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Merged
StephanTLavavej merged 18 commits into from
Aug 17, 2021
Merged

Implement rest of P2259R1, Repairing Input Range Adaptors #2059

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c87ce0f
Implement rest of P2259
miscco Jul 13, 2021
f7e1671
WIP
CaseyCarter Jun 30, 2021
3be319a
Merge remote-tracking branch 'origin/main' into merge
CaseyCarter Jul 16, 2021
5e89ddc
Merge Casey's work-in-process branch
CaseyCarter Jul 16, 2021
6e7eace
test fallout
CaseyCarter Jul 16, 2021
24f6966
Apply suggestions from code review
miscco Jul 18, 2021
30b155d
Merge branch 'main' into P2259-iterator-fixes
miscco Jul 20, 2021
c99168d
Merge branch 'main' into P2259-iterator-fixes
miscco Aug 3, 2021
fab7f47
Make _Iterator a aggregate
miscco Aug 3, 2021
52cbf13
Fix filter_view iterator category
miscco Aug 3, 2021
4cd172d
Properly test against prvalue for elements_view
miscco Aug 3, 2021
3069ebf
Remove implementation of LWG-3283
CaseyCarter Jul 27, 2021
91aea86
Address Tim's comment on my comment
CaseyCarter Aug 2, 2021
c510f4e
Merge branch 'main' into P2259-iterator-fixes
miscco Aug 6, 2021
bbe520a
Bring iota_view::iterator (plain _Ioterator for us) into compliance
CaseyCarter Aug 12, 2021
93f942e
Remove parentheses in `assert`s
CaseyCarter Aug 12, 2021
1d083ca
Fix bug that causes test::iterator to sometimes lie about category
CaseyCarter Aug 13, 2021
0ee79a0
Consistently use _NODISCARD for defaulted <=>
CaseyCarter Aug 13, 2021
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19 changes: 12 additions & 7 deletions stl/inc/iterator
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Original file line number Diff line number Diff line change
Expand Up @@ -1016,15 +1016,20 @@ struct _Common_iterator_pointer_type<_Iter> {
using pointer = decltype(_STD declval<_Iter&>().operator->());
};

template <class _Iter>
concept _Has_forward_category = requires {
typename _Iter_cat_t<_Iter>;
requires derived_from<_Iter_cat_t<_Iter>, forward_iterator_tag>;
};

template <input_iterator _Iter, class _Se>
struct iterator_traits<common_iterator<_Iter, _Se>> {
using iterator_concept = conditional_t<forward_iterator<_Iter>, forward_iterator_tag, input_iterator_tag>;
using iterator_category =
conditional_t<derived_from<_Iter_cat_t<_Iter>, forward_iterator_tag>, forward_iterator_tag, input_iterator_tag>;
using value_type = iter_value_t<_Iter>;
using difference_type = iter_difference_t<_Iter>;
using pointer = typename _Common_iterator_pointer_type<_Iter>::pointer;
using reference = iter_reference_t<_Iter>;
using iterator_concept = conditional_t<forward_iterator<_Iter>, forward_iterator_tag, input_iterator_tag>;
using iterator_category = conditional_t<_Has_forward_category<_Iter>, forward_iterator_tag, input_iterator_tag>;
using value_type = iter_value_t<_Iter>;
using difference_type = iter_difference_t<_Iter>;
using pointer = typename _Common_iterator_pointer_type<_Iter>::pointer;
using reference = iter_reference_t<_Iter>;
};

template <class _Iter>
Expand Down
120 changes: 64 additions & 56 deletions stl/inc/ranges
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Expand Up @@ -776,18 +776,36 @@ namespace ranges {
{ __j - __j } -> convertible_to<_Iota_diff_t<_Ty>>;
};

template <class _Wi>
struct _Ioterator_category_base {
_NODISCARD auto operator<=>(const _Ioterator_category_base&) const = default;
};

template <incrementable _Wi>
struct _Ioterator_category_base<_Wi> {
using iterator_category = input_iterator_tag;

