[libcxx-commits] [libcxx] 205557c - [libc++][ranges] Implement ranges::max_element
Nikolas Klauser via libcxx-commits
libcxx-commits at lists.llvm.org
Mon Mar 7 08:17:05 PST 2022
Author: Nikolas Klauser
Date: 2022-03-07T17:11:23+01:00
New Revision: 205557c908ff24e7b691c8948aaa516e61b9428d
URL: https://github.com/llvm/llvm-project/commit/205557c908ff24e7b691c8948aaa516e61b9428d
DIFF: https://github.com/llvm/llvm-project/commit/205557c908ff24e7b691c8948aaa516e61b9428d.diff
LOG: [libc++][ranges] Implement ranges::max_element
Implement ranges::max_element
Reviewed By: Quuxplusone, #libc
Spies: libcxx-commits, mgorny
Differential Revision: https://reviews.llvm.org/D117523
Added:
libcxx/include/__algorithm/ranges_max_element.h
libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_max_element.module.verify.cpp
libcxx/test/std/algorithms/alg.sorting/alg.min.max/ranges.max_element.pass.cpp
Modified:
libcxx/include/CMakeLists.txt
libcxx/include/algorithm
libcxx/include/module.modulemap
libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
Removed:
################################################################################
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index cc0a0ee421e1b..df30c80997e82 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -66,6 +66,7 @@ set(files
__algorithm/pop_heap.h
__algorithm/prev_permutation.h
__algorithm/push_heap.h
+ __algorithm/ranges_max_element.h
__algorithm/ranges_min_element.h
__algorithm/ranges_swap_ranges.h
__algorithm/remove.h
diff --git a/libcxx/include/__algorithm/ranges_max_element.h b/libcxx/include/__algorithm/ranges_max_element.h
new file mode 100644
index 0000000000000..80aafbe568580
--- /dev/null
+++ b/libcxx/include/__algorithm/ranges_max_element.h
@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___ALGORITHM_RANGES_MAX_ELEMENT_H
+#define _LIBCPP___ALGORITHM_RANGES_MAX_ELEMENT_H
+
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/invoke.h>
+#include <__functional/ranges_operations.h>
+#include <__iterator/concepts.h>
+#include <__iterator/projected.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+namespace __max_element {
+struct __fn {
+ template <class _Ip, class _Sp, class _Proj, class _Comp>
+ _LIBCPP_HIDE_FROM_ABI static constexpr
+ _Ip __go(_Ip __first, _Sp __last, _Comp& __comp, _Proj& __proj) {
+ if (__first == __last)
+ return __first;
+
+ _Ip __i = __first;
+ while (++__i != __last)
+ if (std::invoke(__comp, std::invoke(__proj, *__first), std::invoke(__proj, *__i)))
+ __first = __i;
+ return __first;
+ }
+
+ template <forward_iterator _Ip, sentinel_for<_Ip> _Sp, class _Proj = identity,
+ indirect_strict_weak_order<projected<_Ip, _Proj>> _Comp = ranges::less>
+ _LIBCPP_HIDE_FROM_ABI constexpr
+ _Ip operator()(_Ip __first, _Sp __last, _Comp __comp = {}, _Proj __proj = {}) const {
+ return __go(__first, __last, __comp, __proj);
+ }
+
+ template <forward_range _Rp, class _Proj = identity,
+ indirect_strict_weak_order<projected<iterator_t<_Rp>, _Proj>> _Comp = ranges::less>
+ _LIBCPP_HIDE_FROM_ABI constexpr
+ borrowed_iterator_t<_Rp> operator()(_Rp&& __r, _Comp __comp = {}, _Proj __proj = {}) const {
+ return __go(ranges::begin(__r), ranges::end(__r), __comp, __proj);
+ }
+};
+} // namespace __max_element
+
+inline namespace __cpo {
+ inline constexpr auto max_element = __max_element::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+#endif // _LIBCPP___ALGORITHM_RANGES_MAX_ELEMENT_H
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 8bff2069c4308..6b5bc0cd9acb9 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -763,6 +763,7 @@ template <class BidirectionalIterator, class Compare>
#include <__algorithm/pop_heap.h>
#include <__algorithm/prev_permutation.h>
#include <__algorithm/push_heap.h>
+#include <__algorithm/ranges_max_element.h>
#include <__algorithm/ranges_min_element.h>
#include <__algorithm/ranges_swap_ranges.h>
#include <__algorithm/remove.h>
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
index 48f05bab1b2e6..1577c005dae40 100644
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -294,6 +294,7 @@ module std [system] {
module pop_heap { private header "__algorithm/pop_heap.h" }
module prev_permutation { private header "__algorithm/prev_permutation.h" }
module push_heap { private header "__algorithm/push_heap.h" }
+ module ranges_max_element { private header "__algorithm/ranges_max_element.h" }
module ranges_min_element { private header "__algorithm/ranges_min_element.h" }
module ranges_swap_ranges { private header "__algorithm/ranges_swap_ranges.h" }
module remove { private header "__algorithm/remove.h" }
diff --git a/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_max_element.module.verify.cpp b/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_max_element.module.verify.cpp
new file mode 100644
index 0000000000000..e92bbd7fe8504
--- /dev/null
+++ b/libcxx/test/libcxx/diagnostics/detail.headers/algorithm/ranges_max_element.module.verify.cpp
@@ -0,0 +1,15 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: modules-build
+
+// WARNING: This test was generated by 'generate_private_header_tests.py'
+// and should not be edited manually.
