ceph/src/boost/libs/metaparse/doc/in_range.qbk

   1 [#in_range]
   2 [section in_range]
   3
   4 [h1 Synopsis]
   5
   6   namespace util
   7   {
   8     template <class LowerBound, class UpperBound, class Item>
   9     struct in_range;
  10   }
  11
  12 This is a [link metafunction template metafunction] supporting
  13 [link currying currying].
  14
  15 [table Arguments
  16   [[Name]         [Type]]
  17   [[`LowerBound`] [[link boxed_value boxed integral value]]]
  18   [[`UpperBound`] [[link boxed_value boxed integral value]]]
  19   [[`Item`]       [[link boxed_value boxed integral value]]]
  20 ]
  21
  22 [h1 Description]
  23
  24 It returns a boxed boolean value. The value is `true` when `Item` is in the
  25 range `[LowerBound..UpperBound]` and `false` otherwise. `boost::mpl::less_equal`
  26 is used for comparison.
  27
  28 [h1 Header]
  29
  30   #include <boost/metaparse/util/in_range.hpp>
  31
  32 [h1 Expression semantics]
  33
  34 For any `L`, `U` and `T` classes the following are equivalent:
  35
  36   in_range<L, U>::apply<T>::type::value
  37
  38   boost::mpl::less_equal<L, T>::type::value
  39     && boost::mpl::less_equal<T, U>::type::value
  40
  41 [h1 Example]
  42
  43   #include <boost/metaparse/util/in_range.hpp>
  44
  45   #include <boost/mpl/int.hpp>
  46
  47   using namespace boost::metaparse;
  48
  49   static_assert(
  50     !util::in_range<
  51       boost::mpl::int_<11>,
  52       boost::mpl::int_<13>,
  53       boost::mpl::int_<10>
  54     >::type::value,
  55     "A value below the lower bound should not be in the range"
  56   );
  57
  58   static_assert(
  59     !util::in_range<
  60       boost::mpl::int_<11>,
  61       boost::mpl::int_<13>,
  62       boost::mpl::int_<14>
  63     >::type::value,
  64     "A value above the upper bound should not be in the range"
  65   );
  66
  67   static_assert(
  68     util::in_range<
  69       boost::mpl::int_<11>,
  70       boost::mpl::int_<13>,
  71       boost::mpl::int_<11>
  72     >::type::value,
  73     "The lower bound should be in the range"
  74   );
  75
  76   static_assert(
  77     util::in_range<
  78       boost::mpl::int_<11>,
  79       boost::mpl::int_<13>,
  80       boost::mpl::int_<13>
  81     >::type::value,
  82     "The upper bound should be in the range"
  83   );
  84
  85   static_assert(
  86     util::in_range<
  87       boost::mpl::int_<11>,
  88       boost::mpl::int_<13>,
  89       boost::mpl::int_<12>
  90     >::type::value,
  91     "A value between the bounds should be in the range"
  92   );
  93
  94   static_assert(
  95     util::in_range<>
  96       ::apply<boost::mpl::int_<11>>::type
  97       ::apply<boost::mpl::int_<13>>::type
  98       ::apply<boost::mpl::int_<12>>::type
  99       ::type::value,
 100     "It should support currying"
 101   );
 102
 103 [endsect]
 104