text: #ifndef SPROUT_ITERATOR_INSERT_RANGE_ITERATOR_HPP
  #define SPROUT_ITERATOR_INSERT_RANGE_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/iterator/type_traits/common.hpp>
  #include <sprout/utility/swap.hpp>
  #include <sprout/utility/limited.hpp>
  #include <sprout/type_traits/arithmetic_promote.hpp>
  
  namespace sprout {
  	//
  	// insert_range_iterator
  	//
  	template<typename DstIterator, typename SrcIterator>
  	class insert_range_iterator
  		: public std::iterator<
  			typename sprout::common_iterator_category<DstIterator, SrcIterator>::type,
  			typename sprout::common_iterator_value_type<DstIterator, SrcIterator>::type,
  			typename sprout::common_iterator_difference_type<DstIterator, SrcIterator>::type,
  			typename sprout::common_iterator_pointer<DstIterator, SrcIterator>::type,
  			typename sprout::common_iterator_reference<DstIterator, SrcIterator>::type
  		>
  	{
  	public:
  		typedef DstIterator iterator_type;
  		typedef SrcIterator iterator2_type;
  		typedef typename sprout::common_iterator_category<DstIterator, SrcIterator>::type iterator_category;
  		typedef typename sprout::common_iterator_value_type<DstIterator, SrcIterator>::type value_type;
  		typedef typename sprout::common_iterator_difference_type<DstIterator, SrcIterator>::type difference_type;
  		typedef typename sprout::common_iterator_pointer<DstIterator, SrcIterator>::type pointer;
  		typedef typename sprout::common_iterator_reference<DstIterator, SrcIterator>::type reference;
  	protected:
  		iterator_type current1;
  		iterator_type pos1;
  		iterator2_type current2;
  		iterator2_type first2;
  		iterator2_type last2;
  	private:
  		SPROUT_CONSTEXPR insert_range_iterator advance_impl(difference_type n) const {
  			return n >= 0
  				? current1 > pos1 ? insert_range_iterator(sprout::next(current1, n), pos1, current2, first2, last2)
  					: current1 == pos1 ? current2 == last2 ? insert_range_iterator(sprout::next(current1, n), pos1, current2, first2, last2)
  						: n <= sprout::distance(current2, last2) ? insert_range_iterator(current1, pos1, last2, sprout::next(current2, n), first2, last2)
  						: insert_range_iterator(sprout::next(current1, n - sprout::distance(current2, last2)), pos1, last2, first2, last2)
  					: n <= sprout::distance(current1, pos1) ? insert_range_iterator(sprout::next(current1, n), pos1, current2, first2, last2)
  					: n <= sprout::distance(current1, pos1) + sprout::distance(current2, last2)
  						? insert_range_iterator(pos1, pos1, last2, sprout::next(current2, n - sprout::distance(current1, pos1)), first2, last2)
  					: insert_range_iterator(sprout::next(current1, n - sprout::distance(current1, pos1) - sprout::distance(current2, last2)), pos1, last2, first2, last2)
  				: current1 < pos1 ? insert_range_iterator(sprout::next(current1, n), pos1, current2, first2, last2)
  					: current1 == pos1 ? current2 == first2 ? insert_range_iterator(sprout::next(current1, n), pos1, current2, first2, last2)
  						: -n <= sprout::distance(first2, current2) ? insert_range_iterator(current1, pos1, last2, sprout::next(current2, n), first2, last2)
  						: insert_range_iterator(sprout::next(current1, n - sprout::distance(first2, current2)), pos1, first2, first2, last2)
  					: -n <= sprout::distance(pos1, current1) ? insert_range_iterator(sprout::next(current1, n), pos1, current2, first2, last2)
  					: -n <= sprout::distance(pos1, current1) + sprout::distance(first2, current2)
  						? insert_range_iterator(pos1, pos1, last2, sprout::next(current2, n - sprout::distance(pos1, current1)), first2, last2)
  					: insert_range_iterator(sprout::next(current1, n - sprout::distance(pos1, current1) - sprout::distance(first2, current2)), pos1, first2, first2, last2)
  				;
  		}
  	public:
  		insert_range_iterator() = default;
  		insert_range_iterator(insert_range_iterator const&) = default;
  		SPROUT_CONSTEXPR insert_range_iterator(iterator_type it1, iterator_type pos1, iterator2_type it2, iterator2_type first2, iterator2_type last2)
  			: current1(it1), pos1(pos1)
  			, current2(it2), first2(first2), last2(last2)
  		{}
  		template<typename U, typename V>
  		SPROUT_CONSTEXPR insert_range_iterator(insert_range_iterator<U, V> const& it)
  			: current1(it.base()), pos1(it.position())
  			, current2(it.base2()), first2(it.first()), last2(it.last())
  		{}
  		template<typename U, typename V>
  		insert_range_iterator& operator=(insert_range_iterator<U, V> const& it) {
  			insert_range_iterator temp(it);
  			temp.swap(*this);
  			return *this;
  		}
  		SPROUT_CONSTEXPR iterator_type base() const {
  			return current1;
  		}
  		SPROUT_CONSTEXPR iterator_type position() const {
  			return pos1;
  		}
  		SPROUT_CONSTEXPR iterator2_type base2() const {
  			return current2;
  		}
  		SPROUT_CONSTEXPR iterator2_type first() const {
  			return first2;
  		}
  		SPROUT_CONSTEXPR iterator2_type last() const {
  			return last2;
  		}
  		SPROUT_CONSTEXPR bool is_in_base() const {
  			return current1 != pos1 || current2 == last2;
  		}
  		SPROUT_CONSTEXPR reference operator*() const {
  			return is_in_base() ? *current1 : *current2;
  		}
  		SPROUT_CONSTEXPR pointer operator->() const {
  			return &*(*this);
  		}
  		insert_range_iterator& operator++() {
  			if (is_in_base()) {
  				++current1;
  			} else {
  				++current2;
  			}
  			return *this;
  		}
  		insert_range_iterator operator++(int) {
  			insert_range_iterator result(*this);
  			if (is_in_base()) {
  				++current1;
  			} else {
  				++current2;
  			}
  			return result;
  		}
  		insert_range_iterator& operator--() {
  			if (current1 != pos1 || current2 == first2) {
  				--current1;
  			} else {
  				--current2;
  			}
  			return *this;
  		}
  		insert_range_iterator operator--(int) {
  			insert_range_iterator temp(*this);
  			if (current1 != pos1 || current2 == first2) {
  				--current1;
  			} else {
  				--current2;
  			}
  			return temp;
  		}
  		SPROUT_CONSTEXPR insert_range_iterator operator+(difference_type n) const {
  			return advance_impl(n);
  		}
  		SPROUT_CONSTEXPR insert_range_iterator operator-(difference_type n) const {
  			return advance_impl(-n);
  		}
  		insert_range_iterator& operator+=(difference_type n) {
  			insert_range_iterator temp(*this + n);
  			temp.swap(*this);
  			return *this;
  		}
  		insert_range_iterator& operator-=(difference_type n) {
  			insert_range_iterator temp(*this - n);
  			temp.swap(*this);
  			return *this;
  		}
  		SPROUT_CONSTEXPR reference operator[](difference_type n) const {
  			return *(*this + n);
  		}
  		SPROUT_CONSTEXPR insert_range_iterator next() const {
  			return is_in_base() ? insert_range_iterator(sprout::next(current1), pos1, current2, first2, last2)
  				: insert_range_iterator(current1, pos1, sprout::next(current2), first2, last2)
  				;
  		}
  		SPROUT_CONSTEXPR insert_range_iterator prev() const {
  			return current1 != pos1 || current2 == first2 ? insert_range_iterator(sprout::prev(current1), pos1, current2, first2, last2)
  				: insert_range_iterator(current1, pos1, sprout::prev(current2), first2, last2)
  				;
  		}
  		void swap(insert_range_iterator& other)
  		SPROUT_NOEXCEPT_EXPR(
  			SPROUT_NOEXCEPT_EXPR(sprout::swap(current1, other.current1))
  			&& SPROUT_NOEXCEPT_EXPR(sprout::swap(pos1, other.pos1))
  			&& SPROUT_NOEXCEPT_EXPR(sprout::swap(current2, other.current2))
  			&& SPROUT_NOEXCEPT_EXPR(sprout::swap(first2, other.first2))
  			&& SPROUT_NOEXCEPT_EXPR(sprout::swap(last2, other.last2))
  			)
  		{
  			sprout::swap(current1, other.current1);
  			sprout::swap(pos1, other.pos1);
  			sprout::swap(current2, other.current2);
  			sprout::swap(first2, other.first2);
  			sprout::swap(last2, other.last2);
  		}
  	};
  
