diff --git a/example/fizzbuzz/main.cpp b/example/fizzbuzz/main.cpp
index 07159fe7..0737c9f0 100644
--- a/example/fizzbuzz/main.cpp
+++ b/example/fizzbuzz/main.cpp
@@ -1,99 +1,99 @@
-//
-// Sprout C++ Library
-//
-// Copyright (c) 2012
-// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
-// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
-// 
-// Readme:
-// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
-//
-// License:
-// Boost Software License - Version 1.0
-// <http://www.boost.org/LICENSE_1_0.txt>
-//
-#include <sprout/algorithm/transform.hpp>
-#include <sprout/array.hpp>
-#include <sprout/string.hpp>
-#include <sprout/numeric/iota.hpp>
-#include <sprout/pit.hpp>
-#include <iostream>
-
-
-struct fizzbuzz{
-	typedef sprout::string<12> result_type;
-
-	constexpr result_type
-	operator ()(int n) const{
-		return n % 15 == 0 ? sprout::to_string("FizzBuzz")
-			 : n %  3 == 0 ? sprout::to_string("Fizz")
-			 : n %  5 == 0 ? sprout::to_string("Buzz")
-			 : sprout::to_string(n);
-	}
-};
-
-
-int
-main(){
-	typedef fizzbuzz::result_type string;
-
-	//
-	// Test
-	//
-	static_assert(fizzbuzz()( 1) == "1", "");
-	static_assert(fizzbuzz()( 2) == "2", "");
-	static_assert(fizzbuzz()( 3) == "Fizz", "");
-	static_assert(fizzbuzz()( 5) == "Buzz", "");
-	static_assert(fizzbuzz()(15) == "FizzBuzz", "");
-	
-	//
-	// Sequence [1..15]
-	//
-	constexpr auto source = sprout::iota(
-		sprout::pit<sprout::array<int, 15> >(),
-		1
-	);
-
-	//
-	// Transform to FizzBuzz
-	//
-	constexpr auto result = sprout::transform(
-		sprout::begin(source),
-		sprout::end(source),
-		sprout::pit<sprout::array<string, 15> >(),
-		fizzbuzz()
-	);
-	
-	//
-	// Check result
-	//
-	constexpr auto fizzbuzz_result = sprout::make_array<string>(
-		sprout::to_string("1"),
-		sprout::to_string("2"),
-		sprout::to_string("Fizz"),
-		sprout::to_string("4"),
-		sprout::to_string("Buzz"),
-		sprout::to_string("Fizz"),
-		sprout::to_string("7"),
-		sprout::to_string("8"),
-		sprout::to_string("Fizz"),
-		sprout::to_string("Buzz"),
-		sprout::to_string("11"),
-		sprout::to_string("Fizz"),
-		sprout::to_string("13"),
-		sprout::to_string("14"),
-		sprout::to_string("FizzBuzz")
-	);
-	// Equal result sequence
-	static_assert(result == fizzbuzz_result, "");
-
-	//
-	// Output
-	//
-	for(auto&& str : result){
-		std::cout << str << ", ";
-	}
-	std::cout << std::endl;
-
-	return 0;
-}
+//
+// Sprout C++ Library
+//
+// Copyright (c) 2012
+// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
+// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
+// 
+// Readme:
+// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
+//
+// License:
+// Boost Software License - Version 1.0
+// <http://www.boost.org/LICENSE_1_0.txt>
+//
+#include <sprout/algorithm/transform.hpp>
+#include <sprout/array.hpp>
+#include <sprout/string.hpp>
+#include <sprout/numeric/iota.hpp>
+#include <sprout/pit.hpp>
+#include <iostream>
+
+
+struct fizzbuzz{
+	typedef sprout::string<12> result_type;
+
+	constexpr result_type
+	operator ()(int n) const{
+		return n % 15 == 0 ? sprout::to_string("FizzBuzz")
+			 : n %  3 == 0 ? sprout::to_string("Fizz")
+			 : n %  5 == 0 ? sprout::to_string("Buzz")
+			 : sprout::to_string(n);
+	}
+};
+
+
+int
+main(){
+	typedef fizzbuzz::result_type string;
+
+	//
+	// Test
+	//
+	static_assert(fizzbuzz()( 1) == "1", "");
+	static_assert(fizzbuzz()( 2) == "2", "");
+	static_assert(fizzbuzz()( 3) == "Fizz", "");
+	static_assert(fizzbuzz()( 5) == "Buzz", "");
+	static_assert(fizzbuzz()(15) == "FizzBuzz", "");
+	
+	//
+	// Sequence [1..15]
+	//
+	constexpr auto source = sprout::iota(
+		sprout::pit<sprout::array<int, 15> >(),
+		1
+	);
+
+	//
+	// Transform to FizzBuzz
+	//
+	constexpr auto result = sprout::transform(
+		sprout::begin(source),
+		sprout::end(source),
+		sprout::pit<sprout::array<string, 15> >(),
+		fizzbuzz()
+	);
+	
+	//
+	// Check result
+	//
