[libc++][ranges] P2542R8: Implement views::concat
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implement views::concat (P2542)
Revert "implement views::concat (P2542) "
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@llvm/pr-subscribers-libcxx Author: Nhat Nguyen (changkhothuychung) ChangesPatch is 52.01 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/120920.diff 14 Files Affected:
diff --git a/libcxx/include/__ranges/concat_view.h b/libcxx/include/__ranges/concat_view.h
new file mode 100644
index 00000000000000..9d17aae65ecaf5
--- /dev/null
+++ b/libcxx/include/__ranges/concat_view.h
@@ -0,0 +1,624 @@
+// -*- 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___RANGES_CONCAT_VIEW_H
+#define _LIBCPP___RANGES_CONCAT_VIEW_H
+
+#include <__algorithm/ranges_find_if.h>
+#include <__assert>
+#include <__concepts/constructible.h>
+#include <__concepts/copyable.h>
+#include <__concepts/derived_from.h>
+#include <__concepts/equality_comparable.h>
+#include <__config>
+#include <__functional/bind_back.h>
+#include <__functional/invoke.h>
+#include <__functional/reference_wrapper.h>
+#include <__iterator/concepts.h>
+#include <__iterator/default_sentinel.h>
+#include <__iterator/distance.h>
+#include <__iterator/iter_move.h>
+#include <__iterator/iter_swap.h>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
+#include <__memory/addressof.h>
+#include <__ranges/access.h>
+#include <__ranges/all.h>
+#include <__ranges/concepts.h>
+#include <__ranges/movable_box.h>
+#include <__ranges/non_propagating_cache.h>
+#include <__ranges/range_adaptor.h>
+#include <__ranges/view_interface.h>
+#include <__type_traits/conditional.h>
+#include <__type_traits/decay.h>
+#include <__type_traits/is_nothrow_constructible.h>
+#include <__type_traits/is_nothrow_convertible.h>
+#include <__type_traits/is_object.h>
+#include <__type_traits/maybe_const.h>
+#include <__utility/forward.h>
+#include <__utility/in_place.h>
+#include <__utility/move.h>
+#include <tuple>
+#include <variant>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 20
+
+namespace ranges {
+
+template <class T, class... Ts>
+struct extract_last : extract_last<Ts...> {};
+
+template <class T>
+struct extract_last<T> {
+ using type = T;
+};
+
+template <class _T, class... _Ts>
+struct derived_from_pack {
+ constexpr static bool value =
+ derived_from_pack<_T, typename extract_last<_Ts...>::type>::value && derived_from_pack<_Ts...>::value;
+};
+
+template <class _T, class _IterCategory>
+struct derived_from_pack<_T, _IterCategory> {
+ constexpr static bool value = derived_from<_T, _IterCategory>;
+};
+
+template <class View, class... Views>
+struct last_view : last_view<Views...> {};
+
+template <class View>
+struct last_view<View> {
+ using type = View;
+};
+
+template <class Ref, class RRef, class It>
+concept concat_indirectly_readable_impl = requires(const It it) {
+ { *it } -> convertible_to<Ref>;
+ { ranges::iter_move(it) } -> convertible_to<RRef>;
+};
+
+template <class... Rs>
+using concat_reference_t = common_reference_t<range_reference_t<Rs>...>;
+
+template <class... Rs>
+using concat_value_t = common_type_t<range_value_t<Rs>...>;
+
+template <class... Rs>
+using concat_rvalue_reference_t = common_reference_t<range_rvalue_reference_t<Rs>...>;
+
+template <class... Rs>
+concept concat_indirectly_readable =
+ common_reference_with<concat_reference_t<Rs...>&&, concat_value_t<Rs...>&> &&
