diff --git a/sprout/compressed_pair.hpp b/sprout/compressed_pair.hpp
new file mode 100644
index 00000000..c7e78a6e
--- /dev/null
+++ b/sprout/compressed_pair.hpp
@@ -0,0 +1,430 @@
+#ifndef SPROUT_COMPRESSED_PAIR_HPP
+#define SPROUT_COMPRESSED_PAIR_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+#include <sprout/detail/call_traits.hpp>
+
+namespace sprout {
+	namespace detail {
+		template<typename T1, typename T2, bool IsSame, bool FirstEmpty, bool SecondEmpty>
+		struct compressed_pair_switch;
+		template<typename T1, typename T2>
+		struct compressed_pair_switch<T1, T2, false, false, false>
+			: public std::integral_constant<int, 0>
+		{};
+		template<typename T1, typename T2>
+		struct compressed_pair_switch<T1, T2, false, true, false>
+			: public std::integral_constant<int, 1>
+		{};
+		template<typename T1, typename T2>
+		struct compressed_pair_switch<T1, T2, false, false, true>
+			: public std::integral_constant<int, 2>
+		{};
+		template<typename T1, typename T2>
+		struct compressed_pair_switch<T1, T2, false, true, true>
+			: public std::integral_constant<int, 3>
+		{};
+		template<typename T1, typename T2>
+		struct compressed_pair_switch<T1, T2, true, true, true>
+			: public std::integral_constant<int, 4>
+		{};
+		template<typename T1, typename T2>
+		struct compressed_pair_switch<T1, T2, true, false, false>
+			: public std::integral_constant<int, 5>
+		{};
+
+		template<typename T1, typename T2, int Version>
+		class compressed_pair_impl;
+		template<typename T1, typename T2>
+		class compressed_pair_impl<T1, T2, 0>
+		{
+		public:
+			typedef T1 first_type;
+			typedef T2 second_type;
+			typedef typename sprout::detail::call_traits<first_type>::param_type first_param_type;
+			typedef typename sprout::detail::call_traits<second_type>::param_type second_param_type;
+			typedef typename sprout::detail::call_traits<first_type>::reference first_reference;
+			typedef typename sprout::detail::call_traits<second_type>::reference second_reference;
+			typedef typename sprout::detail::call_traits<first_type>::const_reference first_const_reference;
+			typedef typename sprout::detail::call_traits<second_type>::const_reference second_const_reference;
+		private:
+			first_type first_;
+			second_type second_;
+		public:
+			SPROUT_CONSTEXPR compressed_pair_impl() {}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x, second_param_type y)
+				: first_(x)
+				, second_(y)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x)
+				: first_(x)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(second_param_type y)
+				: second_(y)
+			{}
+			first_reference first() {
+				return first_;
+			}
+			SPROUT_CONSTEXPR first_const_reference first() const {
+				return first_;
+			}
+			second_reference second() {
+				return second_;
+			}
+			SPROUT_CONSTEXPR second_const_reference second() const {
+				return second_;
+			}
+			void swap(compressed_pair_impl& other) {
+				using std::swap;
+				swap(first_, other.first_);
+				swap(second_, other.second_);
+			}
+		};
+		template<typename T1, typename T2>
+		class compressed_pair_impl<T1, T2, 1>
+			: protected std::remove_cv<T1>::type
+		{
+		public:
+			typedef T1 first_type;
+			typedef T2 second_type;
+			typedef typename sprout::detail::call_traits<first_type>::param_type first_param_type;
+			typedef typename sprout::detail::call_traits<second_type>::param_type second_param_type;
+			typedef typename sprout::detail::call_traits<first_type>::reference first_reference;
+			typedef typename sprout::detail::call_traits<second_type>::reference second_reference;
+			typedef typename sprout::detail::call_traits<first_type>::const_reference first_const_reference;
+			typedef typename sprout::detail::call_traits<second_type>::const_reference second_const_reference;
+		private:
+			second_type second_;
+		public:
+			SPROUT_CONSTEXPR compressed_pair_impl() {}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x, second_param_type y)
+				: first_type(x)
+				, second_(y)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x)
+				: first_type(x)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(second_param_type y)