+	constexpr auto fizzbuzz_result = sprout::make_array<string>(
+		sprout::to_string("1"),
+		sprout::to_string("2"),
+		sprout::to_string("Fizz"),
+		sprout::to_string("4"),
+		sprout::to_string("Buzz"),
+		sprout::to_string("Fizz"),
+		sprout::to_string("7"),
+		sprout::to_string("8"),
+		sprout::to_string("Fizz"),
+		sprout::to_string("Buzz"),
+		sprout::to_string("11"),
+		sprout::to_string("Fizz"),
+		sprout::to_string("13"),
+		sprout::to_string("14"),
+		sprout::to_string("FizzBuzz")
+	);
+	// Equal result sequence
+	static_assert(result == fizzbuzz_result, "");
+
+	//
+	// Output
+	//
+	for(auto&& str : result){
+		std::cout << str << ", ";
+	}
+	std::cout << std::endl;
+
+	return 0;
+}
diff --git a/libs/string/example/literals_to_string.cpp b/libs/string/example/literals_to_string.cpp
index 6be849c5..7aad1c08 100644
--- a/libs/string/example/literals_to_string.cpp
+++ b/libs/string/example/literals_to_string.cpp
@@ -1,60 +1,60 @@
-//
-// Sprout C++ Library
-//
-// Copyright (c) 2012
-// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
-// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
-// 
-// Readme:
-// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
-//
-// License:
-// Boost Software License - Version 1.0
-// <http://www.boost.org/LICENSE_1_0.txt>
-//
-#include <sprout/string.hpp>
-
-
-int
-main(){
-	
-	//
-	// String literal to Sprout.String
-	//
-	{
-		static constexpr auto str1 = sprout::to_string("homu");
-		static_assert(str1 == "homu", "");
-		static_assert(std::is_same<decltype(str1), sprout::string<4> const>{}, "");
-
-		static constexpr auto str2 = sprout::to_string(L"ほむほむ");
-		static_assert(str2 == L"ほむほむ", "");
-		static_assert(std::is_same<decltype(str2), sprout::wstring<4> const>{}, "");
-	}
-	
-	//
-	// Integer literal to Sprout.String
-	//
-	{
-		static constexpr auto str = sprout::to_string(42);
-		static_assert(str == "42", "");
-	}
-	
-	//
-	// Float literal to Sprout.String
-	//
-	{
-		static constexpr auto str = sprout::to_string(3.14f);
-		static_assert(str == "3.140000", "");
-	}
-
-	//
-	// Char literal to Sprout.String
-	//
-	{
-		static constexpr auto str = sprout::make_string('m', 'a', 'd', 'o');
-		static_assert(str == "mado", "");
-		static_assert(std::is_same<decltype(str), sprout::string<4> const>{}, "");
-	}
-
-	return 0;
-}
+//
+// Sprout C++ Library
+//
+// Copyright (c) 2012
+// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
+// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
+// 
+// Readme:
+// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
+//
+// License:
+// Boost Software License - Version 1.0
+// <http://www.boost.org/LICENSE_1_0.txt>
+//
+#include <sprout/string.hpp>
+
+
+int
+main(){
+	
+	//
+	// String literal to Sprout.String
+	//
+	{
+		static constexpr auto str1 = sprout::to_string("homu");
+		static_assert(str1 == "homu", "");
+		static_assert(std::is_same<decltype(str1), sprout::string<4> const>{}, "");
+
+		static constexpr auto str2 = sprout::to_string(L"ほむほむ");
+		static_assert(str2 == L"ほむほむ", "");
+		static_assert(std::is_same<decltype(str2), sprout::wstring<4> const>{}, "");
+	}
+	
+	//
+	// Integer literal to Sprout.String
+	//
+	{
+		static constexpr auto str = sprout::to_string(42);
+		static_assert(str == "42", "");
+	}
+	
+	//
+	// Float literal to Sprout.String
+	//
+	{
+		static constexpr auto str = sprout::to_string(3.14f);
+		static_assert(str == "3.140000", "");
+	}
+
+	//
+	// Char literal to Sprout.String
+	//
+	{
+		static constexpr auto str = sprout::make_string('m', 'a', 'd', 'o');
+		static_assert(str == "mado", "");
+		static_assert(std::is_same<decltype(str), sprout::string<4> const>{}, "");
+	}
+
+	return 0;
+}
diff --git a/libs/string/example/simple.cpp b/libs/string/example/simple.cpp
index 6e1c97a0..38c624c6 100644
--- a/libs/string/example/simple.cpp
+++ b/libs/string/example/simple.cpp
@@ -1,86 +1,86 @@
-//
-// Sprout C++ Library
-//
-// Copyright (c) 2012
-// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
-// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
-// 
-// Readme:
-// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
-//
-// License:
-// Boost Software License - Version 1.0
-// <http://www.boost.org/LICENSE_1_0.txt>
-//
-#include <sprout/string.hpp>
-#include <sstream>
-#include <cassert>
-
-
-//
-// Sprout.String is constexpr string object
-//
-int
-main(){
-	
-	//
-	// String literal to Sprout.String
-	//
-	static constexpr sprout::string<4> str1 = sprout::to_string("homu");
-	static constexpr auto              str2 = sprout::to_string("mado");
-	static constexpr auto              str3 = sprout::to_string(42);
-
-	//
-	// Comparison
-	//
-	static_assert(str1 == sprout::to_string("homu"), "");
-	static_assert(str2 == "mado", "");
-	static_assert(str3 == "42", "");
-	static_assert(str1 != str2, "");
-
-	//
-	// Accessor
-	//
-	static_assert(str1.front() == 'h', "");
-	static_assert(str1[1]      == 'o', "");
-	static_assert(str1.at(2)   == 'm', "");
-	static_assert(str1.back()  == 'u', "");
-
-	//
-	// String concatenation
-	//
-	static_assert((str1 + "homu") == "homuhomu", "");
-	static_assert((str1 + str2)   == "homumado", "");
-	static_assert((str1 + sprout::to_string("42"))   == "homu42", "");
-
-	//
-	// C style string
-	//
-	constexpr char const* cp = str1.c_str();
-	static_assert(cp[0] == 'h', "");
-
-	//
-	// Iterator
-	//
-	static_assert(*str1.begin()        == 'h', "");
-	static_assert(*(str1.end() - 1)    == 'u', "");
-	static_assert(*(str1.rbegin() + 1) == 'm', "");
-	static_assert(*(str1.rend() - 2)   == 'o', "");
-	
-	//
-	// IOStream
-	//
-	{
-		std::ostringstream os;
-		os << str1;
-		assert(os.str() == "homu");
-	}
-	{
-		std::istringstream is("mami");
-		sprout::string<4> str;
-		is >> str;
-		assert(str == "mami");
-	}
-
-	return 0;
-}
+//
+// Sprout C++ Library
+//
+// Copyright (c) 2012
+// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
+// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
+// 
+// Readme:
+// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
+//
+// License:
+// Boost Software License - Version 1.0
+// <http://www.boost.org/LICENSE_1_0.txt>
+//
+#include <sprout/string.hpp>
+#include <sstream>
+#include <cassert>
+
+
+//
+// Sprout.String is constexpr string object
+//
+int
+main(){
+	
+	//
+	// String literal to Sprout.String
+	//
+	static constexpr sprout::string<4> str1 = sprout::to_string("homu");
+	static constexpr auto              str2 = sprout::to_string("mado");
+	static constexpr auto              str3 = sprout::to_string(42);
+
+	//
+	// Comparison
+	//
+	static_assert(str1 == sprout::to_string("homu"), "");
+	static_assert(str2 == "mado", "");
+	static_assert(str3 == "42", "");
+	static_assert(str1 != str2, "");
+
+	//
+	// Accessor
+	//
+	static_assert(str1.front() == 'h', "");
+	static_assert(str1[1]      == 'o', "");
+	static_assert(str1.at(2)   == 'm', "");
+	static_assert(str1.back()  == 'u', "");
+
+	//
+	// String concatenation
+	//
+	static_assert((str1 + "homu") == "homuhomu", "");
+	static_assert((str1 + str2)   == "homumado", "");
+	static_assert((str1 + sprout::to_string("42"))   == "homu42", "");
+
+	//
+	// C style string
+	//
+	constexpr char const* cp = str1.c_str();
+	static_assert(cp[0] == 'h', "");
+
+	//
+	// Iterator
+	//
+	static_assert(*str1.begin()        == 'h', "");
+	static_assert(*(str1.end() - 1)    == 'u', "");
+	static_assert(*(str1.rbegin() + 1) == 'm', "");
+	static_assert(*(str1.rend() - 2)   == 'o', "");
+	
+	//
+	// IOStream
+	//
+	{
+		std::ostringstream os;
+		os << str1;
+		assert(os.str() == "homu");
+	}
+	{
+		std::istringstream is("mami");
+		sprout::string<4> str;
+		is >> str;
+		assert(str == "mami");
+	}
+
+	return 0;
+}
diff --git a/libs/weed/example/__TIME__.cpp b/libs/weed/example/__TIME__.cpp
index 7f4f6868..26ec1eab 100644
--- a/libs/weed/example/__TIME__.cpp
