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44cc873fba
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/56830 Opt into formatting on GitHub and format everything. This is a trial run before turning on formatting for more and eventually all of the codebase. Test Plan: CI Reviewed By: zertosh Differential Revision: D27979080 fbshipit-source-id: a80f0c48691c08ae8ca0af06377b87e6a2351151
294 lines
8.6 KiB
C++
294 lines
8.6 KiB
C++
#pragma once
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/**
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* A constexpr std::reverse_iterator for C++11.
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* Implementation taken from libstdc++,
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* https://raw.githubusercontent.com/gcc-mirror/gcc/gcc-9_2_0-release/libstdc%2B%2B-v3/include/bits/stl_iterator.h
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* adapted to our code base and constexpr'ified.
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*/
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// Copyright (C) 2001-2019 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library 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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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/*
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*
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* Copyright (c) 1994
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* Hewlett-Packard Company
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Hewlett-Packard Company makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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*
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* Copyright (c) 1996-1998
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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#include <c10/util/C++17.h>
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#include <iterator>
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namespace c10 {
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template <typename _Iterator>
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class reverse_iterator
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: public std::iterator<
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typename std::iterator_traits<_Iterator>::iterator_category,
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typename std::iterator_traits<_Iterator>::value_type,
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typename std::iterator_traits<_Iterator>::difference_type,
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typename std::iterator_traits<_Iterator>::pointer,
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typename std::iterator_traits<_Iterator>::reference> {
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protected:
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_Iterator current;
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using __traits_type = std::iterator_traits<_Iterator>;
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public:
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using iterator_type = _Iterator;
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using difference_type = typename __traits_type::difference_type;
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using pointer = typename __traits_type::pointer;
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using reference = typename __traits_type::reference;
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constexpr reverse_iterator() : current() {}
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explicit constexpr reverse_iterator(iterator_type __x) : current(__x) {}
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constexpr reverse_iterator(const reverse_iterator& __x)
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: current(__x.current) {}
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constexpr reverse_iterator& operator=(const reverse_iterator& rhs) noexcept {
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current = rhs.current;
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return current;
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}
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template <typename _Iter>
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constexpr reverse_iterator(const reverse_iterator<_Iter>& __x)
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: current(__x.base()) {}
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constexpr iterator_type base() const {
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return current;
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}
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constexpr reference operator*() const {
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#if defined(__cpp_constexpr) && __cpp_constexpr >= 201304
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_Iterator iter = current;
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return *--iter;
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#else
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// Only works for random access iterators if we're not C++14 :(
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return *(current - 1);
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#endif
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}
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constexpr pointer operator->() const {
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#if defined(__cpp_constexpr) && __cpp_constexpr >= 201304
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_Iterator iter = current;
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return _S_to_pointer(--iter);
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#else
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// Only works for random access iterators if we're not C++14 :(
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return _S_to_pointer(current - 1);
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#endif
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}
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constexpr reverse_iterator& operator++() {
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--current;
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return *this;
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}
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constexpr reverse_iterator operator++(int) {
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reverse_iterator __tmp = *this;
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--current;
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return __tmp;
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}
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constexpr reverse_iterator& operator--() {
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++current;
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return *this;
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}
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constexpr reverse_iterator operator--(int) {
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reverse_iterator __tmp = *this;
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++current;
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return __tmp;
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}
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constexpr reverse_iterator operator+(difference_type __n) const {
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return reverse_iterator(current - __n);
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}
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constexpr reverse_iterator& operator+=(difference_type __n) {
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current -= __n;
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return *this;
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}
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constexpr reverse_iterator operator-(difference_type __n) const {
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return reverse_iterator(current + __n);
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}
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constexpr reverse_iterator& operator-=(difference_type __n) {
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current += __n;
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return *this;
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}
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constexpr reference operator[](difference_type __n) const {
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return *(*this + __n);
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}
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private:
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template <typename _Tp>
