500 lines
19 KiB
C++
500 lines
19 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_H
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#define BLT_ITERATOR_H
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#include <blt/std/types.h>
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#include <blt/std/logging.h>
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#include <blt/meta/meta.h>
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#include <blt/meta/iterator.h>
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#include <type_traits>
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#include <iterator>
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namespace blt
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{
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// forward declare useful types
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template<typename Iter, typename = std::void_t<>>
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class enumerator;
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template<typename Iter, typename = std::void_t<>>
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class enumerator_rev;
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namespace iterator
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{
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template<typename Iter, typename = std::void_t<>>
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class enumerate_wrapper;
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/**
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* struct which is returned by the enumerator.
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* @tparam T type to store.
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*/
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template<typename T>
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struct enumerate_item
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{
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blt::size_t index;
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T value;
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};
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/**
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* base class for iterators which operate on pairs of values. Handles comparison.
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* @tparam Iter1 first iterator type. this will be used for comparison.
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* @tparam Iter2 second iterator type. this value is not modified by this class.
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*/
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template<typename Iter1, typename Iter2>
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class pair_iterator_base
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{
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public:
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explicit pair_iterator_base(Iter1 iter1, Iter2 iter2): m_iter1(std::move(iter1)), m_iter2(std::move(iter2))
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{}
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friend bool operator==(const pair_iterator_base& a, const pair_iterator_base& b)
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{
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return a.m_iter1 == b.m_iter1;
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}
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friend bool operator!=(const pair_iterator_base& a, const pair_iterator_base& b)
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{
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return a.m_iter1 != b.m_iter1;
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}
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auto iter1() const
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{
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return m_iter1;
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}
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auto iter2() const
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{
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return m_iter2;
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}
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protected:
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Iter1 m_iter1;
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Iter2 m_iter2;
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};
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/**
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* Base class for all enumerator iterators. Handles the deference (*) operator.
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* @tparam Iter iterator type
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*/
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template<typename Iter>
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class enumerate_iterator_base : public pair_iterator_base<Iter, blt::size_t>
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{
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public:
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explicit enumerate_iterator_base(Iter iter, blt::size_t place = 0):
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pair_iterator_base<Iter, blt::size_t>(std::move(iter), place)
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{}
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enumerate_item<blt::meta::deref_return_t<Iter>> operator*() const
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{
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return {this->m_iter2, *this->m_iter1};
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}
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auto base() const
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{
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return this->iter1();
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}
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auto get_index() const
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{
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return this->iter2();
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}
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};
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/**
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* Forward iterator base class for the enumerator. Contains the ++ operator.
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* @tparam Iter iterator type.
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*/
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template<typename Iter>
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class enumerate_forward_iterator : public enumerate_iterator_base<Iter>
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{
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public:
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using enumerate_iterator_base<Iter>::enumerate_iterator_base;
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enumerate_forward_iterator& operator++()
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{
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++this->m_iter1;
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++this->m_iter2;
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return *this;
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}
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enumerate_forward_iterator operator++(int)
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{
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auto tmp = *this;
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++*this;
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return tmp;
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}
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};
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/**
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* Bidirectional iterator base class for the enumerator. Contains the -- operator.
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* @tparam Iter iterator type.
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*/
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template<typename Iter>
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class enumerate_bidirectional_iterator : public enumerate_forward_iterator<Iter>
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{
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public:
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using enumerate_forward_iterator<Iter>::enumerate_forward_iterator;
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enumerate_bidirectional_iterator& operator--()
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{
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--this->m_iter1;
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--this->m_iter2;
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return *this;
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}
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enumerate_bidirectional_iterator operator--(int)
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{
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auto tmp = *this;
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--*this;
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return tmp;
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}
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};
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/**
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* Wrapper class specialization for forward iterators.
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* @tparam Iter iterator type
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*/
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template<typename Iter>
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class enumerate_wrapper<Iter, std::enable_if_t<blt::meta::is_forward_iterator_v<Iter>, std::void_t<std::forward_iterator_tag>>>
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: public enumerate_forward_iterator<Iter>
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{
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public:
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using iterator_category = std::forward_iterator_tag;
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using value_type = enumerate_item<blt::meta::deref_return_t<Iter>>;
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using difference_type = typename std::iterator_traits<Iter>::difference_type;
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using pointer = value_type;
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using reference = value_type;
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using iterator_type = Iter;
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using enumerate_forward_iterator<Iter>::enumerate_forward_iterator;
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};
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/**
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* Wrapper class for bidirectional iterators or random access iterators.
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* @tparam Iter iterator type.
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*/
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template<typename Iter>
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class enumerate_wrapper<Iter, std::enable_if_t<blt::meta::is_bidirectional_or_better_v<Iter>, std::void_t<std::bidirectional_iterator_tag>>>
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: public enumerate_bidirectional_iterator<Iter>
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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 = enumerate_item<blt::meta::deref_return_t<Iter>>;
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using difference_type = typename std::iterator_traits<Iter>::difference_type;
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using pointer = value_type;
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using reference = value_type;
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using iterator_type = Iter;
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using enumerate_bidirectional_iterator<Iter>::enumerate_bidirectional_iterator;
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};
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/**
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* Base class for the enumerator. Holds the begin and end iterators.
