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llvm-project/libcxx/include/__iterator/reverse_iterator.h

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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___ITERATOR_REVERSE_ITERATOR_H
#define _LIBCPP___ITERATOR_REVERSE_ITERATOR_H
#include <__algorithm/unwrap_iter.h>
#include <__compare/compare_three_way_result.h>
#include <__compare/three_way_comparable.h>
#include <__concepts/convertible_to.h>
#include <__config>
#include <__iterator/concepts.h>
#include <__iterator/incrementable_traits.h>
#include <__iterator/iter_move.h>
#include <__iterator/iter_swap.h>
#include <__iterator/iterator.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/prev.h>
#include <__iterator/readable_traits.h>
#include <__memory/addressof.h>
#include <__utility/move.h>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
_LIBCPP_SUPPRESS_DEPRECATED_PUSH
template <class _Iter>
class _LIBCPP_TEMPLATE_VIS reverse_iterator
#if _LIBCPP_STD_VER <= 14 || !defined(_LIBCPP_ABI_NO_ITERATOR_BASES)
: public iterator<typename iterator_traits<_Iter>::iterator_category,
typename iterator_traits<_Iter>::value_type,
typename iterator_traits<_Iter>::difference_type,
typename iterator_traits<_Iter>::pointer,
typename iterator_traits<_Iter>::reference>
#endif
{
_LIBCPP_SUPPRESS_DEPRECATED_POP
private:
#ifndef _LIBCPP_ABI_NO_ITERATOR_BASES
_Iter __t; // no longer used as of LWG #2360, not removed due to ABI break
#endif
#if _LIBCPP_STD_VER > 17
static_assert(__is_cpp17_bidirectional_iterator<_Iter>::value || bidirectional_iterator<_Iter>,
"reverse_iterator<It> requires It to be a bidirectional iterator.");
#endif // _LIBCPP_STD_VER > 17
protected:
_Iter current;
public:
using iterator_type = _Iter;
using iterator_category = _If<__is_cpp17_random_access_iterator<_Iter>::value,
random_access_iterator_tag,
typename iterator_traits<_Iter>::iterator_category>;
using pointer = typename iterator_traits<_Iter>::pointer;
#if _LIBCPP_STD_VER > 17
using iterator_concept = _If<__is_cpp17_random_access_iterator<_Iter>::value,
random_access_iterator_tag,
bidirectional_iterator_tag>;
using value_type = iter_value_t<_Iter>;
using difference_type = iter_difference_t<_Iter>;
using reference = iter_reference_t<_Iter>;
#else
using value_type = typename iterator_traits<_Iter>::value_type;
using difference_type = typename iterator_traits<_Iter>::difference_type;
using reference = typename iterator_traits<_Iter>::reference;
#endif
#ifndef _LIBCPP_ABI_NO_ITERATOR_BASES
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator() : __t(), current() {}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
explicit reverse_iterator(_Iter __x) : __t(__x), current(__x) {}
template <class _Up, class = __enable_if_t<
!is_same<_Up, _Iter>::value && is_convertible<_Up const&, _Iter>::value
> >
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator(const reverse_iterator<_Up>& __u)
: __t(__u.base()), current(__u.base())
{ }
template <class _Up, class = __enable_if_t<
!is_same<_Up, _Iter>::value &&
is_convertible<_Up const&, _Iter>::value &&
is_assignable<_Iter&, _Up const&>::value
> >
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator& operator=(const reverse_iterator<_Up>& __u) {
__t = current = __u.base();
return *this;
}
#else
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator() : current() {}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
explicit reverse_iterator(_Iter __x) : current(__x) {}
template <class _Up, class = __enable_if_t<
!is_same<_Up, _Iter>::value && is_convertible<_Up const&, _Iter>::value
> >
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator(const reverse_iterator<_Up>& __u)
: current(__u.base())
{ }
template <class _Up, class = __enable_if_t<
!is_same<_Up, _Iter>::value &&
is_convertible<_Up const&, _Iter>::value &&
is_assignable<_Iter&, _Up const&>::value
> >