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static constexpr _Tp* _S_to_pointer(_Tp* __p) {
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return __p;
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}
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template <typename _Tp>
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static constexpr pointer _S_to_pointer(_Tp __t) {
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return __t.operator->();
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}
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};
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template <typename _Iterator>
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inline constexpr bool operator==(
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const reverse_iterator<_Iterator>& __x,
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const reverse_iterator<_Iterator>& __y) {
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return __x.base() == __y.base();
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}
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template <typename _Iterator>
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inline constexpr bool operator<(
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const reverse_iterator<_Iterator>& __x,
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const reverse_iterator<_Iterator>& __y) {
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return __y.base() < __x.base();
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}
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template <typename _Iterator>
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inline constexpr bool operator!=(
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const reverse_iterator<_Iterator>& __x,
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const reverse_iterator<_Iterator>& __y) {
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return !(__x == __y);
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}
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template <typename _Iterator>
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inline constexpr bool operator>(
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const reverse_iterator<_Iterator>& __x,
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const reverse_iterator<_Iterator>& __y) {
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return __y < __x;
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}
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template <typename _Iterator>
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inline constexpr bool operator<=(
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const reverse_iterator<_Iterator>& __x,
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const reverse_iterator<_Iterator>& __y) {
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return !(__y < __x);
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}
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template <typename _Iterator>
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inline constexpr bool operator>=(
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const reverse_iterator<_Iterator>& __x,
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const reverse_iterator<_Iterator>& __y) {
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return !(__x < __y);
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}
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template <typename _IteratorL, typename _IteratorR>
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inline constexpr bool operator==(
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const reverse_iterator<_IteratorL>& __x,
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const reverse_iterator<_IteratorR>& __y) {
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return __x.base() == __y.base();
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}
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template <typename _IteratorL, typename _IteratorR>
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inline constexpr bool operator<(
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const reverse_iterator<_IteratorL>& __x,
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const reverse_iterator<_IteratorR>& __y) {
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return __y.base() < __x.base();
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}
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template <typename _IteratorL, typename _IteratorR>
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inline constexpr bool operator!=(
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const reverse_iterator<_IteratorL>& __x,
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const reverse_iterator<_IteratorR>& __y) {
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return !(__x == __y);
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}
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template <typename _IteratorL, typename _IteratorR>
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inline constexpr bool operator>(
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const reverse_iterator<_IteratorL>& __x,
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const reverse_iterator<_IteratorR>& __y) {
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return __y < __x;
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}
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template <typename _IteratorL, typename _IteratorR>
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inline constexpr bool operator<=(
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const reverse_iterator<_IteratorL>& __x,
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const reverse_iterator<_IteratorR>& __y) {
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return !(__y < __x);
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}
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template <typename _IteratorL, typename _IteratorR>
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inline constexpr bool operator>=(
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const reverse_iterator<_IteratorL>& __x,
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const reverse_iterator<_IteratorR>& __y) {
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return !(__x < __y);
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}
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template <typename _IteratorL, typename _IteratorR>
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inline constexpr decltype(auto) operator-(
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const reverse_iterator<_IteratorL>& __x,
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const reverse_iterator<_IteratorR>& __y) {
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return __y.base() - __x.base();
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}
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template <typename _Iterator>
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inline constexpr reverse_iterator<_Iterator> operator+(
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typename reverse_iterator<_Iterator>::difference_type __n,
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const reverse_iterator<_Iterator>& __x) {
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return reverse_iterator<_Iterator>(__x.base() - __n);
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}
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template <typename _Iterator>
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inline constexpr reverse_iterator<_Iterator> __make_reverse_iterator(
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_Iterator __i) {
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return reverse_iterator<_Iterator>(__i);
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}
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template <typename _Iterator>
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inline constexpr reverse_iterator<_Iterator> make_reverse_iterator(
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_Iterator __i) {
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return reverse_iterator<_Iterator>(__i);
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}
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template <typename _Iterator>
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decltype(auto) __niter_base(reverse_iterator<_Iterator> __it) {
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return __make_reverse_iterator(__niter_base(__it.base()));
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}
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} // namespace c10
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