text: #ifndef SPROUT_WEED_PARSER_DIRECTIVE_AS_TUPLE_HPP
  #define SPROUT_WEED_PARSER_DIRECTIVE_AS_TUPLE_HPP
  
  #include <cstddef>
  #include <sprout/config.hpp>
  #include <sprout/tuple/tuple.hpp>
  #include <sprout/type_traits/identity.hpp>
  #include <sprout/weed/parser_result.hpp>
  #include <sprout/weed/expr/make_terminal_or_expr.hpp>
  #include <sprout/weed/expr/eval.hpp>
  #include <sprout/weed/parser/parser_base.hpp>
  #include <sprout/weed/traits/type/is_unused.hpp>
  #include <sprout/weed/traits/expr/terminal_or_expr_of.hpp>
  #include <sprout/weed/traits/parser/attribute_of.hpp>
  
  namespace sprout {
  	namespace weed {
  		//
  		// as_tuple_p
  		//
  		template<typename Parser>
  		struct as_tuple_p
  			: public sprout::weed::parser_base
  		{
  		public:
  			template<typename Context, typename Iterator>
  			struct attribute {
  			private:
  				typedef typename sprout::weed::traits::attribute_of<Parser, Iterator, Context>::type attr_type;
  			private:
  				static_assert(!sprout::weed::traits::is_unused<attr_type>::value, "invalid attribute : unused");
  			public:
  				typedef sprout::tuples::tuple<attr_type> type;
  			};
  			template<typename Context, typename Iterator>
  			struct result
  				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
  			{};
  		private:
  			typedef typename sprout::weed::traits::terminal_or_expr_of<Parser>::type expr_type;
  		private:
  			expr_type expr_;
  		private:
  			template<typename Context, typename Iterator, typename Result>
  			SPROUT_CONSTEXPR typename result<Context, Iterator>::type call(
  				Iterator first,
  				Result const& res
  				) const
  			{
  				typedef typename result<Context, Iterator>::type result_type;
  				typedef typename attribute<Context, Iterator>::type attribute_type;
  				return res.success()
  					? result_type(true, res.current(), attribute_type(res.attr()))
  					: result_type(false, first, attribute_type())
  					;
  			}
  		public:
  			as_tuple_p() = default;
  			explicit SPROUT_CONSTEXPR as_tuple_p(
  				Parser const& p
  				)
  				: expr_(sprout::weed::make_terminal_or_expr(p))
  			{}
  			template<typename Context, typename Iterator>
  			SPROUT_CONSTEXPR typename result<Context, Iterator>::type operator()(
  				Iterator first,
  				Iterator last,
  				Context const& ctx
  				) const
  			{
  				return call<Context>(first, sprout::weed::eval(expr_, ctx));
  			}
  		};
  		//
  		// as_tuple_d
  		//
  		struct as_tuple_d {
  		public:
  			template<typename Parser>
  			SPROUT_CONSTEXPR sprout::weed::as_tuple_p<Parser> operator[](Parser const& p) const {
  				return sprout::weed::as_tuple_p<Parser>(p);
  			}
  		};
  		//
  		// as_tuple
  		//
  		SPROUT_CONSTEXPR sprout::weed::as_tuple_d as_tuple = sprout::weed::as_tuple_d();
  	}	// namespace weed
  }	// namespace sprout
  
  #endif	// #ifndef SPROUT_WEED_PARSER_DIRECTIVE_AS_TUPLE_HPP
  