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

   1 [#build_parser]
   2 [section build_parser]
   3
   4 [h1 Synopsis]
   5
   6   template <class P>
   7   struct build_parser;
   8
   9 This is a [link metafunction template metafunction].
  10
  11 [table Arguments
  12   [[Name] [Type]]
  13   [[`P`]  [[link parser parser]]]
  14 ]
  15
  16 [h1 Description]
  17
  18 It generates a simple interface for parser. It returns a metafunction class that
  19 takes an input string, parses it with `P` and returns the result of parsing. It
  20 generates a compilation error when parsing fails.
  21
  22 [h1 Return value]
  23
  24 It returns a [link metafunction_class template metafunction class]:
  25
  26   struct
  27   {
  28     template <class S>
  29     struct apply;
  30   };
  31
  32 [table Arguments
  33   [[Name] [Type]]
  34   [[`S`] [[link string string]]]
  35 ]
  36
  37 [h1 Header]
  38
  39   #include <boost/metaparse/build_parser.hpp>
  40
  41 [h1 Expression semantics]
  42
  43 For any `p` parser and `s` compile-time string
  44
  45   build_parser<p>::type::apply<s>
  46
  47 is equivalent to
  48
  49   get_result<p::apply<s>>
  50
  51 [h1 Example]
  52
  53   #include <boost/metaparse/build_parser.hpp>
  54   #include <boost/metaparse/int_.hpp>
  55   #include <boost/metaparse/string.hpp>
  56
  57   using namespace boost::metaparse;
  58
  59   using string_to_int = build_parser<int_>::type;
  60
  61   static_assert(
  62     string_to_int::apply<BOOST_METAPARSE_STRING("1113")>::type::value == 1113,
  63     "string_to_int should be a metafunction turning a string into an int"
  64   );
  65
  66 [endsect]
  67