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Sprout/sprout/iterator/distance.hpp
2012-04-04 17:48:02 +09:00

36 lines
1.1 KiB
C++

#ifndef SPROUT_ITERATOR_DISTANCE_HPP
#define SPROUT_ITERATOR_DISTANCE_HPP
#include <iterator>
#include <sprout/config.hpp>
#include <sprout/iterator/next.hpp>
namespace sprout {
namespace detail {
// Copyright (C) 2011 RiSK (sscrisk)
template<typename InputIterator>
SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
distance(InputIterator first, InputIterator last) {
return first == last ? 0
: 1 + sprout::detail::distance(sprout::next(first), last)
;
}
template<typename InputIterator>
SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
distance_impl(InputIterator first, InputIterator last) {
using sprout::detail::distance;
return distance(first, last);
}
} // namespace detail
//
// distance
//
template<typename InputIterator>
SPROUT_CONSTEXPR typename std::iterator_traits<InputIterator>::difference_type
distance(InputIterator first, InputIterator last) {
return sprout::detail::distance_impl(first, last);
}
} // namespace sprout
#endif // #ifndef SPROUT_ITERATOR_DISTANCE_HPP