diff --git a/sprout/config/suffix.hpp b/sprout/config/suffix.hpp
index 1cac8d53..054bf319 100644
--- a/sprout/config/suffix.hpp
+++ b/sprout/config/suffix.hpp
@@ -100,4 +100,10 @@
 #	define SPROUT_USE_INDEX_ITERATOR_IMPLEMENTATION 0
 #endif	// #ifndef SPROUT_CONFIG_DISABLE_SUPPORT_TEMPORARY_CONTAINER_ITERATION
 
+#ifndef SPROUT_CONFIG_DISABLE_SUPPORT_EFFICIENT_ARRAY_ITERATION
+#	define SPROUT_USE_PTR_INDEX_ITERATOR_IMPLEMENTATION 1
+#else	// #ifndef SPROUT_CONFIG_DISABLE_SUPPORT_EFFICIENT_ARRAY_ITERATION
+#	define SPROUT_USE_PTR_INDEX_ITERATOR_IMPLEMENTATION 0
+#endif	// #ifndef SPROUT_CONFIG_DISABLE_SUPPORT_EFFICIENT_ARRAY_ITERATION
+
 #endif	// #ifndef SPROUT_CONFIG_SUFFIX_HPP
diff --git a/sprout/container/begin.hpp b/sprout/container/begin.hpp
index c5397e7d..ded390bc 100644
--- a/sprout/container/begin.hpp
+++ b/sprout/container/begin.hpp
@@ -22,6 +22,19 @@ namespace sprout {
 		range_begin(Container const& cont) {
 			return cont.begin();
 		}
+
+		template<typename T, std::size_t N>
+		inline typename sprout::container_traits<T[N]>::iterator
+		range_begin(T (& arr)[N]) {
+			typedef typename sprout::container_traits<T[N]>::iterator iterator;
+			return iterator(arr);
+		}
+		template<typename T, std::size_t N>
+		inline SPROUT_CONSTEXPR typename sprout::container_traits<T const[N]>::const_iterator
+		range_begin(T const (& arr)[N]) {
+			typedef typename sprout::container_traits<T const[N]>::const_iterator iterator;
+			return iterator(arr);
+		}
 	}	// namespace container_detail
 }	// namespace sprout
 
@@ -46,12 +59,12 @@ namespace sprout {
 	template<typename T, std::size_t N>
 	inline typename sprout::container_traits<T[N]>::iterator
 	begin(T (& arr)[N]) {
-		return arr;
+		return sprout::container_detail::range_begin(arr);
 	}
 	template<typename T, std::size_t N>
 	inline SPROUT_CONSTEXPR typename sprout::container_traits<T const[N]>::const_iterator
 	begin(T const (& arr)[N]) {
-		return arr;
+		return sprout::container_detail::range_begin(arr);
 	}
 
 	//
@@ -67,7 +80,7 @@ namespace sprout {
 	template<typename T, std::size_t N>
 	inline SPROUT_CONSTEXPR typename sprout::container_traits<T const[N]>::const_iterator
 	cbegin(T const (& arr)[N]) {
-		return arr;
+		return sprout::container_detail::range_begin(arr);
 	}
 }	// namespace sprout
 
diff --git a/sprout/container/container_traits.hpp b/sprout/container/container_traits.hpp
index 2bcde15a..3afb36f1 100644
--- a/sprout/container/container_traits.hpp
+++ b/sprout/container/container_traits.hpp
@@ -9,6 +9,9 @@
 #include <sprout/type_traits/has_xxx.hpp>
 #include <sprout/type_traits/inherit_if_xxx.hpp>
 #include <sprout/container/detail/array_like.hpp>
+#if SPROUT_USE_PTR_INDEX_ITERATOR_IMPLEMENTATION
+#	include <sprout/iterator/ptr_index_iterator.hpp>
+#endif
 
 namespace sprout {
 	template<typename Container>
@@ -428,8 +431,13 @@ namespace sprout {
 		struct container_traits_default<T[N]> {
 		public:
 			typedef T value_type;
+#if SPROUT_USE_PTR_INDEX_ITERATOR_IMPLEMENTATION
+			typedef sprout::ptr_index_iterator<T> iterator;
+			typedef sprout::ptr_index_iterator<T const> const_iterator;
+#else
 			typedef T* iterator;
 			typedef T const* const_iterator;
+#endif
 			typedef T& reference;
 			typedef T const& const_reference;
 			typedef std::size_t size_type;
diff --git a/sprout/container/end.hpp b/sprout/container/end.hpp
index dc150daa..4ab01e4e 100644
--- a/sprout/container/end.hpp
+++ b/sprout/container/end.hpp
@@ -22,6 +22,19 @@ namespace sprout {
 		range_end(Container const& cont) {
 			return cont.end();
 		}
+
+		template<typename T, std::size_t N>
