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

   1 [#one_char_except]
   2 [section one_char_except]
   3
   4 [h1 Synopsis]
   5
   6   template <class C1, class C2, /* ... */, class Cn>
   7   struct one_char_except;
   8
   9 This is a [link parser parser].
  10
  11 [table Arguments
  12   [[Name]       [Type]]
  13   [[`C1`..`Cn`] [[link boxed_value boxed] character values]]
  14 ]
  15
  16 [h1 Description]
  17
  18 `one_char_except` accepts one character except any of `C1` ... `Cn`. When the
  19 input is empty or begins with one of the non-accepted characters,
  20 `one_char_except` rejects the input. Otherwise it accepts the input and the
  21 result of parsing is the character value.
  22
  23 The maximum number of template arguments this class can have is the value the
  24 macro `BOOST_METAPARSE_LIMIT_ONE_CHAR_EXCEPT_SIZE` expands to. Its default value
  25 is 10.
  26
  27 [h1 Header]
  28
  29   #include <boost/metaparse/one_char_except.hpp>
  30
  31 [h1 Expression semantics]
  32
  33 For any `c1`, ..., `cn` boxed characters the following are equivalent
  34
  35   one_char_except<c1, ..., cn>
  36
  37   one_char_except_c<c1::type::value, ..., cn::type::value>
  38
  39 [h1 Example]
  40
  41   #include <boost/metaparse/one_char_except.hpp>
  42   #include <boost/metaparse/lit_c.hpp>
  43   #include <boost/metaparse/middle_of.hpp>
  44   #include <boost/metaparse/repeated.hpp>
  45   #include <boost/metaparse/start.hpp>
  46   #include <boost/metaparse/string.hpp>
  47   #include <boost/metaparse/get_result.hpp>
  48
  49   #include <boost/mpl/vector.hpp>
  50   #include <boost/mpl/char.hpp>
  51   #include <boost/mpl/equal.hpp>
  52
  53   #include <type_traits>
  54
  55   using namespace boost::metaparse;
  56
  57   using string_literal_parser =
  58     middle_of<
  59       lit_c<'"'>,
  60       repeated<one_char_except<std::integral_constant<char, '"'>>>,
  61       lit_c<'"'>
  62     >;
  63
  64   static_assert(
  65     boost::mpl::equal<
  66       boost::mpl::vector<
  67         boost::mpl::char_<'h'>,
  68         boost::mpl::char_<'e'>,
  69         boost::mpl::char_<'l'>,
  70         boost::mpl::char_<'l'>,
  71         boost::mpl::char_<'o'>
  72       >,
  73       get_result<
  74         string_literal_parser::apply<BOOST_METAPARSE_STRING("\"hello\""), start>
  75       >::type
  76     >::type::value,
  77     "it should return the content of the string literal"
  78   );
  79
  80 [endsect]
  81