ceph/src/boost/boost/mpl/if.hpp

   1
   2 #ifndef BOOST_MPL_IF_HPP_INCLUDED
   3 #define BOOST_MPL_IF_HPP_INCLUDED
   4
   5 // Copyright Aleksey Gurtovoy 2000-2004
   6 //
   7 // Distributed under the Boost Software License, Version 1.0.
   8 // (See accompanying file LICENSE_1_0.txt or copy at
   9 // http://www.boost.org/LICENSE_1_0.txt)
  10 //
  11 // See http://www.boost.org/libs/mpl for documentation.
  12
  13 // $Id$
  14 // $Date$
  15 // $Revision$
  16
  17 #include <boost/mpl/aux_/value_wknd.hpp>
  18 #include <boost/mpl/aux_/static_cast.hpp>
  19 #include <boost/mpl/aux_/na_spec.hpp>
  20 #include <boost/mpl/aux_/lambda_support.hpp>
  21 #include <boost/mpl/aux_/config/integral.hpp>
  22 #include <boost/mpl/aux_/config/ctps.hpp>
  23 #include <boost/mpl/aux_/config/workaround.hpp>
  24
  25 namespace boost { namespace mpl {
  26
  27 #if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
  28
  29 template<
  30       bool C
  31     , typename T1
  32     , typename T2
  33     >
  34 struct if_c
  35 {
  36     typedef T1 type;
  37 };
  38
  39 template<
  40       typename T1
  41     , typename T2
  42     >
  43 struct if_c<false,T1,T2>
  44 {
  45     typedef T2 type;
  46 };
  47
  48 // agurt, 05/sep/04: nondescriptive parameter names for the sake of DigitalMars
  49 // (and possibly MWCW < 8.0); see http://article.gmane.org/gmane.comp.lib.boost.devel/108959
  50 template<
  51       typename BOOST_MPL_AUX_NA_PARAM(T1)
  52     , typename BOOST_MPL_AUX_NA_PARAM(T2)
  53     , typename BOOST_MPL_AUX_NA_PARAM(T3)
  54     >
  55 struct if_
  56 {
  57  private:
  58     // agurt, 02/jan/03: two-step 'type' definition for the sake of aCC
  59     typedef if_c<
  60 #if defined(BOOST_MPL_CFG_BCC_INTEGRAL_CONSTANTS)
  61           BOOST_MPL_AUX_VALUE_WKND(T1)::value
  62 #else
  63           BOOST_MPL_AUX_STATIC_CAST(bool, BOOST_MPL_AUX_VALUE_WKND(T1)::value)
  64 #endif
  65         , T2
  66         , T3
  67         > almost_type_;
  68
  69  public:
  70     typedef typename almost_type_::type type;
  71
  72     BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(T1,T2,T3))
  73 };
  74
  75 #else
  76
  77 // no partial class template specialization
  78
  79 namespace aux {
  80
  81 template< bool C >
  82 struct if_impl
  83 {
  84     template< typename T1, typename T2 > struct result_
  85     {
  86         typedef T1 type;
  87     };
  88 };
  89
  90 template<>
  91 struct if_impl<false>
  92 {
  93     template< typename T1, typename T2 > struct result_
  94     {
  95         typedef T2 type;
  96     };
  97 };
  98
  99 } // namespace aux
 100
 101 template<
 102       bool C_
 103     , typename T1
 104     , typename T2
 105     >
 106 struct if_c
 107 {
 108     typedef typename aux::if_impl< C_ >
 109         ::template result_<T1,T2>::type type;
 110 };
 111
 112 // (almost) copy & paste in order to save one more
 113 // recursively nested template instantiation to user
 114 template<
 115       typename BOOST_MPL_AUX_NA_PARAM(C_)
 116     , typename BOOST_MPL_AUX_NA_PARAM(T1)
 117     , typename BOOST_MPL_AUX_NA_PARAM(T2)
 118     >
 119 struct if_
 120 {
 121     enum { msvc_wknd_ = BOOST_MPL_AUX_MSVC_VALUE_WKND(C_)::value };
 122
 123     typedef typename aux::if_impl< BOOST_MPL_AUX_STATIC_CAST(bool, msvc_wknd_) >
 124         ::template result_<T1,T2>::type type;
 125
 126     BOOST_MPL_AUX_LAMBDA_SUPPORT(3,if_,(C_,T1,T2))
 127 };
 128
 129 #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 130
 131 BOOST_MPL_AUX_NA_SPEC(3, if_)
 132
 133 }}
 134
 135 #endif // BOOST_MPL_IF_HPP_INCLUDED