_NODISCARD auto operator<=>(const _Ioterator_category_base&) const = default;
};

template <weakly_incrementable _Wi>
requires copyable<_Wi>
struct _Ioterator {
struct _Ioterator : _Ioterator_category_base<_Wi> {
// clang-format on
/* [[no_unique_address]] */ _Wi _Current;
/* [[no_unique_address]] */ _Wi _Current{};

using iterator_concept = conditional_t<_Advanceable<_Wi>, random_access_iterator_tag,
using iterator_concept = conditional_t<_Advanceable<_Wi>, random_access_iterator_tag,
conditional_t<_Decrementable<_Wi>, bidirectional_iterator_tag,
conditional_t<incrementable<_Wi>, forward_iterator_tag, input_iterator_tag>>>;
using iterator_category = input_iterator_tag;
using value_type = _Wi;
using difference_type = _Iota_diff_t<_Wi>;
using value_type = _Wi;
using difference_type = _Iota_diff_t<_Wi>;

// clang-format off
_Ioterator() requires default_initializable<_Wi> = default;
// clang-format on

constexpr explicit _Ioterator(_Wi _Val) noexcept(is_nothrow_move_constructible_v<_Wi>) /* strengthened */
: _Current(_STD move(_Val)) {}

_NODISCARD constexpr _Wi operator*() const noexcept(is_nothrow_copy_constructible_v<_Wi>) {
return _Current;
Expand Down Expand Up @@ -914,13 +932,11 @@ namespace ranges {
noexcept(!(_Left._Current < _Right._Current))) /* strengthened */ requires totally_ordered<_Wi> {
return !(_Left._Current < _Right._Current);
}

// clang-format off
_NODISCARD friend constexpr auto operator<=>(const _Ioterator& _Left, const _Ioterator& _Right) noexcept(
noexcept(_Left._Current <=> _Right._Current)) /* strengthened */
requires totally_ordered<_Wi> && three_way_comparable<_Wi> {
// clang-format on
return _Left._Current <=> _Right._Current;
}
_NODISCARD friend constexpr auto operator<=>(const _Ioterator& _Left, const _Ioterator& _Right)
requires totally_ordered<_Wi> && three_way_comparable<_Wi> = default;
// clang-format on

_NODISCARD friend constexpr _Ioterator operator+(_Ioterator _It, const difference_type _Off) noexcept(
noexcept(static_cast<_Wi>(_It._Current + _Off))) /* strengthened */ requires _Advanceable<_Wi> {
Expand Down Expand Up @@ -1028,7 +1044,9 @@ namespace ranges {
}

_NODISCARD constexpr _Se end() const noexcept(is_nothrow_copy_constructible_v<_Bo>) /* strengthened */ {
if constexpr (same_as<_Bo, unreachable_sentinel_t>) {
if constexpr (same_as<_Wi, _Bo>) {
return _It{_Bound};
} else if constexpr (same_as<_Bo, unreachable_sentinel_t>) {
return unreachable_sentinel;
} else {
return _Se{_Bound};
Expand Down Expand Up @@ -1289,20 +1307,20 @@ namespace ranges {
/* [[no_unique_address]] */ _Vw _Range{};
/* [[no_unique_address]] */ _Copyable_box<_Pr> _Pred{};

template <class _Traits> // TRANSITION, LWG-3289
template <class _View>
struct _Category_base {};
// clang-format off
template <_Has_member_iterator_category _Traits>
struct _Category_base<_Traits> {
template <forward_range _View>
struct _Category_base<_View> {
// clang-format on
using iterator_category =
conditional_t<derived_from<typename _Traits::iterator_category, bidirectional_iterator_tag>,
conditional_t<derived_from<_Iter_cat_t<iterator_t<_View>>, bidirectional_iterator_tag>,
bidirectional_iterator_tag,
conditional_t<derived_from<typename _Traits::iterator_category, forward_iterator_tag>,
forward_iterator_tag, input_iterator_tag>>;
conditional_t<derived_from<_Iter_cat_t<iterator_t<_View>>, forward_iterator_tag>,
forward_iterator_tag, _Iter_cat_t<iterator_t<_View>>>>;
};

class _Iterator : public _Category_base<iterator_traits<iterator_t<_Vw>>> {
class _Iterator : public _Category_base<_Vw> {
private:
/* [[no_unique_address]] */ iterator_t<_Vw> _Current{};
filter_view* _Parent{};
Expand Down Expand Up @@ -1574,21 +1592,21 @@ namespace ranges {
template <bool _Const>
class _Sentinel;