+		inline typename sprout::container_traits<T[N]>::iterator
+		range_end(T (& arr)[N]) {
+			typedef typename sprout::container_traits<T[N]>::iterator iterator;
+			return iterator(arr) + N;
+		}
+		template<typename T, std::size_t N>
+		inline SPROUT_CONSTEXPR typename sprout::container_traits<T const[N]>::const_iterator
+		range_end(T const (& arr)[N]) {
+			typedef typename sprout::container_traits<T const[N]>::const_iterator iterator;
+			return iterator(arr) + N;
+		}
 	}	// namespace container_detail
 }	// namespace sprout
 
@@ -46,12 +59,12 @@ namespace sprout {
 	template<typename T, std::size_t N>
 	inline typename sprout::container_traits<T[N]>::iterator
 	end(T (& arr)[N]) {
-		return arr + N;
+		return sprout::container_detail::range_end(arr);
 	}
 	template<typename T, std::size_t N>
 	inline SPROUT_CONSTEXPR typename sprout::container_traits<T const[N]>::const_iterator
 	end(T const (& arr)[N]) {
-		return arr + N;
+		return sprout::container_detail::range_end(arr);
 	}
 
 	//
@@ -67,7 +80,7 @@ namespace sprout {
 	template<typename T, std::size_t N>
 	inline SPROUT_CONSTEXPR typename sprout::container_traits<T const[N]>::const_iterator
 	cend(T const (& arr)[N]) {
-		return arr + N;
+		return sprout::container_detail::range_end(arr);
 	}
 }	// namespace sprout
 
diff --git a/sprout/cstring/strlen.hpp b/sprout/cstring/strlen.hpp
index 61d8d5c3..44809ff9 100644
--- a/sprout/cstring/strlen.hpp
+++ b/sprout/cstring/strlen.hpp
@@ -5,21 +5,12 @@
 #include <sprout/config.hpp>
 
 namespace sprout {
-	// Copyright (C) 2011 RiSK (sscrisk)
-
-	namespace detail {
-		inline SPROUT_CONSTEXPR std::size_t
-		strlen_impl(char const* s, std::size_t n) {
-			return !*s ? n :
-				sprout::detail::strlen_impl(s + 1, n + 1)
-				;
-		}
-	}	// namespace detail
-
 	// 7.21.6.3  strlen �֐�
 	inline SPROUT_CONSTEXPR std::size_t
 	strlen(char const* s) {
-		return sprout::detail::strlen_impl(s, 0);
+		return !*s ? 0
+			: 1 + sprout::strlen(s + 1)
+			;
 	}
 }	// namespace sprout
 
diff --git a/sprout/cwchar/wcslen.hpp b/sprout/cwchar/wcslen.hpp
index 1a68ba4a..b901a4c7 100644
--- a/sprout/cwchar/wcslen.hpp
+++ b/sprout/cwchar/wcslen.hpp
@@ -5,20 +5,11 @@
 #include <sprout/config.hpp>
 
 namespace sprout {
-	// Copyright (C) 2011 RiSK (sscrisk)
-
-	namespace detail {
-		inline SPROUT_CONSTEXPR std::size_t
-		wcslen_impl(wchar_t const* s, std::size_t n) {
-			return !*s ? n :
-				sprout::detail::wcslen_impl(s + 1, n + 1)
-				;
-		}
-	}	// namespace detail
-
 	inline SPROUT_CONSTEXPR std::size_t
 	wcslen(wchar_t const* s) {
-		return sprout::detail::wcslen_impl(s, 0);
+		return !*s ? 0
+			: 1 + sprout::wcslen(s + 1)
+			;
 	}
 }	// namespace sprout
 
diff --git a/sprout/iterator/index_iterator.hpp b/sprout/iterator/index_iterator.hpp
index 2de357cb..b8ccc67d 100644
--- a/sprout/iterator/index_iterator.hpp
+++ b/sprout/iterator/index_iterator.hpp
@@ -20,27 +20,27 @@ namespace sprout {
 	class index_iterator
 		: public std::iterator<
 			std::random_access_iterator_tag,
-			typename sprout::container_traits<typename std::decay<Container>::type>::value_type,
-			typename sprout::container_traits<typename std::decay<Container>::type>::difference_type,
+			typename sprout::container_traits<typename std::remove_reference<Container>::type>::value_type,
+			typename sprout::container_traits<typename std::remove_reference<Container>::type>::difference_type,
 			typename std::conditional<
 				std::is_const<typename std::remove_reference<Container>::type>::value,
-				typename sprout::container_traits<typename std::decay<Container>::type>::const_pointer,