+ common_reference_with<concat_reference_t<Rs...>&&, concat_rvalue_reference_t<Rs...>&&> &&
+ common_reference_with<concat_rvalue_reference_t<Rs...>&&, concat_value_t<Rs...> const&> &&
+ (concat_indirectly_readable_impl<concat_reference_t<Rs...>, concat_rvalue_reference_t<Rs...>, iterator_t<Rs>> &&
+ ...);
+
+template <class... Rs>
+concept concatable = requires { // exposition only
+ typename concat_reference_t<Rs...>;
+ typename concat_value_t<Rs...>;
+ typename concat_rvalue_reference_t<Rs...>;
+} && concat_indirectly_readable<Rs...>;
+
+template <bool Const, class... Rs>
+concept concat_is_random_access =
+ (random_access_range<__maybe_const<Const, Rs>> && ...) && (sized_range<__maybe_const<Const, Rs>> && ...);
+
+template <class R>
+concept constant_time_reversible = // exposition only
+ (bidirectional_range<R> && common_range<R>) || (sized_range<R> && random_access_range<R>);
+
+template <bool Const, class... Rs>
+concept concat_is_bidirectional =
+ ((bidirectional_range<__maybe_const<Const, Rs>> && ...) &&
+ (constant_time_reversible<__maybe_const<Const, Rs>> && ...));
+
+template <bool Const, class... Views>
+concept all_forward = // exposition only
+ (forward_range<__maybe_const<Const, Views>> && ...);
+
+template <bool Const, class... Ts>
+struct apply_drop_first;
+
+template <bool Const, class Head, class... Tail>
+struct apply_drop_first<Const, Head, Tail...> {
+ static constexpr bool value = (sized_range<__maybe_const<Const, Tail>> && ...);
+};
+
+template <input_range... Views>
+ requires(view<Views> && ...) && (sizeof...(Views) > 0) && concatable<Views...>
+class concat_view : public view_interface<concat_view<Views...>> {
+ tuple<Views...> views_;
+
+ template <bool Const>
+ class iterator;
+ class sentinel;
+
+public:
+ _LIBCPP_HIDE_FROM_ABI constexpr concat_view() = default;
+
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit concat_view(Views... views) : views_(std::move(views)...) {}
+
+ constexpr iterator<false> begin()
+ requires(!(__simple_view<Views> && ...))
+ {
+ iterator<false> it(this, in_place_index<0>, ranges::begin(get<0>(views_)));
+ it.template satisfy<0>();
+ return it;
+ }
+
+ constexpr iterator<true> begin() const
+ requires((range<const Views> && ...) && concatable<const Views...>)
+ {
+ iterator<true> it(this, in_place_index<0>, ranges::begin(get<0>(views_)));
+ it.template satisfy<0>();
+ return it;
+ }
+
+ constexpr auto end()
+ requires(!(__simple_view<Views> && ...))
+ {
+ if constexpr (common_range<typename last_view<Views...>::type>) {
+ // last_view to be implemented
+ constexpr auto N = sizeof...(Views);
+ return iterator<false>(this, in_place_index<N - 1>, ranges::end(get<N - 1>(views_)));
+ } else {
+ return default_sentinel;
+ }
+ }
+
+ constexpr auto end() const
+ requires(range<const Views> && ...)
+ {
+ if constexpr (common_range<typename last_view<Views...>::type>) {
+ // last_view to be implemented
+ constexpr auto N = sizeof...(Views);
+ return iterator<true>(this, in_place_index<N - 1>, ranges::end(get<N - 1>(views_)));
+ } else {
+ return default_sentinel;
+ }
+ }
+
+ constexpr auto size()
+ requires(sized_range<Views> && ...)
+ {
+ return apply(
+ [](auto... sizes) {
+ using CT = make_unsigned_t<common_type_t<decltype(sizes)...>>;
+ return (CT(sizes) + ...);
+ },
+ tuple_transform(ranges::size, views_));
+ }
+
+ constexpr auto size() const
+ requires(sized_range<const Views> && ...)
