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Diffstat (limited to 'src/boost/libs/metaparse/example/meta_metaparse/main.cpp')
| -rw-r--r-- | src/boost/libs/metaparse/example/meta_metaparse/main.cpp | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/src/boost/libs/metaparse/example/meta_metaparse/main.cpp b/src/boost/libs/metaparse/example/meta_metaparse/main.cpp new file mode 100644 index 00000000..44254983 --- /dev/null +++ b/src/boost/libs/metaparse/example/meta_metaparse/main.cpp @@ -0,0 +1,258 @@ +// 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) + +#define BOOST_MPL_LIMIT_STRING_SIZE 64 +#define BOOST_METAPARSE_LIMIT_STRING_SIZE BOOST_MPL_LIMIT_STRING_SIZE + +#include <boost/metaparse/grammar.hpp> + +#include <boost/metaparse/string.hpp> +#include <boost/metaparse/build_parser.hpp> +#include <boost/metaparse/token.hpp> +#include <boost/metaparse/entire_input.hpp> +#include <boost/metaparse/int_.hpp> +#include <boost/metaparse/transform.hpp> + +#include <boost/mpl/apply_wrap.hpp> +#include <boost/mpl/front.hpp> +#include <boost/mpl/back.hpp> +#include <boost/mpl/if.hpp> +#include <boost/mpl/bool.hpp> +#include <boost/mpl/fold.hpp> + +using boost::mpl::apply_wrap1; +using boost::mpl::front; +using boost::mpl::back; +using boost::mpl::if_; +using boost::mpl::bool_; + +using boost::metaparse::build_parser; +using boost::metaparse::token; +using boost::metaparse::entire_input; +using boost::metaparse::int_; +using boost::metaparse::grammar; +using boost::metaparse::transform; + +#if BOOST_METAPARSE_STD < 2011 +int main() +{ + std::cout << "Please use a compiler that supports constexpr" << std::endl; +} +#else + +#ifdef _STR +# error _STR already defined +#endif +#define _STR BOOST_METAPARSE_STRING + +template <class T, char C> +struct is_c : bool_<T::type::value == C> {}; + +struct build_plus_impl +{ + 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_plus +{ + typedef build_plus type; + + template <class Seq> + struct apply : + boost::mpl::fold< + typename back<Seq>::type, + typename front<Seq>::type, + build_plus_impl + > + {}; +}; + +struct build_mult_impl +{ + 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_mult +{ + typedef build_mult type; + + template <class Seq> + struct apply : + boost::mpl::fold< + typename back<Seq>::type, + typename front<Seq>::type, + build_mult_impl + > + {}; +}; + +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 build_arg +{ + typedef build_arg type; + + template <class> + struct apply + { + typedef apply type; + + template <class T> + T operator()(T t) const + { + return t; + } + }; +}; + +struct keep_front +{ + typedef keep_front type; + + template <class Seq> + struct apply : front<Seq> {}; +}; + +typedef + grammar<_STR("plus_exp")> + ::import<_STR("int_token"), token<transform<int_, build_value>>>::type + + ::rule<_STR("ws ::= (' ' | '\n' | '\r' | '\t')*")>::type + ::rule<_STR("plus_token ::= '+' ws"), keep_front>::type + ::rule<_STR("minus_token ::= '-' ws"), keep_front>::type + ::rule<_STR("mult_token ::= '*' ws"), keep_front>::type + ::rule<_STR("div_token ::= '/' ws"), keep_front>::type + ::rule<_STR("arg_token ::= '_' ws"), keep_front>::type + + ::rule<_STR("plus_exp ::= prod_exp ((plus_token | minus_token) prod_exp)*"), build_plus>::type + ::rule<_STR("prod_exp ::= value_exp ((mult_token | div_token) value_exp)*"), build_mult>::type + ::rule<_STR("value_exp ::= int_token | arg_exp")>::type + ::rule<_STR("arg_exp ::= arg_token"), build_arg>::type + g; + +typedef build_parser<entire_input<g>> function_parser; + +#ifdef LAMBDA + #error LAMBDA already defined +#endif +#define LAMBDA(exp) apply_wrap1<function_parser, _STR(#exp)>::type + +LAMBDA(13) f1; +LAMBDA(2 + 3) f2; +LAMBDA(2 * 3) f3; +LAMBDA(1+ 2*4-6/2) f4; +LAMBDA(2 * _) f5; + +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 + ; +} + +#endif + + |