mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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77 lines
2.7 KiB
C++
77 lines
2.7 KiB
C++
#ifndef SPROUT_ITERATOR_PREV_HPP
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#define SPROUT_ITERATOR_PREV_HPP
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#include <iterator>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/utility/forward.hpp>
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namespace sprout {
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namespace detail {
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template<typename RandomAccessIterator>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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std::is_literal_type<typename std::decay<RandomAccessIterator>::type>::value,
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typename std::decay<RandomAccessIterator>::type
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>::type prev_impl(
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RandomAccessIterator&& it,
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std::random_access_iterator_tag*
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)
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{
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return sprout::forward<RandomAccessIterator>(it) - 1;
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}
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template<typename BidirectionalIterator>
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inline SPROUT_CONSTEXPR typename std::decay<BidirectionalIterator>::type prev_impl(
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BidirectionalIterator&& it,
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void*
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)
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{
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return std::prev(sprout::forward<BidirectionalIterator>(it));
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}
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template<typename RandomAccessIterator>
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inline SPROUT_CONSTEXPR typename std::enable_if<
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std::is_literal_type<typename std::decay<RandomAccessIterator>::type>::value,
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typename std::decay<RandomAccessIterator>::type
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>::type prev_impl(
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RandomAccessIterator&& it,
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typename std::iterator_traits<typename std::decay<RandomAccessIterator>::type>::difference_type n,
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std::random_access_iterator_tag*
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)
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{
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return sprout::forward<RandomAccessIterator>(it) - n;
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}
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template<typename BidirectionalIterator>
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inline SPROUT_CONSTEXPR typename std::decay<BidirectionalIterator>::type prev_impl(
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BidirectionalIterator it,
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typename std::iterator_traits<typename std::decay<BidirectionalIterator>::type>::difference_type n,
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void*
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)
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{
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return std::prev(sprout::forward<BidirectionalIterator>(it), n);
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}
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} // namespace detail
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//
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// prev
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//
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template<typename BidirectionalIterator>
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inline SPROUT_CONSTEXPR typename std::decay<BidirectionalIterator>::type
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prev(BidirectionalIterator&& it) {
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typedef typename std::iterator_traits<typename std::decay<BidirectionalIterator>::type>::iterator_category* category;
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return sprout::detail::prev_impl(
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sprout::forward<BidirectionalIterator>(it),
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category()
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);
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}
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template<typename BidirectionalIterator>
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inline SPROUT_CONSTEXPR typename std::decay<BidirectionalIterator>::type
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prev(BidirectionalIterator&& it, typename std::iterator_traits<typename std::decay<BidirectionalIterator>::type>::difference_type n) {
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typedef typename std::iterator_traits<typename std::decay<BidirectionalIterator>::type>::iterator_category* category;
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return sprout::detail::prev_impl(
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sprout::forward<BidirectionalIterator>(it),
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n,
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category()
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);
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ITERATOR_PREV_HPP
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