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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_COMMON_ITERATOR_H
#define _LIBCPP___ITERATOR_COMMON_ITERATOR_H
#include <__assert>
#include <__config>
#include <__iterator/concepts.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 <concepts>
#include <variant>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER > 17
template<class _Iter>
concept __can_use_postfix_proxy =
constructible_from<iter_value_t<_Iter>, iter_reference_t<_Iter>> &&
move_constructible<iter_value_t<_Iter>>;
template<input_or_output_iterator _Iter, sentinel_for<_Iter> _Sent>
requires (!same_as<_Iter, _Sent> && copyable<_Iter>)
class common_iterator {
struct __proxy {
constexpr const iter_value_t<_Iter>* operator->() const noexcept {
return _VSTD::addressof(__value_);
}
iter_value_t<_Iter> __value_;
};
struct __postfix_proxy {
constexpr const iter_value_t<_Iter>& operator*() const noexcept {
return __value_;
}
iter_value_t<_Iter> __value_;
};
public:
variant<_Iter, _Sent> __hold_;
common_iterator() requires default_initializable<_Iter> = default;
constexpr common_iterator(_Iter __i) : __hold_(in_place_type<_Iter>, _VSTD::move(__i)) {}
constexpr common_iterator(_Sent __s) : __hold_(in_place_type<_Sent>, _VSTD::move(__s)) {}
template<class _I2, class _S2>
requires convertible_to<const _I2&, _Iter> && convertible_to<const _S2&, _Sent>
constexpr common_iterator(const common_iterator<_I2, _S2>& __other)
: __hold_([&]() -> variant<_Iter, _Sent> {
_LIBCPP_ASSERT(!__other.__hold_.valueless_by_exception(), "Attempted to construct from a valueless common_iterator");
if (__other.__hold_.index() == 0)
return variant<_Iter, _Sent>{in_place_index<0>, _VSTD::__unchecked_get<0>(__other.__hold_)};
return variant<_Iter, _Sent>{in_place_index<1>, _VSTD::__unchecked_get<1>(__other.__hold_)};
}()) {}
template<class _I2, class _S2>
requires convertible_to<const _I2&, _Iter> && convertible_to<const _S2&, _Sent> &&
assignable_from<_Iter&, const _I2&> && assignable_from<_Sent&, const _S2&>
common_iterator& operator=(const common_iterator<_I2, _S2>& __other) {
_LIBCPP_ASSERT(!__other.__hold_.valueless_by_exception(), "Attempted to assign from a valueless common_iterator");
auto __idx = __hold_.index();
auto __other_idx = __other.__hold_.index();
// If they're the same index, just assign.
if (__idx == 0 && __other_idx == 0)
_VSTD::__unchecked_get<0>(__hold_) = _VSTD::__unchecked_get<0>(__other.__hold_);
else if (__idx == 1 && __other_idx == 1)
_VSTD::__unchecked_get<1>(__hold_) = _VSTD::__unchecked_get<1>(__other.__hold_);
// Otherwise replace with the oposite element.