+++ b/libs/weed/example/__TIME__.cpp
@@ -1,68 +1,68 @@
-//
-// Sprout C++ Library
-//
-// Copyright (c) 2012
-// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
-// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
-// 
-// Readme:
-// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
-//
-// License:
-// Boost Software License - Version 1.0
-// <http://www.boost.org/LICENSE_1_0.txt>
-//
-#include <sprout/weed.hpp>
-#include <boost/mpl/print.hpp>
-#include <boost/mpl/int.hpp>
-#include <iostream>
-
-//
-// __TIME__ Parser
-//
-int
-main(){
-	namespace w = sprout::weed;
-	
-	//
-	// __TIME__ to Sprout.String
-	//
-	static constexpr auto time = sprout::to_string(__TIME__);
-// 	static constexpr auto time = sprout::to_string("23:22:45");
-	
-
-	//
-	// parse __TIME__
-	//
-	constexpr auto parser = w::int_ >> ':' >> w::int_ >> ':' >> w::int_;
-	static constexpr auto result = w::parse(time.begin(), time.end(), parser);
-	static_assert(result.success(), "failed parse");
-	
-	
-	//
-	// get result
-	//
-	static constexpr sprout::array<long long int, 3> result_attr = result.attr();
-	static constexpr auto hour    = result_attr[0];
-	static constexpr auto minute = result_attr[1];
-	static constexpr auto second  = result_attr[2];
-
-// 	static_assert(hour   == 23, "");
-// 	static_assert(minute == 22, "");
-// 	static_assert(second == 45, "");
-
-	std::cout << hour << std::endl;
-	std::cout << minute << std::endl;
-	std::cout << second << std::endl;
-	
-	
-	//
-	// compile time output
-	//
-	namespace m = boost::mpl;
-	typedef m::print<m::int_<hour>>::type   hour_;
-	typedef m::print<m::int_<minute>>::type minute_;
-	typedef m::print<m::int_<second>>::type second_;
-
-	return 0;
-}
+//
+// Sprout C++ Library
+//
+// Copyright (c) 2012
+// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
+// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
+// 
+// Readme:
+// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
+//
+// License:
+// Boost Software License - Version 1.0
+// <http://www.boost.org/LICENSE_1_0.txt>
+//
+#include <sprout/weed.hpp>
+#include <boost/mpl/print.hpp>
+#include <boost/mpl/int.hpp>
+#include <iostream>
+
+//
+// __TIME__ Parser
+//
+int
+main(){
+	namespace w = sprout::weed;
+	
+	//
+	// __TIME__ to Sprout.String
+	//
+	static constexpr auto time = sprout::to_string(__TIME__);
+// 	static constexpr auto time = sprout::to_string("23:22:45");
+	
+
+	//
+	// parse __TIME__
+	//
+	constexpr auto parser = w::int_ >> ':' >> w::int_ >> ':' >> w::int_;
+	static constexpr auto result = w::parse(time.begin(), time.end(), parser);
+	static_assert(result.success(), "failed parse");
+	
+	
+	//
+	// get result
+	//
+	static constexpr sprout::array<long long int, 3> result_attr = result.attr();
+	static constexpr auto hour    = result_attr[0];
+	static constexpr auto minute = result_attr[1];
+	static constexpr auto second  = result_attr[2];
+
+// 	static_assert(hour   == 23, "");
+// 	static_assert(minute == 22, "");
+// 	static_assert(second == 45, "");
+
+	std::cout << hour << std::endl;
+	std::cout << minute << std::endl;
+	std::cout << second << std::endl;
+	
+	
+	//
+	// compile time output
+	//
+	namespace m = boost::mpl;
+	typedef m::print<m::int_<hour>>::type   hour_;
+	typedef m::print<m::int_<minute>>::type minute_;
+	typedef m::print<m::int_<second>>::type second_;
+
+	return 0;
+}
diff --git a/libs/weed/example/remove_space.cpp b/libs/weed/example/remove_space.cpp
index 60a72142..29c3786b 100644
--- a/libs/weed/example/remove_space.cpp
+++ b/libs/weed/example/remove_space.cpp
@@ -1,36 +1,36 @@
-//
-// Sprout C++ Library
-//
-// Copyright (c) 2012
-// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
-// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
-// 
-// Readme:
-// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
-//
-// License:
-// Boost Software License - Version 1.0
-// <http://www.boost.org/LICENSE_1_0.txt>