+ {
+ return apply(
+ [](auto... sizes) {
+ using CT = make_unsigned_t<common_type_t<decltype(sizes)...>>;
+ return (CT(sizes) + ...);
+ },
+ tuple_transform(ranges::size, views_));
+ }
+};
+
+template <class... _Views>
+concat_view(_Views&&...) -> concat_view<views::all_t<_Views>...>;
+
+template <input_range... Views>
+ requires(view<Views> && ...) && (sizeof...(Views) > 0) && concatable<Views...>
+template <bool Const>
+class concat_view<Views...>::iterator {
+public:
+ constexpr static bool derive_pack_random_iterator =
+ derived_from_pack<typename iterator_traits<iterator_t<__maybe_const<Const, Views>>>::iterator_category...,
+ random_access_iterator_tag>::value;
+ constexpr static bool derive_pack_bidirectional_iterator =
+ derived_from_pack<typename iterator_traits<iterator_t<__maybe_const<Const, Views>>>::iterator_category...,
+ bidirectional_iterator_tag>::value;
+ constexpr static bool derive_pack_forward_iterator =
+ derived_from_pack<typename iterator_traits< iterator_t<__maybe_const<Const, Views>>>::iterator_category...,
+ forward_iterator_tag>::value;
+ using iterator_category =
+ _If<!is_reference_v<concat_reference_t<__maybe_const<Const, Views>...>>,
+ input_iterator_tag,
+ _If<derive_pack_random_iterator,
+ random_access_iterator_tag,
+ _If<derive_pack_bidirectional_iterator,
+ bidirectional_iterator_tag,
+ _If<derive_pack_forward_iterator, forward_iterator_tag, input_iterator_tag > > > >;
+ using iterator_concept =
+ _If<concat_is_random_access<Const, Views...>,
+ random_access_iterator_tag,
+ _If<concat_is_bidirectional<Const, Views...>,
+ bidirectional_iterator_tag,
+ _If< all_forward<Const, Views...>, forward_iterator_tag, input_iterator_tag > > >;
+ using value_type = concat_value_t<__maybe_const<Const, Views>...>;
+ using difference_type = common_type_t<range_difference_t<__maybe_const<Const, Views>>...>;
+ using base_iter = variant<iterator_t<__maybe_const<Const, Views>>...>;
+
+ base_iter it_; // exposition only
+ __maybe_const<Const, concat_view>* parent_ = nullptr; // exposition only
+
+ template <std::size_t N>
+ constexpr void satisfy() {
+ if constexpr (N < (sizeof...(Views) - 1)) {
+ if (get<N>(it_) == ranges::end(get<N>(parent_->views_))) {
+ it_.template emplace<N + 1>(ranges::begin(get<N + 1>(parent_->views_)));
+ satisfy<N + 1>();
+ }
+ }
+ }
+
+ template <std::size_t N>
+ constexpr void prev() {
+ if constexpr (N == 0) {
+ --get<0>(it_);
+ } else {
+ if (get<N>(it_) == ranges::begin(get<N>(parent_->views_))) {
+ using prev_view = __maybe_const<Const, tuple_element_t<N - 1, tuple<Views...>>>;
+ if constexpr (common_range<prev_view>) {
+ it_.emplace<N - 1>(ranges::end(get<N - 1>(parent_->views_)));
+ } else {
+ it_.emplace<N - 1>(
+ ranges::__next(ranges::begin(get<N - 1>(parent_->views_)), ranges::size(get<N - 1>(parent_->views_))));
+ }
+ prev<N - 1>();
+ } else {
+ --get<N>(it_);
+ }
+ }
+ }
+
+ template <std::size_t N>
+ constexpr void advance_fwd(difference_type offset, difference_type steps) {
+ using underlying_diff_type = iter_difference_t<variant_alternative_t<N, base_iter>>;
+ if constexpr (N == sizeof...(Views) - 1) {
+ get<N>(it_) += static_cast<underlying_diff_type>(steps);
+ } else {
+ difference_type n_size = ranges::size(get<N>(parent_->views_));
+ if (offset + steps < n_size) {
+ get<N>(it_) += static_cast<underlying_diff_type>(steps);
+ } else {
+ it_.template emplace<N + 1>(ranges::begin(get<N + 1>(parent_->views_)));
+ advance_fwd<N + 1>(0, offset + steps - n_size);
+ }
+ }
+ }
+
+ template <std::size_t N>
+ constexpr void advance_bwd(difference_type offset, difference_type steps) {
+ using underlying_diff_type = iter_difference_t<variant_alternative_t<N, base_iter>>;
+ if constexpr (N == 0) {
+ get<N>(it_) -= static_cast<underlying_diff_type>(steps);
+ } else {
+ if (offset >= steps) {
+ get<N>(it_) -= static_cast<underlying_diff_type>(steps);
+ } else {
+ auto prev_size = ranges::__distance(get<N - 1>(parent_->views_));
+ it_.emplace<N - 1>(ranges::begin(get<N - 1>(parent_->views_)) + prev_size);
+ advance_bwd<N - 1>(prev_size, steps - offset);
+ }
+ }
+ }
+
+ template <size_t... Is, typename Func>
+ constexpr void apply_fn_with_const_index(size_t index, Func&& func, std::index_sequence<Is...>) {
+ ((index == Is ? (func(std::integral_constant<size_t, Is>{}), 0) : 0), ...);
+ }
+
+ template <size_t N, typename Func>
+ constexpr void apply_fn_with_const_index(size_t index, Func&& func) {
+ apply_fn_with_const_index(index, std::forward<Func>(func), std::make_index_sequence<N>{});
+ }
+
+ template <class... Args>
+ explicit constexpr iterator(__maybe_const<Const, concat_view>* parent, Args&&... args)
+ requires constructible_from<base_iter, Args&&...>
+ : it_(std::forward<Args>(args)...), parent_(parent) {}
+
+public:
+ iterator() = default;
+
+ constexpr iterator(iterator<!Const> i)
+ requires Const && (convertible_to<iterator_t<Views>, iterator_t<const Views>> && ...)
