304 lines
8.7 KiB
C++
304 lines
8.7 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___ITERATOR_COUNTED_ITERATOR_H
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#define _LIBCPP___ITERATOR_COUNTED_ITERATOR_H
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#include <__assert>
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#include <__config>
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#include <__iterator/concepts.h>
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#include <__iterator/default_sentinel.h>
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#include <__iterator/incrementable_traits.h>
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#include <__iterator/iter_move.h>
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#include <__iterator/iter_swap.h>
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#include <__iterator/iterator_traits.h>
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#include <__iterator/readable_traits.h>
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#include <__memory/pointer_traits.h>
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#include <__utility/move.h>
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#include <compare>
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#include <concepts>
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#include <type_traits>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER > 17
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template<class>
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struct __counted_iterator_concept {};
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template<class _Iter>
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requires requires { typename _Iter::iterator_concept; }
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struct __counted_iterator_concept<_Iter> {
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using iterator_concept = typename _Iter::iterator_concept;
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};
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template<class>
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struct __counted_iterator_category {};
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template<class _Iter>
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requires requires { typename _Iter::iterator_category; }
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struct __counted_iterator_category<_Iter> {
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using iterator_category = typename _Iter::iterator_category;
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};
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template<class>
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struct __counted_iterator_value_type {};
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template<indirectly_readable _Iter>
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struct __counted_iterator_value_type<_Iter> {
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using value_type = iter_value_t<_Iter>;
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};
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template<input_or_output_iterator _Iter>
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class counted_iterator
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: public __counted_iterator_concept<_Iter>
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, public __counted_iterator_category<_Iter>
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, public __counted_iterator_value_type<_Iter>
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{
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public:
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_LIBCPP_NO_UNIQUE_ADDRESS _Iter __current_ = _Iter();
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iter_difference_t<_Iter> __count_ = 0;
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using iterator_type = _Iter;
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using difference_type = iter_difference_t<_Iter>;
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator() requires default_initializable<_Iter> = default;
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator(_Iter __iter, iter_difference_t<_Iter> __n)
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: __current_(_VSTD::move(__iter)), __count_(__n) {
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_LIBCPP_ASSERT(__n >= 0, "__n must not be negative.");
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}
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template<class _I2>
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requires convertible_to<const _I2&, _Iter>
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator(const counted_iterator<_I2>& __other)
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: __current_(__other.__current_), __count_(__other.__count_) {}
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template<class _I2>
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requires assignable_from<_Iter&, const _I2&>
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator& operator=(const counted_iterator<_I2>& __other) {
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__current_ = __other.__current_;
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__count_ = __other.__count_;
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return *this;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr const _Iter& base() const& noexcept { return __current_; }
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_LIBCPP_HIDE_FROM_ABI
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constexpr _Iter base() && { return _VSTD::move(__current_); }
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_LIBCPP_HIDE_FROM_ABI
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constexpr iter_difference_t<_Iter> count() const noexcept { return __count_; }
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_LIBCPP_HIDE_FROM_ABI
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constexpr decltype(auto) operator*() {
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_LIBCPP_ASSERT(__count_ > 0, "Iterator is equal to or past end.");
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return *__current_;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr decltype(auto) operator*() const
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requires __dereferenceable<const _Iter>
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{
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_LIBCPP_ASSERT(__count_ > 0, "Iterator is equal to or past end.");
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return *__current_;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr auto operator->() const noexcept
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requires contiguous_iterator<_Iter>
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{
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return _VSTD::to_address(__current_);
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator& operator++() {
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_LIBCPP_ASSERT(__count_ > 0, "Iterator already at or past end.");
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++__current_;
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--__count_;
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return *this;
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}
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_LIBCPP_HIDE_FROM_ABI
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decltype(auto) operator++(int) {
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_LIBCPP_ASSERT(__count_ > 0, "Iterator already at or past end.");
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--__count_;
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#ifndef _LIBCPP_NO_EXCEPTIONS
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try { return __current_++; }
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catch(...) { ++__count_; throw; }
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#else
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return __current_++;
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#endif // _LIBCPP_NO_EXCEPTIONS
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator operator++(int)
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requires forward_iterator<_Iter>
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{
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_LIBCPP_ASSERT(__count_ > 0, "Iterator already at or past end.");
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counted_iterator __tmp = *this;
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++*this;
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return __tmp;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator& operator--()
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requires bidirectional_iterator<_Iter>
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{
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--__current_;
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++__count_;
