// -*- 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_COUNTED_ITERATOR_H
#define _LIBCPP___ITERATOR_COUNTED_ITERATOR_H
#include <__assert>
#include <__concepts/assignable.h>
#include <__concepts/common_with.h>
#include <__concepts/constructible.h>
#include <__concepts/convertible_to.h>
#include <__concepts/same_as.h>
#include <__config>
#include <__iterator/concepts.h>
#include <__iterator/default_sentinel.h>
#include <__iterator/incrementable_traits.h>
#include <__iterator/iter_move.h>
#include <__iterator/iter_swap.h>
#include <__iterator/iterator_traits.h>
#include <__iterator/readable_traits.h>
#include <__memory/pointer_traits.h>
#include <__type_traits/add_pointer.h>
#include <__type_traits/conditional.h>
#include <__utility/move.h>
#include <compare>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 20
template <class>
struct __counted_iterator_concept {};
template <class _Iter>
requires requires { typename _Iter::iterator_concept; }
struct __counted_iterator_concept<_Iter> {
using iterator_concept = typename _Iter::iterator_concept;
};
template <class>
struct __counted_iterator_category {};
template <class _Iter>
requires requires { typename _Iter::iterator_category; }
struct __counted_iterator_category<_Iter> {
using iterator_category = typename _Iter::iterator_category;
};
template <class>
struct __counted_iterator_value_type {};
template <indirectly_readable _Iter>
struct __counted_iterator_value_type<_Iter> {
using value_type = iter_value_t<_Iter>;
};
template <input_or_output_iterator _Iter>
class counted_iterator
: public __counted_iterator_concept<_Iter>,
public __counted_iterator_category<_Iter>,
public __counted_iterator_value_type<_Iter> {
public:
using iterator_type = _Iter;
using difference_type = iter_difference_t<_Iter>;
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator()
requires default_initializable<_Iter>
= default;
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator(_Iter __iter, iter_difference_t<_Iter> __n)
: __current_(std::move(__iter)), __count_(__n) {
_LIBCPP_ASSERT_UNCATEGORIZED(__n >= 0, "__n must not be negative.");
}
template <class _I2>
requires convertible_to<const _I2&, _Iter>
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator(const counted_iterator<_I2>& __other)
: __current_(__other.__current_), __count_(__other.__count_) {}
template <class _I2>
requires assignable_from<_Iter&, const _I2&>
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator& operator=(const counted_iterator<_I2>& __other) {
__current_ = __other.__current_;
__count_ = __other.__count_;
return *this;
}
_LIBCPP_HIDE_FROM_ABI constexpr const _Iter& base() const& noexcept { return __current_; }
_LIBCPP_HIDE_FROM_ABI constexpr _Iter base() && { return std::move(__current_); }
_LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Iter> count() const noexcept { return __count_; }
_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__count_ > 0, "Iterator is equal to or past end.");
return *__current_;
}
_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const
requires __dereferenceable<const _Iter>
{
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__count_ > 0, "Iterator is equal to or past end.");
return *__current_;
}
_LIBCPP_HIDE_FROM_ABI constexpr auto operator->() const noexcept
requires contiguous_iterator<_Iter>
{
return std::to_address(__current_);
}
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator& operator++() {
_LIBCPP_ASSERT_UNCATEGORIZED(__count_ > 0, "Iterator already at or past end.");
++__current_;
--__count_;
return *this;
}
_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator++(int) {
_LIBCPP_ASSERT_UNCATEGORIZED(__count_ > 0, "Iterator already at or past end.");
--__count_;
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
try {
return __current_++;
} catch (...) {
++__count_;
throw;
}
# else
return __current_++;
# endif // _LIBCPP_HAS_NO_EXCEPTIONS
}
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator operator++(int)
requires forward_iterator<_Iter>
{
_LIBCPP_ASSERT_UNCATEGORIZED(__count_ > 0, "Iterator already at or past end.");
counted_iterator __tmp = *this;
++*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator& operator--()
requires bidirectional_iterator<_Iter>
