337 lines
12 KiB
C++
337 lines
12 KiB
C++
#pragma once
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/*
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* Copyright (C) 2024 Brett Terpstra
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef BLT_ITERATOR_ZIP
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#define BLT_ITERATOR_ZIP
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#include <blt/iterator/common.h>
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#include <blt/meta/meta.h>
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#include <blt/meta/iterator.h>
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#include <tuple>
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namespace blt
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{
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namespace iterator
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{
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template<typename... Iter>
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class zip_wrapper : public wrapper_base<zip_wrapper<Iter...>>
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{
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public:
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using iterator_category = meta::lowest_iterator_category_t<Iter...>;
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using value_type = std::tuple<meta::deref_return_t<Iter>...>;
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using difference_type = blt::ptrdiff_t;
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using pointer = value_type;
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using reference = value_type;
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explicit zip_wrapper(Iter... iter): iter(std::make_tuple(iter...))
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{}
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std::tuple<meta::deref_return_t<Iter>...> operator*() const
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{
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return std::apply([](auto& ... i) { return std::tuple<meta::deref_return_t<Iter>...>{*i...}; }, iter);
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}
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zip_wrapper& operator++()
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{
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std::apply([](auto& ... i) { ((++i), ...); }, iter);
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return *this;
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}
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zip_wrapper& operator--()
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{
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std::apply([](auto& ... i) { ((--i), ...); }, this->iter);
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return *this;
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}
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zip_wrapper& operator+=(blt::ptrdiff_t n)
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{
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std::apply([n](auto& ... i) { ((i += n), ...); }, this->iter);
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return *this;
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}
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zip_wrapper& operator-=(blt::ptrdiff_t n)
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{
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std::apply([n](auto& ... i) { ((i -= n), ...); }, this->iter);
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return *this;
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}
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friend blt::ptrdiff_t operator-(const zip_wrapper& a, const zip_wrapper& b)
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{
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return sub(a, b, std::index_sequence_for<Iter...>());
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}
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auto base()
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{
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return iter;
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}
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protected:
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std::tuple<Iter...> iter;
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template<typename T, T... n>
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static blt::ptrdiff_t sub(const zip_wrapper& a, const zip_wrapper& b,
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std::integer_sequence<T, n...>)
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{
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blt::ptrdiff_t min = std::numeric_limits<blt::ptrdiff_t>::max();
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((min = std::min(min, std::get<n>(a.iter) - std::get<n>(b.iter))), ...);
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return min;
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}
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};
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BLT_META_MAKE_FUNCTION_CHECK(base);
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template<typename Iter>
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auto get_base(Iter iter)
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{
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if constexpr (has_func_base_v<Iter>)
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{
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return std::move(iter).base();
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} else
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{
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return std::move(iter);
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}
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}
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template<typename Derived>
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class take_impl
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{
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private:
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template<bool check>
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auto take_base(blt::size_t n)
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{
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static_assert(!std::is_same_v<typename Derived::iterator_category, std::input_iterator_tag>,
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"Cannot .take() on an input iterator!");
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auto* d = static_cast<Derived*>(this);
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auto begin = d->begin();
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auto end = d->end();
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// take variant for forward and bidirectional iterators
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if constexpr (std::is_same_v<typename Derived::iterator_category, std::forward_iterator_tag> ||
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std::is_same_v<typename Derived::iterator_category, std::bidirectional_iterator_tag>)
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{
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// with these guys we have to loop forward to move the iterators. an unfortunate inefficiency
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auto new_end = begin;
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for (blt::size_t i = 0; i < n; i++)
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{
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if constexpr (check)
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{
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if (new_end == end)
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break;
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}
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++new_end;
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}
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return Derived{get_base(std::move(begin)), get_base(std::move(new_end))};
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} else if constexpr (std::is_same_v<typename Derived::iterator_category, std::random_access_iterator_tag>)
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{
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// random access iterators can have math directly applied to them.
