#ifndef SPROUT_ALGORITHM_EQUAL_HPP
#define SPROUT_ALGORITHM_EQUAL_HPP

#include <iterator>
#include <sprout/config.hpp>
#include <sprout/iterator/operation.hpp>
#include <sprout/iterator/type_traits/common.hpp>
#include <sprout/functional/equal_to.hpp>
#include HDR_ITERATOR_SSCRISK_CEL_OR_SPROUT

namespace sprout {
	namespace detail {
		template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename BinaryPredicate>
		inline SPROUT_CONSTEXPR bool
		equal_impl_ra(
			RandomAccessIterator1 first1, RandomAccessIterator1 last1, RandomAccessIterator2 first2, BinaryPredicate pred,
			typename std::iterator_traits<RandomAccessIterator1>::difference_type pivot
			)
		{
			return pivot == 0 ? pred(*first1, *first2)
				: sprout::detail::equal_impl_ra(
					first1, sprout::next(first1, pivot), first2, pred,
					pivot / 2
					)
					&& sprout::detail::equal_impl_ra(
						sprout::next(first1, pivot), last1, sprout::next(first2, pivot), pred,
						(NS_SSCRISK_CEL_OR_SPROUT::distance(first1, last1) - pivot) / 2
						)
				;
		}
		template<typename RandomAccessIterator1, typename RandomAccessIterator2, typename BinaryPredicate>
		inline SPROUT_CONSTEXPR bool
		equal(
			RandomAccessIterator1 first1, RandomAccessIterator1 last1, RandomAccessIterator2 first2, BinaryPredicate pred,
			std::random_access_iterator_tag*
			)
		{
			return first1 == last1 ? true
				: sprout::detail::equal_impl_ra(
					first1, last1, first2, pred,
					NS_SSCRISK_CEL_OR_SPROUT::distance(first1, last1) / 2
					)
				;
		}

		// Copyright (C) 2011 RiSK (sscrisk)
		template<typename InputIterator1, typename InputIterator2, typename BinaryPredicate>
		inline SPROUT_CONSTEXPR bool
		equal_impl(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, BinaryPredicate pred) {
			return first1 == last1 ? true
				: pred(*first1, *first2) && sprout::detail::equal_impl(sprout::next(first1), last1, sprout::next(first2), pred)
				;
		}
		template<typename InputIterator1, typename InputIterator2, typename BinaryPredicate>
		inline SPROUT_CONSTEXPR bool
		equal(
			InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, BinaryPredicate pred,
			void*
			)
		{
			return sprout::detail::equal_impl(first1, last1, first2, pred);
		}
	}	//namespace detail

	// 25.2.11 Equal
	//
	//	recursion depth:
	//		[first1, last1), first2 are RandomAccessIterator -> O(log N)
	//		otherwise -> O(N)
	//
	template<typename InputIterator1, typename InputIterator2, typename BinaryPredicate>
	inline SPROUT_CONSTEXPR bool
	equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, BinaryPredicate pred) {
		typedef typename sprout::common_iterator_category<InputIterator1, InputIterator2>::type* category;
		return sprout::detail::equal(first1, last1, first2, pred, category());
	}

	template<typename InputIterator1, typename InputIterator2>
	inline SPROUT_CONSTEXPR bool
	equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2) {
		return sprout::equal(first1, last1, first2, sprout::equal_to<>());
	}
}	// namespace sprout

#endif	// #ifndef SPROUT_ALGORITHM_EQUAL_HPP