-//
-#include <sprout/weed.hpp>
-
-
-int
-main(){
-	namespace w = sprout::weed;
-	
-	static constexpr auto max_string_size = 32;
-	static constexpr auto space = *w::omit[ w::space ];
-	static constexpr auto remove_space = *w::lim<max_string_size>(space >> w::char_);
-	
-	static constexpr auto source = sprout::to_string("  homu  :  mami=   10 ");
-	static constexpr auto result = w::parse(
-		sprout::begin(source), sprout::end(source),
-		remove_space
-	);
-
-	static_assert(result.success(), "fail remove_space parse");
-	static_assert(result.attr() == "homu:mami=10", "");
-
-	return 0;
-}
+//
+// Sprout C++ Library
+//
+// Copyright (c) 2012
+// bolero-MURAKAMI : http://d.hatena.ne.jp/boleros/
+// osyo-manga : http://d.hatena.ne.jp/osyo-manga/
+// 
+// Readme:
+// https://github.com/bolero-MURAKAMI/Sprout/blob/master/README
+//
+// License:
+// Boost Software License - Version 1.0
+// <http://www.boost.org/LICENSE_1_0.txt>
+//
+#include <sprout/weed.hpp>
+
+
+int
+main(){
+	namespace w = sprout::weed;
+	
+	static constexpr auto max_string_size = 32;
+	static constexpr auto space = *w::omit[ w::space ];
+	static constexpr auto remove_space = *w::lim<max_string_size>(space >> w::char_);
+	
+	static constexpr auto source = sprout::to_string("  homu  :  mami=   10 ");
+	static constexpr auto result = w::parse(
+		sprout::begin(source), sprout::end(source),
+		remove_space
+	);
+
+	static_assert(result.success(), "fail remove_space parse");
+	static_assert(result.attr() == "homu:mami=10", "");
+
+	return 0;
+}
diff --git a/sprout/iterator/counting_iterator.hpp b/sprout/iterator/counting_iterator.hpp
new file mode 100644
index 00000000..727adf7e
--- /dev/null
+++ b/sprout/iterator/counting_iterator.hpp
@@ -0,0 +1,243 @@
+#ifndef SPROUT_ITERATOR_COUNTING_ITERATOR_HPP
+#define SPROUT_ITERATOR_COUNTING_ITERATOR_HPP
+
+#include <cstddef>
+#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>
+
+namespace sprout {
+	//
+	// counting_iterator
+	//
+	template<typename Incrementable>
+	class counting_iterator
+		: public std::iterator<
+			std::random_access_iterator_tag,
+			Incrementable,
+			std::ptrdiff_t,
+			Incrementable*,
+			Incrementable
+		>
+	{
+	public:
+		typedef std::random_access_iterator_tag iterator_category;
+		typedef Incrementable value_type;
+		typedef std::ptrdiff_t difference_type;
+		typedef value_type* pointer;
+		typedef value_type reference;
+	private:
+		value_type current_;
+	private:
+	public:
+		counting_iterator() = default;
+		counting_iterator(counting_iterator const&) = default;
+		explicit SPROUT_CONSTEXPR counting_iterator(value_type const& v)
+			: current_(v)
+		{}
+		template<typename U>
+		SPROUT_CONSTEXPR counting_iterator(counting_iterator<U> const& it)
+			: current_(it.current_)
+		{}
+		template<typename U>
+		counting_iterator& operator=(counting_iterator<U> const& it) {
+			counting_iterator temp(it);
+			temp.swap(*this);
+			return *this;
+		}
+		SPROUT_CONSTEXPR reference operator*() const {
+			return current_;
+		}
+		SPROUT_CONSTEXPR pointer operator->() const {
+			return &current_;
+		}
+		counting_iterator& operator++() {
+			++current_;
+			return *this;
+		}
+		counting_iterator operator++(int) {
+			counting_iterator result(*this);
+			++current_;
+			return result;
+		}
+		counting_iterator& operator--() {
+			--current_;
+			return *this;
+		}
+		counting_iterator operator--(int) {
+			counting_iterator temp(*this);
+			--current_;
+			return temp;
+		}
+		SPROUT_CONSTEXPR counting_iterator operator+(difference_type n) const {
+			return counting_iterator(current_ + n);
+		}
+		SPROUT_CONSTEXPR counting_iterator operator-(difference_type n) const {
+			return counting_iterator(current_ - n);
+		}
+		counting_iterator& operator+=(difference_type n) {
+			counting_iterator temp(current_ + n);
+			temp.swap(*this);
+			return *this;
+		}
+		counting_iterator& operator-=(difference_type n) {