{
--__current_;
++__count_;
return *this;
}
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator operator--(int)
requires bidirectional_iterator<_Iter>
{
counted_iterator __tmp = *this;
--*this;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator operator+(iter_difference_t<_Iter> __n) const
requires random_access_iterator<_Iter>
{
return counted_iterator(__current_ + __n, __count_ - __n);
}
_LIBCPP_HIDE_FROM_ABI friend constexpr counted_iterator
operator+(iter_difference_t<_Iter> __n, const counted_iterator& __x)
requires random_access_iterator<_Iter>
{
return __x + __n;
}
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator& operator+=(iter_difference_t<_Iter> __n)
requires random_access_iterator<_Iter>
{
_LIBCPP_ASSERT_UNCATEGORIZED(__n <= __count_, "Cannot advance iterator past end.");
__current_ += __n;
__count_ -= __n;
return *this;
}
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator operator-(iter_difference_t<_Iter> __n) const
requires random_access_iterator<_Iter>
{
return counted_iterator(__current_ - __n, __count_ + __n);
}
template <common_with<_Iter> _I2>
_LIBCPP_HIDE_FROM_ABI friend constexpr iter_difference_t<_I2>
operator-(const counted_iterator& __lhs, const counted_iterator<_I2>& __rhs) {
return __rhs.__count_ - __lhs.__count_;
}
_LIBCPP_HIDE_FROM_ABI friend constexpr iter_difference_t<_Iter>
operator-(const counted_iterator& __lhs, default_sentinel_t) {
return -__lhs.__count_;
}
_LIBCPP_HIDE_FROM_ABI friend constexpr iter_difference_t<_Iter>
operator-(default_sentinel_t, const counted_iterator& __rhs) {
return __rhs.__count_;
}
_LIBCPP_HIDE_FROM_ABI constexpr counted_iterator& operator-=(iter_difference_t<_Iter> __n)
requires random_access_iterator<_Iter>
{
_LIBCPP_ASSERT_UNCATEGORIZED(
-__n <= __count_,
"Attempt to subtract too large of a size: "
"counted_iterator would be decremented before the "
"first element of its range.");
__current_ -= __n;
__count_ += __n;
return *this;
}
_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator[](iter_difference_t<_Iter> __n) const
requires random_access_iterator<_Iter>
{
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__n < __count_, "Subscript argument must be less than size.");
return __current_[__n];
}
template <common_with<_Iter> _I2>
_LIBCPP_HIDE_FROM_ABI friend constexpr bool
operator==(const counted_iterator& __lhs, const counted_iterator<_I2>& __rhs) {
return __lhs.__count_ == __rhs.__count_;
}
_LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const counted_iterator& __lhs, default_sentinel_t) {
return __lhs.__count_ == 0;
}
template <common_with<_Iter> _I2>
_LIBCPP_HIDE_FROM_ABI friend constexpr strong_ordering
operator<=>(const counted_iterator& __lhs, const counted_iterator<_I2>& __rhs) {
return __rhs.__count_ <=> __lhs.__count_;
}
_LIBCPP_HIDE_FROM_ABI friend constexpr iter_rvalue_reference_t<_Iter>
iter_move(const counted_iterator& __i) noexcept(noexcept(ranges::iter_move(__i.__current_)))
requires input_iterator<_Iter>
{
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__i.__count_ > 0, "Iterator must not be past end of range.");
return ranges::iter_move(__i.__current_);
}
template <indirectly_swappable<_Iter> _I2>
_LIBCPP_HIDE_FROM_ABI friend constexpr void
iter_swap(const counted_iterator& __x,
const counted_iterator<_I2>& __y) noexcept(noexcept(ranges::iter_swap(__x.__current_, __y.__current_))) {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__x.__count_ > 0 && __y.__count_ > 0, "Iterators must not be past end of range.");
return ranges::iter_swap(__x.__current_, __y.__current_);
}
private:
_LIBCPP_NO_UNIQUE_ADDRESS _Iter __current_ = _Iter();
iter_difference_t<_Iter> __count_ = 0;
template <input_or_output_iterator _OtherIter>
friend class counted_iterator;
};
_LIBCPP_CTAD_SUPPORTED_FOR_TYPE(counted_iterator);
template <input_iterator _Iter>
requires same_as<_ITER_TRAITS<_Iter>, iterator_traits<_Iter>>
struct iterator_traits<counted_iterator<_Iter>> : iterator_traits<_Iter> {
using pointer = conditional_t<contiguous_iterator<_Iter>, add_pointer_t<iter_reference_t<_Iter>>, void>;
};
#endif // _LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___ITERATOR_COUNTED_ITERATOR_H
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