ceph/src/boost/boost/detail/is_incrementable.hpp

   1 // Copyright David Abrahams 2004. Use, modification and distribution is
   2 // subject to the Boost Software License, Version 1.0. (See accompanying
   3 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   4 #ifndef IS_INCREMENTABLE_DWA200415_HPP
   5 # define IS_INCREMENTABLE_DWA200415_HPP
   6
   7 # include <boost/type_traits/integral_constant.hpp>
   8 # include <boost/type_traits/remove_cv.hpp>
   9 # include <boost/mpl/aux_/lambda_support.hpp>
  10 # include <boost/mpl/bool.hpp>
  11 # include <boost/detail/workaround.hpp>
  12
  13 namespace boost { namespace detail {
  14
  15 // is_incrementable<T> metafunction
  16 //
  17 // Requires: Given x of type T&, if the expression ++x is well-formed
  18 // it must have complete type; otherwise, it must neither be ambiguous
  19 // nor violate access.
  20
  21 // This namespace ensures that ADL doesn't mess things up.
  22 namespace is_incrementable_
  23 {
  24   // a type returned from operator++ when no increment is found in the
  25   // type's own namespace
  26   struct tag {};
  27
  28   // any soaks up implicit conversions and makes the following
  29   // operator++ less-preferred than any other such operator that
  30   // might be found via ADL.
  31   struct any { template <class T> any(T const&); };
  32
  33   // This is a last-resort operator++ for when none other is found
  34 # if BOOST_WORKAROUND(__GNUC__, == 4) && __GNUC_MINOR__ == 0 && __GNUC_PATCHLEVEL__ == 2
  35
  36 }
  37
  38 namespace is_incrementable_2
  39 {
  40   is_incrementable_::tag operator++(is_incrementable_::any const&);
  41   is_incrementable_::tag operator++(is_incrementable_::any const&,int);
  42 }
  43 using namespace is_incrementable_2;
  44
  45 namespace is_incrementable_
  46 {
  47
  48 # else
  49
  50   tag operator++(any const&);
  51   tag operator++(any const&,int);
  52
  53 # endif
  54
  55 # if BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3202))
  56 #  define BOOST_comma(a,b) (a)
  57 # else
  58   // In case an operator++ is found that returns void, we'll use ++x,0
  59   tag operator,(tag,int);
  60 #  define BOOST_comma(a,b) (a,b)
  61 # endif
  62
  63 # if defined(BOOST_MSVC)
  64 #  pragma warning(push)
  65 #  pragma warning(disable:4913) // Warning about operator,
  66 # endif
  67
  68   // two check overloads help us identify which operator++ was picked
  69   char (& check_(tag) )[2];
  70
  71   template <class T>
  72   char check_(T const&);
  73
  74
  75   template <class T>
  76   struct impl
  77   {
  78       static typename boost::remove_cv<T>::type& x;
  79
  80       BOOST_STATIC_CONSTANT(
  81           bool
  82         , value = sizeof(is_incrementable_::check_(BOOST_comma(++x,0))) == 1
  83       );
  84   };
  85
  86   template <class T>
  87   struct postfix_impl
  88   {
  89       static typename boost::remove_cv<T>::type& x;
  90
  91       BOOST_STATIC_CONSTANT(
  92           bool
  93         , value = sizeof(is_incrementable_::check_(BOOST_comma(x++,0))) == 1
  94       );
  95   };
  96
  97 # if defined(BOOST_MSVC)
  98 #  pragma warning(pop)
  99 # endif
 100
 101 }
 102
 103 # undef BOOST_comma
 104
 105 template<typename T>
 106 struct is_incrementable :
 107     public boost::integral_constant<bool, boost::detail::is_incrementable_::impl<T>::value>
 108 {
 109     BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_incrementable,(T))
 110 };
 111
 112 template<typename T>
 113 struct is_postfix_incrementable :
 114     public boost::integral_constant<bool, boost::detail::is_incrementable_::postfix_impl<T>::value>
 115 {
 116     BOOST_MPL_AUX_LAMBDA_SUPPORT(1,is_postfix_incrementable,(T))
 117 };
 118
 119 } // namespace detail
 120
 121 } // namespace boost
 122
 123 # include <boost/type_traits/detail/bool_trait_undef.hpp>
 124
 125 #endif // IS_INCREMENTABLE_DWA200415_HPP