+				: second_(y)
+			{}
+			first_reference first() {
+				return *this;
+			}
+			SPROUT_CONSTEXPR first_const_reference first() const {
+				return *this;
+			}
+			second_reference second() {
+				return second_;
+			}
+			SPROUT_CONSTEXPR second_const_reference second() const {
+				return second_;
+			}
+			void swap(compressed_pair_impl& other) {
+				using std::swap;
+				swap(second_, other.second_);
+			}
+		};
+		template<typename T1, typename T2>
+		class compressed_pair_impl<T1, T2, 2>
+			: protected std::remove_cv<T1>::type
+		{
+		public:
+			typedef T1 first_type;
+			typedef T2 second_type;
+			typedef typename sprout::detail::call_traits<first_type>::param_type first_param_type;
+			typedef typename sprout::detail::call_traits<second_type>::param_type second_param_type;
+			typedef typename sprout::detail::call_traits<first_type>::reference first_reference;
+			typedef typename sprout::detail::call_traits<second_type>::reference second_reference;
+			typedef typename sprout::detail::call_traits<first_type>::const_reference first_const_reference;
+			typedef typename sprout::detail::call_traits<second_type>::const_reference second_const_reference;
+		private:
+			first_type first_;
+		public:
+			SPROUT_CONSTEXPR compressed_pair_impl() {}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x, second_param_type y)
+				: first_(x)
+				, second_type(y)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x)
+				: first_(x)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(second_param_type y)
+				: second_type(y)
+			{}
+			first_reference first() {
+				return first_;
+			}
+			SPROUT_CONSTEXPR first_const_reference first() const {
+				return first_;
+			}
+			second_reference second() {
+				return *this;
+			}
+			SPROUT_CONSTEXPR second_const_reference second() const {
+				return *this;
+			}
+			void swap(compressed_pair_impl& other) {
+				using std::swap;
+				swap(first_, other.first_);
+			}
+		};
+		template<typename T1, typename T2>
+		class compressed_pair_impl<T1, T2, 3>
+			: protected std::remove_cv<T1>::type
+			, protected std::remove_cv<T2>::type
+		{
+		public:
+			typedef T1 first_type;
+			typedef T2 second_type;
+			typedef typename sprout::detail::call_traits<first_type>::param_type first_param_type;
+			typedef typename sprout::detail::call_traits<second_type>::param_type second_param_type;
+			typedef typename sprout::detail::call_traits<first_type>::reference first_reference;
+			typedef typename sprout::detail::call_traits<second_type>::reference second_reference;
+			typedef typename sprout::detail::call_traits<first_type>::const_reference first_const_reference;
+			typedef typename sprout::detail::call_traits<second_type>::const_reference second_const_reference;
+		public:
+			SPROUT_CONSTEXPR compressed_pair_impl() {}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x, second_param_type y)
+				: first_type(x)
+				, second_type(y)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x)
+				: first_type(x)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(second_param_type y)
+				: second_type(y)
+			{}
+			first_reference first() {
+				return *this;
+			}
+			SPROUT_CONSTEXPR first_const_reference first() const {
+				return *this;
+			}
+			second_reference second() {
+				return *this;
+			}
+			SPROUT_CONSTEXPR second_const_reference second() const {
+				return *this;
+			}
+			void swap(compressed_pair_impl& other) {}
+		};
+		template<typename T1, typename T2>
+		class compressed_pair_impl<T1, T2, 4>
+			: protected std::remove_cv<T1>::type
+		{
+		public:
+			typedef T1 first_type;
+			typedef T2 second_type;
+			typedef typename sprout::detail::call_traits<first_type>::param_type first_param_type;
+			typedef typename sprout::detail::call_traits<second_type>::param_type second_param_type;
+			typedef typename sprout::detail::call_traits<first_type>::reference first_reference;
+			typedef typename sprout::detail::call_traits<second_type>::reference second_reference;
+			typedef typename sprout::detail::call_traits<first_type>::const_reference first_const_reference;