-				typename sprout::container_traits<typename std::decay<Container>::type>::pointer
+				typename sprout::container_traits<typename std::remove_reference<Container>::type>::const_pointer,
+				typename sprout::container_traits<typename std::remove_reference<Container>::type>::pointer
 			>::type,
 			typename std::conditional<
 				std::is_const<typename std::remove_reference<Container>::type>::value,
-				typename sprout::container_traits<typename std::decay<Container>::type>::const_reference,
-				typename sprout::container_traits<typename std::decay<Container>::type>::reference
+				typename sprout::container_traits<typename std::remove_reference<Container>::type>::const_reference,
+				typename sprout::container_traits<typename std::remove_reference<Container>::type>::reference
 			>::type
 		>
 	{
 	public:
 		typedef Container container_type;
-		typedef typename sprout::container_traits<typename std::decay<container_type>::type> traits_type;
+		typedef typename sprout::container_traits<typename std::remove_reference<container_type>::type> traits_type;
 		typedef typename std::conditional<
 			std::is_reference<container_type>::value,
-			typename std::decay<container_type>::type const&,
-			typename std::decay<container_type>::type const
+			typename std::remove_reference<container_type>::type const&,
+			typename std::remove_reference<container_type>::type const
 		>::type const_container_type;
 	private:
 		typedef std::iterator<
@@ -58,6 +58,7 @@ namespace sprout {
 				typename traits_type::reference
 			>::type
 		> base_type;
+		typedef sprout::value_holder<container_type> holder_type;
 	public:
 		typedef typename base_type::iterator_category iterator_category;
 		typedef typename base_type::value_type value_type;
@@ -66,10 +67,10 @@ namespace sprout {
 		typedef typename base_type::reference reference;
 		typedef typename traits_type::size_type size_type;
 	private:
-		sprout::value_holder<container_type> holder_;
+		holder_type holder_;
 		size_type index_;
 	private:
-		SPROUT_CONSTEXPR index_iterator(sprout::value_holder<container_type> const& r, size_type index)
+		SPROUT_CONSTEXPR index_iterator(holder_type const& r, size_type index)
 			: holder_(r)
 			, index_(index)
 		{}
@@ -79,13 +80,23 @@ namespace sprout {
 			, index_()
 		{}
 		index_iterator(index_iterator const&) = default;
-		SPROUT_CONSTEXPR index_iterator(typename sprout::value_holder<container_type>::param_type p, size_type index)
+		explicit SPROUT_CONSTEXPR index_iterator(typename holder_type::param_type p)
+			: holder_(p)
+			, index_(0)
+		{}
+		SPROUT_CONSTEXPR index_iterator(typename holder_type::param_type p, size_type index)
 			: holder_(p)
 			, index_(index)
 		{}
 		operator index_iterator<const_container_type>() const {
 			return index_iterator<const_container_type>(holder_.get(), index_);
 		}
+		SPROUT_CONSTEXPR typename holder_type::mutable_or_const_reference base() const {
+			return holder_.get();
+		}
+		SPROUT_CONSTEXPR size_type index() const {
+			return index_;
+		}
 		SPROUT_CONSTEXPR index_iterator next() const {
 			return index_iterator(holder_, index_ + 1);
 		}
diff --git a/sprout/iterator/ptr_index_iterator.hpp b/sprout/iterator/ptr_index_iterator.hpp
new file mode 100644
index 00000000..83c76ce2
--- /dev/null
+++ b/sprout/iterator/ptr_index_iterator.hpp
@@ -0,0 +1,286 @@
+#ifndef SPROUT_ITERATOR_PTR_INDEX_ITERATOR_HPP
+#define SPROUT_ITERATOR_PTR_INDEX_ITERATOR_HPP
+
+#include <iterator>
+#include <utility>
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/iterator/next.hpp>