else if (__other_idx == 1)
__hold_.template emplace<1>(_VSTD::__unchecked_get<1>(__other.__hold_));
else if (__other_idx == 0)
__hold_.template emplace<0>(_VSTD::__unchecked_get<0>(__other.__hold_));
return *this;
}
constexpr decltype(auto) operator*()
{
_LIBCPP_ASSERT(holds_alternative<_Iter>(__hold_), "Attempted to dereference a non-dereferenceable common_iterator");
return *_VSTD::__unchecked_get<_Iter>(__hold_);
}
constexpr decltype(auto) operator*() const
requires __dereferenceable<const _Iter>
{
_LIBCPP_ASSERT(holds_alternative<_Iter>(__hold_), "Attempted to dereference a non-dereferenceable common_iterator");
return *_VSTD::__unchecked_get<_Iter>(__hold_);
}
template<class _I2 = _Iter>
decltype(auto) operator->() const
requires indirectly_readable<const _I2> &&
(requires(const _I2& __i) { __i.operator->(); } ||
is_reference_v<iter_reference_t<_I2>> ||
constructible_from<iter_value_t<_I2>, iter_reference_t<_I2>>)
{
_LIBCPP_ASSERT(holds_alternative<_Iter>(__hold_), "Attempted to dereference a non-dereferenceable common_iterator");
if constexpr (is_pointer_v<_Iter> || requires(const _Iter& __i) { __i.operator->(); }) {
return _VSTD::__unchecked_get<_Iter>(__hold_);
} else if constexpr (is_reference_v<iter_reference_t<_Iter>>) {
auto&& __tmp = *_VSTD::__unchecked_get<_Iter>(__hold_);
return _VSTD::addressof(__tmp);
} else {
return __proxy{*_VSTD::__unchecked_get<_Iter>(__hold_)};
}
}
common_iterator& operator++() {
_LIBCPP_ASSERT(holds_alternative<_Iter>(__hold_), "Attempted to increment a non-dereferenceable common_iterator");
++_VSTD::__unchecked_get<_Iter>(__hold_); return *this;
}
decltype(auto) operator++(int) {
_LIBCPP_ASSERT(holds_alternative<_Iter>(__hold_), "Attempted to increment a non-dereferenceable common_iterator");
if constexpr (forward_iterator<_Iter>) {
auto __tmp = *this;
++*this;
return __tmp;
} else if constexpr (requires (_Iter& __i) { { *__i++ } -> __can_reference; } ||
!__can_use_postfix_proxy<_Iter>) {
return _VSTD::__unchecked_get<_Iter>(__hold_)++;
} else {
auto __p = __postfix_proxy{**this};
++*this;
return __p;
}
}
template<class _I2, sentinel_for<_Iter> _S2>
requires sentinel_for<_Sent, _I2>
friend constexpr bool operator==(const common_iterator& __x, const common_iterator<_I2, _S2>& __y) {
_LIBCPP_ASSERT(!__x.__hold_.valueless_by_exception(), "Attempted to compare a valueless common_iterator");
_LIBCPP_ASSERT(!__y.__hold_.valueless_by_exception(), "Attempted to compare a valueless common_iterator");
auto __x_index = __x.__hold_.index();
auto __y_index = __y.__hold_.index();
if (__x_index == __y_index)
return true;
if (__x_index == 0)
return _VSTD::__unchecked_get<_Iter>(__x.__hold_) == _VSTD::__unchecked_get<_S2>(__y.__hold_);
return _VSTD::__unchecked_get<_Sent>(__x.__hold_) == _VSTD::__unchecked_get<_I2>(__y.__hold_);
}
template<class _I2, sentinel_for<_Iter> _S2>
requires sentinel_for<_Sent, _I2> && equality_comparable_with<_Iter, _I2>
friend constexpr bool operator==(const common_iterator& __x, const common_iterator<_I2, _S2>& __y) {
_LIBCPP_ASSERT(!__x.__hold_.valueless_by_exception(), "Attempted to compare a valueless common_iterator");
_LIBCPP_ASSERT(!__y.__hold_.valueless_by_exception(), "Attempted to compare a valueless common_iterator");
auto __x_index = __x.__hold_.index();
auto __y_index = __y.__hold_.index();
if (__x_index == 1 && __y_index == 1)
return true;
if (__x_index == 0 && __y_index == 0)
return _VSTD::__unchecked_get<_Iter>(__x.__hold_) == _VSTD::__unchecked_get<_I2>(__y.__hold_);
