diff --git a/sprout/algorithm/tristate_lexicographical_compare.hpp b/sprout/algorithm/tristate_lexicographical_compare.hpp
index 9c2f911c..e750defd 100644
--- a/sprout/algorithm/tristate_lexicographical_compare.hpp
+++ b/sprout/algorithm/tristate_lexicographical_compare.hpp
@@ -130,6 +130,143 @@ namespace sprout {
 			sprout::less<>()
 			);
 	}
+
+	namespace detail {
+		template<typename RandomAccessIterator1, typename T1, typename RandomAccessIterator2, typename T2, typename Compare>
+		inline SPROUT_CONSTEXPR int
+		tristate_lexicographical_compare_2_impl_ra_2(
+			RandomAccessIterator1 last1, T1 const& delim1, RandomAccessIterator2 last2, T2 const& delim2, Compare comp,
+			sprout::pair<RandomAccessIterator1, RandomAccessIterator2> const& found
+			)
+		{
+			return found.second == last2 || (!comp(*found.second, delim2) && !comp(delim2, *found.second))
+					? (found.first == last1 || (!comp(*found.first, delim1) && !comp(delim1, *found.first)) ? 0 : 1)
+				: found.first == last1 || (!comp(*found.first, delim1) && !comp(delim1, *found.first)) ? -1
+				: comp(*found.first, *found.second) ? -1
+				: comp(*found.second, *found.first) ? 1
+				: 0
+				;
+		}
+		template<typename RandomAccessIterator1, typename T1, typename RandomAccessIterator2, typename T2, typename Compare>
+		inline SPROUT_CONSTEXPR sprout::pair<RandomAccessIterator1, RandomAccessIterator2>
+		tristate_lexicographical_compare_2_impl_ra_1(
+			RandomAccessIterator1 first1, RandomAccessIterator1 last1, T1 const& delim1,
+			RandomAccessIterator2 first2, RandomAccessIterator2 last2, T2 const& delim2,
+			Compare comp,
+			typename std::iterator_traits<RandomAccessIterator1>::difference_type pivot, sprout::pair<RandomAccessIterator1, RandomAccessIterator2> const& found
+			)
+		{
+			typedef sprout::pair<RandomAccessIterator1, RandomAccessIterator2> found_type;
+			return found.first != first1 ? found
+				: pivot == 0 ? (
+					comp(*first1, *first2) || comp(*first2, *first1) || (!comp(*first1, delim1) && !comp(delim1, *first1)) || (!comp(*first2, delim2) && !comp(delim2, *first2))
+						? found_type(first1, first2) : found_type(last1, last2)
+					)
+				: sprout::detail::tristate_lexicographical_compare_2_impl_ra_1(
+					sprout::next(first1, pivot), last1, delim1, sprout::next(first2, pivot), last2, delim2, comp,
+					(NS_SSCRISK_CEL_OR_SPROUT::distance(first1, last1) - pivot) / 2,
+					sprout::detail::tristate_lexicographical_compare_2_impl_ra_1(
+						first1, sprout::next(first1, pivot), delim1, first2, sprout::next(first2, pivot), delim2, comp,
+						pivot / 2,
+						found_type(first1, first2)
+						)
+					)
+				;
+		}
+		template<typename RandomAccessIterator1, typename T1, typename RandomAccessIterator2, typename T2, typename Compare>
+		inline SPROUT_CONSTEXPR int
+		tristate_lexicographical_compare_2_impl_ra(
+			RandomAccessIterator1 first1, RandomAccessIterator1 last1, T1 const& delim1,
+			RandomAccessIterator2 first2, RandomAccessIterator2 last2, T2 const& delim2,
+			Compare comp,
+			typename std::iterator_traits<RandomAccessIterator1>::difference_type size
+			)
+		{