+			typedef typename sprout::detail::call_traits<second_type>::const_reference second_const_reference;
+		private:
+			second_type second_;
+		public:
+			SPROUT_CONSTEXPR compressed_pair_impl() {}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x, second_param_type y)
+				: first_type(x)
+				, second_(y)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x)
+				: first_type(x)
+				, second_(x)
+			{}
+			first_reference first() {
+				return *this;
+			}
+			SPROUT_CONSTEXPR first_const_reference first() const {
+				return *this;
+			}
+			second_reference second() {
+				return second_;
+			}
+			SPROUT_CONSTEXPR second_const_reference second() const {
+				return second_;
+			}
+			void swap(compressed_pair_impl& other) {}
+		};
+		template<typename T1, typename T2>
+		class compressed_pair_impl<T1, T2, 5>
+		{
+		public:
+			typedef T1 first_type;
+			typedef T2 second_type;
+			typedef typename sprout::detail::call_traits<first_type>::param_type first_param_type;
+			typedef typename sprout::detail::call_traits<second_type>::param_type second_param_type;
+			typedef typename sprout::detail::call_traits<first_type>::reference first_reference;
+			typedef typename sprout::detail::call_traits<second_type>::reference second_reference;
+			typedef typename sprout::detail::call_traits<first_type>::const_reference first_const_reference;
+			typedef typename sprout::detail::call_traits<second_type>::const_reference second_const_reference;
+		private:
+			first_type first_;
+			second_type second_;
+		public:
+			SPROUT_CONSTEXPR compressed_pair_impl() {}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x, second_param_type y)
+				: first_(x)
+				, second_(y)
+			{}
+			SPROUT_CONSTEXPR compressed_pair_impl(first_param_type x)
+				: first_(x)
+				, second_(x)
+			{}
+			first_reference first() {
+				return first_;
+			}
+			SPROUT_CONSTEXPR first_const_reference first() const {
+				return first_;
+			}
+			second_reference second() {
+				return second_;
+			}
+			SPROUT_CONSTEXPR second_const_reference second() const {
+				return second_;
+			}
+			void swap(compressed_pair_impl& other) {
+				using std::swap;
+				swap(first_, other.first_);
+				swap(second_, other.second_);
+			}
+		};
+	}	// namespace detail
+	
+	//
+	// compressed_pair
+	//
+	template<typename T1, typename T2>
+	class compressed_pair
+		: private sprout::detail::compressed_pair_impl<
+			T1,
+			T2,
+			sprout::detail::compressed_pair_switch<
+				T1,
+				T2,
+				std::is_same<typename std::remove_cv<T1>::type, typename std::remove_cv<T2>::type>::value,
+				std::is_empty<T1>::value,
+				std::is_empty<T2>::value
+			>::value
+		>
+	{
+	private:
+		typedef sprout::detail::compressed_pair_impl<
+			T1,
+			T2,
+			sprout::detail::compressed_pair_switch<
+				T1,
+				T2,
+				std::is_same<typename std::remove_cv<T1>::type, typename std::remove_cv<T2>::type>::value,
+				std::is_empty<T1>::value,
+				std::is_empty<T2>::value
+			>::value
+		> base_type;
+	public:
+		typedef T1 first_type;
+		typedef T2 second_type;
+		typedef typename sprout::detail::call_traits<first_type>::param_type first_param_type;
+		typedef typename sprout::detail::call_traits<second_type>::param_type second_param_type;
+		typedef typename sprout::detail::call_traits<first_type>::reference first_reference;
+		typedef typename sprout::detail::call_traits<second_type>::reference second_reference;
+		typedef typename sprout::detail::call_traits<first_type>::const_reference first_const_reference;
+		typedef typename sprout::detail::call_traits<second_type>::const_reference second_const_reference;
+	public:
+		SPROUT_CONSTEXPR compressed_pair()
+			: base_type()
+		{}
+		SPROUT_CONSTEXPR compressed_pair(first_param_type x, second_param_type y)
+			: base_type(x, y)
+		{}
+		SPROUT_CONSTEXPR explicit compressed_pair(first_param_type x)
+			: base_type(x)
+		{}
+		SPROUT_CONSTEXPR explicit compressed_pair(second_param_type y)
+			: base_type(y)
+		{}
+		first_reference first() {
+			return base_type::first();
+		}
+		SPROUT_CONSTEXPR first_const_reference first() const {