if (__x_index == 0)
return _VSTD::__unchecked_get<_Iter>(__x.__hold_) == _VSTD::__unchecked_get<_S2>(__y.__hold_);
return _VSTD::__unchecked_get<_Sent>(__x.__hold_) == _VSTD::__unchecked_get<_I2>(__y.__hold_);
}
template<sized_sentinel_for<_Iter> _I2, sized_sentinel_for<_Iter> _S2>
requires sized_sentinel_for<_Sent, _I2>
friend constexpr iter_difference_t<_I2> operator-(const common_iterator& __x, const common_iterator<_I2, _S2>& __y) {
_LIBCPP_ASSERT(!__x.__hold_.valueless_by_exception(), "Attempted to subtract from a valueless common_iterator");
_LIBCPP_ASSERT(!__y.__hold_.valueless_by_exception(), "Attempted to subtract a valueless common_iterator");
auto __x_index = __x.__hold_.index();
auto __y_index = __y.__hold_.index();
if (__x_index == 1 && __y_index == 1)
return 0;
if (__x_index == 0 && __y_index == 0)
return _VSTD::__unchecked_get<_Iter>(__x.__hold_) - _VSTD::__unchecked_get<_I2>(__y.__hold_);
if (__x_index == 0)
return _VSTD::__unchecked_get<_Iter>(__x.__hold_) - _VSTD::__unchecked_get<_S2>(__y.__hold_);
return _VSTD::__unchecked_get<_Sent>(__x.__hold_) - _VSTD::__unchecked_get<_I2>(__y.__hold_);
}
friend constexpr iter_rvalue_reference_t<_Iter> iter_move(const common_iterator& __i)
noexcept(noexcept(ranges::iter_move(declval<const _Iter&>())))
requires input_iterator<_Iter>
{
_LIBCPP_ASSERT(holds_alternative<_Iter>(__i.__hold_), "Attempted to iter_move a non-dereferenceable common_iterator");
return ranges::iter_move( _VSTD::__unchecked_get<_Iter>(__i.__hold_));
}
template<indirectly_swappable<_Iter> _I2, class _S2>
friend constexpr void iter_swap(const common_iterator& __x, const common_iterator<_I2, _S2>& __y)
noexcept(noexcept(ranges::iter_swap(declval<const _Iter&>(), declval<const _I2&>())))
{
_LIBCPP_ASSERT(holds_alternative<_Iter>(__x.__hold_), "Attempted to iter_swap a non-dereferenceable common_iterator");
_LIBCPP_ASSERT(holds_alternative<_I2>(__y.__hold_), "Attempted to iter_swap a non-dereferenceable common_iterator");
return ranges::iter_swap(_VSTD::__unchecked_get<_Iter>(__x.__hold_), _VSTD::__unchecked_get<_I2>(__y.__hold_));
}
};
template<class _Iter, class _Sent>
struct incrementable_traits<common_iterator<_Iter, _Sent>> {
using difference_type = iter_difference_t<_Iter>;
};
template<class _Iter>
concept __denotes_forward_iter =
requires { typename iterator_traits<_Iter>::iterator_category; } &&
derived_from<typename iterator_traits<_Iter>::iterator_category, forward_iterator_tag>;
template<class _Iter, class _Sent>
concept __common_iter_has_ptr_op = requires(const common_iterator<_Iter, _Sent>& __a) {
__a.operator->();
};
template<class, class>
struct __arrow_type_or_void {
using type = void;
};
template<class _Iter, class _Sent>
requires __common_iter_has_ptr_op<_Iter, _Sent>
struct __arrow_type_or_void<_Iter, _Sent> {
using type = decltype(declval<const common_iterator<_Iter, _Sent>&>().operator->());
};
template<input_iterator _Iter, class _Sent>
struct iterator_traits<common_iterator<_Iter, _Sent>> {
using iterator_concept = _If<forward_iterator<_Iter>,
forward_iterator_tag,
input_iterator_tag>;
using iterator_category = _If<__denotes_forward_iter<_Iter>,
forward_iterator_tag,
input_iterator_tag>;
using pointer = typename __arrow_type_or_void<_Iter, _Sent>::type;
using value_type = iter_value_t<_Iter>;
using difference_type = iter_difference_t<_Iter>;
using reference = iter_reference_t<_Iter>;
};
#endif // _LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___ITERATOR_COMMON_ITERATOR_H
|