+			typedef sprout::pair<RandomAccessIterator1, RandomAccessIterator2> found_type;
+			return sprout::detail::tristate_lexicographical_compare_2_impl_ra_2(
+				last1, delim1, last2, delim2, comp,
+				sprout::detail::tristate_lexicographical_compare_2_impl_ra_1(
+					first1, sprout::next(first1, size), delim1, first2, sprout::next(first2, size), delim2, comp,
+					size / 2, found_type(first1, first2)
+					)
+				);
+		}
+		template<typename RandomAccessIterator1, typename T1, typename RandomAccessIterator2, typename T2, typename Compare>
+		inline SPROUT_CONSTEXPR int
+		tristate_lexicographical_compare_2(
+			RandomAccessIterator1 first1, RandomAccessIterator1 last1, T1 const& delim1,
+			RandomAccessIterator2 first2, RandomAccessIterator2 last2, T2 const& delim2,
+			Compare comp,
+			std::random_access_iterator_tag*
+			)
+		{
+			return first2 == last2 || (!comp(*first2, delim2) && !comp(delim2, *first2)) ? (first1 == last1 || (!comp(*first1, delim1) && !comp(delim1, *first1)) ? 0 : 1)
+				: first1 == last1 || (!comp(*first1, delim1) && !comp(delim1, *first1)) ? -1
+				: sprout::detail::tristate_lexicographical_compare_2_impl_ra(
+					first1, last1, delim1, first2, last2, delim2, comp,
+					sprout::min(NS_SSCRISK_CEL_OR_SPROUT::distance(first1, last1), NS_SSCRISK_CEL_OR_SPROUT::distance(first2, last2))
+					)
+				;
+		}
+
+		template<typename InputIterator1, typename T1, typename InputIterator2, typename T2, typename Compare>
+		inline SPROUT_CONSTEXPR int
+		tristate_lexicographical_compare_2_impl(
+			InputIterator1 first1, InputIterator1 last1, T1 const& delim1,
+			InputIterator2 first2, InputIterator2 last2, T2 const& delim2,
+			Compare comp
+			)
+		{
+			return first2 == last2 || (!comp(*first2, delim2) && !comp(delim2, *first2)) ? (first1 == last1 || (!comp(*first1, delim1) && !comp(delim1, *first1)) ? 0 : 1)
+				: first1 == last1 || (!comp(*first1, delim1) && !comp(delim1, *first1)) || comp(*first1, *first2) ? -1
+				: comp(*first2, *first1) ? 1
+				: sprout::detail::tristate_lexicographical_compare_2_impl(sprout::next(first1), last1, delim1, sprout::next(first2), last2, delim2, comp)
+				;
+		}
+		template<typename InputIterator1, typename T1, typename InputIterator2, typename T2, typename Compare>
+		inline SPROUT_CONSTEXPR int
+		tristate_lexicographical_compare_2(
+			InputIterator1 first1, InputIterator1 last1, T1 const& delim1,
+			InputIterator2 first2, InputIterator2 last2, T2 const& delim2,
+			Compare comp,
+			void*
+			)
+		{
+			return sprout::detail::tristate_lexicographical_compare_2_impl(first1, last1, delim1, first2, last2, delim2, comp);
+		}
+	}	//namespace detail
+
+	//
+	// tristate_lexicographical_compare
+	//
+	//	recursion depth:
+	//		[first1, last1), [first2, last2) are RandomAccessIterator -> O(log N)
+	//		otherwise -> O(N)
+	//
+	template<typename InputIterator1, typename T1, typename InputIterator2, typename T2, typename Compare>
+	inline SPROUT_CONSTEXPR int
+	tristate_lexicographical_compare(
+		InputIterator1 first1, InputIterator1 last1, T1 const& delim1,
+		InputIterator2 first2, InputIterator2 last2, T2 const& delim2,
+		Compare comp
+		)
+	{