+ : it_(base_iter(in_place_index<i.index()>, std::get<i.index()>(std::move(i.it_)))), parent_(i.parent_) {}
+
+ constexpr decltype(auto) operator*() const {
+ using reference = concat_reference_t<__maybe_const<Const, Views>...>;
+ return std::visit([](auto&& it) -> reference { return *it; }, it_);
+ }
+
+ constexpr iterator& operator++() {
+ size_t active_index = it_.index();
+ apply_fn_with_const_index<std::variant_size_v<decltype(it_)>>(active_index, [&](auto index_constant) {
+ constexpr size_t i = index_constant.value;
+ ++get<i>(it_);
+ satisfy<i>();
+ });
+ return *this;
+ }
+
+ constexpr void operator++(int) { ++*this; }
+
+ constexpr iterator operator++(int)
+ requires(forward_range<__maybe_const<Const, Views>> && ...)
+ {
+ auto tmp = *this;
+ ++*this;
+ return tmp;
+ }
+
+ constexpr iterator& operator--()
+ requires concat_is_bidirectional<Const, Views...>
+ {
+ size_t active_index = it_.index();
+ apply_fn_with_const_index<std::variant_size_v<decltype(it_)>>(active_index, [&](auto index_constant) {
+ constexpr size_t i = index_constant.value;
+ prev<i>();
+ });
+ return *this;
+ }
+
+ constexpr iterator operator--(int)
+ requires concat_is_bidirectional<Const, Views...>
+ {
+ auto __tmp = *this;
+ --*this;
+ return __tmp;
+ }
+
+ friend constexpr bool operator==(const iterator& x, const iterator& y)
+ requires(equality_comparable<iterator_t<__maybe_const<Const, Views>>> && ...)
+ {
+ return x.it_ == y.it_;
+ }
+
+ constexpr decltype(auto) operator[](difference_type n) const
+ requires concat_is_random_access<Const, Views...>
+ {
+ return *((*this) + n);
+ }
+
+ friend constexpr iterator operator+(const iterator& it, difference_type n)
+ requires concat_is_random_access<Const, Views...>
+ {
+ auto temp = it;
+ temp += n;
+ return temp;
+ }
+
+ friend constexpr iterator operator+(difference_type n, const iterator& it)
+ requires concat_is_random_access<Const, Views...>
+ {
+ return it + n;
+ }
+
+ constexpr iterator& operator+=(difference_type n)
+ requires concat_is_random_access<Const, Views...>
+ {
+ size_t active_index = it_.index();
+ if (n > 0) {
+ std::visit(
+ [&](auto& active_it) {
+ apply_fn_with_const_index<std::tuple_size_v<decltype(parent_->views_)>>(
+ active_index, [&](auto index_constant) {
+ constexpr size_t I = index_constant.value;
+ auto& active_view = std::get<I>(parent_->views_);
+ difference_type idx = active_it - ranges::begin(active_view);
+ advance_fwd<I>(idx, n);
+ });
+ },
+ it_);
+ }
+
+ else if (n < 0) {
+ std::visit(
+ [&](auto& active_it) {
+ apply_fn_with_const_index<std::tuple_size_v<decltype(parent_->views_)>>(
+ active_index, [&](auto index_constant) {
+ constexpr size_t I = index_constant.value;
+ auto& active_view = std::get<I>(parent_->views_);
+ difference_type idx = active_it - ranges::begin(active_view);
+ advance_bwd<I>(idx, -n);
+ });
+ },
+ it_);
+ }
+
+ return *this;
+ }
+
+ constexpr iterator& operator-=(difference_type n)
+ requires concat_is_random_access<Const, Views...>
+ {
+ *this += -n;
+ return *this;
+ }
+
+ friend constexpr bool operator==(const iterator& it, default_sentinel_t) {
+ constexpr auto last_idx = sizeof...(Views) - 1;
+ return it.it_.index() == last_idx &&
+ std::get<last_idx>(it.it_) == ranges::end(std::get<last_idx>(it.parent_->views_));
+ }
+
+ friend constexpr bool operator<(const iterator& x, const iterator& y)
+ requires(random_access_range<__maybe_const<Const, Views>> && ...)