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator& operator=(const reverse_iterator<_Up>& __u) {
current = __u.base();
return *this;
}
#endif
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
_Iter base() const {return current;}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reference operator*() const {_Iter __tmp = current; return *--__tmp;}
#if _LIBCPP_STD_VER > 17
_LIBCPP_INLINE_VISIBILITY
constexpr pointer operator->() const
requires is_pointer_v<_Iter> || requires(const _Iter i) { i.operator->(); }
{
if constexpr (is_pointer_v<_Iter>) {
return std::prev(current);
} else {
return std::prev(current).operator->();
}
}
#else
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
pointer operator->() const {
return std::addressof(operator*());
}
#endif // _LIBCPP_STD_VER > 17
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator& operator++() {--current; return *this;}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator operator++(int) {reverse_iterator __tmp(*this); --current; return __tmp;}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator& operator--() {++current; return *this;}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator operator--(int) {reverse_iterator __tmp(*this); ++current; return __tmp;}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator operator+(difference_type __n) const {return reverse_iterator(current - __n);}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator& operator+=(difference_type __n) {current -= __n; return *this;}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator operator-(difference_type __n) const {return reverse_iterator(current + __n);}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator& operator-=(difference_type __n) {current += __n; return *this;}
_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reference operator[](difference_type __n) const {return *(*this + __n);}
#if _LIBCPP_STD_VER > 17
_LIBCPP_HIDE_FROM_ABI friend constexpr
iter_rvalue_reference_t<_Iter> iter_move(const reverse_iterator& __i)
noexcept(is_nothrow_copy_constructible_v<_Iter> &&
noexcept(ranges::iter_move(--declval<_Iter&>()))) {
auto __tmp = __i.base();
return ranges::iter_move(--__tmp);
}
template <indirectly_swappable<_Iter> _Iter2>
_LIBCPP_HIDE_FROM_ABI friend constexpr
void iter_swap(const reverse_iterator& __x, const reverse_iterator<_Iter2>& __y)
noexcept(is_nothrow_copy_constructible_v<_Iter> &&
is_nothrow_copy_constructible_v<_Iter2> &&
noexcept(ranges::iter_swap(--declval<_Iter&>(), --declval<_Iter2&>()))) {
auto __xtmp = __x.base();
auto __ytmp = __y.base();
ranges::iter_swap(--__xtmp, --__ytmp);
}
#endif // _LIBCPP_STD_VER > 17
};
template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
bool
operator==(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
#if _LIBCPP_STD_VER > 17
requires requires {
{ __x.base() == __y.base() } -> convertible_to<bool>;
}
#endif // _LIBCPP_STD_VER > 17
{
return __x.base() == __y.base();
}
template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
bool
operator<(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
#if _LIBCPP_STD_VER > 17
requires requires {
{ __x.base() > __y.base() } -> convertible_to<bool>;
}
#endif // _LIBCPP_STD_VER > 17
{
return __x.base() > __y.base();
}
template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
bool
operator!=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
#if _LIBCPP_STD_VER > 17
requires requires {
{ __x.base() != __y.base() } -> convertible_to<bool>;
}
#endif // _LIBCPP_STD_VER > 17
{
return __x.base() != __y.base();
}
template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
bool
operator>(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
#if _LIBCPP_STD_VER > 17
requires requires {
{ __x.base() < __y.base() } -> convertible_to<bool>;
}
#endif // _LIBCPP_STD_VER > 17
{
return __x.base() < __y.base();
}