+#include <sprout/iterator/prev.hpp>
+#include <sprout/iterator/distance.hpp>
+#include <sprout/utility/swap.hpp>
+
+namespace sprout {
+	//
+	// ptr_index_iterator
+	//
+	template<typename T>
+	class ptr_index_iterator
+		: public std::iterator<
+			typename std::iterator_traits<T*>::iterator_category,
+			typename std::iterator_traits<T*>::value_type,
+			typename std::iterator_traits<T*>::difference_type,
+			typename std::iterator_traits<T*>::pointer,
+			typename std::iterator_traits<T*>::reference
+		>
+	{
+	public:
+		typedef T type;
+	private:
+		typedef std::iterator<
+			typename std::iterator_traits<T*>::iterator_category,
+			typename std::iterator_traits<T*>::value_type,
+			typename std::iterator_traits<T*>::difference_type,
+			typename std::iterator_traits<T*>::pointer,
+			typename std::iterator_traits<T*>::reference
+		> base_type;
+	public:
+		typedef typename base_type::iterator_category iterator_category;
+		typedef typename base_type::value_type value_type;
+		typedef typename base_type::difference_type difference_type;
+		typedef typename base_type::pointer pointer;
+		typedef typename base_type::reference reference;
+		typedef typename std::remove_pointer<pointer>::type const* const_pointer;
+	private:
+		pointer p_;
+		difference_type index_;
+	public:
+		SPROUT_CONSTEXPR ptr_index_iterator()
+			: p_()
+			, index_()
+		{}
+		ptr_index_iterator(ptr_index_iterator const&) = default;
+		explicit SPROUT_CONSTEXPR ptr_index_iterator(pointer p)
+			: p_(p)
+			, index_(0)
+		{}
+		SPROUT_CONSTEXPR ptr_index_iterator(pointer p, difference_type index)
+			: p_(p)
+			, index_(index)
+		{}
+		operator ptr_index_iterator<const_pointer>() const {
+			return ptr_index_iterator<const_pointer>(p_, index_);
+		}
+		SPROUT_CONSTEXPR pointer base() const {
+			return p_;
+		}
+		SPROUT_CONSTEXPR difference_type index() const {
+			return index_;
+		}
+		SPROUT_CONSTEXPR pointer ptr() const {
+			return p_ + index_;
+		}
+		SPROUT_CONSTEXPR ptr_index_iterator next() const {
+			return ptr_index_iterator(p_, index_ + 1);
+		}
+		SPROUT_CONSTEXPR ptr_index_iterator prev() const {
+			return ptr_index_iterator(p_, index_ - 1);
+		}
+		void swap(ptr_index_iterator& other)
+		SPROUT_NOEXCEPT
+		{
+			sprout::swap(p_, other.p_);
+			sprout::swap(index_, other.index_);
+		}
+		friend SPROUT_CONSTEXPR bool operator==(ptr_index_iterator const& lhs, ptr_index_iterator const& rhs) {
+			return lhs.index_ == rhs.index_;
+		}
+		friend SPROUT_CONSTEXPR bool operator!=(ptr_index_iterator const& lhs, ptr_index_iterator const& rhs) {
+			return !(lhs == rhs);
+		}
+		friend SPROUT_CONSTEXPR bool operator<(ptr_index_iterator const& lhs, ptr_index_iterator const& rhs) {
+			return lhs.index_ < rhs.index_;
+		}
+		friend SPROUT_CONSTEXPR bool operator>(ptr_index_iterator const& lhs, ptr_index_iterator const& rhs) {
+			return rhs < lhs;
+		}
+		friend SPROUT_CONSTEXPR bool operator<=(ptr_index_iterator const& lhs, ptr_index_iterator const& rhs) {
+			return !(rhs < lhs);
+		}
+		friend SPROUT_CONSTEXPR bool operator>=(ptr_index_iterator const& lhs, ptr_index_iterator const& rhs) {
+			return !(lhs < rhs);
+		}
+		SPROUT_CONSTEXPR reference operator*() const {
+			return p_[index_];
+		}
+		SPROUT_CONSTEXPR pointer operator->() const {
+			return p_ + index_;
+		}
+		ptr_index_iterator& operator++() {
+			ptr_index_iterator temp(next());
+			temp.swap(*this);
+			return *this;
+		}
+		ptr_index_iterator operator++(int) {
+			ptr_index_iterator result(*this);
+			++*this;
+			return result;
+		}
