ceph/src/boost/boost/parameter/aux_/default.hpp

   1 // Copyright Daniel Wallin, David Abrahams 2005.
   2 // Copyright Cromwell D. Enage 2017.
   3 // Distributed under the Boost Software License, Version 1.0.
   4 // (See accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6
   7 #ifndef BOOST_PARAMETER_AUX_DEFAULT_HPP
   8 #define BOOST_PARAMETER_AUX_DEFAULT_HPP
   9
  10 namespace boost { namespace parameter { namespace aux {
  11
  12     // A wrapper for the default value passed by the user when resolving
  13     // the value of the parameter with the given Keyword
  14     template <typename Keyword, typename Value>
  15     struct default_
  16     {
  17         inline BOOST_CONSTEXPR default_(Value& x) : value(x)
  18         {
  19         }
  20
  21         Value& value;
  22     };
  23 }}} // namespace boost::parameter::aux
  24
  25 #include <boost/parameter/config.hpp>
  26
  27 namespace boost { namespace parameter { namespace aux {
  28
  29     // lazy_default -- A wrapper for the default value computation function
  30     // passed by the user when resolving the value of the parameter with the
  31     // given keyword.
  32 #if BOOST_WORKAROUND(__EDG_VERSION__, <= 300)
  33     // These compilers need a little extra help with overload resolution;
  34     // we have empty_arg_list's operator[] accept a base class
  35     // to make that overload less preferable.
  36     template <typename KW, typename DefaultComputer>
  37     struct lazy_default_base
  38     {
  39         inline BOOST_CONSTEXPR lazy_default_base(DefaultComputer& x)
  40           : compute_default(x)
  41         {
  42         }
  43
  44         DefaultComputer& compute_default;
  45     };
  46
  47     template <typename KW, typename DefaultComputer>
  48     struct lazy_default
  49       : ::boost::parameter::aux::lazy_default_base<KW,DefaultComputer>
  50     {
  51         inline BOOST_CONSTEXPR lazy_default(DefaultComputer& x)
  52           : ::boost::parameter::aux::lazy_default_base<KW,DefaultComputer>(x)
  53         {
  54         }
  55     };
  56 #else   // !BOOST_WORKAROUND(__EDG_VERSION__, <= 300)
  57     template <typename KW, typename DefaultComputer>
  58     struct lazy_default
  59     {
  60         inline BOOST_CONSTEXPR lazy_default(DefaultComputer& x)
  61           : compute_default(x)
  62         {
  63         }
  64
  65         DefaultComputer& compute_default;
  66     };
  67 #endif  // EDG workarounds needed.
  68 }}} // namespace boost::parameter::aux
  69
  70 #if BOOST_WORKAROUND(__EDG_VERSION__, <= 300)
  71 #define BOOST_PARAMETER_lazy_default_fallback \
  72     ::boost::parameter::aux::lazy_default_base
  73 /**/
  74 #else
  75 #define BOOST_PARAMETER_lazy_default_fallback \
  76     ::boost::parameter::aux::lazy_default
  77 /**/
  78 #endif
  79
  80 #if defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
  81
  82 #include <utility>
  83
  84 namespace boost { namespace parameter { namespace aux {
  85
  86     template <typename Keyword, typename Value>
  87     struct default_r_
  88     {
  89         inline BOOST_CONSTEXPR default_r_(Value&& x)
  90           : value(::std::forward<Value>(x))
  91         {
  92         }
  93
  94         Value&& value;
  95     };
  96 }}} // namespace boost::parameter::aux
  97
  98 #endif  // BOOST_PARAMETER_HAS_PERFECT_FORWARDING
  99 #endif  // include guard
 100