From c78e1d0e6d8c9dd5f7d31efd97d25dd43b20edb2 Mon Sep 17 00:00:00 2001
From: bolero-MURAKAMI <bolero.murakami@gmail.com>
Date: Mon, 25 Mar 2013 12:43:47 +0900
Subject: [PATCH] fix weed type_traits

---
 sprout/type_traits/float_promote.hpp          | 12 +--
 sprout/type_traits/is_c_str.hpp               | 16 ----
 sprout/weed/attr_cnv/result_of/bitwise_or.hpp | 76 ++++++++----------
 sprout/weed/attr_cnv/result_of/negate.hpp     |  8 +-
 sprout/weed/attr_cnv/result_of/shift_left.hpp | 80 ++++++++-----------
 sprout/weed/attr_cnv/result_of/times.hpp      | 26 +++---
 sprout/weed/detail/c_str_as_string.hpp        | 32 +++++++-
 sprout/weed/parser/auxiliary/eoi.hpp          | 15 ++--
 sprout/weed/parser/auxiliary/eol.hpp          | 15 ++--
 sprout/weed/parser/auxiliary/eps.hpp          | 15 ++--
 sprout/weed/parser/char/char.hpp              | 43 +++++-----
 sprout/weed/parser/char/char_class.hpp        | 17 ++--
 sprout/weed/parser/directive/as_array.hpp     |  8 +-
 sprout/weed/parser/directive/as_tuple.hpp     |  8 +-
 sprout/weed/parser/directive/omit.hpp         | 15 ++--
 sprout/weed/parser/directive/repeat.hpp       | 17 ++--
 sprout/weed/parser/directive/replace.hpp      | 15 ++--
 sprout/weed/parser/lim.hpp                    | 15 ++--
 sprout/weed/parser/numeric/int_p.hpp          | 15 ++--
 sprout/weed/parser/numeric/uint_p.hpp         | 15 ++--
 sprout/weed/parser/string/string.hpp          | 29 +++----
 sprout/weed/traits/expr/expr_of.hpp           | 20 ++---
 sprout/weed/traits/expr/tag_of.hpp            |  8 +-
 sprout/weed/traits/expr/terminal_of.hpp       | 35 ++++----
 .../weed/traits/expr/terminal_or_expr_of.hpp  | 13 ++-
 sprout/weed/traits/parser/attribute_of.hpp    | 15 ++--
 sprout/weed/traits/parser/is_parser.hpp       |  2 +-
 27 files changed, 279 insertions(+), 306 deletions(-)

diff --git a/sprout/type_traits/float_promote.hpp b/sprout/type_traits/float_promote.hpp
index dbb2742a..d82fee6a 100644
--- a/sprout/type_traits/float_promote.hpp
+++ b/sprout/type_traits/float_promote.hpp
@@ -11,9 +11,9 @@ namespace sprout {
 		struct float_promote1
 			: public std::conditional<
 				std::is_floating_point<T>::value,
-				sprout::identity<T>,
-				sprout::identity<double>
-			>::type
+				T,
+				double
+			>
 		{
 			static_assert(
 				std::is_arithmetic<T>::value,
@@ -25,13 +25,13 @@ namespace sprout {
 		struct float_promote2
 			: public std::conditional<
 				(std::is_same<T, long double>::value || std::is_same<U, long double>::value),
-				sprout::identity<long double>,
+				long double,
 				typename std::conditional<
 					(std::is_same<T, float>::value && std::is_same<U, float>::value),
 					float,
 					double
-				>
-			>::type
+				>::type
+			>
 		{
 			static_assert(
 				std::is_arithmetic<T>::value && std::is_arithmetic<U>::value,
diff --git a/sprout/type_traits/is_c_str.hpp b/sprout/type_traits/is_c_str.hpp
index 757e52ac..5553bbd1 100644
--- a/sprout/type_traits/is_c_str.hpp
+++ b/sprout/type_traits/is_c_str.hpp
@@ -40,22 +40,6 @@ namespace sprout {
 	struct is_c_str<char32_t[N]>
 		: public std::true_type
 	{};
-	template<std::size_t N>
-	struct is_c_str<char const[N]>
-		: public std::true_type
-	{};
-	template<std::size_t N>
-	struct is_c_str<wchar_t const[N]>
-		: public std::true_type
-	{};
-	template<std::size_t N>
-	struct is_c_str<char16_t const[N]>
-		: public std::true_type
-	{};
-	template<std::size_t N>
-	struct is_c_str<char32_t const[N]>
-		: public std::true_type
-	{};
 
