90 lines
2.9 KiB
C++
90 lines
2.9 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_FLATTEN_H
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#define BLT_ITERATOR_FLATTEN_H
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#include <blt/iterator/common.h>
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#include <blt/meta/type_traits.h>
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#include <tuple>
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namespace blt::iterator
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{
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namespace detail
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{
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template <typename Tuple>
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static auto flatten_recursive(Tuple&& tuple) -> decltype(auto)
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{
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using Decay = std::decay_t<Tuple>;
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if constexpr (meta::is_tuple_v<Decay> || meta::is_pair_v<Decay>)
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{
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return std::apply([](auto&&... args)
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{
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return std::tuple_cat(flatten_recursive(std::forward<decltype(args)>(args))...);
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}, std::forward<Tuple>(tuple));
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}
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else
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{
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return forward_as_tuple(std::forward<Tuple>(tuple));
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}
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}
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template <typename Tuple>
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static auto flatten(Tuple&& tuple) -> decltype(auto)
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{
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return std::apply([](auto&&... args)
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{
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return std::tuple_cat(ensure_tuple(std::forward<decltype(args)>(args))...);
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}, std::forward<Tuple>(tuple));
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}
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}
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template <typename Iter, bool Recursive>
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class flatten_wrapper : public deref_only_wrapper<Iter, flatten_wrapper<Iter, Recursive>>
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{
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public:
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using iterator_category = typename std::iterator_traits<Iter>::iterator_category;
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using value_type = std::conditional_t<Recursive,
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std::remove_reference_t<decltype(detail::flatten_recursive(*std::declval<Iter>()))>,
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std::remove_reference_t<decltype(detail::flatten(*std::declval<Iter>()))>>;
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using difference_type = ptrdiff_t;
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using pointer = value_type*;
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using reference = value_type&;
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explicit flatten_wrapper(Iter iter):
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deref_only_wrapper<Iter, flatten_wrapper>(std::move(iter))
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{
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}
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auto operator*() const -> decltype(auto)
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{
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if constexpr (Recursive)
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{
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return detail::flatten_recursive(*this->iter);
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}
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else
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{
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return detail::flatten(*this->iter);
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}
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}
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};
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}
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#endif //BLT_ITERATOR_FLATTEN_H
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