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// Copyright Abel Sinkovics (abel@sinkovics.hu) 2012.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#include <boost/metaparse/repeated.hpp>
#include <boost/metaparse/sequence.hpp>
#include <boost/metaparse/lit_c.hpp>
#include <boost/metaparse/last_of.hpp>
#include <boost/metaparse/space.hpp>
#include <boost/metaparse/int_.hpp>
#include <boost/metaparse/foldl_reject_incomplete_start_with_parser.hpp>
#include <boost/metaparse/one_of.hpp>
#include <boost/metaparse/get_result.hpp>
#include <boost/metaparse/token.hpp>
#include <boost/metaparse/entire_input.hpp>
#include <boost/metaparse/string.hpp>
#include <boost/metaparse/transform.hpp>
#include <boost/metaparse/always.hpp>
#include <boost/metaparse/build_parser.hpp>
#include <boost/mpl/apply_wrap.hpp>
#include <boost/mpl/front.hpp>
#include <boost/mpl/back.hpp>
#include <boost/mpl/bool.hpp>
#include <boost/mpl/if.hpp>
using boost::metaparse::sequence;
using boost::metaparse::lit_c;
using boost::metaparse::last_of;
using boost::metaparse::space;
using boost::metaparse::repeated;
using boost::metaparse::build_parser;
using boost::metaparse::int_;
using boost::metaparse::foldl_reject_incomplete_start_with_parser;
using boost::metaparse::get_result;
using boost::metaparse::one_of;
using boost::metaparse::token;
using boost::metaparse::entire_input;
using boost::metaparse::transform;
using boost::metaparse::always;
using boost::mpl::apply_wrap1;
using boost::mpl::front;
using boost::mpl::back;
using boost::mpl::if_;
using boost::mpl::bool_;
/*
* The grammar
*
* expression ::= plus_exp
* plus_exp ::= prod_exp ((plus_token | minus_token) prod_exp)*
* prod_exp ::= value_exp ((mult_token | div_token) value_exp)*
* value_exp ::= int_token | '_'
*/
typedef token<lit_c<'+'> > plus_token;
typedef token<lit_c<'-'> > minus_token;
typedef token<lit_c<'*'> > mult_token;
typedef token<lit_c<'/'> > div_token;
typedef token<int_> int_token;
typedef token<lit_c<'_'> > arg_token;
template <class T, char C>
struct is_c : bool_<T::type::value == C> {};
struct build_plus
{
template <class A, class B>
class _plus
{
public:
typedef _plus type;
template <class T>
T operator()(T t) const
{
return _left(t) + _right(t);
}
private:
typename A::type _left;
typename B::type _right;
};
template <class A, class B>
class _minus
{
public:
typedef _minus type;
template <class T>
T operator()(T t) const
{
return _left(t) - _right(t);
}
private:
typename A::type _left;
typename B::type _right;
};
template <class State, class C>
struct apply :
if_<
typename is_c<front<C>, '+'>::type,
_plus<State, typename back<C>::type>,
_minus<State, typename back<C>::type>
>
{};
};
struct build_mult
{
template <class A, class B>
class _mult
{
public:
typedef _mult type;
template <class T>
T operator()(T t) const
{
return _left(t) * _right(t);
}
private:
typename A::type _left;
typename B::type _right;
};
template <class A, class B>
class _div
{
public:
typedef _div type;
template <class T>
T operator()(T t) const
{
return _left(t) / _right(t);
}
private:
typename A::type _left;
typename B::type _right;
};
template <class State, class C>
struct apply :
if_<
typename is_c<front<C>, '*'>::type,
_mult<State, typename back<C>::type>,
_div<State, typename back<C>::type>
>
{};
};
struct build_value
{
typedef build_value type;
template <class V>
struct apply
{
typedef apply type;
template <class T>
int operator()(T) const
{
return V::type::value;
}
};
};
struct arg
{
typedef arg type;
template <class T>
T operator()(T t) const
{
return t;
}
};
typedef
one_of<transform<int_token, build_value>, always<arg_token, arg> >
value_exp;
typedef
foldl_reject_incomplete_start_with_parser<
sequence<one_of<mult_token, div_token>, value_exp>,
value_exp,
build_mult
>
prod_exp;
typedef
foldl_reject_incomplete_start_with_parser<
sequence<one_of<plus_token, minus_token>, prod_exp>,
prod_exp,
build_plus
>
plus_exp;
typedef last_of<repeated<space>, plus_exp> expression;
typedef build_parser<entire_input<expression> > function_parser;
#if BOOST_METAPARSE_STD < 2011
template <class Exp>
struct lambda : apply_wrap1<function_parser, Exp> {};
using boost::metaparse::string;
lambda<string<'1','3'> >::type f1;
lambda<string<'2',' ','+',' ','3'> >::type f2;
lambda<string<'2',' ','*',' ','2'> >::type f3;
lambda<string<' ','1','+',' ','2','*','4','-','6','/','2'> >::type f4;
lambda<string<'2',' ','*',' ','_'> >::type f5;
#else
#ifdef LAMBDA
#error LAMBDA already defined
#endif
#define LAMBDA(exp) apply_wrap1<function_parser, BOOST_METAPARSE_STRING(#exp)>::type
LAMBDA(13) f1;
LAMBDA(2 + 3) f2;
LAMBDA(2 * 2) f3;
LAMBDA( 1+ 2*4-6/2) f4;
LAMBDA(2 * _) f5;
#endif
int main()
{
using std::cout;
using std::endl;
cout
<< f1(11) << endl
<< f2(11) << endl
<< f3(11) << endl
<< f4(11) << endl
<< f5(11) << endl
<< f5(1.1) << endl
;
}
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