#ifndef SPROUT_DETAIL_ALGORITHM_OVERLAP_COUNT_HPP
#define SPROUT_DETAIL_ALGORITHM_OVERLAP_COUNT_HPP

#include <iterator>
#include <sprout/config.hpp>
#include <sprout/iterator/operation.hpp>
#include HDR_FUNCTIONAL_SSCRISK_CEL_OR_SPROUT

namespace sprout {
	namespace detail {
		template<typename InputIterator, typename BinaryPredicate>
		inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
		overlap_count_impl(
			InputIterator first, InputIterator last,
			BinaryPredicate pred, typename std::iterator_traits<InputIterator>::value_type const& value
			)
		{
			return first == last ? 0
				: pred(*first, value) ? 1 + sprout::detail::overlap_count_impl(sprout::next(first), last, pred, value)
				: sprout::detail::overlap_count_impl(sprout::next(first), last, pred, *first)
				;
		}

		//
		// overlap_count
		//
		template<typename InputIterator, typename BinaryPredicate>
		inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
		overlap_count(InputIterator first, InputIterator last, BinaryPredicate pred) {
			return first == last ? 0
				: sprout::detail::overlap_count_impl(sprout::next(first), last, pred, *first)
				;
		}

		template<typename InputIterator>
		inline SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
		overlap_count(InputIterator first, InputIterator last) {
			return sprout::detail::overlap_count(
				first, last,
				NS_SSCRISK_CEL_OR_SPROUT::equal_to<typename std::iterator_traits<InputIterator>::value_type>()
				);
		}
	}	// namespace detail
}	// namespace sprout

#endif	// #ifndef SPROUT_DETAIL_ALGORITHM_OVERLAP_COUNT_HPP