+ {
+ return x.it_ < y.it_;
+ }
+
+ friend constexpr bool operator>(const iterator& x, const iterator& y)
+ requires(random_access_range<__maybe_const<Const, Views>> && ...)
+ {
+ return x.it_ > y.it_;
+ }
+
+ friend constexpr bool operator<=(const iterator& x, const iterator& y)
+ requires(random_access_range<__maybe_const<Const, Views>> && ...)
+ {
+ return x.it_ <= y.it_;
+ }
+
+ friend constexpr bool operator>=(const iterator& x, const iterator& y)
+ requires(random_access_range<__maybe_const<Const, Views>> && ...)
+ {
+ return x.it_ >= y.it_;
+ }
+
+ friend constexpr auto operator<=>(const iterator& x, const iterator& y)
+ requires((random_access_range<__maybe_const<Const, Views>> && ...) &&
+ (three_way_comparable<__maybe_const<Const, Views>> && ...))
+ {
+ return x.it_ <=> y.it_;
+ }
+
+ friend constexpr decltype(auto) iter_move(const iterator& it) noexcept(
+
+ ((is_nothrow_invocable_v< decltype(ranges::iter_move), const iterator_t<__maybe_const<Const, Views>>& >) &&
+ ...) &&
+ ((is_nothrow_convertible_v< range_rvalue_reference_t<__maybe_const<Const, Views>>,
+ concat_rvalue_reference_t<__maybe_const<Const, Views>...> >) &&
+ ...))
+
+ {
+ return std::visit(
+ [](const auto& i) -> concat_rvalue_reference_t<__maybe_const<Const, Views>...> { return ranges::iter_move(i); },
+ it.it_);
+ }
+
+ friend constexpr void iter_swap(const iterator& x, const iterator& y)
+
+ noexcept((noexcept(ranges::swap(*x, *y))) &&
+ (noexcept(ranges::iter_swap(std::declval<const iterator_t<__maybe_const<Const, Views>>>(),
+ std::declval<const iterator_t<__maybe_const<Const, Views>>>())) &&
+ ...))
+
+ requires swappable_with<iter_reference_t<iterator>, iter_reference_t<iterator>> &&
+ (... && indirectly_swappable<iterator_t<__maybe_const<Const, Views>>>)
+ {
+ std::visit(
+ [&](const auto& it1, const auto& it2) {
+ if constexpr (is_same_v<decltype(it1), decltype(it2)>) {
+ ranges::iter_swap(it1, it2);
+ } else {
+ ranges::swap(*x, *y);
+ }
+ },
+ x.it_,
+ y.it_);
+ }
+
+ friend constexpr difference_type operator-(const iterator& x, const iterator& y)
+ requires concat_is_random_access<Const, Views...>
+ {
+ size_t ix = x.it_.index();
+ size_t iy = y.it_.index();
+
+ if (ix > iy) {
+ std::visit(
+ [&](auto& it_x, auto& it_y) {
+ it_x.apply_fn_with_const_index<std::tuple_size_v<decltype(x.parent_->views_)>>(
+ ix, [&](auto index_constant) {
+ constexpr size_t index_x = index_constant.value;
+ auto dx = ranges::__distance(ranges::begin(std::get<index_x>(x.parent_->views_)), it_x);
+
+ it_y.apply_fn_with_const_index<std::tuple_size_v<decltype(y.parent_->views_)>>(
+ iy, [&](auto index_constant) {
+ constexpr size_t index_y = index_constant.value;
+ auto dy = ranges::__distance(ranges::begin(std::get<index_y>(y.parent_->views_)), it_y);
+ difference_type s = 0;
+ for (size_t idx = index_y + 1; idx < index_x; idx++) {
+ s += ranges::size(std::get<idx>(x.parent_->views_));
+ }
+ return dy + s + dx;
+ });
+ });
+ },
+ x.it_,
+ y.it_);
+ } else if (ix < iy) {
+ return -(y - x);
+ } else {
+ std::visit([&](const auto& it1, const auto& it2) { return it1 - it2; }, x.it_, y.it_);
+ }
+ }
+
+ friend constexpr iterator operator-(const iterator& it, difference_type n)
+ requires concat_is_random_access<Const, Views...>
+ {
+ auto temp = it;
+ temp -= n;
+ re...