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if constexpr (check)
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{
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return Derived{get_base(begin),
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get_base(begin + std::min(static_cast<blt::ptrdiff_t>(n), std::distance(begin, end)))};
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} else
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{
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return Derived{get_base(begin), get_base(begin + n)};
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}
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}
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}
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public:
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auto take(blt::size_t n)
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{ return take_base<false>(n); }
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auto take_or(blt::size_t n)
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{ return take_base<true>(n); }
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};
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template<typename Derived>
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class skip_impl
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{
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private:
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template<bool check>
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auto skip_base(blt::size_t n)
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{
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auto* d = static_cast<Derived*>(this);
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auto begin = d->begin();
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auto end = d->end();
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if constexpr (std::is_same_v<typename Derived::iterator_category, std::random_access_iterator_tag>)
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{
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if constexpr (check)
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{
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return Derived{begin + std::min(static_cast<blt::ptrdiff_t>(n), std::distance(begin, end))};
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} else
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{
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return Derived{begin + n, end};
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}
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} else
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{
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for (blt::size_t i = 0; i < n; i++)
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{
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if constexpr (check)
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{
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if (begin == end)
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break;
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}
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++begin;
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}
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return Derived{begin, end};
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}
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}
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public:
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void skip(blt::size_t n)
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{ return skip_base<false>(n); }
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void skip_or(blt::size_t n)
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{ return skip_base<true>(n); }
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};
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}
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template<typename Iter>
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struct iterator_pair
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{
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using type = Iter;
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iterator_pair(Iter begin, Iter end): begin(std::move(begin)), end(std::move(end))
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{}
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Iter begin;
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Iter end;
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};
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template<typename... Iter>
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class zip_iterator_storage;
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template<typename... Iter>
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class zip_iterator_storage_rev;
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template<typename... Iter>
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class zip_iterator_storage : public iterator::take_impl<zip_iterator_storage<Iter...>>
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{
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public:
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using iterator_category = meta::lowest_iterator_category_t<Iter...>;
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public:
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zip_iterator_storage(iterator_pair<Iter>... iterator_pairs):
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m_begins(std::move(iterator_pairs.begin)...), m_ends(std::move(iterator_pairs.end)...)
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{}
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zip_iterator_storage(iterator::zip_wrapper<Iter...> begins, iterator::zip_wrapper<Iter...> ends):
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m_begins(std::move(begins)), m_ends(std::move(ends))
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{}
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auto rev()
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{
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static_assert((std::is_same_v<iterator_category, std::bidirectional_iterator_tag> ||
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std::is_same_v<iterator_category, std::random_access_iterator_tag>),
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".rev() must be used with bidirectional (or better) iterators!");
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return zip_iterator_storage_rev{m_ends, m_begins};
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}
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auto skip(blt::size_t n)
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{
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if constexpr (std::is_same_v<iterator_category, std::input_iterator_tag>)
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{
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}
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}
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auto begin() const
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{
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return m_begins;
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}
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auto end() const
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{
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return m_ends;
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}
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private:
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iterator::zip_wrapper<Iter...> m_begins;
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iterator::zip_wrapper<Iter...> m_ends;
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};
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template<typename... Iter>
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class zip_iterator_storage_rev : public iterator::take_impl<zip_iterator_storage_rev<Iter...>>
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{
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public:
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using iterator_category = meta::lowest_iterator_category_t<Iter...>;
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public:
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zip_iterator_storage_rev(iterator_pair<Iter>... iterator_pairs): m_begins(iterator_pairs.begin...), m_ends(iterator_pairs.end...)
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{
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static_assert((std::is_same_v<iterator_category, std::bidirectional_iterator_tag> ||
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std::is_same_v<iterator_category, std::random_access_iterator_tag>),
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"reverse iteration is only supported on bidirectional or better iterators!");
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}
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zip_iterator_storage_rev(iterator::zip_wrapper<Iter...> begins,
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iterator::zip_wrapper<Iter...> ends): m_begins(std::move(begins)), m_ends(std::move(ends))
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{
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static_assert((std::is_same_v<iterator_category, std::bidirectional_iterator_tag> ||
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std::is_same_v<iterator_category, std::random_access_iterator_tag>),
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"reverse iteration is only supported on bidirectional or better iterators!");
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}
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auto rev()
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{
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return zip_iterator_storage{m_ends.base(), m_begins.base()};
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}
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auto begin() const
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{
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return m_begins;
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}
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auto end() const
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{
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return m_ends;
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}
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private:
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std::reverse_iterator<iterator::zip_wrapper<Iter...>> m_begins;
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std::reverse_iterator<iterator::zip_wrapper<Iter...>> m_ends;
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};
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/*
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* CTAD for the zip containers
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*/
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template<typename... Iter>
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zip_iterator_storage(iterator_pair<Iter>...) -> zip_iterator_storage<Iter...>;
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template<typename... Iter>
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zip_iterator_storage(std::initializer_list<Iter>...) -> zip_iterator_storage<Iter...>;
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template<typename... Iter>
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zip_iterator_storage_rev(iterator_pair<Iter>...) -> zip_iterator_storage_rev<Iter...>;
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template<typename... Iter>
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zip_iterator_storage_rev(std::initializer_list<Iter>...) -> zip_iterator_storage_rev<Iter...>;
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/*
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* Helper functions for creating zip containers
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*/
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template<typename... Container>
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auto zip(Container& ... container)
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{
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return blt::zip_iterator_storage{iterator_pair{container.begin(), container.end()}...};
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}
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}
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#endif //BLT_ITERATOR_ZIP
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