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

   1 [#is_lcase_letter]
   2 [section is_lcase_letter]
   3
   4 [h1 Synopsis]
   5
   6   namespace util
   7   {
   8     template <class C>
   9     struct is_lcase_letter;
  10   }
  11
  12 This is a [link lazy_metafunction lazy template metafunction] that supports
  13 [link currying currying].
  14
  15 [table Arguments
  16   [[Name] [Type]]
  17   [[`C`]  [[link boxed_value boxed] character value]]
  18 ]
  19
  20 [h1 Description]
  21
  22 Checks if `C` is a lower case letter. Returns a boxed boolean value.
  23
  24 [h1 Header]
  25
  26   #include <boost/metaparse/util/is_lcase_letter.hpp>
  27
  28 [h1 Expression semantics]
  29
  30 The following expressions are equivalent:
  31
  32   is_lcase_letter<>::apply<boost::mpl::char_<'a'>>::type
  33   boost::mpl::true_
  34
  35   is_lcase_letter<>::apply<boost::mpl::char_<'z'>>::type
  36   boost::mpl::true_
  37
  38   is_lcase_letter<>::apply<c>::type
  39   boost::mpl::false_
  40
  41 [h1 Example]
  42
  43   #include <boost/metaparse/util/is_lcase_letter.hpp>
  44
  45   #include <type_traits>
  46
  47   using namespace boost::metaparse;
  48
  49   struct returns_char
  50   {
  51     using type = std::integral_constant<char, 'a'>;
  52   };
  53
  54   static_assert(
  55     util::is_lcase_letter<std::integral_constant<char, 'a'>>::type::value,
  56     "a should be a lower case letter"
  57   );
  58
  59   static_assert(
  60     !util::is_lcase_letter<std::integral_constant<char, 'A'>>::type::value,
  61     "A should not be a lower case letter"
  62   );
  63
  64   static_assert(
  65     util::is_lcase_letter<>::type
  66       ::apply<std::integral_constant<char, 'a'>>::type::value,
  67     "it should support currying"
  68   );
  69
  70   static_assert(
  71     util::is_lcase_letter<returns_char>::type::value,
  72     "it should support lazy evaluation"
  73   );
  74
  75
  76 [endsect]
  77