[#before_11_3_1]
['Definitions before section 11.3.1.]

  #include <boost/metaparse/string.hpp>
  #include <boost/metaparse/int_.hpp>

  #include <boost/metaparse/build_parser.hpp>

  using namespace boost::metaparse;

  using exp_parser1 = build_parser<int_>;
  #include <boost/metaparse/entire_input.hpp>

  using exp_parser2 = build_parser<entire_input<int_>>;
  #include <boost/metaparse/token.hpp>

  using exp_parser3 = build_parser<entire_input<token<int_>>>;
  #include <boost/metaparse/lit_c.hpp>

  #include <boost/metaparse/sequence.hpp>

  using exp_parser4 = build_parser<sequence<token<int_>, token<lit_c<'+'>>, token<int_>>>;

  #include <metashell/formatter.hpp>
  
  using int_token = token<int_>;

  using plus_token = token<lit_c<'+'>>;

  using exp_parser5 = build_parser<sequence<int_token, plus_token, int_token>>;
  #include <boost/metaparse/transform.hpp>

  #include <boost/mpl/plus.hpp>

  #include <boost/mpl/at.hpp>

  template <class Vector> 
   struct eval_plus : 
     boost::mpl::plus< 
       typename boost::mpl::at_c<Vector, 0>::type, 
       typename boost::mpl::at_c<Vector, 2>::type 
     > {};

  #include <boost/mpl/quote.hpp>

  using exp_parser6 = 
   build_parser< 
     transform< 
       sequence<int_token, plus_token, int_token>, 
       boost::mpl::quote1<eval_plus> 
     > 
   >;
  #include <boost/metaparse/any.hpp>

  using exp_parser7 = 
   build_parser< 
     sequence< 
       int_token,                                /* The first <number> */ 
       repeated<sequence<plus_token, int_token>> /* The "+ <number>" elements */ 
     > 
   >;
  using temp_result = exp_parser7::apply<BOOST_METAPARSE_STRING("1 + 2 + 3 + 4")>::type;
  #include <boost/mpl/fold.hpp>

  using vector_of_numbers = 
   boost::mpl::vector< 
     boost::mpl::int_<2>, 
     boost::mpl::int_<5>, 
     boost::mpl::int_<6> 
   >;

  template <class Vector> 
   struct sum_vector : 
      boost::mpl::fold< 
        Vector, 
        boost::mpl::int_<0>, 
        boost::mpl::lambda< 
          boost::mpl::plus<boost::mpl::_1, boost::mpl::_2> 
        >::type 
      > 
    {};

  template <class Sum, class Item> 
     struct sum_items : 
       boost::mpl::plus< 
         Sum, 
         typename boost::mpl::at_c<Item, 1>::type 
       > 
   {};
  using exp_parser8 = 
   build_parser< 
     sequence< 
       int_token, /* parse the first <number> */ 
       transform< 
         repeated<sequence<plus_token, int_token>>, /* parse the "+ <number>" elements */ 
         /* lambda expression summarising the "+ <number>" elements using fold */ 
         boost::mpl::lambda< 
           /* The folding expression we have just created */ 
           boost::mpl::fold< 
             boost::mpl::_1, /* the argument of the lambda expression, the result */ 
                             /* of the repeated<...> parser */ 
             boost::mpl::int_<0>, 
             boost::mpl::quote2<sum_items> 
           > 
         >::type 
       > 
     > 
   >;

  using exp_parser9 = 
   build_parser< 
     transform< 
       /* What we had so far */ 
       sequence< 
         int_token, 
         transform< 
           repeated<sequence<plus_token, int_token>>, 
           boost::mpl::lambda< 
             boost::mpl::fold< 
               boost::mpl::_1, 
               boost::mpl::int_<0>, 
               boost::mpl::quote2<sum_items> 
             > 
           >::type 
         > 
       >, 
       boost::mpl::quote1<sum_vector> /* summarise the vector of numbers */ 
     > 
   >;
  #include <boost/metaparse/foldl.hpp>