+		typedef typename sprout::common_iterator_category<InputIterator1, InputIterator2>::type* category;
+		return sprout::detail::tristate_lexicographical_compare_2(first1, last1, delim1, first2, last2, delim2, comp, category());
+	}
+
+	template<typename InputIterator1, typename T1, typename InputIterator2, typename T2>
+	inline SPROUT_CONSTEXPR int
+	tristate_lexicographical_compare(
+		InputIterator1 first1, InputIterator1 last1, T1 const& delim1,
+		InputIterator2 first2, InputIterator2 last2, T2 const& delim2
+		)
+	{
+		return sprout::tristate_lexicographical_compare(
+			first1, last1, delim1, first2, last2, delim2,
+			sprout::less<>()
+			);
+	}
 }	// namespace sprout
 
 #endif	// #ifndef SPROUT_ALGORITHM_TRISTATE_LEXICOGRAPHICAL_COMPARE_HPP
diff --git a/sprout/cstring/strncmp.hpp b/sprout/cstring/strncmp.hpp
index 56bac73a..e2ed314e 100644
--- a/sprout/cstring/strncmp.hpp
+++ b/sprout/cstring/strncmp.hpp
@@ -5,7 +5,6 @@
 #include <sprout/config.hpp>
 #include <sprout/iterator/ptr_index_iterator.hpp>
 #include <sprout/algorithm/tristate_lexicographical_compare.hpp>
-#include <sprout/cstring/strlen.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
 
 namespace sprout {
@@ -13,8 +12,8 @@ namespace sprout {
 	inline SPROUT_CONSTEXPR int
 	strncmp(char const* s1, char const* s2, std::size_t n) {
 		return sprout::tristate_lexicographical_compare(
-			sprout::as_iterator(s1), sprout::as_iterator(s1, sprout::strlen(s1, n)),
-			sprout::as_iterator(s2), sprout::as_iterator(s2, sprout::strlen(s2, n))
+			sprout::as_iterator(s1), sprout::as_iterator(s1, n), '\0',
+			sprout::as_iterator(s2), sprout::as_iterator(s2, n), '\0'
 			);
 	}
 }	// namespace sprout
diff --git a/sprout/cwchar/wcsncmp.hpp b/sprout/cwchar/wcsncmp.hpp
index ecf7c083..5ea05182 100644
--- a/sprout/cwchar/wcsncmp.hpp
+++ b/sprout/cwchar/wcsncmp.hpp
@@ -5,7 +5,6 @@
 #include <sprout/config.hpp>
 #include <sprout/iterator/ptr_index_iterator.hpp>
 #include <sprout/algorithm/tristate_lexicographical_compare.hpp>
-#include <sprout/cwchar/wcslen.hpp>
 #include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
 
 namespace sprout {
@@ -15,8 +14,8 @@ namespace sprout {
 	inline SPROUT_CONSTEXPR int
 	wcsncmp(wchar_t const* s1, wchar_t const* s2, std::size_t n) {
 		return sprout::tristate_lexicographical_compare(
-			sprout::as_iterator(s1), sprout::as_iterator(s1, sprout::wcslen(s1, n)),
-			sprout::as_iterator(s2), sprout::as_iterator(s2, sprout::wcslen(s2, n))
+			sprout::as_iterator(s1), sprout::as_iterator(s1, n), L'\0',
+			sprout::as_iterator(s2), sprout::as_iterator(s2, n), L'\0'
 			);
 	}
 }	// namespace sprout
diff --git a/sprout/range/algorithm/tristate_lexicographical_compare.hpp b/sprout/range/algorithm/tristate_lexicographical_compare.hpp
index b36dae78..825eccd2 100644
--- a/sprout/range/algorithm/tristate_lexicographical_compare.hpp
+++ b/sprout/range/algorithm/tristate_lexicographical_compare.hpp
@@ -25,6 +25,22 @@ namespace sprout {
 				sprout::begin(range1), sprout::end(range1), sprout::begin(range2), sprout::end(range2), comp
 				);
 		}
+
+		template<typename Range1, typename T1, typename Range2, typename T2>
