EQ2EMu/EQ2/source/depends/boost_1_72_0/libs/metaparse/doc/int_to_digit.qbk

[#int_to_digit]
[section int_to_digit]

[h1 Synopsis]

  namespace util
  {
    template <class D>
    struct int_to_digit;
  }

This is a [link lazy_metafunction lazy template metafunction] that supports
[link currying currying].

[table Arguments
  [[Name] [Type]]
  [[`D`]  [[link boxed_value boxed] integer value]]
]

[h1 Description]

Converts a boxed integer value in the range `[0-9]` to a character representing
that decimal value.

[h1 Header]

  #include <boost/metaparse/util/int_to_digit.hpp>

[h1 Expression semantics]

The following pairs of expressions are equivalent

  int_to_digit<boost::mpl::int_<0>>::type
  boost::mpl::char_<'0'>

  int_to_digit<boost::mpl::int_<9>>::type
  boost::mpl::char_<'9'>

[h1 Example]

  #include <boost/metaparse/util/int_to_digit.hpp>
  
  #include <type_traits>
  
  using namespace boost::metaparse;
  
  struct nullary_metafunction_returning_4
  {
    using type = std::integral_constant<int, 4>;
  };
  
  static_assert(
    util::int_to_digit<std::integral_constant<int, 0>>::type::value == '0',
    "it should convert an integer value to the corresponding character"
  );
  
  static_assert(
    util::int_to_digit<>::type
      ::apply<std::integral_constant<int, 7>>::type::value == '7',
    "it should support currying"
  );
  
  static_assert(
    util::int_to_digit<nullary_metafunction_returning_4>::type::value == '4',
    "it should support lazy evaluation"
  );

[endsect]