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/Src/Dependencies/Boost/boost/iostreams/detail/select.hpp

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 1// (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 BOOST_IOSTREAMS_SELECT_HPP_INCLUDED
26#define BOOST_IOSTREAMS_SELECT_HPP_INCLUDED   
27
28#if defined(_MSC_VER) && (_MSC_VER >= 1020)
29# pragma once
30#endif                  
31 
32#include <boost/type_traits/is_base_and_derived.hpp>
33#include <boost/mpl/eval_if.hpp>
34#include <boost/mpl/identity.hpp>
35#include <boost/mpl/if.hpp>
36#include <boost/mpl/void.hpp>
37
38namespace boost { 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 BOOST_IOSTREAMS_SELECT_HPP_INCLUDED