mirror of
https://github.com/bolero-MURAKAMI/Sprout.git
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307 lines
9.9 KiB
C++
307 lines
9.9 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2015 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef SPROUT_ITERATOR_ALTERNATE_ITERATOR_HPP
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#define SPROUT_ITERATOR_ALTERNATE_ITERATOR_HPP
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#include <iterator>
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#include <utility>
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/iterator/next.hpp>
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#include <sprout/iterator/prev.hpp>
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#include <sprout/iterator/distance.hpp>
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#include <sprout/iterator/type_traits/common.hpp>
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#include <sprout/utility/swap.hpp>
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#include <sprout/utility/limited.hpp>
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namespace sprout {
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//
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// alternate_iterator
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//
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template<typename LIterator, typename RIterator>
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class alternate_iterator
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: public std::iterator<
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typename sprout::common_iterator_category<LIterator, RIterator>::type,
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typename sprout::common_iterator_value_type<LIterator, RIterator>::type,
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typename sprout::common_iterator_difference_type<LIterator, RIterator>::type,
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typename sprout::common_iterator_pointer<LIterator, RIterator>::type,
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typename sprout::common_iterator_reference<LIterator, RIterator>::type
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>
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{
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public:
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typedef LIterator iterator_type;
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typedef RIterator iterator2_type;
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typedef typename sprout::common_iterator_category<LIterator, RIterator>::type iterator_category;
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typedef typename sprout::common_iterator_value_type<LIterator, RIterator>::type value_type;
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typedef typename sprout::common_iterator_difference_type<LIterator, RIterator>::type difference_type;
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typedef typename sprout::common_iterator_pointer<LIterator, RIterator>::type pointer;
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typedef typename sprout::common_iterator_reference<LIterator, RIterator>::type reference;
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protected:
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iterator_type current1;
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iterator2_type current2;
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bool in_left;
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private:
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SPROUT_CONSTEXPR alternate_iterator advance_impl_1(difference_type n) const {
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return alternate_iterator(sprout::next(current1, n / 2), sprout::next(current2, n / 2), !(n % 2));
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}
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SPROUT_CONSTEXPR alternate_iterator advance_impl(difference_type n) const {
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return advance_impl_1(n + (!is_in_left() ? 1 : 0));
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}
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SPROUT_CONSTEXPR alternate_iterator(iterator_type it1, iterator2_type it2, bool in_left)
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: current1(it1), current2(it2), in_left(in_left)
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{}
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public:
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SPROUT_CONSTEXPR alternate_iterator()
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: current1(), current2(), in_left(true)
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{}
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alternate_iterator(alternate_iterator const&) = default;
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SPROUT_CONSTEXPR alternate_iterator(iterator_type it1, iterator2_type it2)
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: current1(it1), current2(it2), in_left(true)
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{}
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template<typename U, typename V>
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SPROUT_CONSTEXPR alternate_iterator(alternate_iterator<U, V> const& it)
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: current1(it.base()), current2(it.base2()), in_left(it.is_in_left())
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{}
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template<typename U, typename V>
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SPROUT_CXX14_CONSTEXPR alternate_iterator& operator=(alternate_iterator<U, V> const& it) {
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alternate_iterator temp(it);
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temp.swap(*this);
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return *this;
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}
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SPROUT_CONSTEXPR iterator_type base() const {
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return current1;
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}
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SPROUT_CONSTEXPR iterator2_type base2() const {
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return current2;
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}
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SPROUT_CONSTEXPR bool is_in_left() const {
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return in_left;
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}
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SPROUT_CONSTEXPR reference operator*() const {
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return is_in_left() ? *current1 : *current2;
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}
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SPROUT_CONSTEXPR pointer operator->() const {
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return &*(*this);
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}
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SPROUT_CXX14_CONSTEXPR alternate_iterator& operator++() {
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if (is_in_left()) {
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in_left = false;
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} else {
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in_left = true;
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++current1;
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++current2;
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}
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return *this;
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}
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SPROUT_CXX14_CONSTEXPR alternate_iterator operator++(int) {
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alternate_iterator result(*this);
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if (is_in_left()) {
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in_left = false;
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} else {
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in_left = true;
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++current1;
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++current2;
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}
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return result;
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}
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SPROUT_CXX14_CONSTEXPR alternate_iterator& operator--() {
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if (is_in_left()) {
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in_left = false;
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--current1;
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--current2;
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} else {
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in_left = true;
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}
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return *this;
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}
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SPROUT_CXX14_CONSTEXPR alternate_iterator operator--(int) {
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alternate_iterator temp(*this);
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if (is_in_left()) {
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in_left = false;
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--current1;
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--current2;
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} else {
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in_left = true;
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}
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return temp;
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}
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SPROUT_CONSTEXPR alternate_iterator operator+(difference_type n) const {
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return advance_impl(n);
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}
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SPROUT_CONSTEXPR alternate_iterator operator-(difference_type n) const {
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return advance_impl(-n);
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}
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SPROUT_CXX14_CONSTEXPR alternate_iterator& operator+=(difference_type n) {
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alternate_iterator temp(*this + n);
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temp.swap(*this);
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return *this;
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}
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SPROUT_CXX14_CONSTEXPR alternate_iterator& operator-=(difference_type n) {
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alternate_iterator temp(*this - n);
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temp.swap(*this);
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return *this;
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}
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SPROUT_CONSTEXPR reference operator[](difference_type n) const {
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return *(*this + n);
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}
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SPROUT_CONSTEXPR alternate_iterator next() const {
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return is_in_left() ? alternate_iterator(current1, current2, false)