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* @tparam Iter iterator type.
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* @tparam IterWrapper wrapper used to iterate (enumerate_wrapper)
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*/
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template<typename Iter, typename IterWrapper>
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class enumerator_base
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{
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public:
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explicit enumerator_base(Iter begin, Iter end): begin_(std::move(begin)), end_(std::move(end))
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{}
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explicit enumerator_base(IterWrapper begin, IterWrapper end): begin_(std::move(begin)), end_(std::move(end))
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{}
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auto begin()
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{
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return begin_;
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}
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auto end()
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{
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return end_;
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}
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/**
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* Creates an enumerator that skips the first n elements.
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* @param amount amount of values to skip.
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*/
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auto skip(blt::size_t amount)
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{
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auto begin = this->begin_;
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for (blt::size_t i = 0; i < amount; i++)
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++begin;
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return enumerator<Iter>{begin.base(),
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this->end_.base(),
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begin.get_index(),
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this->end_.get_index()};
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}
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/**
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* Creates an enumerator that yields the first n elements, or UB if the underlying iterator ends sooner.
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* @param amount amount to take.
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*/
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auto take(blt::size_t amount)
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{
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auto end = this->begin();
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for (blt::size_t i = 0; i < amount; i++)
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++end;
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return enumerator<Iter>{this->begin_.base(),
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end.base(),
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this->begin_.get_index(),
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end.get_index()};
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}
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protected:
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IterWrapper begin_;
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IterWrapper end_;
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};
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/**
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* Reversible (bidirectional) base class for the enumerator.
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* @tparam Iter iterator type.
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* @tparam IterWrapper wrapper used to iterate (enumerate_wrapper).
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*/
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template<typename Iter, typename IterWrapper>
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class enumerator_reversible : public enumerator_base<Iter, IterWrapper>
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{
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public:
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explicit enumerator_reversible(Iter begin, Iter end, blt::size_t container_size):
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enumerator_base<Iter, IterWrapper>{IterWrapper{enumerate_wrapper<Iter>{std::move(begin), 0}},
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IterWrapper{enumerate_wrapper<Iter>{std::move(end), container_size}}}
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{}
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explicit enumerator_reversible(Iter begin, Iter end, blt::size_t begin_index, blt::size_t end_index):
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enumerator_base<Iter, IterWrapper>(IterWrapper{enumerate_wrapper<Iter>{std::move(begin), begin_index}},
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IterWrapper{enumerate_wrapper<Iter>{std::move(end), end_index}})
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{}
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/**
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* Reverses the enumerator’s direction.
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*/
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auto rev() const
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{
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return enumerator_rev<Iter>{this->end_.base(),
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this->begin_.base(),
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this->end_.get_index(),
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this->begin_.get_index()};
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}
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};
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/**
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* Random access base class for the enumerator. Has updated skip and take methods which make use of the random access nature of the iterator.
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* @tparam Iter iterator type.
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* @tparam IterWrapper wrapper used to iterate (enumerate_wrapper).
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*/
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template<typename Iter, typename IterWrapper>
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class enumerator_random_access : public enumerator_reversible<Iter, IterWrapper>
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{
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public:
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using enumerator_reversible<Iter, IterWrapper>::enumerator_reversible;
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auto skip(blt::size_t amount)
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{
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return enumerator<Iter>{this->begin_.base() + amount,
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this->end_.base(),
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this->begin_.get_index() + amount,
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this->end_.get_index()};
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}
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auto take(blt::size_t amount)
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{
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return enumerator<Iter>{this->begin_.base(),
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this->begin_.base() + amount,
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this->begin_.get_index(),
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this->begin_.get_index() + amount};
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}
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};
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/**
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* Reversible (bidirectional) base class for the enumerator, operates in reverse for reverse enumeration.
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* @tparam Iter iterator type.
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* @tparam IterWrapper wrapper used to iterate (std::reverse_iterator<enumerate_wrapper>).
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*/
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template<typename Iter, typename IterWrapper>
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class enumerator_reversible_rev : public enumerator_reversible<Iter, IterWrapper>
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{
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public:
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using enumerator_reversible<Iter, IterWrapper>::enumerator_reversible;
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auto rev() const
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{
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return enumerator<Iter>{this->end_.base().base(),
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this->begin_.base().base(),
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this->end_.base().get_index(),
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this->begin_.base().get_index()};
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}
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auto skip(blt::size_t amount)
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{
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auto begin = this->begin_.base();
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for (blt::size_t i = 0; i < amount; i++)
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--begin;
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return enumerator_rev<Iter>{begin.base(),
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this->end_.base().base(),
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begin.get_index(),
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this->end_.base().get_index()};
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}
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auto take(blt::size_t amount)
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{
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auto end = this->begin_.base();
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for (blt::size_t i = 0; i < amount; i++)
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--end;
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return enumerator_rev<Iter>{
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this->begin_.base().base(),
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end.base(),
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this->begin_.base().get_index(),
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end.get_index()};
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}
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};
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/**
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* Random access base class for the enumerator. Has updated skip and take methods which make use of the random access nature of the iterator.
