[libcxx-commits] [libcxx] [libc++][ranges] LWG4001: `iota_view` should provide `empty` (PR #79687)
Hristo Hristov via libcxx-commits
libcxx-commits at lists.llvm.org
Sat Jan 27 14:57:58 PST 2024
https://github.com/Zingam updated https://github.com/llvm/llvm-project/pull/79687
>From 87fe530b0a6afffb041f727ce261affc59d39d50 Mon Sep 17 00:00:00 2001
From: Zingam <zingam at outlook.com>
Date: Thu, 11 Jan 2024 10:04:20 +0200
Subject: [PATCH 1/2] [libc++][ranges] LWG4001: `iota_view` should provide
`empty`
Implements: https://wg21.link/LWG4001
- https://eel.is/c++draft/range.iota.view
---
libcxx/docs/Status/Cxx2cIssues.csv | 2 +-
libcxx/include/__ranges/iota_view.h | 2 +
.../range.iota.view/empty.pass.cpp | 136 ++++++++++++++++++
3 files changed, 139 insertions(+), 1 deletion(-)
create mode 100644 libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp
diff --git a/libcxx/docs/Status/Cxx2cIssues.csv b/libcxx/docs/Status/Cxx2cIssues.csv
index b69b0948325412d..6401c7c6d8fc7d2 100644
--- a/libcxx/docs/Status/Cxx2cIssues.csv
+++ b/libcxx/docs/Status/Cxx2cIssues.csv
@@ -38,7 +38,7 @@
"`3974 <https://wg21.link/LWG3974>`__","``mdspan::operator[]`` should not copy ``OtherIndexTypes``","Kona November 2023","","",""
"`3987 <https://wg21.link/LWG3987>`__","Including ``<flat_foo>`` doesn't provide ``std::begin``/``end``","Kona November 2023","","","|flat_containers|"
"`3990 <https://wg21.link/LWG3990>`__","Program-defined specializations of ``std::tuple`` and ``std::variant`` can't be properly supported","Kona November 2023","","",""
-"`4001 <https://wg21.link/LWG4001>`__","``iota_view`` should provide ``empty``","Kona November 2023","","","|ranges|"
+"`4001 <https://wg21.link/LWG4001>`__","``iota_view`` should provide ``empty``","Kona November 2023","|Complete|","19.0","|ranges|"
"","","","","",""
"`3343 <https://wg21.link/LWG3343>`__","Ordering of calls to ``unlock()`` and ``notify_all()`` in Effects element of ``notify_all_at_thread_exit()`` should be reversed","Not Yet Adopted","|Complete|","16.0",""
"","","","","",""
diff --git a/libcxx/include/__ranges/iota_view.h b/libcxx/include/__ranges/iota_view.h
index c8314dd848b4473..6c5923c7ef013c2 100644
--- a/libcxx/include/__ranges/iota_view.h
+++ b/libcxx/include/__ranges/iota_view.h
@@ -345,6 +345,8 @@ class iota_view : public view_interface<iota_view<_Start, _BoundSentinel>> {
return __iterator{__bound_sentinel_};
}
+ _LIBCPP_HIDE_FROM_ABI constexpr bool empty() const { return __value_ == __bound_sentinel_; }
+
_LIBCPP_HIDE_FROM_ABI constexpr auto size() const
requires(same_as<_Start, _BoundSentinel> && __advanceable<_Start>) ||
(integral<_Start> && integral<_BoundSentinel>) || sized_sentinel_for<_BoundSentinel, _Start>
diff --git a/libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp b/libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp
new file mode 100644
index 000000000000000..e7adffaf63b4c91
--- /dev/null
+++ b/libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp
@@ -0,0 +1,136 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+
+// constexpr bool empty() const;
+
+#include <cassert>
+#include <concepts>
+#include <ranges>
+#include <utility>
+#include <vector>
+
+#include "types.h"
+
+template <typename R>
+concept HasFreeEmpty = requires(R r) { std::ranges::empty(r); };
+
+template <typename R>
+concept HasMemberEmpty = requires(R r) {
+ { r.empty() } -> std::same_as<bool>;
+};
+
+constexpr void test_empty_iota() {
+ std::vector<int> ev;
+
+ // Both parameters are non-const
+ {
+ auto iv = std::views::iota(std::ranges::begin(ev), std::ranges::end(ev));
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(iv.empty());
+ }
+ // Left paramter is const
+ {
+ auto iv = std::views::iota(std::ranges::begin(std::as_const(ev)), std::ranges::end(ev));
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(iv.empty());
+ }
+ // Right paramter is const
+ {
+ auto iv = std::views::iota(std::ranges::begin(ev), std::ranges::end(std::as_const(ev)));
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(iv.empty());
+ }
+ // Both parameters are const
+ {
+ auto iv = std::views::iota(std::ranges::begin(std::as_const(ev)), std::ranges::end(std::as_const(ev)));
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(iv.empty());
+ }
+
+ std::vector<char> v{'b', 'a', 'b', 'a', 'z', 'm', 't'};
+ auto fv = v | std::views::filter([](auto val) { return val == '0'; });
+
+ {
+ auto iv = std::views::iota(std::ranges::begin(fv), std::ranges::end(fv));
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(iv.empty());
+ }
+}
+
+constexpr void test_nonempty_iota() {
+ // Default ctr
+ {
+ std::ranges::iota_view<Int42<DefaultTo42>> iv;
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(!iv.empty());
+ }
+ // Value pass
+ {
+ std::ranges::iota_view<SomeInt> iv(SomeInt(94));
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(!iv.empty());
+ }
+
+ {
+ std::vector<char> v;
+ auto it = std::back_inserter(v);
+ auto iv = std::views::iota(it);
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(!iv.empty());
+ }
+ {
+ std::vector<char> v{'b', 'a', 'b', 'a', 'z', 'm', 't'};
+ auto it = std::back_inserter(v);
+ auto iv = std::views::iota(it);
+
+ static_assert(HasFreeEmpty<decltype(iv)>);
+ static_assert(HasMemberEmpty<decltype(iv)>);
+
+ assert(!iv.empty());
+ }
+}
+
+constexpr bool test() {
+ test_empty_iota();
+ test_nonempty_iota();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
>From 550a505f37c23c90bd10a0802ab0144d4e57ed70 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <zingam at outlook.com>
Date: Sun, 28 Jan 2024 00:57:51 +0200
Subject: [PATCH 2/2] Update
libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp
Co-authored-by: Will Hawkins <whh8b at obs.cr>
---
.../std/ranges/range.factories/range.iota.view/empty.pass.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp b/libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp
index e7adffaf63b4c91..28af27297cbd88a 100644
--- a/libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp
+++ b/libcxx/test/std/ranges/range.factories/range.iota.view/empty.pass.cpp
@@ -38,7 +38,7 @@ constexpr void test_empty_iota() {
assert(iv.empty());
}
- // Left paramter is const
+ // Left parameter is const
{
auto iv = std::views::iota(std::ranges::begin(std::as_const(ev)), std::ranges::end(ev));
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