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: alternate_iterator(sprout::next(current1), sprout::next(current2), true)
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;
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}
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SPROUT_CONSTEXPR alternate_iterator prev() const {
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return is_in_left() ? alternate_iterator(sprout::prev(current1), sprout::prev(current2), false)
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: alternate_iterator(current1, current2, true)
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;
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}
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SPROUT_CXX14_CONSTEXPR void swap(alternate_iterator& other)
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SPROUT_NOEXCEPT_IF(
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SPROUT_NOEXCEPT_EXPR(sprout::swap(current1, other.current1))
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&& SPROUT_NOEXCEPT_EXPR(sprout::swap(current2, other.current2))
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&& SPROUT_NOEXCEPT_EXPR(sprout::swap(in_left, other.in_left))
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)
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{
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sprout::swap(current1, other.current1);
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sprout::swap(current2, other.current2);
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sprout::swap(in_left, other.in_left);
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}
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};
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template<
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typename LIterator1, typename RIterator1,
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typename LIterator2, typename RIterator2
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>
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inline SPROUT_CONSTEXPR bool operator==(
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sprout::alternate_iterator<LIterator1, RIterator1> const& lhs,
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sprout::alternate_iterator<LIterator2, RIterator2> const& rhs
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)
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{
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return lhs.base() == rhs.base() && (lhs.is_in_left() == rhs.is_in_left());
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}
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template<
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typename LIterator1, typename RIterator1,
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typename LIterator2, typename RIterator2
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>
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inline SPROUT_CONSTEXPR bool operator!=(
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sprout::alternate_iterator<LIterator1, RIterator1> const& lhs,
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sprout::alternate_iterator<LIterator2, RIterator2> const& rhs
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)
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{
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return !(lhs == rhs);
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}
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template<
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typename LIterator1, typename RIterator1,
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typename LIterator2, typename RIterator2
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>
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inline SPROUT_CONSTEXPR bool operator<(
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sprout::alternate_iterator<LIterator1, RIterator1> const& lhs,
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sprout::alternate_iterator<LIterator2, RIterator2> const& rhs
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)
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{
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return lhs.base() < rhs.base() || (lhs.base() == rhs.base() && lhs.is_in_left() && !rhs.is_in_left());
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}
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template<
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typename LIterator1, typename RIterator1,
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typename LIterator2, typename RIterator2
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>
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inline SPROUT_CONSTEXPR bool operator>(
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sprout::alternate_iterator<LIterator1, RIterator1> const& lhs,
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sprout::alternate_iterator<LIterator2, RIterator2> const& rhs
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)
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{
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return rhs < lhs;
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}
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template<
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typename LIterator1, typename RIterator1,
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typename LIterator2, typename RIterator2
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>
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inline SPROUT_CONSTEXPR bool operator<=(
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sprout::alternate_iterator<LIterator1, RIterator1> const& lhs,
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sprout::alternate_iterator<LIterator2, RIterator2> const& rhs
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)
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{
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return !(rhs < lhs);
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}
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template<
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typename LIterator1, typename RIterator1,
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typename LIterator2, typename RIterator2
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>
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inline SPROUT_CONSTEXPR bool operator>=(
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sprout::alternate_iterator<LIterator1, RIterator1> const& lhs,
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sprout::alternate_iterator<LIterator2, RIterator2> const& rhs
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)
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{
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return !(lhs < rhs);
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}
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template<
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typename LIterator1, typename RIterator1,
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typename LIterator2, typename RIterator2
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>
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inline SPROUT_CONSTEXPR decltype(std::declval<LIterator1>() - std::declval<LIterator2>())
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operator-(
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sprout::alternate_iterator<LIterator1, RIterator1> const& lhs,
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sprout::alternate_iterator<LIterator2, RIterator2> const& rhs
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)
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{
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return sprout::limited::plus(
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sprout::limited::multiplies(lhs.base() - rhs.base(), 2),
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lhs.is_in_left() ? (rhs.is_in_left() ? 0 : 1) : (rhs.is_in_left() ? 1 : 0)
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);
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}
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template<typename LIterator, typename RIterator>
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inline SPROUT_CONSTEXPR sprout::alternate_iterator<LIterator, RIterator> operator+(
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typename sprout::alternate_iterator<LIterator, RIterator>::difference_type n,
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sprout::alternate_iterator<LIterator, RIterator> const& it
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)
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{
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return it + n;
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}
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//
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// make_alternate_iterator
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//
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template<typename LIterator, typename RIterator>
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inline SPROUT_CONSTEXPR sprout::alternate_iterator<LIterator, RIterator>
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make_alternate_iterator(LIterator it1, RIterator it2) {
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return sprout::alternate_iterator<LIterator, RIterator>(it1, it2);
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}
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//
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// swap
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//
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template<typename LIterator, typename RIterator>
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inline SPROUT_CXX14_CONSTEXPR void
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swap(
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sprout::alternate_iterator<LIterator, RIterator>& lhs,
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sprout::alternate_iterator<LIterator, RIterator>& rhs
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)
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SPROUT_NOEXCEPT_IF_EXPR(lhs.swap(rhs))
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{
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lhs.swap(rhs);
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}
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//
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// iterator_next
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//
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template<typename LIterator, typename RIterator>
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inline SPROUT_CONSTEXPR sprout::alternate_iterator<LIterator, RIterator>
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iterator_next(sprout::alternate_iterator<LIterator, RIterator> const& it) {
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return it.next();
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}
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//
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// iterator_prev
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//
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template<typename LIterator, typename RIterator>
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inline SPROUT_CONSTEXPR sprout::alternate_iterator<LIterator, RIterator>
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iterator_prev(sprout::alternate_iterator<LIterator, RIterator> const& it) {
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return it.prev();
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_ITERATOR_ALTERNATE_ITERATOR_HPP
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