 #if SPROUT_USE_TEMPLATE_ALIASES
 	template<typename T>
diff --git a/sprout/weed/attr_cnv/result_of/bitwise_or.hpp b/sprout/weed/attr_cnv/result_of/bitwise_or.hpp
index f8f734ea..22c85467 100644
--- a/sprout/weed/attr_cnv/result_of/bitwise_or.hpp
+++ b/sprout/weed/attr_cnv/result_of/bitwise_or.hpp
@@ -7,6 +7,7 @@
 #include <sprout/array/array.hpp>
 #include <sprout/tuple/tuple.hpp>
 #include <sprout/variant/variant.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/traits/type/is_char_type.hpp>
 #include <sprout/weed/detail/is_same_container.hpp>
@@ -36,14 +37,13 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_same_container<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename std::conditional<
+				>
+					: public std::conditional<
 						!(sprout::tuples::tuple_size<T>::value < sprout::tuples::tuple_size<U>::value),
 						T,
 						U
-					>::type type;
-				};
+					>
+				{};
 				// container<V, N> | V -> container<V, N ? N : 1>
 				template<typename T, typename U>
 				struct bitwise_or<
@@ -52,14 +52,13 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_container_and_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename std::conditional<
+				>
+					: public std::conditional<
 						sprout::container_traits<T>::static_size != 0,
 						T,
 						typename sprout::container_transform_traits<T>::template rebind_size<1>::type
-					>::type type;
-				};
+					>
+				{};
 				// V | container<V, N> -> container<V, N ? N : 1>
 				template<typename T, typename U>
 				struct bitwise_or<
@@ -68,14 +67,13 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_elem_and_container<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename std::conditional<
+				>
+					: public std::conditional<
 						sprout::container_traits<T>::static_size != 0,
 						U,
 						typename sprout::container_transform_traits<U>::template rebind_size<1>::type
-					>::type type;
-				};
+					>
+				{};
 				// tuple<Vs...> | tuple<Ws...> -> tuple<max(Vs..., Ws...)>
 				template<typename T, typename U>
 				struct bitwise_or<
@@ -84,14 +82,13 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_both_tuple<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename std::conditional<
+				>
+					: public std::conditional<
 						!(sprout::tuples::tuple_size<T>::value < sprout::tuples::tuple_size<U>::value),
 						T,
 						U
-					>::type type;
-				};
+					>
+				{};
 				// V | V -> V
 				template<typename T, typename U>
 				struct bitwise_or<
@@ -100,10 +97,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_same_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef T type;
-				};
+				>
+					: public sprout::identity<T>
+				{};
 				// V | W -> variant<V, W>
 				template<typename T, typename U>
 				struct bitwise_or<
@@ -112,10 +108,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_different_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef sprout::variant<T, U> type;
-				};
+				>
+					: public sprout::identity<sprout::variant<T, U> >
+				{};
 				// V | unused -> container<V, 1>
 				template<typename T, typename U>
 				struct bitwise_or<
@@ -124,14 +119,13 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_elem_and_unused<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename std::conditional<
+				>
+					: public std::conditional<
 						sprout::weed::traits::is_char_type<T>::value,
 						sprout::basic_string<T, 1>,
 						sprout::array<T, 1>
-					>::type type;
-				};
+					>
+				{};
 				// unused | V -> container<V, 1>
 				template<typename T, typename U>
 				struct bitwise_or<
@@ -140,14 +134,13 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_unused_and_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename std::conditional<
+				>
+					: public std::conditional<
 						sprout::weed::traits::is_char_type<U>::value,
 						sprout::basic_string<U, 1>,
 						sprout::array<U, 1>
-					>::type type;
-				};
+					>
+				{};
 				// unused | unused -> unused
 				template<typename T, typename U>
 				struct bitwise_or<
@@ -156,10 +149,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_both_unused<T, U>::value
 					>::type
-				> {
-				public:
-					typedef sprout::weed::unused type;
-				};
+				>
+					: public sprout::identity<sprout::weed::unused>
+				{};
 			}	// namespace result_of
 		}	// namespace attr_cnv
 	}	// namespace weed
diff --git a/sprout/weed/attr_cnv/result_of/negate.hpp b/sprout/weed/attr_cnv/result_of/negate.hpp
index 226d9848..a6c5bb73 100644
--- a/sprout/weed/attr_cnv/result_of/negate.hpp
+++ b/sprout/weed/attr_cnv/result_of/negate.hpp
@@ -3,6 +3,7 @@
 
 #include <type_traits>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/traits/type/is_unused.hpp>
 
