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

   1 [#get_line]
   2 [section get_line]
   3
   4 [h1 Synopsis]
   5
   6   template <class SourcePosition>
   7   struct get_line;
   8
   9 This is a [link lazy_metafunction lazy template metafunction].
  10
  11 [table Arguments
  12   [[Name]             [Type]]
  13   [[`SourcePosition`] [[link source_position source position]]]
  14 ]
  15
  16 [h1 Description]
  17
  18 Returns the line of a source position.
  19
  20 [h1 Header]
  21
  22   #include <boost/metaparse/get_line.hpp>
  23
  24 [h1 Expression semantics]
  25
  26 For any `l`, `c` compile-time wrapped integral values and `ch` compile-time
  27 wrapped character the following are equivalent
  28
  29   get_line<source_position<l, c, ch>>::type
  30
  31   l::type
  32
  33 [h1 Example]
  34
  35   #include <boost/metaparse/get_line.hpp>
  36   #include <boost/metaparse/source_position.hpp>
  37
  38   #include <type_traits>
  39
  40   using namespace boost::metaparse;
  41
  42   struct returns_source_position
  43   {
  44     using type =
  45       source_position<
  46         std::integral_constant<int, 11>,
  47         std::integral_constant<int, 13>,
  48         std::integral_constant<char, 0>
  49       >;
  50   };
  51
  52   static_assert(
  53     get_line<
  54       source_position<
  55         std::integral_constant<int, 11>,
  56         std::integral_constant<int, 13>,
  57         std::integral_constant<char, 0>
  58       >
  59     >::type::value == 11,
  60     "It should return the line of a source position"
  61   );
  62
  63   static_assert(
  64     get_line<returns_source_position>::type::value == 11,
  65     "It should support lazy evaluation"
  66   );
  67
  68
  69 [endsect]
  70