+			counting_iterator temp(current_ - n);
+			temp.swap(*this);
+			return *this;
+		}
+		SPROUT_CONSTEXPR reference operator[](difference_type n) const {
+			return current_ + n;
+		}
+		SPROUT_CONSTEXPR counting_iterator next() const {
+			return counting_iterator(current_ + 1);
+		}
+		SPROUT_CONSTEXPR counting_iterator prev() const {
+			return counting_iterator(current_ - 1);
+		}
+		void swap(counting_iterator& other) {
+			using std::swap;
+			swap(current_, other.current_);
+		}
+	};
+
+	template<typename Incrementable1, typename Incrementable2>
+	SPROUT_CONSTEXPR bool operator==(
+		sprout::counting_iterator<Incrementable1> const& lhs,
+		sprout::counting_iterator<Incrementable2> const& rhs
+		)
+	{
+		return *lhs == *rhs;
+	}
+	template<typename Incrementable1, typename Incrementable2>
+	SPROUT_CONSTEXPR bool operator!=(
+		sprout::counting_iterator<Incrementable1> const& lhs,
+		sprout::counting_iterator<Incrementable2> const& rhs
+		)
+	{
+		return !(lhs == rhs);
+	}
+	template<typename Incrementable1, typename Incrementable2>
+	SPROUT_CONSTEXPR bool operator<(
+		sprout::counting_iterator<Incrementable1> const& lhs,
+		sprout::counting_iterator<Incrementable2> const& rhs
+		)
+	{
+		return *lhs < *rhs;
+	}
+	template<typename Incrementable1, typename Incrementable2>
+	SPROUT_CONSTEXPR bool operator>(
+		sprout::counting_iterator<Incrementable1> const& lhs,
+		sprout::counting_iterator<Incrementable2> const& rhs
+		)
+	{
+		return rhs < lhs;
+	}
+	template<typename Incrementable1, typename Incrementable2>
+	SPROUT_CONSTEXPR bool operator<=(
+		sprout::counting_iterator<Incrementable1> const& lhs,
+		sprout::counting_iterator<Incrementable2> const& rhs
+		)
+	{
+		return !(rhs < lhs);
+	}
+	template<typename Incrementable1, typename Incrementable2>
+	SPROUT_CONSTEXPR bool operator>=(
+		sprout::counting_iterator<Incrementable1> const& lhs,
+		sprout::counting_iterator<Incrementable2> const& rhs
+		)
+	{
+		return !(lhs < rhs);
+	}
+	template<typename Incrementable1, typename Incrementable2>
+	SPROUT_CONSTEXPR typename sprout::counting_iterator<Incrementable1>::difference_type operator-(
+		sprout::counting_iterator<Incrementable1> const& lhs,
+		sprout::counting_iterator<Incrementable2> const& rhs
+		)
+	{
+		return static_cast<typename sprout::counting_iterator<Incrementable1>::difference_type>(*lhs - *rhs);
+	}
+	template<typename Incrementable>
+	SPROUT_CONSTEXPR sprout::counting_iterator<Incrementable> operator+(
+		typename sprout::counting_iterator<Incrementable>::difference_type n,
+		sprout::counting_iterator<Incrementable> const& it
+		)
+	{
+		return it + n;
+	}
+
+	//
+	// make_counting_iterator
+	//
+	template<typename Incrementable>
+	SPROUT_CONSTEXPR sprout::counting_iterator<Incrementable>
+	make_counting_iterator(Incrementable const& v) {
+		return sprout::counting_iterator<Incrementable>(v);
+	}
+
+	//
+	// swap
+	//
+	template<typename Incrementable>
+	void swap(sprout::counting_iterator<Incrementable>& lhs, sprout::counting_iterator<Incrementable>& rhs)
+	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
+	{
+		lhs.swap(rhs);
+	}
+
+	//
+	// next
+	//
+	template<typename Incrementable>
+	SPROUT_CONSTEXPR sprout::counting_iterator<Incrementable> next(
+		sprout::counting_iterator<Incrementable> const& it
+		)
+	{
+		return it.next();
+	}
+	template<typename Incrementable>
+	SPROUT_CONSTEXPR sprout::counting_iterator<Incrementable> next(
+		sprout::counting_iterator<Incrementable> const& it,
+		typename sprout::counting_iterator<Incrementable>::difference_type n
+		)
+	{
+		return it + n;
+	}
+
+	//
+	// prev
+	//
+	template<typename Incrementable>
+	SPROUT_CONSTEXPR sprout::counting_iterator<Incrementable> prev(
+		sprout::counting_iterator<Incrementable> const& it
+		)
+	{
+		return it.prev();
+	}
+	template<typename Incrementable>
+	SPROUT_CONSTEXPR sprout::counting_iterator<Incrementable> prev(