@@ -22,10 +23,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::traits::is_unused<T>::value
 					>::type
-				> {
-				public:
-					typedef sprout::weed::unused type;
-				};
+				>
+					: public sprout::identity<sprout::weed::unused>
+				{};
 			}	// namespace result_of
 		}	// namespace attr_cnv
 	}	// namespace weed
diff --git a/sprout/weed/attr_cnv/result_of/shift_left.hpp b/sprout/weed/attr_cnv/result_of/shift_left.hpp
index 5167b3c6..e5793a39 100644
--- a/sprout/weed/attr_cnv/result_of/shift_left.hpp
+++ b/sprout/weed/attr_cnv/result_of/shift_left.hpp
@@ -11,6 +11,7 @@
 #include <sprout/tuple/operation/append_back.hpp>
 #include <sprout/tuple/operation/push_back.hpp>
 #include <sprout/tuple/operation/push_front.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/traits/type/is_char_type.hpp>
 #include <sprout/weed/detail/is_same_container.hpp>
@@ -42,10 +43,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_same_container<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename sprout::fixed::result_of::append_back<T, U>::type type;
-				};
+				>
+					: public sprout::fixed::result_of::append_back<T, U>
+				{};
 				// container<V, N> >> V -> container<V, N + 1>
 				template<typename T, typename U>
 				struct shift_left<
@@ -54,10 +54,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_container_and_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename sprout::fixed::result_of::push_back<T, U>::type type;
-				};
+				>
+					: public sprout::fixed::result_of::push_back<T, U>
+				{};
 				// V >> container<V, N> -> container<V, N + 1>
 				template<typename T, typename U>
 				struct shift_left<
@@ -66,10 +65,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_elem_and_container<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename sprout::fixed::result_of::push_front<T, U>::type type;
-				};
+				>
+					: public sprout::fixed::result_of::push_front<T, U>
+				{};
 				// tuple<Vs...> >> tuple<Ws...> -> tuple<Vs..., Ws...>
 				template<typename T, typename U>
 				struct shift_left<
@@ -78,10 +76,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_both_tuple<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename sprout::tuples::result_of::append_back<T, U>::type type;
-				};
+				>
+					: public sprout::tuples::result_of::append_back<T, U>
+				{};
 				// tuple<Vs...> >> V -> tuple<Vs..., V>
 				template<typename T, typename U>
 				struct shift_left<
@@ -90,10 +87,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_tuple_and_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename sprout::tuples::result_of::push_back<T, U>::type type;
-				};
+				>
+					: public sprout::tuples::result_of::push_back<T, U>
+				{};
 				// V >> tuple<Vs...> -> tuple<V, Vs...>
 				template<typename T, typename U>
 				struct shift_left<
@@ -102,10 +98,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_elem_and_tuple<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename sprout::tuples::result_of::push_front<T, U>::type type;
-				};
+				>
+					: public sprout::tuples::result_of::push_front<T, U>
+				{};
 				// V >> V -> container<V, 2>
 				template<typename T, typename U>
 				struct shift_left<
@@ -114,14 +109,13 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_same_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef typename std::conditional<
+				>
+					: public std::conditional<
 						sprout::weed::traits::is_char_type<T>::value,
 						sprout::basic_string<T, 2>,
 						sprout::array<T, 2>
-					>::type type;
-				};
+					>
+				{};
 				// V >> W -> tuple<V, W>
 				template<typename T, typename U>
 				struct shift_left<
@@ -130,10 +124,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_different_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef sprout::tuples::tuple<T, U> type;
-				};
+				>
+					: public sprout::identity<sprout::tuples::tuple<T, U> >
+				{};
 				// V >> unused -> V
 				template<typename T, typename U>
 				struct shift_left<
@@ -142,10 +135,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_elem_and_unused<T, U>::value
 					>::type
-				> {
-				public:
-					typedef T type;
-				};
+				>
+					: public sprout::identity<T>
+				{};
 				// unused >> V -> V
 				template<typename T, typename U>
 				struct shift_left<
@@ -154,10 +146,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_unused_and_elem<T, U>::value
 					>::type
-				> {
-				public:
-					typedef U type;
-				};
+				>
+					: public sprout::identity<U>
+				{};
 				// unused >> unused -> unused
 				template<typename T, typename U>
 				struct shift_left<
@@ -166,10 +157,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::detail::is_both_unused<T, U>::value
 					>::type
-				> {
-				public:
-					typedef sprout::weed::unused type;
-				};
+				>
+					: public sprout::identity<sprout::weed::unused>
+				{};
 			}	// namespace result_of
 		}	// namespace attr_cnv
 	}	// namespace weed
diff --git a/sprout/weed/attr_cnv/result_of/times.hpp b/sprout/weed/attr_cnv/result_of/times.hpp
index 5ec3ab4f..2b49de43 100644
--- a/sprout/weed/attr_cnv/result_of/times.hpp
+++ b/sprout/weed/attr_cnv/result_of/times.hpp
@@ -7,6 +7,7 @@
 #include <sprout/string.hpp>
 #include <sprout/array/array.hpp>
 #include <sprout/algorithm/string/join.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/traits/type/is_char_type.hpp>
 #include <sprout/weed/traits/type/is_container.hpp>
@@ -30,12 +31,11 @@ namespace sprout {
 						Limit != std::size_t(-1)
 						&& sprout::weed::traits::is_container<T>::value
 					>::type
-				> {
-				public:
-					typedef typename sprout::algorithm::result_of::join<
+				>
+					: public sprout::algorithm::result_of::join<
 						sprout::array<T, Limit>
-					>::type type;
-				};
+					>
+				{};
 				// times<N>(V) -> container<V, N>
 				template<std::size_t Limit, typename T>
 				struct times<
@@ -46,14 +46,13 @@ namespace sprout {
 						&& !sprout::weed::traits::is_container<T>::value
 						&& !sprout::weed::traits::is_unused<T>::value
 					>::type
-				> {
-				public:
-					typedef typename std::conditional<
+				>
+					: public std::conditional<
 						sprout::weed::traits::is_char_type<T>::value,
 						sprout::basic_string<T, Limit>,
 						sprout::array<T, Limit>
-					>::type type;
-				};
+					>
+				{};
 				// times<N>(unused) -> unused
 				template<std::size_t Limit, typename T>
 				struct times<
@@ -62,10 +61,9 @@ namespace sprout {
 					typename std::enable_if<
 						sprout::weed::traits::is_unused<T>::value
 					>::type
-				> {
-				public:
-					typedef sprout::weed::unused type;
-				};
+				>
+					: public sprout::identity<sprout::weed::unused>
+				{};
 			}	// namespace result_of
 		}	// namespace attr_cnv
 	}	// namespace weed
diff --git a/sprout/weed/detail/c_str_as_string.hpp b/sprout/weed/detail/c_str_as_string.hpp
index 3135c6a9..fffe3725 100644
--- a/sprout/weed/detail/c_str_as_string.hpp
+++ b/sprout/weed/detail/c_str_as_string.hpp
@@ -4,17 +4,41 @@
 #include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/string.hpp>
+#include <sprout/type_traits/identity.hpp>
 