template <class _Traits, class _Base> // TRANSITION, LWG-3289
template <class _Base>
struct _Category_base {};
// clang-format off
template <_Has_member_iterator_category _Traits, class _Base>
struct _Category_base<_Traits, _Base> {
template <forward_range _Base>
struct _Category_base<_Base> {
// clang-format on
using iterator_category =
conditional_t<is_lvalue_reference_v<invoke_result_t<_Fn&, range_reference_t<_Base>>>,
conditional_t<derived_from<typename _Traits::iterator_category, contiguous_iterator_tag>,
random_access_iterator_tag, typename _Traits::iterator_category>,
conditional_t<derived_from<_Iter_cat_t<iterator_t<_Base>>, contiguous_iterator_tag>,
random_access_iterator_tag, _Iter_cat_t<iterator_t<_Base>>>,
input_iterator_tag>;
};

template <bool _Const>
class _Iterator : public _Category_base<iterator_traits<iterator_t<_Vw>>, _Maybe_const<_Const, _Vw>> {
class _Iterator : public _Category_base<_Maybe_const<_Const, _Vw>> {
private:
template <bool>
friend class _Iterator;
Expand Down Expand Up @@ -2902,34 +2920,24 @@ namespace ranges {
template <bool _Const>
class _Sentinel;

template <class _OuterTraits, class _InnerTraits, bool _Deref_is_glvalue,
bool _Inner_common> // TRANSITION, LWG-3289
template <class _Outer, class _Inner, bool _Deref_is_glvalue>
struct _Category_base {};

// clang-format off
template <class _OuterTraits, class _InnerTraits, bool _Deref_is_glvalue, bool _Inner_common>
requires _Has_member_iterator_category<_OuterTraits> && _Has_member_iterator_category<_InnerTraits>
struct _Category_base<_OuterTraits, _InnerTraits, _Deref_is_glvalue, _Inner_common> {
template <forward_range _Outer, forward_range _Inner>
struct _Category_base<_Outer, _Inner, true> {
using iterator_category =
conditional_t<_Deref_is_glvalue && _Inner_common // per LWG issue unnumbered as of 2021-03-16
&& derived_from<typename _OuterTraits::iterator_category, bidirectional_iterator_tag>
&& derived_from<typename _InnerTraits::iterator_category, bidirectional_iterator_tag>,
conditional_t<common_range<_Inner> // per LWG-3535
&& derived_from<_Iter_cat_t<iterator_t<_Outer>>, bidirectional_iterator_tag> //
&& derived_from<_Iter_cat_t<iterator_t<_Inner>>, bidirectional_iterator_tag>,
bidirectional_iterator_tag,
conditional_t<_Deref_is_glvalue
&& derived_from<typename _OuterTraits::iterator_category, forward_iterator_tag>
&& derived_from<typename _InnerTraits::iterator_category, forward_iterator_tag>,
forward_iterator_tag,
conditional_t<derived_from<typename _OuterTraits::iterator_category, input_iterator_tag>
&& derived_from<typename _InnerTraits::iterator_category, input_iterator_tag>,
input_iterator_tag,
output_iterator_tag>>>;
conditional_t<derived_from<_Iter_cat_t<iterator_t<_Outer>>, forward_iterator_tag> //
&& derived_from<_Iter_cat_t<iterator_t<_Inner>>, forward_iterator_tag>,
forward_iterator_tag, input_iterator_tag>>;
};
// clang-format on

template <bool _Const>
class _Iterator : public _Category_base<iterator_traits<iterator_t<_Maybe_const<_Const, _Vw>>>,
iterator_traits<iterator_t<_InnerRng<_Const>>>, is_reference_v<_InnerRng<_Const>>,
common_range<_InnerRng<_Const>>> {
class _Iterator
: public _Category_base<_Maybe_const<_Const, _Vw>, _InnerRng<_Const>, is_reference_v<_InnerRng<_Const>>> {
private:
template <bool>
friend class _Iterator;
Expand Down Expand Up @@ -3284,10 +3292,8 @@ namespace ranges {
template <class>
class _Outer_iter_base {};

// clang-format off
template <forward_iterator _Iter>
class _Outer_iter_base<_Iter> {
// clang-format on
protected:
_Iter _Current{};