+			return base_type::first();
+		}
+		second_reference second() {
+			return base_type::second();
+		}
+		SPROUT_CONSTEXPR second_const_reference second() const {
+			return base_type::second();
+		}
+		void swap(compressed_pair& other) {
+			base_type::swap(other);
+		}
+	};
+	template<typename T>
+	class compressed_pair<T, T>
+		: private sprout::detail::compressed_pair_impl<
+			T,
+			T,
+			sprout::detail::compressed_pair_switch<
+				T,
+				T,
+				std::is_same<typename std::remove_cv<T>::type, typename std::remove_cv<T>::type>::value,
+				std::is_empty<T>::value,
+				std::is_empty<T>::value
+			>::value
+		>
+	{
+	private:
+		typedef sprout::detail::compressed_pair_impl<
+			T,
+			T,
+			sprout::detail::compressed_pair_switch<
+				T,
+				T,
+				std::is_same<typename std::remove_cv<T>::type, typename std::remove_cv<T>::type>::value,
+				std::is_empty<T>::value,
+				std::is_empty<T>::value
+			>::value
+		> base_type;
+	public:
+		typedef T first_type;
+		typedef T second_type;
+		typedef typename sprout::detail::call_traits<first_type>::param_type first_param_type;
+		typedef typename sprout::detail::call_traits<second_type>::param_type second_param_type;
+		typedef typename sprout::detail::call_traits<first_type>::reference first_reference;
+		typedef typename sprout::detail::call_traits<second_type>::reference second_reference;
+		typedef typename sprout::detail::call_traits<first_type>::const_reference first_const_reference;
+		typedef typename sprout::detail::call_traits<second_type>::const_reference second_const_reference;
+	public:
+		SPROUT_CONSTEXPR compressed_pair()
+			: base_type()
+		{}
+		SPROUT_CONSTEXPR compressed_pair(first_param_type x, second_param_type y)
+			: base_type(x, y)
+		{}
+		SPROUT_CONSTEXPR explicit compressed_pair(first_param_type x)
+			: base_type(x)
+		{}
+		first_reference first() {
+			return base_type::first();
+		}
+		SPROUT_CONSTEXPR first_const_reference first() const {
+			return base_type::first();
+		}
+		second_reference second() {
+			return base_type::second();
+		}
+		SPROUT_CONSTEXPR second_const_reference second() const {
+			return base_type::second();
+		}
+		void swap(compressed_pair& other) {
+			base_type::swap(other);
+		}
+	};
+	template<typename T1, typename T2>
+	inline void swap(sprout::compressed_pair<T1, T2>& lhs, sprout::compressed_pair<T1, T2>& rhs) {
+		lhs.swap(rhs);
+	}
+}	// namespace sprout
+
+#endif // #ifndef SPROUT_COMPRESSED_PAIR_HPP
diff --git a/sprout/detail/call_traits.hpp b/sprout/detail/call_traits.hpp
new file mode 100644
index 00000000..690e4a98
--- /dev/null
+++ b/sprout/detail/call_traits.hpp
@@ -0,0 +1,58 @@
+#ifndef SPROUT_DETAIL_CALL_TRAITS_HPP
+#define SPROUT_DETAIL_CALL_TRAITS_HPP
+
+#include <type_traits>
+#include <sprout/config.hpp>
+
+namespace sprout {
+	namespace detail {
+		template<typename T, bool Small>
+		struct ct_impl_1 {
+		public:
+			typedef T const& param_type;
+		};
+		template<typename T>
+		struct ct_impl_1<T, true> {
+		public:
+			typedef T const param_type;
+		};
+
+		template<typename T, bool IsPointer, bool IsArithmetic>
+		struct ct_impl {
+		public:
+			typedef T const& param_type;
+		};
+		template<typename T, bool IsPointer>
+		struct ct_impl<T, IsPointer, true> {
+		public:
+			typedef typename sprout::detail::ct_impl_1<T, sizeof(T) <= sizeof(void*)>::param_type param_type;
+		};
+		template<typename T, bool IsArithmetic>
+		struct ct_impl<T, true, IsArithmetic> {
+		public:
+			typedef T const param_type;
+		};
+
+		template<typename T>
+		struct call_traits {
+		public:
+			typedef T value_type;
+			typedef T& reference;
+			typedef T const& const_reference;
+			typedef typename sprout::detail::ct_impl<
+				T,
+				std::is_pointer<T>::value,
+				std::is_arithmetic<T>::value
+			>::param_type param_type;
+		};
+		template<typename T>
+		struct call_traits<T&> {
+			typedef T& value_type;
+			typedef T& reference;
+			typedef T const& const_reference;
+			typedef T& param_type;
+		};
+	}	// namespace detail
+}	// namespace sprout
+
+#endif // #ifndef SPROUT_DETAIL_CALL_TRAITS_HPP