  using exp_parser10 = 
   build_parser< 
     transform< 
       sequence< 
         int_token, 
         foldl< 
           sequence<plus_token, int_token>, 
           boost::mpl::int_<0>, 
           boost::mpl::quote2<sum_items> 
         > 
       >, 
       boost::mpl::quote1<sum_vector>> 
   >;
  #include <boost/metaparse/foldl_start_with_parser.hpp>

  using exp_parser11 = 
   build_parser< 
     foldl_start_with_parser< 
       sequence<plus_token, int_token>, /* apply this parser repeatedly */ 
       int_token, /* use this parser to get the initial value */ 
       boost::mpl::quote2<sum_items> /* use this function to add a new value to the summary */ 
     > 
   >;
  using minus_token = token<lit_c<'-'>>;

  #include <boost/metaparse/one_of.hpp>

  using exp_parser12 = 
   build_parser< 
     foldl_start_with_parser< 
       sequence<one_of<plus_token, minus_token>, int_token>, 
       int_token, 
       boost::mpl::quote2<sum_items> 
     > 
   >;
  #include <boost/mpl/minus.hpp>

  template <class L, char Op, class R> struct eval_binary_op;

  template <class L, class R> struct eval_binary_op<L, '+', R> : boost::mpl::plus<L, R>::type {};

  template <class L, class R> struct eval_binary_op<L, '-', R> : boost::mpl::minus<L, R>::type {};

  template <class S, class Item> 
   struct binary_op : 
     eval_binary_op< 
       S, 
       boost::mpl::at_c<Item, 0>::type::value, 
       typename boost::mpl::at_c<Item, 1>::type 
     > 
     {};

  using exp_parser13 = 
   build_parser< 
     foldl_start_with_parser< 
       sequence<one_of<plus_token, minus_token>, int_token>, 
       int_token, 
       boost::mpl::quote2<binary_op> 
     > 
   >;
  #include <boost/mpl/times.hpp>

  template <class L, class R> struct eval_binary_op<L, '*', R> : boost::mpl::times<L, R>::type {};

  using times_token = token<lit_c<'*'>>;

  using exp_parser14 = 
   build_parser< 
     foldl_start_with_parser< 
       sequence<one_of<plus_token, minus_token, times_token>, int_token>, 
       int_token, 
       boost::mpl::quote2<binary_op> 
     > 
   >;
  using mult_exp1 = foldl_start_with_parser<sequence<times_token, int_token>, int_token, boost::mpl::quote2<binary_op>>;

  using exp_parser15 = 
   build_parser< 
     foldl_start_with_parser< 
       sequence<one_of<plus_token, minus_token>, mult_exp1>, 
       mult_exp1, 
       boost::mpl::quote2<binary_op> 
     > 
   >;
  #include <boost/mpl/divides.hpp>

  template <class L, class R> struct eval_binary_op<L, '/', R> : boost::mpl::divides<L, R>::type {};

  using divides_token = token<lit_c<'/'>>;

  using mult_exp2 = 
   foldl_start_with_parser< 
     sequence<one_of<times_token, divides_token>, int_token>, 
     int_token, 
     boost::mpl::quote2<binary_op> 
   >;

  using exp_parser16 = 
   build_parser< 
     foldl_start_with_parser< 
       sequence<one_of<plus_token, minus_token>, mult_exp2>, 
       mult_exp2, 
       boost::mpl::quote2<binary_op> 
     > 
   >;
  template <class S, class Item> 
   struct reverse_binary_op : 
     eval_binary_op< 
       typename boost::mpl::at_c<Item, 0>::type, 
       boost::mpl::at_c<Item, 1>::type::value, 
       S 
     > 
     {};