+		inline SPROUT_CONSTEXPR int
+		tristate_lexicographical_compare(Range1 const& range1, T1 const& delim1, Range2 const& range2, T2 const& delim2) {
+			return sprout::tristate_lexicographical_compare(
+				sprout::begin(range1), sprout::end(range1), delim1, sprout::begin(range2), sprout::end(range2), delim2
+				);
+		}
+
+		template<typename Range1, typename T1, typename Range2, typename T2, typename Compare>
+		inline SPROUT_CONSTEXPR int
+		tristate_lexicographical_compare(Range1 const& range1, T1 const& delim1, Range2 const& range2, T2 const& delim2, Compare comp) {
+			return sprout::tristate_lexicographical_compare(
+				sprout::begin(range1), sprout::end(range1), delim1, sprout::begin(range2), sprout::end(range2), delim2, comp
+				);
+		}
 	}	// namespace range
 }	// namespace sprout
 
diff --git a/sprout/string/char_traits.hpp b/sprout/string/char_traits.hpp
index 46798a23..b7803143 100644
--- a/sprout/string/char_traits.hpp
+++ b/sprout/string/char_traits.hpp
@@ -44,13 +44,6 @@ namespace sprout {
 				: found
 				;
 		}
-		template<typename Iterator>
-		static SPROUT_CONSTEXPR std::size_t len(Iterator s, std::size_t n) {
-			return NS_SSCRISK_CEL_OR_SPROUT::distance(
-				s,
-				NS_SSCRISK_CEL_OR_SPROUT::find(s, s + n, char_type())
-				);
-		}
 	public:
 		static void assign(char_type& c1, char_type const& c2) SPROUT_NOEXCEPT {
 			impl_type::assign(c1, c2);
@@ -63,8 +56,8 @@ namespace sprout {
 		}
 		static SPROUT_CONSTEXPR int compare(char_type const* s1, char_type const* s2, std::size_t n) {
 			return sprout::tristate_lexicographical_compare(
-				sprout::as_iterator(s1), sprout::as_iterator(s1, len(sprout::as_iterator(s1), n)),
-				sprout::as_iterator(s2), sprout::as_iterator(s2, len(sprout::as_iterator(s2), n)),
+				sprout::as_iterator(s1), sprout::as_iterator(s1, n), char_type(),
+				sprout::as_iterator(s2), sprout::as_iterator(s2, n), char_type(),
 				lt_()
 				);
 		}
@@ -112,24 +105,24 @@ namespace sprout {
 		template<typename ConstIterator>
 		static SPROUT_CONSTEXPR int compare(char_type const* s1, ConstIterator s2, std::size_t n) {
 			return sprout::tristate_lexicographical_compare(
-				sprout::as_iterator(s1), sprout::as_iterator(s1, len(sprout::as_iterator(s1), n)),
-				s2, s2 + n,
+				sprout::as_iterator(s1), sprout::as_iterator(s1, n), char_type(),
+				s2, s2 + n, char_type(),
 				lt_()
 				);
 		}
 		template<typename ConstIterator>
 		static SPROUT_CONSTEXPR int compare(ConstIterator s1, char_type const* s2, std::size_t n) {
 			return sprout::tristate_lexicographical_compare(
-				s1, s1 + n,
-				sprout::as_iterator(s2), sprout::as_iterator(s2, len(sprout::as_iterator(s2), n)),
+				s1, s1 + n, char_type(),
+				sprout::as_iterator(s2), sprout::as_iterator(s2, n), char_type(),
 				lt_()
 				);
 		}
 		template<typename ConstIterator1, typename ConstIterator2>
 		static SPROUT_CONSTEXPR int compare(ConstIterator1 s1, ConstIterator2 s2, std::size_t n) {
 			return sprout::tristate_lexicographical_compare(
-				s1, s1 + n,
-				s2, s2 + n,
+				s1, s1 + n, char_type(),
+				s2, s2 + n, char_type(),
 				lt_()
 				);
 		}