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* Operates in reverse for reverse enumeration.
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* @tparam Iter iterator type.
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* @tparam IterWrapper wrapper used to iterate (std::reverse_iterator<enumerate_wrapper>).
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*/
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template<typename Iter, typename IterWrapper>
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class enumerator_random_access_rev : public enumerator_reversible_rev<Iter, IterWrapper>
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{
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public:
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using enumerator_reversible_rev<Iter, IterWrapper>::enumerator_reversible_rev;
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auto skip(blt::size_t amount)
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{
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return enumerator_rev<Iter>{this->begin_.base().base() - amount,
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this->end_.base().base(),
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this->begin_.base().get_index() - amount,
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this->end_.base().get_index()};
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}
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auto take(blt::size_t amount)
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{
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return enumerator_rev<Iter>{this->begin_.base().base(),
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this->begin_.base().base() - amount,
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this->begin_.base().get_index(),
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this->begin_.base().get_index() - amount};
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}
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};
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}
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/**
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* Enumerator specialization for forward iterators
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*/
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template<typename Iter>
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class enumerator<Iter, std::enable_if_t<blt::meta::is_forward_iterator_v<Iter>, std::void_t<std::forward_iterator_tag>>>
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: public iterator::enumerator_base<Iter, iterator::enumerate_wrapper<Iter>>
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{
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public:
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using iterator::enumerator_base<Iter, iterator::enumerate_wrapper<Iter>>::enumerator_base;
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};
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/**
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* Enumerator specialization for bidirectional iterators
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*/
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template<typename Iter>
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class enumerator<Iter, std::enable_if_t<blt::meta::is_bidirectional_iterator_v<Iter>, std::void_t<std::bidirectional_iterator_tag>>>
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: public iterator::enumerator_reversible<Iter, iterator::enumerate_wrapper<Iter>>
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{
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public:
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using iterator::enumerator_reversible<Iter, iterator::enumerate_wrapper<Iter>>::enumerator_reversible;
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};
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/**
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* Enumerator specialization for random access iterators
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*/
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template<typename Iter>
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class enumerator<Iter, std::enable_if_t<blt::meta::is_random_access_iterator_v<Iter>, std::void_t<std::random_access_iterator_tag>>>
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: public iterator::enumerator_random_access<Iter, iterator::enumerate_wrapper<Iter>>
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{
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public:
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using iterator::enumerator_random_access<Iter, iterator::enumerate_wrapper<Iter>>::enumerator_random_access;
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};
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/**
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* Reverse enumerator specialization for bidirectional iterators
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*/
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template<typename Iter>
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class enumerator_rev<Iter, std::enable_if_t<blt::meta::is_bidirectional_iterator_v<Iter>, std::void_t<std::bidirectional_iterator_tag>>>
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: public iterator::enumerator_reversible_rev<Iter, std::reverse_iterator<iterator::enumerate_wrapper<Iter>>>
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{
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public:
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using iterator::enumerator_reversible_rev<Iter, std::reverse_iterator<iterator::enumerate_wrapper<Iter>>>::enumerator_reversible_rev;
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};
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/**
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* Reverse enumerator specialization for random access iterators
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*/
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template<typename Iter>
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class enumerator_rev<Iter, std::enable_if_t<blt::meta::is_random_access_iterator_v<Iter>, std::void_t<std::random_access_iterator_tag>>>
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: public iterator::enumerator_random_access_rev<Iter, std::reverse_iterator<iterator::enumerate_wrapper<Iter>>>
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{
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public:
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using iterator::enumerator_random_access_rev<Iter, std::reverse_iterator<iterator::enumerate_wrapper<Iter>>>::enumerator_random_access_rev;
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};
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// CTAD for enumerators
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template<typename Iter>
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enumerator(Iter, Iter) -> enumerator<Iter>;
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template<typename Iter>
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enumerator(Iter, Iter, blt::size_t) -> enumerator<Iter>;
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template<typename Iter>
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enumerator(Iter, Iter, blt::size_t, blt::size_t) -> enumerator<Iter>;
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template<typename T, blt::size_t size>
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static inline auto enumerate(const T(& container)[size])
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{
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return enumerator{&container[0], &container[size], size};
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}
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template<typename T, blt::size_t size>
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static inline auto enumerate(T(& container)[size])
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{
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return enumerator{&container[0], &container[size], size};
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}
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template<typename T>
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static inline auto enumerate(T& container)
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{
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return enumerator{container.begin(), container.end(), container.size()};
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}
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template<typename T>
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static inline auto enumerate(T&& container)
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{
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return enumerator{container.begin(), container.end(), container.size()};
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}
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template<typename T>
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static inline auto enumerate(const T& container)
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{
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return enumerator{container.begin(), container.end(), container.size()};
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}
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}
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#endif //BLT_ITERATOR_H
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