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return *this;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator operator--(int)
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requires bidirectional_iterator<_Iter>
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{
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counted_iterator __tmp = *this;
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--*this;
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return __tmp;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator operator+(iter_difference_t<_Iter> __n) const
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requires random_access_iterator<_Iter>
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{
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return counted_iterator(__current_ + __n, __count_ - __n);
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}
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_LIBCPP_HIDE_FROM_ABI
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friend constexpr counted_iterator operator+(
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iter_difference_t<_Iter> __n, const counted_iterator& __x)
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requires random_access_iterator<_Iter>
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{
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return __x + __n;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator& operator+=(iter_difference_t<_Iter> __n)
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requires random_access_iterator<_Iter>
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{
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_LIBCPP_ASSERT(__n <= __count_, "Cannot advance iterator past end.");
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__current_ += __n;
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__count_ -= __n;
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return *this;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator operator-(iter_difference_t<_Iter> __n) const
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requires random_access_iterator<_Iter>
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{
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return counted_iterator(__current_ - __n, __count_ + __n);
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}
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template<common_with<_Iter> _I2>
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_LIBCPP_HIDE_FROM_ABI
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friend constexpr iter_difference_t<_I2> operator-(
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const counted_iterator& __lhs, const counted_iterator<_I2>& __rhs)
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{
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return __rhs.__count_ - __lhs.__count_;
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}
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_LIBCPP_HIDE_FROM_ABI
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friend constexpr iter_difference_t<_Iter> operator-(
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const counted_iterator& __lhs, default_sentinel_t)
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{
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return -__lhs.__count_;
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}
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_LIBCPP_HIDE_FROM_ABI
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friend constexpr iter_difference_t<_Iter> operator-(
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default_sentinel_t, const counted_iterator& __rhs)
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{
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return __rhs.__count_;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr counted_iterator& operator-=(iter_difference_t<_Iter> __n)
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requires random_access_iterator<_Iter>
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{
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_LIBCPP_ASSERT(-__n <= __count_, "Attempt to subtract too large of a size: "
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"counted_iterator would be decremented before the "
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"first element of its range.");
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__current_ -= __n;
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__count_ += __n;
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return *this;
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}
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_LIBCPP_HIDE_FROM_ABI
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constexpr decltype(auto) operator[](iter_difference_t<_Iter> __n) const
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requires random_access_iterator<_Iter>
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{
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_LIBCPP_ASSERT(__n < __count_, "Subscript argument must be less than size.");
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return __current_[__n];
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}
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template<common_with<_Iter> _I2>
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_LIBCPP_HIDE_FROM_ABI
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friend constexpr bool operator==(
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const counted_iterator& __lhs, const counted_iterator<_I2>& __rhs)
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{
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return __lhs.__count_ == __rhs.__count_;
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}
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_LIBCPP_HIDE_FROM_ABI
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friend constexpr bool operator==(
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const counted_iterator& __lhs, default_sentinel_t)
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{
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return __lhs.__count_ == 0;
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}
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template<common_with<_Iter> _I2>
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friend constexpr strong_ordering operator<=>(
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const counted_iterator& __lhs, const counted_iterator<_I2>& __rhs)
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{
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return __rhs.__count_ <=> __lhs.__count_;
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}
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_LIBCPP_HIDE_FROM_ABI
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friend constexpr iter_rvalue_reference_t<_Iter> iter_move(const counted_iterator& __i)
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noexcept(noexcept(ranges::iter_move(__i.__current_)))
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requires input_iterator<_Iter>
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{
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_LIBCPP_ASSERT(__i.__count_ > 0, "Iterator must not be past end of range.");
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return ranges::iter_move(__i.__current_);
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}
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template<indirectly_swappable<_Iter> _I2>
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_LIBCPP_HIDE_FROM_ABI
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friend constexpr void iter_swap(const counted_iterator& __x, const counted_iterator<_I2>& __y)
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noexcept(noexcept(ranges::iter_swap(__x.__current_, __y.__current_)))
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{
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_LIBCPP_ASSERT(__x.__count_ > 0 && __y.__count_ > 0,
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"Iterators must not be past end of range.");
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return ranges::iter_swap(__x.__current_, __y.__current_);
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}
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};
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template<input_iterator _Iter>
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requires same_as<_ITER_TRAITS<_Iter>, iterator_traits<_Iter>>
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struct iterator_traits<counted_iterator<_Iter>> : iterator_traits<_Iter> {
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using pointer = conditional_t<contiguous_iterator<_Iter>,
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add_pointer_t<iter_reference_t<_Iter>>, void>;
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};
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#endif // _LIBCPP_STD_VER > 17
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ITERATOR_COUNTED_ITERATOR_H
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