Expand Down Expand Up @@ -4002,18 +4008,20 @@ namespace ranges {
template <bool _Const>
class _Sentinel;

template <class _Traits> // TRANSITION, LWG-3289
template <class _Base>
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@CaseyCarter CaseyCarter Aug 3, 2021

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Note to other reviewers: we already implement the equivalent of the split_view changes from P2259R1.

struct _Category_base {};

// clang-format off
template <_Has_member_iterator_category _Traits>
struct _Category_base<_Traits> {
// clang-format on
using iterator_category = typename _Traits::iterator_category;
template <forward_range _Base>
struct _Category_base<_Base> {
using iterator_category =
conditional_t<!is_lvalue_reference_v<decltype(_STD get<_Index>(*_STD declval<iterator_t<_Base>>()))>,
input_iterator_tag,
conditional_t<derived_from<_Iter_cat_t<iterator_t<_Base>>, random_access_iterator_tag>,
random_access_iterator_tag, _Iter_cat_t<iterator_t<_Base>>>>;
};

template <bool _Const>
class _Iterator : public _Category_base<iterator_traits<iterator_t<_Vw>>> {
class _Iterator : public _Category_base<_Maybe_const<_Const, _Vw>> {
private:
template <bool>
friend class _Iterator;
Expand Down
39 changes: 24 additions & 15 deletions stl/inc/xutility
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Original file line number Diff line number Diff line change
Expand Up @@ -441,8 +441,8 @@ struct _Old_iter_traits_pointer<false> {
template <_Has_iter_types _It>
struct _Iterator_traits_base<_It> {
using iterator_category = typename _It::iterator_category;
using difference_type = typename _It::difference_type;
using value_type = typename _It::value_type;
using difference_type = typename _It::difference_type;
using pointer = typename _Old_iter_traits_pointer<_Has_member_pointer<_It>>::template _Apply<_It>;
using reference = typename _It::reference;
};
Expand Down Expand Up @@ -481,15 +481,12 @@ concept _Cpp17_input_iterator = _Cpp17_iterator<_It>
};

template <class _It>
requires (!_Has_iter_types<_It> && _Cpp17_iterator<_It> && !_Cpp17_input_iterator<_It>
// Implements the proposed resolution of LWG-3283:
&& (!requires { typename _It::iterator_category; }
|| derived_from<typename _It::iterator_category, output_iterator_tag>))
requires (!_Has_iter_types<_It> && _Cpp17_iterator<_It> && !_Cpp17_input_iterator<_It>)
struct _Iterator_traits_base<_It> {
using iterator_category = output_iterator_tag;
using value_type = void;
using difference_type =
typename _Iter_traits_difference<_Has_member_difference_type<incrementable_traits<_It>>>::template _Apply<_It>;
using value_type = void;
using pointer = void;
using reference = void;
};
Expand Down Expand Up @@ -619,8 +616,8 @@ template <class _It>
requires (!_Has_iter_types<_It> && _Cpp17_input_iterator<_It>)
struct _Iterator_traits_base<_It> {
using iterator_category = typename _Iter_traits_category<_Has_member_iterator_category<_It>>::template _Apply<_It>;
using difference_type = typename incrementable_traits<_It>::difference_type;
using value_type = typename indirectly_readable_traits<_It>::value_type;
using difference_type = typename incrementable_traits<_It>::difference_type;
using pointer = typename _Iter_traits_pointer<(
_Has_member_pointer<_It> ? _Itraits_pointer_strategy::_Use_member
: _Has_member_arrow<_It&> ? _Itraits_pointer_strategy::_Use_decltype
Expand Down Expand Up @@ -3551,24 +3548,36 @@ struct _Default_sentinel {}; // empty struct to serve as the end of a range
#ifdef __cpp_lib_concepts
template <semiregular>
class move_sentinel;
#endif // __cpp_lib_concepts

template <class>
struct _Move_iterator_category {};