 namespace sprout {
 	namespace weed {
 		namespace detail {
 			template<typename T>
 			struct c_str_as_string;
+			template<typename T>
+			struct c_str_as_string<T const>
+				: public sprout::weed::detail::c_str_as_string<T>
+			{};
+			template<typename T>
+			struct c_str_as_string<T volatile>
+				: public sprout::weed::detail::c_str_as_string<T>
+			{};
+			template<typename T>
+			struct c_str_as_string<T const volatile>
+				: public sprout::weed::detail::c_str_as_string<T>
+			{};
 			template<typename T, std::size_t N>
-			struct c_str_as_string<T const[N]> {
-			public:
-				typedef sprout::basic_string<T, N - 1> type;
-			};
+			struct c_str_as_string<T[N]>
+				: public sprout::identity<sprout::basic_string<T, N - 1> >
+			{};
+			template<typename T, std::size_t N>
+			struct c_str_as_string<T const[N]>
+				: public sprout::identity<sprout::basic_string<T, N - 1> >
+			{};
+			template<typename T, std::size_t N>
+			struct c_str_as_string<T volatile[N]>
+				: public sprout::identity<sprout::basic_string<T, N - 1> >
+			{};
+			template<typename T, std::size_t N>
+			struct c_str_as_string<T const volatile[N]>
+				: public sprout::identity<sprout::basic_string<T, N - 1> >
+			{};
 		}	// namespace detail
 	}	// namespace weed
 }	// namespace sprout
diff --git a/sprout/weed/parser/auxiliary/eoi.hpp b/sprout/weed/parser/auxiliary/eoi.hpp
index 73fe34d5..97584651 100644
--- a/sprout/weed/parser/auxiliary/eoi.hpp
+++ b/sprout/weed/parser/auxiliary/eoi.hpp
@@ -3,6 +3,7 @@
 