+
+// expected-error@*:* {{use of private header from outside its module: '__algorithm/ranges_max_element.h'}}
+#include <__algorithm/ranges_max_element.h>
diff --git a/libcxx/test/std/algorithms/alg.sorting/alg.min.max/ranges.max_element.pass.cpp b/libcxx/test/std/algorithms/alg.sorting/alg.min.max/ranges.max_element.pass.cpp
new file mode 100644
index 0000000000000..9815e2ad7c139
--- /dev/null
+++ b/libcxx/test/std/algorithms/alg.sorting/alg.min.max/ranges.max_element.pass.cpp
@@ -0,0 +1,194 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// <algorithm>
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: libcpp-has-no-incomplete-ranges
+
+// template<forward_iterator I, sentinel_for<I> S, class Proj = identity,
+// indirect_strict_weak_order<projected<I, Proj>> Comp = ranges::less>
+// constexpr I ranges::max_element(I first, S last, Comp comp = {}, Proj proj = {});
+//
+// template<forward_range R, class Proj = identity,
+// indirect_strict_weak_order<projected<iterator_t<R>, Proj>> Comp = ranges::less>
+// constexpr borrowed_iterator_t<R> ranges::max_element(R&& r, Comp comp = {}, Proj proj = {});
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <random>
+#include <ranges>
+
+#include "test_macros.h"
+#include "test_iterators.h"
+
+template <class T>
+concept HasMaxElement = requires (T t) { std::ranges::max_element(t); };
+
+struct NoLessThanOp {};
+struct NotTotallyOrdered {
+ int i;
+ bool operator<(const NotTotallyOrdered& o) const { return i < o.i; }
+};
+
+static_assert(HasMaxElement<std::array<int, 0>>);
+static_assert(!HasMaxElement<int>);
+static_assert(!HasMaxElement<NoLessThanOp>);
+static_assert(!HasMaxElement<NotTotallyOrdered>);
+
+template <class Iter>
+constexpr void test_iterators(Iter first, Iter last) {
+ std::same_as<Iter> auto it = std::ranges::max_element(first, last);
+ if (first != last) {
+ for (Iter j = first; j != last; ++j)
+ assert(!(*j > *it));
+ } else {
+ assert(it == first);
+ }
+}
+
+template <class Range, class Iter>
+constexpr void test_range(Range&& rng, Iter begin, Iter end) {
+ std::same_as<Iter> auto it = std::ranges::max_element(std::forward<Range>(rng));
+ if (begin != end) {
+ for (Iter j = begin; j != end; ++j)
+ assert(!(*j > *it));
+ } else {
+ assert(it == begin);
+ }
+}
+
+template <class It>
+constexpr void test(std::initializer_list<int> a, int expected) {
+ const int* first = a.begin();
+ const int* last = a.end();
+ {
+ std::same_as<It> auto it = std::ranges::max_element(It(first), It(last));
+ assert(base(it) == first + expected);
+ }
+ {
+ using Sent = sentinel_wrapper<It>;
+ std::same_as<It> auto it = std::ranges::max_element(It(first), Sent(It(last)));
+ assert(base(it) == first + expected);
+ }
+ {
+ auto range = std::ranges::subrange(It(first), It(last));
+ std::same_as<It> auto it = std::ranges::max_element(range);
+ assert(base(it) == first + expected);
+ }
+ {
+ using Sent = sentinel_wrapper<It>;
+ auto range = std::ranges::subrange(It(first), Sent(It(last)));
+ std::same_as<It> auto it = std::ranges::max_element(range);
