ceph/src/boost/libs/metaparse/example/binary_number/main.cpp

   1 // Copyright Abel Sinkovics (abel@sinkovics.hu)  2011.
   2 // Distributed under the Boost Software License, Version 1.0.
   3 //    (See accompanying file LICENSE_1_0.txt or copy at
   4 //          http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #include <boost/metaparse/foldl1.hpp>
   7 #include <boost/metaparse/build_parser.hpp>
   8 #include <boost/metaparse/transform.hpp>
   9 #include <boost/metaparse/one_of_c.hpp>
  10 #include <boost/metaparse/entire_input.hpp>
  11 #include <boost/metaparse/string.hpp>
  12
  13 #include <boost/metaparse/util/digit_to_int.hpp>
  14
  15 #include <boost/mpl/int.hpp>
  16 #include <boost/mpl/plus.hpp>
  17 #include <boost/mpl/times.hpp>
  18
  19 #include <iostream>
  20
  21 using boost::metaparse::foldl1;
  22 using boost::metaparse::build_parser;
  23 using boost::metaparse::transform;
  24 using boost::metaparse::one_of_c;
  25 using boost::metaparse::entire_input;
  26
  27 using boost::metaparse::util::digit_to_int;
  28
  29 using boost::mpl::int_;
  30 using boost::mpl::plus;
  31 using boost::mpl::times;
  32
  33 /*
  34  * The grammar
  35  *
  36  * expression ::= ('1' | '0')*
  37  */
  38
  39 struct next_element
  40 {
  41   template <class Acc, class B>
  42   struct apply : plus<times<Acc, int_<2> >, B> {};
  43 };
  44
  45 typedef
  46   foldl1<transform<one_of_c<'0', '1'>, digit_to_int<> >, int_<0>, next_element>
  47   S;
  48
  49 typedef build_parser<entire_input<S> > binary_parser;
  50
  51 template <class S>
  52 struct binary : binary_parser::apply<S>::type {};
  53
  54 #ifdef _STR
  55 #  error _STR already defined
  56 #endif
  57 #define _STR BOOST_METAPARSE_STRING
  58
  59 #if BOOST_METAPARSE_STD < 2011
  60
  61 int main()
  62 {
  63   using std::cout;
  64   using std::endl;
  65   using boost::metaparse::string;
  66
  67   cout
  68     << binary<string<'1','0','0'> >::value << endl
  69     << binary<string<'1','0','1','1'> >::value << endl
  70     << binary<string<'1'> >::value << endl;
  71 }
  72 #else
  73 int main()
  74 {
  75   using std::cout;
  76   using std::endl;
  77
  78   cout
  79     << binary<_STR("100")>::value << endl
  80     << binary<_STR("1011")>::value << endl
  81     << binary<_STR("1")>::value << endl;
  82 }
  83 #endif
  84
  85