[truncated]
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✅ With the latest revision this PR passed the C/C++ code formatter. |
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I have no idea why I am getting |
changkhothuychung
changed the title
hawkinsw
reviewed
Dec 24, 2024
libcxx/test/std/ranges/range.adaptors/range.concat/ctad.pass.cpp
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philnik777
requested changes
Dec 24, 2024
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Please make sure you're following the libc++ Coding Guidelines.
will take another pass this weekend |
huixie90
requested changes
May 18, 2025
| namespace views { | ||
| namespace __concat { | ||
| struct __fn { | ||
| template <input_range _Range> |
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i would avoid putting extra contraints here and just rely on the return type SFIANE
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i would avoid putting extra contraints here and just rely on the return type SFIANE
This seems more complicated to me. Does views::all already reject non-input ranges?
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It doesn't. This corresponds to LWG4082, and I think it's fine to just use extra constraints.
…e some expositions shareable)
|
Hi @huixie90 , I addressed most of the comments, and need your follow-ups on the remaining ones. Thanks! |
|
will have a pass today |
huixie90
requested changes
Jun 29, 2025
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I only looked the concat_view and the tests for concat_view itself. i have not look at the iterators yet. I think we need a bit more test coverage, especially we need to tests that concat more than one ranges. Could you please also go over the iterator tests with respect to the spec. Ideally, every single word in the spec needs to be tested. Thanks a lot for your contribution
| #include <__ranges/range_adaptor.h> | ||
| #include <__ranges/size.h> | ||
| #include <__ranges/view_interface.h> | ||
| #include <__ranges/zip_view.h> |
There was a problem hiding this comment.
what is the reason to include this header?
| constexpr bool __derived_from_pack<_Tp, _IterCategory> = derived_from<_Tp, _IterCategory>; | ||
|
|
||
| template <class _View, class... _Views> | ||
| struct __last_view : __last_view<_Views...> {}; |
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isn't this just the __extract_last you defined above?
| # endif | ||
|
|
||
| template <class _Tp, class... _Tail> | ||
| constexpr bool __derived_from_pack = |
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missing an inline here.
what is the reason not to follow the spec, which is just
(derived_from<_Tp, _Cat> && ...)
| struct __apply_drop_first; | ||
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| template <bool _Const, class _Head, class... _Tail> | ||
| struct __apply_drop_first<_Const, _Head, _Tail...> { |
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the name of this is a bit confusing. because what it actualy checks is that "all but the first range models sized_range"
| @@ -171,6 +172,34 @@ concept __concatable = requires { | |||
| typename __concat_rvalue_reference_t<_Rs...>; | |||
| } && __concat_indirectly_readable<_Rs...>; | |||
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| template <bool _Const, class... _Views> | |||
| concept __all_random_access = (random_access_range<__maybe_const<_Const, _Views>> && ...); | |||
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I think most of the things added to this file are only used by concat_view. So they should go to concat_view.h
Only __concatable should stay in this file, as join_with view seems to use it
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| #include <cassert> | ||
| #include "test_iterators.h" | ||
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We need to test where the first view is empty and begin is jumping to the begin of the first non empty view
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| #include <cassert> | ||
| #include "test_iterators.h" | ||
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i think this does does not test if constexpr (common_range<maybe-const<is-const, Views...[N - 1]>>) succfiently. if you do, you probably find the bug in the spec
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| } | ||
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| _LIBCPP_HIDE_FROM_ABI constexpr auto size() |
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missing tests for both size functions
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| template <input_range... _Views> | ||
| requires(view<_Views> && ...) && (sizeof...(_Views) > 0) && __concatable<_Views...> |
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it would be good to test all these constraints. especially the negative test cases
| constexpr bool test() { | ||
| { | ||
| View v; | ||
| std::ranges::concat_view view(v); |
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we need tests for concatenating more than one ranges
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Closes #105419
Closes #105348
Closes #105349