+		ptr_index_iterator& operator--() {
+			ptr_index_iterator temp(prev());
+			temp.swap(*this);
+			return *this;
+		}
+		ptr_index_iterator operator--(int) {
+			ptr_index_iterator result(*this);
+			--*this;
+			return result;
+		}
+		SPROUT_CONSTEXPR ptr_index_iterator operator+(difference_type n) const {
+			return ptr_index_iterator(p_, index_ + n);
+		}
+		SPROUT_CONSTEXPR ptr_index_iterator operator-(difference_type n) const {
+			return ptr_index_iterator(p_, index_ - n);
+		}
+		ptr_index_iterator& operator+=(difference_type n) {
+			ptr_index_iterator temp(p_, index_ + n);
+			temp.swap(*this);
+			return *this;
+		}
+		ptr_index_iterator& operator-=(difference_type n) {
+			ptr_index_iterator temp(p_, index_ - n);
+			temp.swap(*this);
+			return *this;
+		}
+		SPROUT_CONSTEXPR reference operator[](difference_type n) const {
+			return p_[index_ + n];
+		}
+		friend SPROUT_CONSTEXPR difference_type operator-(ptr_index_iterator const& lhs, ptr_index_iterator const& rhs) {
+			return lhs.index_ - rhs.index_;
+		}
+		friend SPROUT_CONSTEXPR ptr_index_iterator operator+(difference_type n, ptr_index_iterator const& it) {
+			return it + n;
+		}
+	};
+
+	//
+	// swap
+	//
+	template<typename T>
+	inline void
+	swap(sprout::ptr_index_iterator<T>& lhs, sprout::ptr_index_iterator<T>& rhs)
+	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
+	{
+		lhs.swap(rhs);
+	}
+
+	//
+	// make_ptr_index_iterator
+	//
+	template<typename T>
+	inline SPROUT_CONSTEXPR sprout::ptr_index_iterator<T>
+	make_ptr_index_iterator(T* p) {
+		return sprout::ptr_index_iterator<T>(p);
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR sprout::ptr_index_iterator<T>
+	make_ptr_index_iterator(T* p, typename sprout::ptr_index_iterator<T>::difference_type index) {
+		return sprout::ptr_index_iterator<T>(p, index);
+	}
+
+	//
+	// as_iterator
+	//
+	template<typename T>
+	inline SPROUT_CONSTEXPR sprout::ptr_index_iterator<T>
+	as_iterator(T* p) {
+		return sprout::make_ptr_index_iterator(p);
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR sprout::ptr_index_iterator<T>
+	as_iterator(T* p, typename std::iterator_traits<T*>::difference_type n) {
+		return sprout::make_ptr_index_iterator(p, n);
+	}
+
+	template<typename Iterator>
+	inline SPROUT_CONSTEXPR Iterator
+	as_iterator(Iterator const& it) {
+		return it;
+	}
+	template<typename Iterator>
+	inline SPROUT_CONSTEXPR Iterator
+	as_iterator(Iterator const& it, typename std::iterator_traits<Iterator>::difference_type n) {
+		return sprout::next(it, n);
+	}
+
+	//
+	// as_iterator_base
+	//
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename sprout::ptr_index_iterator<T>::pointer
+	as_iterator_base(sprout::ptr_index_iterator<T> const& it) {
+		return it.ptr();
+	}
+	template<typename Iterator>
+	inline SPROUT_CONSTEXPR Iterator
+	as_iterator_base(Iterator const& it) {
+		return it;
+	}
+
+	//
+	// is_ptr_index_iterator
+	//
+	template<typename T>
+	struct is_ptr_index_iterator
+		: public std::false_type
+	{};
+	template<typename T>
+	struct is_ptr_index_iterator<T const>
+		: public sprout::is_ptr_index_iterator<T>
+	{};
+	template<typename T>
+	struct is_ptr_index_iterator<T const volatile>
+		: public sprout::is_ptr_index_iterator<T>
+	{};
+	template<typename T>
+	struct is_ptr_index_iterator<sprout::ptr_index_iterator<T> >
+		: public std::true_type
+	{};
+
+	//
+	// iterator_distance
+	//
+	template<typename T>
+	inline SPROUT_CONSTEXPR typename std::iterator_traits<sprout::ptr_index_iterator<T> >::difference_type
+	iterator_distance(sprout::ptr_index_iterator<T> first, sprout::ptr_index_iterator<T> last) {