  #include <boost/metaparse/foldr_start_with_parser.hpp>

  using mult_exp3 = 
   foldr_start_with_parser< 
     sequence<int_token, one_of<times_token, divides_token>>, /* The parser applied repeatedly */ 
     int_token, /* The parser parsing the last number */ 
     boost::mpl::quote2<reverse_binary_op> /* The function called for every result */ 
                                           /* of applying the above parser */ 
   >;

  using exp_parser17 = 
   build_parser< 
     foldl_start_with_parser< 
       sequence<one_of<plus_token, minus_token>, mult_exp3>, 
       mult_exp3, 
       boost::mpl::quote2<binary_op> 
     > 
   >;
  #include <boost/mpl/negate.hpp>

  using unary_exp1 = 
   foldr_start_with_parser< 
     minus_token, 
     int_token, 
     boost::mpl::lambda<boost::mpl::negate<boost::mpl::_1>>::type 
   >;

  using mult_exp4 = 
   foldl_start_with_parser< 
     sequence<one_of<times_token, divides_token>, unary_exp1>, 
     unary_exp1, 
     boost::mpl::quote2<binary_op> 
   >;

  using exp_parser18 = 
   build_parser< 
     foldl_start_with_parser< 
       sequence<one_of<plus_token, minus_token>, mult_exp4>, 
       mult_exp4, 
       boost::mpl::quote2<binary_op> 
     > 
   >;
  using lparen_token = token<lit_c<'('>>;

  using rparen_token = token<lit_c<')'>>;

  using plus_exp1 = 
   foldl_start_with_parser< 
     sequence<one_of<plus_token, minus_token>, mult_exp4>, 
     mult_exp4, 
     boost::mpl::quote2<binary_op> 
   >;

  using paren_exp1 = sequence<lparen_token, plus_exp1, rparen_token>;

  #include <boost/metaparse/middle_of.hpp>

  using paren_exp2 = middle_of<lparen_token, plus_exp1, rparen_token>;

  using primary_exp1 = one_of<int_token, paren_exp2>;

  struct plus_exp2;

  using paren_exp3 = middle_of<lparen_token, plus_exp2, rparen_token>;

  using primary_exp2 = one_of<int_token, paren_exp2>;

  using unary_exp2 = 
   foldr_start_with_parser< 
     minus_token, 
     primary_exp2, 
     boost::mpl::lambda<boost::mpl::negate<boost::mpl::_1>>::type 
   >;

  using mult_exp5 = 
   foldl_start_with_parser< 
     sequence<one_of<times_token, divides_token>, unary_exp2>, 
     unary_exp2, 
     boost::mpl::quote2<binary_op> 
   >;

  struct plus_exp2 : 
   foldl_start_with_parser< 
     sequence<one_of<plus_token, minus_token>, mult_exp5>, 
     mult_exp5, 
     boost::mpl::quote2<binary_op> 
   > {};

  using exp_parser19 = build_parser<plus_exp2>;
  #include <boost/metaparse/define_error.hpp>

  BOOST_METAPARSE_DEFINE_ERROR(missing_primary_expression, "Missing primary expression");

  struct plus_exp3;

  using paren_exp4 = middle_of<lparen_token, plus_exp3, rparen_token>;

  #include <boost/metaparse/fail.hpp>

  using primary_exp3 = one_of<int_token, paren_exp4, fail<missing_primary_expression>>;

  using unary_exp3 = 
   foldr_start_with_parser< 
     minus_token, 
     primary_exp3, 
     boost::mpl::lambda<boost::mpl::negate<boost::mpl::_1>>::type 
   >;

  using mult_exp6 = 
   foldl_start_with_parser< 
     sequence<one_of<times_token, divides_token>, unary_exp3>, 
     unary_exp3, 
     boost::mpl::quote2<binary_op> 
   >;

  struct plus_exp3 : 
   foldl_start_with_parser< 
     sequence<one_of<plus_token, minus_token>, mult_exp6>, 
     mult_exp6, 
     boost::mpl::quote2<binary_op> 
   > {};

  using exp_parser20 = build_parser<plus_exp3>;
  #include <boost/metaparse/fail_at_first_char_expected.hpp>

  #include <boost/metaparse/first_of.hpp>

  struct plus_exp4 : 
   first_of< 
     foldl_start_with_parser< 
       sequence<one_of<plus_token, minus_token>, mult_exp6>, 
       mult_exp6, 
       boost::mpl::quote2<binary_op> 
     >, 
     fail_at_first_char_expected< 
       sequence<one_of<plus_token, minus_token>, mult_exp6> 
     > 
   > {};

  using exp_parser21 = build_parser<plus_exp4>;