+ assert(base(it) == first + expected);
+ }
+}
+
+template <class It>
+constexpr bool test() {
+ test<It>({}, 0);
+ test<It>({1}, 0);
+ test<It>({1, 2}, 1);
+ test<It>({2, 1}, 0);
+ test<It>({2, 1, 2}, 0);
+ test<It>({2, 1, 1}, 0);
+
+ return true;
+}
+
+constexpr void test_borrowed_range_and_sentinel() {
+ int a[] = {7, 6, 1, 3, 5, 1, 2, 4};
+
+ int* ret = std::ranges::max_element(std::views::all(a));
+ assert(ret == a + 0);
+ assert(*ret == 7);
+}
+
+constexpr void test_comparator() {
+ int a[] = {7, 6, 9, 3, 5, 1, 2, 4};
+ int* ret = std::ranges::max_element(a, std::ranges::greater{});
+ assert(ret == a + 5);
+ assert(*ret == 1);
+}
+
+constexpr void test_projection() {
+ int a[] = {7, 6, 9, 3, 5, 1, 2, 4};
+ {
+ int* ret = std::ranges::max_element(a, std::ranges::less{}, [](int i) { return i == 5 ? 100 : i; });
+ assert(ret == a + 4);
+ assert(*ret == 5);
+ }
+ {
+ int* ret = std::ranges::max_element(a, std::less<int*>{}, [](int& i) { return &i; });
+ assert(ret == a + 7);
+ assert(*ret == 4);
+ }
+}
+
+struct Immobile {
+ int i;
+
+ constexpr Immobile(int i_) : i(i_) {}
+ Immobile(const Immobile&) = delete;
+ Immobile(Immobile&&) = delete;
+
+ auto operator<=>(const Immobile&) const = default;
+};
+
+constexpr void test_immobile() {
+
+ Immobile arr[] {1, 2, 3};
+ assert(std::ranges::max_element(arr) == arr);
+ assert(std::ranges::max_element(arr, arr + 3) == arr);
+}
+
+constexpr void test_dangling() {
+ int compares = 0;
+ int projections = 0;
+ auto comparator = [&](int a, int b) {
+ ++compares;
+ return a < b;
+ };
+ auto projection = [&](int a) {
+ ++projections;
+ return a;
+ };
+ [[maybe_unused]] std::same_as<std::ranges::dangling> auto ret =
+ std::ranges::max_element(std::array{1, 2, 3}, comparator, projection);
+ assert(compares == 2);
+ assert(projections == 4);
+}
+
+constexpr bool test() {
+
+ test<forward_iterator<const int*>>();
+ test<bidirectional_iterator<const int*>>();
+ test<random_access_iterator<const int*>>();
+ test<const int*>();
+
+ int a[] = {7, 6, 5, 3, 4, 2, 1, 8};
+ test_iterators(a, a + 8);
+ int a2[] = {7, 6, 5, 3, 4, 2, 1, 8};
+ test_range(a2, a2, a2 + 8);
+
+ test_borrowed_range_and_sentinel();
+ test_comparator();
+ test_projection();
+ test_dangling();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp b/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
index fb7039c46c0fa..d2a08ae600f65 100644
--- a/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
+++ b/libcxx/test/std/library/description/conventions/customization.point.object/niebloid.compile.pass.cpp
@@ -98,7 +98,7 @@ int a[10];
//static_assert(test(std::ranges::lower_bound, a, 42));
//static_assert(test(std::ranges::make_heap, a));
//static_assert(test(std::ranges::max, a));
-//static_assert(test(std::ranges::max_element, a));
+static_assert(test(std::ranges::max_element, a));
//static_assert(test(std::ranges::merge, a, a, a));
//static_assert(test(std::ranges::min, a));
static_assert(test(std::ranges::min_element, a));
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