template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
bool
operator>=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
#if _LIBCPP_STD_VER > 17
requires requires {
{ __x.base() <= __y.base() } -> convertible_to<bool>;
}
#endif // _LIBCPP_STD_VER > 17
{
return __x.base() <= __y.base();
}
template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
bool
operator<=(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
#if _LIBCPP_STD_VER > 17
requires requires {
{ __x.base() >= __y.base() } -> convertible_to<bool>;
}
#endif // _LIBCPP_STD_VER > 17
{
return __x.base() >= __y.base();
}
#if _LIBCPP_STD_VER > 17
template <class _Iter1, three_way_comparable_with<_Iter1> _Iter2>
_LIBCPP_HIDE_FROM_ABI constexpr
compare_three_way_result_t<_Iter1, _Iter2>
operator<=>(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
return __y.base() <=> __x.base();
}
#endif // _LIBCPP_STD_VER > 17
#ifndef _LIBCPP_CXX03_LANG
template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
auto
operator-(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
-> decltype(__y.base() - __x.base())
{
return __y.base() - __x.base();
}
#else
template <class _Iter1, class _Iter2>
inline _LIBCPP_INLINE_VISIBILITY
typename reverse_iterator<_Iter1>::difference_type
operator-(const reverse_iterator<_Iter1>& __x, const reverse_iterator<_Iter2>& __y)
{
return __y.base() - __x.base();
}
#endif
template <class _Iter>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator<_Iter>
operator+(typename reverse_iterator<_Iter>::difference_type __n, const reverse_iterator<_Iter>& __x)
{
return reverse_iterator<_Iter>(__x.base() - __n);
}
#if _LIBCPP_STD_VER > 17
template <class _Iter1, class _Iter2>
requires (!sized_sentinel_for<_Iter1, _Iter2>)
inline constexpr bool disable_sized_sentinel_for<reverse_iterator<_Iter1>, reverse_iterator<_Iter2>> = true;
#endif // _LIBCPP_STD_VER > 17
#if _LIBCPP_STD_VER > 11
template <class _Iter>
inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
reverse_iterator<_Iter> make_reverse_iterator(_Iter __i)
{
return reverse_iterator<_Iter>(__i);
}
#endif
template <class _Iter>
using _ReverseWrapper = reverse_iterator<reverse_iterator<_Iter> >;
template <class _Iter, bool __b>
struct __unwrap_iter_impl<_ReverseWrapper<_Iter>, __b> {
static _LIBCPP_CONSTEXPR decltype(std::__unwrap_iter(std::declval<_Iter>()))
__apply(_ReverseWrapper<_Iter> __i) _NOEXCEPT {
return std::__unwrap_iter(__i.base().base());
}
};
template <class _OrigIter, class _UnwrappedIter>
struct __rewrap_iter_impl<_ReverseWrapper<_OrigIter>, _UnwrappedIter> {
template <class _Iter>
struct _ReverseWrapperCount {
static _LIBCPP_CONSTEXPR const size_t value = 1;
};
template <class _Iter>
struct _ReverseWrapperCount<_ReverseWrapper<_Iter> > {
static _LIBCPP_CONSTEXPR const size_t value = 1 + _ReverseWrapperCount<_Iter>::value;
};
template <size_t _RewrapCount, class _OIter, class _UIter, __enable_if_t<_RewrapCount != 0, int> = 0>
_LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR _ReverseWrapper<_OIter> __rewrap(_ReverseWrapper<_OIter> __iter1,
_UIter __iter2) {
return _ReverseWrapper<_OIter>(
reverse_iterator<_OIter>(__rewrap<_RewrapCount - 1>(__iter1.base().base(), __iter2)));
}
template <size_t _RewrapCount, class _OIter, class _UIter, __enable_if_t<_RewrapCount == 0, int> = 0>
_LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR decltype(std::__rewrap_iter(std::declval<_OIter>(),
std::declval<_UIter>()))
__rewrap(_OIter __iter1, _UIter __iter2) {
return std::__rewrap_iter(__iter1, __iter2);
}
_LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR _ReverseWrapper<_OrigIter> __apply(_ReverseWrapper<_OrigIter> __iter1,
_UnwrappedIter __iter2) {
return __rewrap<_ReverseWrapperCount<_OrigIter>::value>(__iter1, __iter2);
}
};
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ITERATOR_REVERSE_ITERATOR_H
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