 #include <cstddef>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/parser/parser_base.hpp>
@@ -17,15 +18,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef sprout::weed::unused type;
-			};
+			struct attribute
+				: public sprout::identity<sprout::weed::unused>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		public:
 			template<typename Context, typename Iterator>
 			SPROUT_CONSTEXPR typename result<Context, Iterator>::type operator()(
diff --git a/sprout/weed/parser/auxiliary/eol.hpp b/sprout/weed/parser/auxiliary/eol.hpp
index 9822e72d..0f761b9b 100644
--- a/sprout/weed/parser/auxiliary/eol.hpp
+++ b/sprout/weed/parser/auxiliary/eol.hpp
@@ -4,6 +4,7 @@
 #include <cstddef>
 #include <sprout/config.hpp>
 #include <sprout/iterator/next.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/parser/parser_base.hpp>
@@ -18,15 +19,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef sprout::weed::unused type;
-			};
+			struct attribute
+				: public sprout::identity<sprout::weed::unused>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		public:
 			template<typename Context, typename Iterator>
 			SPROUT_CONSTEXPR typename result<Context, Iterator>::type operator()(
diff --git a/sprout/weed/parser/auxiliary/eps.hpp b/sprout/weed/parser/auxiliary/eps.hpp
index 35bc0472..956895de 100644
--- a/sprout/weed/parser/auxiliary/eps.hpp
+++ b/sprout/weed/parser/auxiliary/eps.hpp
@@ -3,6 +3,7 @@
 
 #include <cstddef>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/parser/parser_base.hpp>
@@ -17,15 +18,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef sprout::weed::unused type;
-			};
+			struct attribute
+				: public sprout::identity<sprout::weed::unused>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		public:
 			template<typename Context, typename Iterator>
 			SPROUT_CONSTEXPR typename result<Context, Iterator>::type operator()(
diff --git a/sprout/weed/parser/char/char.hpp b/sprout/weed/parser/char/char.hpp
index eae24cec..b825ea33 100644
--- a/sprout/weed/parser/char/char.hpp
+++ b/sprout/weed/parser/char/char.hpp
@@ -5,6 +5,7 @@
 #include <type_traits>
 #include <sprout/config.hpp>
 #include <sprout/iterator/next.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/parser/parser_base.hpp>
@@ -22,15 +23,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef sprout::weed::unused type;
-			};
+			struct attribute
+				: public sprout::identity<sprout::weed::unused>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		private:
 			T t_;
 		public:
@@ -81,15 +80,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef typename std::iterator_traits<Iterator>::value_type type;
-			};
+			struct attribute
+				: public sprout::identity<typename std::iterator_traits<Iterator>::value_type>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		private:
 			T t_;
 		public:
@@ -122,15 +119,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef typename std::iterator_traits<Iterator>::value_type type;
-			};
+			struct attribute
+				: public sprout::identity<typename std::iterator_traits<Iterator>::value_type>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		public:
 			template<typename Context, typename Iterator>
 			SPROUT_CONSTEXPR typename result<Context, Iterator>::type operator()(
diff --git a/sprout/weed/parser/char/char_class.hpp b/sprout/weed/parser/char/char_class.hpp
index e12ac4a1..af19f1a9 100644
--- a/sprout/weed/parser/char/char_class.hpp
+++ b/sprout/weed/parser/char/char_class.hpp
@@ -5,6 +5,7 @@
 #include <sprout/config.hpp>
 #include <sprout/iterator/next.hpp>
 #include <sprout/ctype/ascii.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/parser/parser_base.hpp>
@@ -18,19 +19,17 @@ namespace sprout {
 		{ \
 		public: \
 			template<typename Context, typename Iterator> \
-			struct attribute { \
-			public: \
-				typedef typename std::conditional< \
+			struct attribute \
+				: public std::conditional< \
 					Nil, \
 					sprout::weed::unused, \
 					typename std::iterator_traits<Iterator>::value_type \
-				>::type type; \
-			}; \
+				> \
+			{}; \
 			template<typename Context, typename Iterator> \
-			struct result { \
-			public: \
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type; \
-			}; \
+			struct result \
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> > \
+			{}; \
 		public: \
 			template<typename Context, typename Iterator> \
 			SPROUT_CONSTEXPR typename result<Context, Iterator>::type operator()( \
diff --git a/sprout/weed/parser/directive/as_array.hpp b/sprout/weed/parser/directive/as_array.hpp
index 84171859..9fa705e5 100644
--- a/sprout/weed/parser/directive/as_array.hpp
+++ b/sprout/weed/parser/directive/as_array.hpp
@@ -4,6 +4,7 @@
 #include <cstddef>
 #include <sprout/config.hpp>
 #include <sprout/array/array.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>
@@ -32,10 +33,9 @@ namespace sprout {
 				typedef sprout::array<attr_type, 1> type;
 			};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			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:
diff --git a/sprout/weed/parser/directive/as_tuple.hpp b/sprout/weed/parser/directive/as_tuple.hpp
index 7c610350..d244604d 100644
--- a/sprout/weed/parser/directive/as_tuple.hpp
+++ b/sprout/weed/parser/directive/as_tuple.hpp
@@ -4,6 +4,7 @@
 #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>
@@ -32,10 +33,9 @@ namespace sprout {
 				typedef sprout::tuples::tuple<attr_type> type;
 			};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			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:
diff --git a/sprout/weed/parser/directive/omit.hpp b/sprout/weed/parser/directive/omit.hpp
index 945f273c..56690daa 100644
--- a/sprout/weed/parser/directive/omit.hpp
+++ b/sprout/weed/parser/directive/omit.hpp
@@ -3,6 +3,7 @@
 
