mpl::identity<Type4>, mpl::eval_if<
73 Case5, mpl::identity<Type5>, mpl::eval_if<
74 Case6, mpl::identity<Type6>, mpl::eval_if<
75 Case7, mpl::identity<Type7>, mpl::eval_if<
76 Case8, mpl::identity<Type8>, mpl::eval_if<
77 Case9, mpl::identity<Type9>, mpl::eval_if<
78 Case10, mpl::identity<Type10>, mpl::eval_if<
79 Case11, mpl::identity<Type11>, mpl::if_<
80 Case12, Type12, mpl::void_ > > > > > > > > > > >
81 >::type type;
82};
83
84} } // End namespaces iostreams, boost.
85
86#endif // #ifndef NDNBOOST_IOSTREAMS_SELECT_HPP_INCLUDED