  	template<
  		typename DstIterator1, typename SrcIterator1,
  		typename DstIterator2, typename SrcIterator2
  	>
  	inline SPROUT_CONSTEXPR bool operator==(
  		sprout::insert_range_iterator<DstIterator1, SrcIterator1> const& lhs,
  		sprout::insert_range_iterator<DstIterator2, SrcIterator2> const& rhs
  		)
  	{
  		return lhs.base() == rhs.base() && lhs.base2() == rhs.base2();
  	}
  	template<
  		typename DstIterator1, typename SrcIterator1,
  		typename DstIterator2, typename SrcIterator2
  	>
  	inline SPROUT_CONSTEXPR bool operator!=(
  		sprout::insert_range_iterator<DstIterator1, SrcIterator1> const& lhs,
  		sprout::insert_range_iterator<DstIterator2, SrcIterator2> const& rhs
  		)
  	{
  		return !(lhs == rhs);
  	}
  	template<
  		typename DstIterator1, typename SrcIterator1,
  		typename DstIterator2, typename SrcIterator2
  	>
  	inline SPROUT_CONSTEXPR bool operator<(
  		sprout::insert_range_iterator<DstIterator1, SrcIterator1> const& lhs,
  		sprout::insert_range_iterator<DstIterator2, SrcIterator2> const& rhs
  		)
  	{
  		return lhs.is_in_base() && rhs.is_in_base() ? lhs.base() < rhs.base()
  			: !lhs.is_in_base() && !rhs.is_in_base() ? lhs.base2() < rhs.base2()
  			: lhs.is_in_base()
  			;
  	}
  	template<
  		typename DstIterator1, typename SrcIterator1,
  		typename DstIterator2, typename SrcIterator2
  	>
  	inline SPROUT_CONSTEXPR bool operator>(
  		sprout::insert_range_iterator<DstIterator1, SrcIterator1> const& lhs,
  		sprout::insert_range_iterator<DstIterator2, SrcIterator2> const& rhs
  		)
  	{
  		return rhs < lhs;
  	}
  	template<
  		typename DstIterator1, typename SrcIterator1,
  		typename DstIterator2, typename SrcIterator2
  	>
  	inline SPROUT_CONSTEXPR bool operator<=(
  		sprout::insert_range_iterator<DstIterator1, SrcIterator1> const& lhs,
  		sprout::insert_range_iterator<DstIterator2, SrcIterator2> const& rhs
  		)
  	{
  		return !(rhs < lhs);
  	}
  	template<
  		typename DstIterator1, typename SrcIterator1,
  		typename DstIterator2, typename SrcIterator2
  	>
  	inline SPROUT_CONSTEXPR bool operator>=(
  		sprout::insert_range_iterator<DstIterator1, SrcIterator1> const& lhs,
  		sprout::insert_range_iterator<DstIterator2, SrcIterator2> const& rhs
  		)
  	{
  		return !(lhs < rhs);
  	}
  	template<
  		typename DstIterator1, typename SrcIterator1,
  		typename DstIterator2, typename SrcIterator2
  	>
  	inline SPROUT_CONSTEXPR typename sprout::arithmetic_promote<
  		typename sprout::insert_range_iterator<DstIterator1, SrcIterator1>::difference_type,
  		typename sprout::insert_range_iterator<DstIterator2, SrcIterator2>::difference_type
  	>::type
  	operator-(
  		sprout::insert_range_iterator<DstIterator1, SrcIterator1> const& lhs,
  		sprout::insert_range_iterator<DstIterator2, SrcIterator2> const& rhs
  		)
  	{
  		return sprout::limited::plus(lhs.base() - rhs.base(), lhs.base2() - rhs.base2());
  	}
  	template<typename DstIterator, typename SrcIterator>
  	inline SPROUT_CONSTEXPR sprout::insert_range_iterator<DstIterator, SrcIterator> operator+(
  		typename sprout::insert_range_iterator<DstIterator, SrcIterator>::difference_type n,
  		sprout::insert_range_iterator<DstIterator, SrcIterator> const& it
  		)
  	{
  		return it + n;
  	}
  