+		return last - first;
+	}
+
+	//
+	// iterator_next
+	//
+	template<typename T>
+	inline SPROUT_CONSTEXPR sprout::ptr_index_iterator<T>
+	iterator_next(sprout::ptr_index_iterator<T> const& it) {
+		return it.next();
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR sprout::ptr_index_iterator<T>
+	iterator_next(
+		sprout::ptr_index_iterator<T> const& it,
+		typename sprout::ptr_index_iterator<T>::difference_type n
+		)
+	{
+		return it + n;
+	}
+
+	//
+	// iterator_prev
+	//
+	template<typename T>
+	inline SPROUT_CONSTEXPR sprout::ptr_index_iterator<T>
+	iterator_prev(sprout::ptr_index_iterator<T> const& it) {
+		return it.prev();
+	}
+	template<typename T>
+	inline SPROUT_CONSTEXPR sprout::ptr_index_iterator<T>
+	iterator_prev(
+		sprout::ptr_index_iterator<T> const& it,
+		typename sprout::ptr_index_iterator<T>::difference_type n
+		)
+	{
+		return it - n;
+	}
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_ITERATOR_PTR_INDEX_ITERATOR_HPP
diff --git a/sprout/iterator/various.hpp b/sprout/iterator/various.hpp
index 32e9b38d..07f0109a 100644
--- a/sprout/iterator/various.hpp
+++ b/sprout/iterator/various.hpp
@@ -3,6 +3,7 @@
 
 #include <sprout/config.hpp>
 #include <sprout/iterator/index_iterator.hpp>
+#include <sprout/iterator/ptr_index_iterator.hpp>
 #include <sprout/iterator/value_iterator.hpp>
 #include <sprout/iterator/counting_iterator.hpp>
 #include <sprout/iterator/generator_iterator.hpp>
diff --git a/sprout/string/char_traits.hpp b/sprout/string/char_traits.hpp
index 5718db3e..b7c4b699 100644
--- a/sprout/string/char_traits.hpp
+++ b/sprout/string/char_traits.hpp
@@ -5,6 +5,10 @@
 #include <algorithm>
 #include <string>
 #include <sprout/config.hpp>
+#include <sprout/functional/bind2nd.hpp>
+#include <sprout/iterator/ptr_index_iterator.hpp>
+#include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
+#include HDR_ITERATOR_SSCRISK_CEL_OR_SPROUT
 
 namespace sprout {
 	//
@@ -20,6 +24,19 @@ namespace sprout {
 		typedef typename impl_type::off_type off_type;
 		typedef typename impl_type::pos_type pos_type;
 		typedef typename impl_type::state_type state_type;
+	private:
+		struct eq_ {
+		public:
+			SPROUT_CONSTEXPR bool operator()(char_type c1, char_type c2) const SPROUT_NOEXCEPT {
+				return eq(c1, c2);
+			}
+		};
+	private:
+		static SPROUT_CONSTEXPR char_type const* find_impl(char_type const* found, char_type const* last) {
+			return found == last ? nullptr
+				: found
+				;
+		}
 	public:
 		static void assign(char_type& c1, char_type const& c2) SPROUT_NOEXCEPT {
 			impl_type::assign(c1, c2);
@@ -43,10 +60,15 @@ namespace sprout {
 				;
 		}
 		static SPROUT_CONSTEXPR char_type const* find(char_type const* s, std::size_t n, char_type const& a) {
-			return !n ? nullptr
-				: eq(*s, a) ? s
-				: find(s + 1, n - 1, a)
-				;
+			return find_impl(
+				sprout::as_iterator_base(
+					NS_SSCRISK_CEL_OR_SPROUT::find_if(
+						sprout::as_iterator(s), sprout::as_iterator(s, n),
+						sprout::bind2nd(eq_(), a)
+						)
+					),
+				s + n
+				);
 		}
 		static char_type* move(char_type* s1, char_type const* s2, std::size_t n) {
 			return impl_type::move(s1, s2, n);
@@ -105,10 +127,12 @@ namespace sprout {
 		}
 		template<typename ConstIterator>
 		static SPROUT_CONSTEXPR ConstIterator find(ConstIterator s, std::size_t n, char_type const& a) {
-			return !n ? s
-				: eq(*s, a) ? s
-				: find(s + 1, n - 1, a)
-				;
+			return sprout::as_iterator_base(
+				NS_SSCRISK_CEL_OR_SPROUT::find_if(
+					s, s + n,
+					sprout::bind2nd(eq_(), a)
+					)