+		sprout::counting_iterator<Incrementable> const& it,
+		typename sprout::counting_iterator<Incrementable>::difference_type n
+		)
+	{
+		return it - n;
+	}
+
+	//
+	// distance
+	//
+	template<typename Incrementable>
+	SPROUT_CONSTEXPR typename std::iterator_traits<sprout::counting_iterator<Incrementable> >::difference_type
+	distance(
+		sprout::counting_iterator<Incrementable> first,
+		sprout::counting_iterator<Incrementable> last
+		)
+	{
+		return last - first;
+	}
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_ITERATOR_COUNTING_ITERATOR_HPP
diff --git a/sprout/range/adaptor.hpp b/sprout/range/adaptor.hpp
index 7108e00c..7f9d5938 100644
--- a/sprout/range/adaptor.hpp
+++ b/sprout/range/adaptor.hpp
@@ -4,6 +4,7 @@
 #include <sprout/config.hpp>
 #include <sprout/range/adaptor/copied.hpp>
 #include <sprout/range/adaptor/transformed.hpp>
+#include <sprout/range/adaptor/size_enumed.hpp>
 #include <sprout/range/adaptor/sinusoidal.hpp>
 
 #endif	// #ifndef SPROUT_RANGE_ADAPTOR_HPP
diff --git a/sprout/range/adaptor/counting.hpp b/sprout/range/adaptor/counting.hpp
new file mode 100644
index 00000000..ccd2d6c7
--- /dev/null
+++ b/sprout/range/adaptor/counting.hpp
@@ -0,0 +1,174 @@
+#ifndef SPROUT_RANGE_ADAPTOR_COUNTING_HPP
+#define SPROUT_RANGE_ADAPTOR_COUNTING_HPP
+
+#include <limits>
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/pit.hpp>
+#include <sprout/container/traits.hpp>
+#include <sprout/container/functions.hpp>
+#include <sprout/iterator/counting_iterator.hpp>
+#include <sprout/range/range_container.hpp>
+#include <sprout/range/algorithm/copy.hpp>
+#include <sprout/type_traits/lvalue_reference.hpp>
+#include <sprout/utility/forward.hpp>
+#include <sprout/utility/lvalue_forward.hpp>
+
+namespace sprout {
+	namespace adaptors {
+		//
+		// counting_range
+		//
+		template<typename Incrementable, typename Range = void>
+		class counting_range
+			: public sprout::range::range_container<
+				sprout::counting_iterator<Incrementable>
+			>
+			, public sprout::detail::container_nosy_static_size<Range>
+			, public sprout::detail::container_nosy_fixed_size<Range>
+		{
+		public:
+			typedef Range range_type;
+			typedef sprout::range::range_container<
+				sprout::counting_iterator<Incrementable>
+			> base_type;
+			typedef typename base_type::iterator iterator;
+			typedef typename base_type::value_type value_type;
+			typedef typename base_type::difference_type difference_type;
+		public:
+			counting_range() = default;
+			counting_range(counting_range const&) = default;
+			explicit SPROUT_CONSTEXPR counting_range(range_type& range)
+				: base_type(
+					iterator(),
+					sprout::next(iterator(), sprout::size(range))
+					)
+			{}
+			SPROUT_CONSTEXPR counting_range(
+				range_type& range,
+				value_type const& first
+				)
+				: base_type(
+					iterator(first),
+					sprout::next(iterator(first), sprout::size(range))
+					)
+			{}
+			SPROUT_CONSTEXPR counting_range(
+				range_type& range,
+				value_type const& first,
+				value_type const& last
+				)
+				: base_type(
+					iterator(first),
+					sprout::size(range) < last - first ? sprout::next(iterator(first), sprout::size(range))
+						: iterator(last)
+					)
+			{}
+		};
+
+		template<typename Incrementable>
+		class counting_range<Incrementable, void>
+			: public sprout::range::range_container<
+				sprout::counting_iterator<Incrementable>
+			>
+		{
+		public:
+			typedef sprout::range::range_container<
+				sprout::counting_iterator<Incrementable>
+			> base_type;
+			typedef typename base_type::iterator iterator;
+			typedef typename base_type::value_type value_type;
+			typedef typename base_type::difference_type difference_type;
+		public:
+			counting_range() = default;
+			counting_range(counting_range const&) = default;
+			explicit SPROUT_CONSTEXPR counting_range(value_type const& first)
+				: base_type(
+					iterator(first),
+					iterator(std::numeric_limits<value_type>::max())
