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

   1 [#one_char_except_c]
   2 [section one_char_except_c]
   3
   4 [h1 Synopsis]
   5
   6   template <char C1, char C2, /* ... */, char Cn>
   7   struct one_char_except_c;
   8
   9 This is a [link parser parser].
  10
  11 [table Arguments
  12   [[Name]       [Type]]
  13   [[`C1`..`Cn`] [character values]]
  14 ]
  15
  16 [h1 Description]
  17
  18 `one_char_except_c` 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_c` 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_c.hpp>
  30
  31 [h1 Expression semantics]
  32
  33 For any `s` compile-time string and `c1`, ..., `cn` characters the following are
  34 equivalent
  35
  36   one_char_except_c<c1, ..., cn>::apply<s, pos>
  37
  38   boost::metaparse::one_char::apply<s, pos>
  39
  40 when `s` is empty or it begins with a character other than `c1`, ..., `cn`.
  41 Otherwise `one_char_except_c<c1, ..., cn>::appl<s, pos>` returns a parsing
  42 error.
  43
  44 [h1 Example]
  45
  46   #include <boost/metaparse/one_char_except_c.hpp>
  47   #include <boost/metaparse/lit_c.hpp>
  48   #include <boost/metaparse/middle_of.hpp>
  49   #include <boost/metaparse/repeated.hpp>
  50   #include <boost/metaparse/start.hpp>
  51   #include <boost/metaparse/string.hpp>
  52   #include <boost/metaparse/get_result.hpp>
  53
  54   #include <boost/mpl/vector.hpp>
  55   #include <boost/mpl/char.hpp>
  56   #include <boost/mpl/equal.hpp>
  57
  58   using namespace boost::metaparse;
  59
  60   using string_literal_parser =
  61     middle_of<lit_c<'"'>, repeated<one_char_except_c<'"'>>, lit_c<'"'>>;
  62
  63   static_assert(
  64     boost::mpl::equal<
  65       boost::mpl::vector<
  66         boost::mpl::char_<'h'>,
  67         boost::mpl::char_<'e'>,
  68         boost::mpl::char_<'l'>,
  69         boost::mpl::char_<'l'>,
  70         boost::mpl::char_<'o'>
  71       >,
  72       get_result<
  73         string_literal_parser::apply<BOOST_METAPARSE_STRING("\"hello\""), start>
  74       >::type
  75     >::type::value,
  76     "it should return the content of the string literal"
  77   );
  78
  79 [endsect]
  80