+				);
 		}
 		template<typename Iterator, typename ConstIterator>
 		static Iterator move(Iterator s1, ConstIterator s2, std::size_t n) {
@@ -140,23 +164,45 @@ namespace sprout {
 		typedef typename traits_type::off_type off_type;
 		typedef typename traits_type::pos_type pos_type;
 		typedef typename traits_type::state_type state_type;
+	private:
+		struct eq_ {
+		public:
+			SPROUT_CONSTEXPR bool operator()(char_type c1, char_type c2) const SPROUT_NOEXCEPT {
+				return traits_type::eq(c1, c2);
+			}
+		};
 	public:
+		static SPROUT_CONSTEXPR std::size_t length(char_type const* s, std::size_t n) {
+			return NS_SSCRISK_CEL_OR_SPROUT::distance(
+				sprout::as_iterator(s),
+				find(sprout::as_iterator(s), n, char_type())
+				);
+		}
 		static SPROUT_CONSTEXPR char_type const* find(char_type const* s, std::size_t n, char_type const& a) {
-			return !n ? s
-				: traits_type::eq(*s, a) ? s
-				: find(s + 1, n - 1, a)
-				;
+			return sprout::as_iterator_base(
+				NS_SSCRISK_CEL_OR_SPROUT::find_if(
+					sprout::as_iterator(s), sprout::as_iterator(s, n),
+					sprout::bind2nd(eq_(), a)
+					)
+				);
 		}
 		static SPROUT_CONSTEXPR bool is_found(char_type const* found, char_type const* last) {
 			return found != last;
 		}
 #if SPROUT_USE_INDEX_ITERATOR_IMPLEMENTATION
+		template<typename ConstIterator>
+		static SPROUT_CONSTEXPR std::size_t length(ConstIterator s, std::size_t n) {
+			return NS_SSCRISK_CEL_OR_SPROUT::distance(
+				s,
+				find(s, n, char_type())
+				);
+		}
 		template<typename ConstIterator>
 		static SPROUT_CONSTEXPR ConstIterator find(ConstIterator s, std::size_t n, char_type const& a) {
-			return !n ? s
-				: traits_type::eq(*s, a) ? s
-				: find(s + 1, n - 1, a)
-				;
+			return NS_SSCRISK_CEL_OR_SPROUT::find_if(
+				s, s + n,
+				sprout::bind2nd(eq_(), a)
+				);
 		}
 		template<typename ConstIterator>
 		static SPROUT_CONSTEXPR bool is_found(ConstIterator found, ConstIterator last) {
diff --git a/sprout/string/concat.hpp b/sprout/string/concat.hpp
index 51082ef9..25f7c075 100644
--- a/sprout/string/concat.hpp
+++ b/sprout/string/concat.hpp
@@ -126,17 +126,19 @@ namespace sprout {
 	template<typename T, std::size_t N, typename Traits, std::size_t M>
 	inline SPROUT_CONSTEXPR sprout::basic_string<T, N + (M - 1), Traits>
 	operator+(sprout::basic_string<T, N, Traits> const& lhs, T const (& rhs)[M]) {
+		typedef sprout::char_traits_helper<Traits> traits_type;
 		return sprout::detail::string_concat(
 			lhs, lhs.size(),
-			rhs, sprout::char_traits<T>::length(rhs),
+			rhs, traits_type::length(rhs, M - 1),
 			sprout::index_range<0, N + (M - 1)>::make()
 			);
 	}
 	template<typename T, std::size_t N, typename Traits, std::size_t M>
 	inline SPROUT_CONSTEXPR sprout::basic_string<T, (M - 1) + N, Traits>
 	operator+(T const (& lhs)[M], sprout::basic_string<T, N, Traits> const& rhs) {
+		typedef sprout::char_traits_helper<Traits> traits_type;
 		return sprout::detail::string_concat(
-			lhs, sprout::char_traits<T>::length(lhs),
+			lhs, traits_type::length(lhs, M - 1),
 			rhs, rhs.size(),
 			sprout::index_range<0, (M - 1) + N>::make()
 			);
diff --git a/sprout/string/string.hpp b/sprout/string/string.hpp
index d4448226..cedad5b0 100644
--- a/sprout/string/string.hpp
+++ b/sprout/string/string.hpp
@@ -874,7 +874,8 @@ namespace sprout {
 		template<typename T, std::size_t N, sprout::index_t... Indexes>
 		inline SPROUT_CONSTEXPR sprout::basic_string<T, N - 1>
 		to_string_impl(T const(& arr)[N], sprout::index_tuple<Indexes...>) {