 #include <cstddef>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/expr/make_terminal_or_expr.hpp>
@@ -22,15 +23,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef sprout::weed::unused type;
-			};
+			struct attribute
+				: public sprout::identity<sprout::weed::unused>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			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:
diff --git a/sprout/weed/parser/directive/repeat.hpp b/sprout/weed/parser/directive/repeat.hpp
index 5f1743a3..b83ec8c1 100644
--- a/sprout/weed/parser/directive/repeat.hpp
+++ b/sprout/weed/parser/directive/repeat.hpp
@@ -3,6 +3,7 @@
 
 #include <cstddef>
 #include <sprout/config.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>
@@ -142,18 +143,16 @@ namespace sprout {
 			};
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef typename sprout::weed::attr_cnv::result_of::times<
+			struct attribute
+				: public sprout::weed::attr_cnv::result_of::times<
 					sprout::weed::traits::limit_of<Parser, Iterator, Context>::value,
 					typename sprout::weed::traits::attribute_of<Parser, Iterator, Context>::type
-				>::type type;
-			};
+				>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			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:
diff --git a/sprout/weed/parser/directive/replace.hpp b/sprout/weed/parser/directive/replace.hpp
index 8e13ff23..08381641 100644
--- a/sprout/weed/parser/directive/replace.hpp
+++ b/sprout/weed/parser/directive/replace.hpp
@@ -3,6 +3,7 @@
 
 #include <cstddef>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/expr/make_terminal_or_expr.hpp>
@@ -23,15 +24,13 @@ namespace sprout {
 		public:
 			typedef T value_type;
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef value_type type;
-			};
+			struct attribute
+				: public sprout::identity<value_type>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			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:
diff --git a/sprout/weed/parser/lim.hpp b/sprout/weed/parser/lim.hpp
index 718367b2..81a7dc4a 100644
--- a/sprout/weed/parser/lim.hpp
+++ b/sprout/weed/parser/lim.hpp
@@ -3,6 +3,7 @@
 
 #include <cstddef>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/limited.hpp>
 #include <sprout/weed/expr/make_terminal_or_expr.hpp>
@@ -25,15 +26,13 @@ namespace sprout {
 			SPROUT_STATIC_CONSTEXPR std::size_t limit = Limit;
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef typename sprout::weed::traits::attribute_of<Parser, Iterator, Context>::type type;
-			};
+			struct attribute
+				: public sprout::weed::traits::attribute_of<Parser, Iterator, Context>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			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:
diff --git a/sprout/weed/parser/numeric/int_p.hpp b/sprout/weed/parser/numeric/int_p.hpp
index d460b08d..56d7f759 100644
--- a/sprout/weed/parser/numeric/int_p.hpp
+++ b/sprout/weed/parser/numeric/int_p.hpp
@@ -6,6 +6,7 @@
 #include <sprout/iterator/next.hpp>
 #include <sprout/tuple/tuple.hpp>
 #include <sprout/integer/integer_digits.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/parser/parser_base.hpp>
@@ -32,15 +33,13 @@ namespace sprout {
 				;
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef IntType type;
-			};
+			struct attribute
+				: public sprout::identity<IntType>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		private:
 			template<typename Context, typename Iterator>
 			SPROUT_CONSTEXPR typename result<Context, Iterator>::type make_result(
diff --git a/sprout/weed/parser/numeric/uint_p.hpp b/sprout/weed/parser/numeric/uint_p.hpp
index e3296521..1bc19321 100644
--- a/sprout/weed/parser/numeric/uint_p.hpp
+++ b/sprout/weed/parser/numeric/uint_p.hpp
@@ -6,6 +6,7 @@
 #include <sprout/iterator/next.hpp>
 #include <sprout/tuple/tuple.hpp>
 #include <sprout/integer/integer_digits.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/parser/parser_base.hpp>
@@ -32,15 +33,13 @@ namespace sprout {
 				;
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef UIntType type;
-			};
+			struct attribute
+				: public sprout::identity<UIntType>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		private:
 			template<typename Context, typename Iterator>
 			SPROUT_CONSTEXPR typename result<Context, Iterator>::type make_result(
diff --git a/sprout/weed/parser/string/string.hpp b/sprout/weed/parser/string/string.hpp
index 270fd5b0..faf20225 100644
--- a/sprout/weed/parser/string/string.hpp
+++ b/sprout/weed/parser/string/string.hpp
@@ -9,6 +9,7 @@
 #include <sprout/container/size.hpp>
 #include <sprout/iterator/operation.hpp>
 #include <sprout/algorithm/equal.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/parser_result.hpp>
 #include <sprout/weed/parser/parser_base.hpp>
@@ -27,15 +28,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef sprout::weed::unused type;
-			};
+			struct attribute
+				: public sprout::identity<sprout::weed::unused>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		private:
 			T t_;
 		public:
@@ -102,15 +101,13 @@ namespace sprout {
 		{
 		public:
 			template<typename Context, typename Iterator>
-			struct attribute {
-			public:
-				typedef T type;
-			};
+			struct attribute
+				: public sprout::identity<T>
+			{};
 			template<typename Context, typename Iterator>
-			struct result {
-			public:
-				typedef sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> type;
-			};
+			struct result
+				: public sprout::identity<sprout::weed::parser_result<Iterator, typename attribute<Context, Iterator>::type> >
+			{};
 		private:
 			T t_;
 		public:
diff --git a/sprout/weed/traits/expr/expr_of.hpp b/sprout/weed/traits/expr/expr_of.hpp
index 0f183103..bad3daa9 100644
--- a/sprout/weed/traits/expr/expr_of.hpp
+++ b/sprout/weed/traits/expr/expr_of.hpp
@@ -3,6 +3,7 @@
 
