bump version to 12.2.2-pve1

[ceph.git] / ceph / src / boost / libs / metaparse / doc / range.qbk

[#range]
[section range]

[h1 Synopsis]

  template <class From, class To>
  struct range;

This is a [link parser parser].

[table Arguments
  [[Name]   [Type]]
  [[`From`] [[link boxed_value boxed] character value]]
  [[`To`]   [[link boxed_value boxed] character value]]
]

[h1 Description]

`range` accepts one character in the range `[From..To]`. The result of the
parser is the accepted character.

[h1 Header]

  #include <boost/metaparse/range.hpp>

[h1 Expression semantics]

For any `A`, `B` wrapped characters the following are equivalent:

  range<A, B>
  
  accept_when<one_char, util::in_range<A, B>, errors::unexpected_character>

[h1 Example]

  #include <boost/metaparse/range.hpp>
  #include <boost/metaparse/start.hpp>
  #include <boost/metaparse/string.hpp>
  #include <boost/metaparse/is_error.hpp>
  #include <boost/metaparse/get_result.hpp>
  
  #include <type_traits>
  
  using namespace boost::metaparse;
  
  using one_digit =
    range<std::integral_constant<char, '0'>, std::integral_constant<char, '9'>>;
  
  static_assert(
    !is_error<one_digit::apply<BOOST_METAPARSE_STRING("0"), start>>::type::value,
    "one_digit should accept a digit"
  );
  
  static_assert(
    is_error<one_digit::apply<BOOST_METAPARSE_STRING("x"), start>>::type::value,
    "one_digit should reject a value outside of ['0'..'9']"
  );
  
  static_assert(
    get_result<
      one_digit::apply<BOOST_METAPARSE_STRING("0"), start>
    >::type::value == '0',
    "the result of parsing should be the character value"
  );

[endsect]