ceph/src/boost/libs/metaparse/example/calculator/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/repeated.hpp>
   7 #include <boost/metaparse/sequence.hpp>
   8 #include <boost/metaparse/lit_c.hpp>
   9 #include <boost/metaparse/last_of.hpp>
  10 #include <boost/metaparse/first_of.hpp>
  11 #include <boost/metaparse/space.hpp>
  12 #include <boost/metaparse/int_.hpp>
  13 #include <boost/metaparse/foldl_reject_incomplete_start_with_parser.hpp>
  14 #include <boost/metaparse/one_of.hpp>
  15 #include <boost/metaparse/get_result.hpp>
  16 #include <boost/metaparse/token.hpp>
  17 #include <boost/metaparse/entire_input.hpp>
  18 #include <boost/metaparse/string.hpp>
  19 #include <boost/metaparse/build_parser.hpp>
  20
  21 #include <boost/mpl/apply_wrap.hpp>
  22 #include <boost/mpl/fold.hpp>
  23 #include <boost/mpl/front.hpp>
  24 #include <boost/mpl/back.hpp>
  25 #include <boost/mpl/plus.hpp>
  26 #include <boost/mpl/minus.hpp>
  27 #include <boost/mpl/times.hpp>
  28 #include <boost/mpl/divides.hpp>
  29 #include <boost/mpl/bool.hpp>
  30 #include <boost/mpl/equal_to.hpp>
  31 #include <boost/mpl/eval_if.hpp>
  32 #include <boost/mpl/bool.hpp>
  33
  34 using boost::metaparse::sequence;
  35 using boost::metaparse::lit_c;
  36 using boost::metaparse::last_of;
  37 using boost::metaparse::first_of;
  38 using boost::metaparse::space;
  39 using boost::metaparse::repeated;
  40 using boost::metaparse::build_parser;
  41 using boost::metaparse::int_;
  42 using boost::metaparse::foldl_reject_incomplete_start_with_parser;
  43 using boost::metaparse::get_result;
  44 using boost::metaparse::one_of;
  45 using boost::metaparse::token;
  46 using boost::metaparse::entire_input;
  47
  48 using boost::mpl::apply_wrap1;
  49 using boost::mpl::fold;
  50 using boost::mpl::front;
  51 using boost::mpl::back;
  52 using boost::mpl::plus;
  53 using boost::mpl::minus;
  54 using boost::mpl::times;
  55 using boost::mpl::divides;
  56 using boost::mpl::eval_if;
  57 using boost::mpl::bool_;
  58 using boost::mpl::equal_to;
  59 using boost::mpl::bool_;
  60
  61 /*
  62  * The grammar
  63  *
  64  * expression ::= plus_exp
  65  * plus_exp ::= prod_exp ((plus_token | minus_token) prod_exp)*
  66  * prod_exp ::= int_token ((mult_token | div_token) int_token)*
  67  */
  68
  69 typedef token<lit_c<'+'> > plus_token;
  70 typedef token<lit_c<'-'> > minus_token;
  71 typedef token<lit_c<'*'> > mult_token;
  72 typedef token<lit_c<'/'> > div_token;
  73
  74 typedef token<int_> int_token;
  75
  76 template <class T, char C>
  77 struct is_c : bool_<T::type::value == C> {};
  78
  79 struct eval_plus
  80 {
  81   template <class State, class C>
  82   struct apply :
  83     eval_if<
  84       is_c<front<C>, '+'>,
  85       plus<typename State::type, typename back<C>::type>,
  86       minus<typename State::type, typename back<C>::type>
  87     >
  88   {};
  89 };
  90
  91 struct eval_mult
  92 {
  93   template <class State, class C>
  94   struct apply :
  95     eval_if<
  96       is_c<front<C>, '*'>,
  97       times<typename State::type, typename back<C>::type>,
  98       divides<typename State::type, typename back<C>::type>
  99     >
 100   {};
 101 };
 102
 103 typedef
 104   foldl_reject_incomplete_start_with_parser<
 105     sequence<one_of<mult_token, div_token>, int_token>,
 106     int_token,
 107     eval_mult
 108   >
 109   prod_exp;
 110
 111 typedef
 112   foldl_reject_incomplete_start_with_parser<
 113     sequence<one_of<plus_token, minus_token>, prod_exp>,
 114     prod_exp,
 115     eval_plus
 116   >
 117   plus_exp;
 118
 119 typedef last_of<repeated<space>, plus_exp> expression;
 120
 121 typedef build_parser<entire_input<expression> > calculator_parser;
 122
 123 #ifdef _STR
 124 #  error _STR already defined
 125 #endif
 126 #define _STR BOOST_METAPARSE_STRING
 127
 128 #ifdef BOOST_NO_CXX11_CONSTEXPR
 129 int main()
 130 {
 131   using std::cout;
 132   using std::endl;
 133   using boost::metaparse::string;
 134
 135   cout
 136     << apply_wrap1<calculator_parser, string<'1','3'> >::type::value << endl
 137     <<
 138       apply_wrap1<
 139         calculator_parser, string<' ','1','+',' ','2','*','4','-','6','/','2'>
 140       >::type::value
 141     << endl
 142     ;
 143 }
 144 #else
 145 int main()
 146 {
 147   using std::cout;
 148   using std::endl;
 149
 150   cout
 151     << apply_wrap1<calculator_parser, _STR("13")>::type::value << endl
 152     << apply_wrap1<calculator_parser, _STR(" 1+ 2*4-6/2")>::type::value << endl
 153     ;
 154 }
 155 #endif
 156
 157