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

   1 // Copyright Abel Sinkovics (abel@sinkovics.hu)  2014.
   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/middle_of.hpp>
  12 #include <boost/metaparse/space.hpp>
  13 #include <boost/metaparse/int_.hpp>
  14 #include <boost/metaparse/foldl_reject_incomplete_start_with_parser.hpp>
  15 #include <boost/metaparse/one_of.hpp>
  16 #include <boost/metaparse/get_result.hpp>
  17 #include <boost/metaparse/token.hpp>
  18 #include <boost/metaparse/entire_input.hpp>
  19 #include <boost/metaparse/string.hpp>
  20 #include <boost/metaparse/build_parser.hpp>
  21
  22 #include <boost/mpl/apply_wrap.hpp>
  23 #include <boost/mpl/fold.hpp>
  24 #include <boost/mpl/front.hpp>
  25 #include <boost/mpl/back.hpp>
  26 #include <boost/mpl/plus.hpp>
  27 #include <boost/mpl/minus.hpp>
  28 #include <boost/mpl/times.hpp>
  29 #include <boost/mpl/divides.hpp>
  30 #include <boost/mpl/bool.hpp>
  31 #include <boost/mpl/equal_to.hpp>
  32 #include <boost/mpl/eval_if.hpp>
  33 #include <boost/mpl/bool.hpp>
  34
  35 using boost::metaparse::sequence;
  36 using boost::metaparse::lit_c;
  37 using boost::metaparse::last_of;
  38 using boost::metaparse::first_of;
  39 using boost::metaparse::middle_of;
  40 using boost::metaparse::space;
  41 using boost::metaparse::repeated;
  42 using boost::metaparse::build_parser;
  43 using boost::metaparse::int_;
  44 using boost::metaparse::foldl_reject_incomplete_start_with_parser;
  45 using boost::metaparse::get_result;
  46 using boost::metaparse::one_of;
  47 using boost::metaparse::token;
  48 using boost::metaparse::entire_input;
  49
  50 using boost::mpl::apply_wrap1;
  51 using boost::mpl::fold;
  52 using boost::mpl::front;
  53 using boost::mpl::back;
  54 using boost::mpl::plus;
  55 using boost::mpl::minus;
  56 using boost::mpl::times;
  57 using boost::mpl::divides;
  58 using boost::mpl::eval_if;
  59 using boost::mpl::bool_;
  60 using boost::mpl::equal_to;
  61 using boost::mpl::bool_;
  62
  63 /*
  64  * The grammar
  65  *
  66  * expression ::= plus_exp
  67  * plus_exp ::= prod_exp ((plus_token | minus_token) prod_exp)*
  68  * prod_exp ::= int_token ((mult_token | div_token) simple_exp)*
  69  * simple_exp ::= int_token | paren_exp
  70  * paren_exp ::= open_paren_token expression close_paren_token
  71  */
  72
  73 typedef token<lit_c<'+'> > plus_token;
  74 typedef token<lit_c<'-'> > minus_token;
  75 typedef token<lit_c<'*'> > mult_token;
  76 typedef token<lit_c<'/'> > div_token;
  77
  78 typedef token<lit_c<'('> > open_paren_token;
  79 typedef token<lit_c<')'> > close_paren_token;
  80
  81 typedef token<int_> int_token;
  82
  83 template <class T, char C>
  84 struct is_c : bool_<T::type::value == C> {};
  85
  86 struct eval_plus
  87 {
  88   template <class State, class C>
  89   struct apply :
  90     eval_if<
  91       is_c<front<C>, '+'>,
  92       plus<typename State::type, typename back<C>::type>,
  93       minus<typename State::type, typename back<C>::type>
  94     >
  95   {};
  96 };
  97
  98 struct eval_mult
  99 {
 100   template <class State, class C>
 101   struct apply :
 102     eval_if<
 103       is_c<front<C>, '*'>,
 104       times<typename State::type, typename back<C>::type>,
 105       divides<typename State::type, typename back<C>::type>
 106     >
 107   {};
 108 };
 109
 110 struct plus_exp;
 111
 112 typedef middle_of<open_paren_token, plus_exp, close_paren_token> paren_exp;
 113
 114 typedef one_of<int_token, paren_exp> simple_exp;
 115
 116 typedef
 117   foldl_reject_incomplete_start_with_parser<
 118     sequence<one_of<mult_token, div_token>, simple_exp>,
 119     simple_exp,
 120     eval_mult
 121   >
 122   prod_exp;
 123
 124 struct plus_exp :
 125   foldl_reject_incomplete_start_with_parser<
 126     sequence<one_of<plus_token, minus_token>, prod_exp>,
 127     prod_exp,
 128     eval_plus
 129   >
 130 {};
 131
 132 typedef last_of<repeated<space>, plus_exp> expression;
 133
 134 typedef build_parser<entire_input<expression> > calculator_parser;
 135
 136 #ifdef _STR
 137 #  error _STR already defined
 138 #endif
 139 #define _STR BOOST_METAPARSE_STRING
 140
 141 #ifdef BOOST_NO_CXX11_CONSTEXPR
 142 int main()
 143 {
 144   std::cout << "Please use a compiler that support constexpr" << std::endl;
 145 }
 146 #else
 147 int main()
 148 {
 149   using std::cout;
 150   using std::endl;
 151
 152   cout
 153     << apply_wrap1<calculator_parser, _STR("13")>::type::value << endl
 154     << apply_wrap1<calculator_parser, _STR(" 1+ 2*4-6/2")>::type::value << endl
 155     << apply_wrap1<calculator_parser, _STR("1+2*3+4")>::type::value << endl
 156     << apply_wrap1<calculator_parser, _STR("(1+2)*(3+4)")>::type::value << endl
 157     << apply_wrap1<calculator_parser, _STR("(2*3)+(4*5)")>::type::value << endl
 158     << apply_wrap1<calculator_parser, _STR("2 * 3 + 4")>::type::value << endl
 159     << apply_wrap1<calculator_parser, _STR("2 + (3 * 4)")>::type::value << endl
 160     ;
 161 }
 162 #endif
 163