-			return to_string_impl_1(arr, sprout::char_traits<T>::length(arr), sprout::index_tuple<Indexes...>());
+			typedef sprout::char_traits_helper<sprout::char_traits<T> > traits_type;
+			return to_string_impl_1(arr, traits_type::length(arr, N - 1), sprout::index_tuple<Indexes...>());
 		}
 	}	// namespace detail
 	//
diff --git a/sprout/variant.hpp b/sprout/variant.hpp
index 4fc2dc61..8da23dae 100644
--- a/sprout/variant.hpp
+++ b/sprout/variant.hpp
@@ -8,6 +8,7 @@
 #include <sprout/variant/get.hpp>
 #include <sprout/variant/static_visitor.hpp>
 #include <sprout/variant/static_variant_visitor.hpp>
+#include <sprout/variant/as_visitor.hpp>
 #include <sprout/variant/as_variant_visitor.hpp>
 #include <sprout/variant/visitor_result.hpp>
 #include <sprout/variant/apply_visitor.hpp>
diff --git a/sprout/variant/as_visitor.hpp b/sprout/variant/as_visitor.hpp
new file mode 100644
index 00000000..85b298ad
--- /dev/null
+++ b/sprout/variant/as_visitor.hpp
@@ -0,0 +1,82 @@
+#ifndef SPROUT_VARIANT_AS_VISITOR_HPP
+#define SPROUT_VARIANT_AS_VISITOR_HPP
+
+#include <utility>
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/utility/forward.hpp>
+#include <sprout/utility/lvalue_forward.hpp>
+#include <sprout/utility/value_holder.hpp>
+#include <sprout/type_traits/lvalue_reference.hpp>
+#include <sprout/variant/static_visitor.hpp>
+#include <sprout/functional/type_traits/has_type.hpp>
+#include <sprout/functional/type_traits/weak_result_type.hpp>
+
+namespace sprout {
+	namespace detail {
+		template<typename T, typename = void>
+		struct result_type_or_void;
+		template<typename T>
+		struct result_type_or_void<
+			T,
+			typename std::enable_if<sprout::has_result_type<sprout::weak_result_type<T> >::value>::type
+		> {
+		public:
+			typedef typename sprout::weak_result_type<T>::result_type type;
+		};
+		template<typename T>
+		struct result_type_or_void<
+			T,
+			typename std::enable_if<!sprout::has_result_type<sprout::weak_result_type<T> >::value>::type
+		> {
+		public:
+			typedef void type;
+		};
+	}	// namespace detail
+
+	//
+	// visitor_wrapper
+	//
+	template<
+		typename Visitor,
+		typename R = typename sprout::detail::result_type_or_void<Visitor>::type
+	>
+	class visitor_wrapper
+		: public sprout::static_visitor<R>
+	{
+	public:
+		typedef Visitor visitor_type;
+		typedef sprout::value_holder<visitor_type&> holder_type;
+	private:
+		holder_type v_;
+	public:
+		SPROUT_CONSTEXPR explicit visitor_wrapper(typename holder_type::param_type v)
+			: v_(v)
+		{}
+		template<typename T>
+		SPROUT_CONSTEXPR auto operator()(T&& t)
+		-> decltype(std::declval<holder_type const>().get()(sprout::forward<T>(t))) const
+		{
+			return v_.get()(sprout::forward<T>(t));
+		}
+	};
+
+	//
+	// as_visitor
+	//
+	template<typename Visitor>
+	inline SPROUT_CONSTEXPR sprout::visitor_wrapper<typename std::remove_reference<typename sprout::lvalue_reference<Visitor>::type>::type>
+	as_visitor(Visitor&& visitor) {
+		typedef sprout::visitor_wrapper<typename std::remove_reference<typename sprout::lvalue_reference<Visitor>::type>::type> type;
+		return type(sprout::lvalue_forward<Visitor>(visitor));
+	}
+
+	template<typename R, typename Visitor>
+	inline SPROUT_CONSTEXPR sprout::visitor_wrapper<typename std::remove_reference<typename sprout::lvalue_reference<Visitor>::type>::type, R>
+	as_visitor(Visitor&& visitor) {
+		typedef sprout::visitor_wrapper<typename std::remove_reference<typename sprout::lvalue_reference<Visitor>::type>::type, R> type;
+		return type(sprout::lvalue_forward<Visitor>(visitor));
+	}
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_VARIANT_AS_VISITOR_HPP