 #include <type_traits>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/type_traits/remove_shallow_cvref.hpp>
 #include <sprout/weed/expr/expr_fwd.hpp>
 #include <sprout/weed/traits/expr/terminal_or_expr_of.hpp>
@@ -14,15 +15,16 @@ namespace sprout {
 			// expr_of
 			//
 			template<typename Tag, typename... Args>
-			struct expr_of {
-			public:
-				typedef sprout::weed::expr<
-					Tag,
-					typename sprout::weed::traits::terminal_or_expr_of<
-						typename sprout::remove_shallow_cvref<Args>::type
-					>::type...
-				> type;
-			};
+			struct expr_of
+				: public sprout::identity<
+					sprout::weed::expr<
+						Tag,
+						typename sprout::weed::traits::terminal_or_expr_of<
+							typename sprout::remove_shallow_cvref<Args>::type
+						>::type...
+					>
+				>
+			{};
 		}	// namespace traits
 	}	// namespace weed
 }	// namespace sprout
diff --git a/sprout/weed/traits/expr/tag_of.hpp b/sprout/weed/traits/expr/tag_of.hpp
index fd88d7c3..5f809830 100644
--- a/sprout/weed/traits/expr/tag_of.hpp
+++ b/sprout/weed/traits/expr/tag_of.hpp
@@ -3,6 +3,7 @@
 
 #include <type_traits>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/weed/traits/expr/is_expr.hpp>
 
 namespace sprout {
@@ -23,10 +24,9 @@ namespace sprout {
 				typename std::enable_if<
 					sprout::weed::traits::is_expr<Expr>::value
 				>::type
-			> {
-			public:
-				typedef typename Expr::expr_tag type;
-			};
+			>
+				: public sprout::identity<typename Expr::expr_tag>
+			{};
 		}	// namespace traits
 	}	// namespace weed
 }	// namespace sprout
diff --git a/sprout/weed/traits/expr/terminal_of.hpp b/sprout/weed/traits/expr/terminal_of.hpp
index fdd72f57..a4a630d7 100644
--- a/sprout/weed/traits/expr/terminal_of.hpp
+++ b/sprout/weed/traits/expr/terminal_of.hpp
@@ -3,6 +3,7 @@
 
