bump version to 12.2.2-pve1

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

[#entire_input]
[section entire_input]

[h1 Synopsis]

  template <class P, class Msg = error::end_of_input_expected>
  struct entire_input;

This is a [link parser_combinator parser combinator].

[table Arguments
  [[Name]  [Type]]
  [[`P`]   [[link parser parser]]]
  [[`Msg`] [[link parsing_error_message parsing error message]]]
]

[h1 Description]

It parses the input using `P` and checks if it consumes the entire input. If `P`
fails or doesn't consume the entire input, `entire_input` fails. Otherwise
`entire_input` returns the result of `P`. When `P` does not consume the entire
input, the error message returned by `entire_input` is `Msg`.

[h1 Header]

  #include <boost/metaparse/entire_input.hpp>

[h1 Expression semantics]

For any `p` parser and `e` parsing error message the following are equivalent

  entire_input<p, e>
  
  first_of<
    p,
    change_error_message<empty</* some metaprogramming value */>, e>
  >

[h1 Example]

  #include <boost/metaparse/entire_input.hpp>
  #include <boost/metaparse/int_.hpp>
  #include <boost/metaparse/string.hpp>
  #include <boost/metaparse/start.hpp>
  #include <boost/metaparse/get_result.hpp>
  #include <boost/metaparse/get_message.hpp>
  #include <boost/metaparse/define_error.hpp>
  
  using namespace boost::metaparse;
  
  BOOST_METAPARSE_DEFINE_ERROR(extra_chars_at_end, "Extra chars at end");
  
  using int_parser = entire_input<int_, extra_chars_at_end>;
  
  static_assert(
    get_result<
      int_parser::apply<BOOST_METAPARSE_STRING("1113"), start>
    >::type::value == 1113,
    "it should parse the input if it contains only an integer"
  );
  
  static_assert(
    std::is_same<
      get_message<
        int_parser::apply<BOOST_METAPARSE_STRING("1113mm"), start>
      >::type,
      extra_chars_at_end
    >::type::value,
    "it should return the specified error message when there are extra characters"
  );

[endsect]