+					)
+			{}
+			SPROUT_CONSTEXPR counting_range(
+				value_type const& first,
+				value_type const& last
+				)
+				: base_type(
+					iterator(first),
+					iterator(last)
+					)
+			{}
+		};
+
+		//
+		// counting_forwarder
+		//
+		class counting_forwarder {
+		public:
+			template<typename Incrementable>
+			SPROUT_CONSTEXPR sprout::adaptors::counting_range<Incrementable>
+			operator()(Incrementable const& first) const {
+				return sprout::adaptors::counting_range<Incrementable>(first);
+			}
+			template<typename Incrementable>
+			SPROUT_CONSTEXPR sprout::adaptors::counting_range<Incrementable>
+			operator()(Incrementable const& first, Incrementable const& last) const {
+				return sprout::adaptors::counting_range<Incrementable>(first, last);
+			}
+		};
+
+		//
+		// counting
+		//
+		namespace {
+			SPROUT_STATIC_CONSTEXPR sprout::adaptors::counting_forwarder counting{};
+		}	// anonymous-namespace
+
+		//
+		// operator|
+		//
+		template<typename Range, typename Incrementable>
+		inline SPROUT_CONSTEXPR sprout::adaptors::counting_range<
+			Incrementable,
+			typename std::remove_reference<typename sprout::lvalue_reference<Range>::type>::type
+		>
+		operator|(Range&& lhs, sprout::adaptors::counting_range<Incrementable> const& rhs) {
+			return sprout::adaptors::counting_range<
+				Incrementable,
+				typename std::remove_reference<typename sprout::lvalue_reference<Range>::type>::type
+			>(
+				sprout::lvalue_forward<Range>(lhs),
+				*rhs.begin(),
+				*rhs.end()
+				);
+		}
+	}	// namespace adaptors
+
+	//
+	// container_construct_traits
+	//
+	template<typename Incrementable, typename Range>
+	struct container_construct_traits<sprout::adaptors::counting_range<Incrementable, Range> > {
+	public:
+		typedef typename sprout::container_construct_traits<Range>::copied_type copied_type;
+	public:
+		template<typename Cont>
+		static SPROUT_CONSTEXPR copied_type deep_copy(Cont&& cont) {
+			return sprout::range::fixed::copy(sprout::forward<Cont>(cont), sprout::pit<copied_type>());
+		}
+		template<typename... Args>
+		static SPROUT_CONSTEXPR copied_type make(Args&&... args) {
+			return sprout::make<copied_type>(sprout::forward<Args>(args)...);
+		}
+		template<typename Cont, typename... Args>
+		static SPROUT_CONSTEXPR copied_type remake(
+			Cont&& cont,
+			typename sprout::container_traits<sprout::adaptors::counting_range<Incrementable, Range> >::difference_type size,
+			Args&&... args
+			)
+		{
+			return sprout::remake<copied_type>(sprout::forward<Cont>(cont), size, sprout::forward<Args>(args)...);
+		}
+	};
+}	// namespace sprout
+
+#endif	// #ifndef SPROUT_RANGE_ADAPTOR_COUNTING_HPP
diff --git a/sprout/range/adaptor/transformed.hpp b/sprout/range/adaptor/transformed.hpp
index d984a5fb..cddfc138 100644
--- a/sprout/range/adaptor/transformed.hpp
+++ b/sprout/range/adaptor/transformed.hpp
@@ -45,8 +45,8 @@ namespace sprout {
 			typedef typename base_type::iterator iterator;
 			typedef typename base_type::size_type size_type;
 		public:
-			SPROUT_CONSTEXPR transformed_range() = default;
-			SPROUT_CONSTEXPR transformed_range(transformed_range const&) = default;
+			transformed_range() = default;
+			transformed_range(transformed_range const&) = default;
 			SPROUT_CONSTEXPR transformed_range(functor_type func, range_type& range1, range2_type& range2)
 				: base_type(
 					iterator(sprout::begin(range1), sprout::begin(range2), func),
@@ -77,8 +77,8 @@ namespace sprout {
 			> base_type;
 			typedef typename base_type::iterator iterator;
 		public:
-			SPROUT_CONSTEXPR transformed_range() = default;
-			SPROUT_CONSTEXPR transformed_range(transformed_range const&) = default;
+			transformed_range() = default;
+			transformed_range(transformed_range const&) = default;
 			SPROUT_CONSTEXPR transformed_range(functor_type func, range_type& range)
 				: base_type(
 					iterator(sprout::begin(range), func),