  	//
  	// make_insert_range_iterator
  	//
  	template<typename DstIterator, typename SrcIterator>
  	inline SPROUT_CONSTEXPR sprout::insert_range_iterator<DstIterator, SrcIterator>
  	make_insert_range_iterator(DstIterator it1, DstIterator pos1, SrcIterator it2, SrcIterator first2, SrcIterator last2) {
  		return sprout::insert_range_iterator<DstIterator, SrcIterator>(it1, pos1, it2, first2, last2);
  	}
  
  	//
  	// swap
  	//
  	template<typename DstIterator, typename SrcIterator>
  	inline void
  	swap(
  		sprout::insert_range_iterator<DstIterator, SrcIterator>& lhs,
  		sprout::insert_range_iterator<DstIterator, SrcIterator>& rhs
  		)
  	SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(lhs.swap(rhs)))
  	{
  		lhs.swap(rhs);
  	}
  
  	//
  	// iterator_next
  	//
  	template<typename DstIterator, typename SrcIterator>
  	inline SPROUT_CONSTEXPR sprout::insert_range_iterator<DstIterator, SrcIterator>
  	iterator_next(sprout::insert_range_iterator<DstIterator, SrcIterator> const& it) {
  		return it.next();
  	}
  
  	//
  	// iterator_prev
  	//
  	template<typename DstIterator, typename SrcIterator>
  	inline SPROUT_CONSTEXPR sprout::insert_range_iterator<DstIterator, SrcIterator>
  	iterator_prev(sprout::insert_range_iterator<DstIterator, SrcIterator> const& it) {
  		return it.prev();
  	}
  }	// namespace sprout
  
  #endif	// #ifndef SPROUT_ITERATOR_INSERT_RANGE_ITERATOR_HPP
  