// clang-format off
template <class _Iter>
class move_iterator {
public:
using iterator_type = _Iter;
#ifdef __cpp_lib_concepts
using iterator_concept = input_iterator_tag;
requires requires { typename _Iter_cat_t<_Iter>; }
struct _Move_iterator_category<_Iter> {
using iterator_category = conditional_t<derived_from<_Iter_cat_t<_Iter>, random_access_iterator_tag>,
random_access_iterator_tag, _Iter_cat_t<_Iter>>;
#else // ^^^ __cpp_lib_concepts / !__cpp_lib_concepts vvv
};
// clang-format on
#else // ^^^ Ranges / no Ranges vvv
template <class _Iter>
struct _Move_iterator_category {
using iterator_category = _Iter_cat_t<_Iter>;
};
#endif // __cpp_lib_concepts

template <class _Iter>
class move_iterator : public _Move_iterator_category<_Iter> {
public:
using iterator_type = _Iter;
using value_type = _Iter_value_t<_Iter>;
using difference_type = _Iter_diff_t<_Iter>;
using pointer = _Iter;

#ifdef __cpp_lib_concepts
using reference = iter_rvalue_reference_t<_Iter>;
using iterator_concept = input_iterator_tag;
using reference = iter_rvalue_reference_t<_Iter>;
#else // ^^^ __cpp_lib_concepts / !__cpp_lib_concepts vvv
using reference =
conditional_t<is_reference_v<_Iter_ref_t<_Iter>>, remove_reference_t<_Iter_ref_t<_Iter>>&&, _Iter_ref_t<_Iter>>;
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@CaseyCarter CaseyCarter Aug 3, 2021

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Note to reviewers: #1939 already implemented the counted_iterator changes from P2259R1.

Expand Down
1 change: 0 additions & 1 deletion stl/inc/yvals_core.h
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Expand Up @@ -247,7 +247,6 @@
// P2106R0 Range Algorithm Result Types
// P2116R0 Removing tuple-Like Protocol Support From Fixed-Extent span
// P2259R1 Repairing Input Range Adaptors And counted_iterator
// (partially implemented)
// P2325R3 Views Should Not Be Required To Be Default Constructible
// P????R? directory_entry::clear_cache()

Expand Down
35 changes: 26 additions & 9 deletions tests/std/include/range_algorithm_support.hpp
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Expand Up @@ -592,19 +592,36 @@ namespace test {
}
};
// clang-format on

template <class Category, bool IsForward, bool IsProxy, bool EqAndCopy>
struct iterator_traits_base {};

template <class Category>
struct iterator_traits_base<Category, true, false, true> {
using iterator_category = Category;
};

template <class Category>
struct iterator_traits_base<Category, true, true, true> {
using iterator_category = input;
};

template <class Category, bool IsProxy>
struct iterator_traits_base<Category, false, IsProxy, true> {
using iterator_category = input;
};
} // namespace test

template <class Category, class Element, ::test::CanDifference Diff, ::test::CanCompare Eq, ::test::ProxyRef Proxy,
::test::IsWrapped Wrapped>
struct std::iterator_traits<::test::iterator<Category, Element, Diff, Eq, Proxy, Wrapped>> {
using iterator_concept = Category;
using iterator_category = conditional_t<derived_from<Category, forward_iterator_tag>, //
conditional_t<Proxy == ::test::ProxyRef::no, Category, input_iterator_tag>, //
conditional_t<static_cast<bool>(Eq), Category, void>>; // TRANSITION, LWG-3289
using value_type = remove_cv_t<Element>;
using difference_type = ptrdiff_t;
using pointer = conditional_t<derived_from<Category, contiguous_iterator_tag>, Element*, void>;
using reference = iter_reference_t<::test::iterator<Category, Element, Diff, Eq, Proxy, Wrapped>>;
struct std::iterator_traits<::test::iterator<Category, Element, Diff, Eq, Proxy, Wrapped>>
: ::test::iterator_traits_base<Category, derived_from<Category, forward_iterator_tag>,
Proxy == ::test::ProxyRef::yes, Eq == ::test::CanCompare::yes> {
using iterator_concept = Category;
using value_type = remove_cv_t<Element>;
using difference_type = ptrdiff_t;
using pointer = conditional_t<derived_from<Category, contiguous_iterator_tag>, Element*, void>;
using reference = iter_reference_t<::test::iterator<Category, Element, Diff, Eq, Proxy, Wrapped>>;
};

template <class Element, ::test::CanDifference Diff, ::test::IsWrapped Wrapped>
Expand Down
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