 #include <type_traits>
 #include <sprout/config.hpp>
+#include <sprout/type_traits/identity.hpp>
 #include <sprout/type_traits/remove_shallow_cvref.hpp>
 #include <sprout/weed/expr/expr_fwd.hpp>
 #include <sprout/weed/expr/tag.hpp>
@@ -25,13 +26,14 @@ namespace sprout {
 						typename sprout::remove_shallow_cvref<Arg>::type
 					>::value
 				>::type
-			> {
-			public:
-				typedef sprout::weed::expr<
-					sprout::weed::tag::terminal,
-					typename sprout::remove_shallow_cvref<Arg>::type
-				> type;
-			};
+			>
+				: public sprout::identity<
+					sprout::weed::expr<
+						sprout::weed::tag::terminal,
+						typename sprout::remove_shallow_cvref<Arg>::type
+					>
+				>
+			{};
 			template<typename Arg>
 			struct terminal_of<
 				Arg,
@@ -40,15 +42,16 @@ namespace sprout {
 						typename sprout::remove_shallow_cvref<Arg>::type
 					>::value
 				>::type
-			> {
-			public:
-				typedef sprout::weed::expr<
-					sprout::weed::tag::terminal,
-					typename sprout::weed::detail::c_str_as_string<
-						typename sprout::remove_shallow_cvref<Arg>::type
-					>::type
-				> type;
-			};
+			>
+				: public sprout::identity<
+					sprout::weed::expr<
+						sprout::weed::tag::terminal,
+						typename sprout::weed::detail::c_str_as_string<
+							typename sprout::remove_shallow_cvref<Arg>::type
+						>::type
+					>
+				>
+			{};
 		}	// namespace traits
 	}	// namespace weed
 }	// namespace sprout
diff --git a/sprout/weed/traits/expr/terminal_or_expr_of.hpp b/sprout/weed/traits/expr/terminal_or_expr_of.hpp
index 4219dbfc..9470c998 100644
--- a/sprout/weed/traits/expr/terminal_or_expr_of.hpp
+++ b/sprout/weed/traits/expr/terminal_or_expr_of.hpp
@@ -14,16 +14,15 @@ namespace sprout {
 			// terminal_or_expr_of
 			//
 			template<typename Arg>
-			struct terminal_or_expr_of {
-			public:
-				typedef typename std::conditional<
+			struct terminal_or_expr_of
+				: public std::conditional<
 					sprout::weed::traits::is_expr<
 						typename sprout::remove_shallow_cvref<Arg>::type
 					>::value,
-					typename sprout::remove_shallow_cvref<Arg>::type,
-					typename sprout::weed::traits::terminal_of<Arg>::type
-				>::type type;
-			};
+					sprout::remove_shallow_cvref<Arg>,
+					sprout::weed::traits::terminal_of<Arg>
+				>::type
+			{};
 		}	// namespace traits
 	}	// namespace weed
 }	// namespace sprout
diff --git a/sprout/weed/traits/parser/attribute_of.hpp b/sprout/weed/traits/parser/attribute_of.hpp
index f6b22caa..e8db6ad1 100644
--- a/sprout/weed/traits/parser/attribute_of.hpp
+++ b/sprout/weed/traits/parser/attribute_of.hpp
@@ -3,6 +3,7 @@
 
 #include <type_traits>
 #include <sprout/config.hpp>
+#include <sprout/weed/traits/expr/is_expr.hpp>
 #include <sprout/weed/unused.hpp>
 #include <sprout/weed/expr/expr.hpp>
 #include <sprout/weed/expr/tag.hpp>
@@ -37,10 +38,9 @@ namespace sprout {
 					&& !sprout::weed::traits::is_c_str<T>::value
 					&& !sprout::weed::traits::is_string<T>::value
 				>::type
-			> {
-			public:
-				typedef typename T::template attribute<Context, Iterator>::type type;
-			};
+			>
+				: public T::template attribute<Context, Iterator>
+			{};
 			template<typename T, typename Iterator, typename Context>
 			struct attribute_of<
 				T,
@@ -49,10 +49,9 @@ namespace sprout {
 				typename std::enable_if<
 					sprout::weed::traits::is_expr<T>::value
 				>::type
-			> {
-			public:
-				typedef typename Context::template eval<T>::attribute_type type;
-			};
+			>
+				: public sprout::identity<typename Context::template eval<T>::attribute_type>
+			{};
 			template<typename T, typename Iterator, typename Context>
 			struct attribute_of<
 				T,
diff --git a/sprout/weed/traits/parser/is_parser.hpp b/sprout/weed/traits/parser/is_parser.hpp
index 39205590..6854f0b4 100644
--- a/sprout/weed/traits/parser/is_parser.hpp
+++ b/sprout/weed/traits/parser/is_parser.hpp
@@ -52,6 +52,7 @@ namespace sprout {
 				T,
 				typename std::enable_if<
 					sprout::weed::traits::is_c_str<T>::value
+					&& !std::is_const<T>::value
 				>::type
 			>
 				: public std::true_type
@@ -61,7 +62,6 @@ namespace sprout {
 				T,
 				typename std::enable_if<
 					std::is_const<T>::value
-					&& !std::is_array<T>::value
 				>::type
 			>
 				: public sprout::weed::traits::is_parser<