[libcxx-commits] [PATCH] D146094: [libc++][spaceship] Implement `operator<=>` for `stack`

[Hristo Hristov via Phabricator via libcxx-commits]

H-G-Hristov created this revision.
Herald added a subscriber: yaxunl.
Herald added a project: All.
H-G-Hristov requested review of this revision.
Herald added a project: libc++.
Herald added a subscriber: libcxx-commits.
Herald added a reviewer: libc++.

Depends on D146066 <https://reviews.llvm.org/D146066>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D146094

Files:
  libcxx/docs/Status/SpaceshipProjects.csv
  libcxx/include/stack
  libcxx/test/std/containers/container.adaptors/stack/compare.three_way.pass.cpp


Index: libcxx/test/std/containers/container.adaptors/stack/compare.three_way.pass.cpp
===================================================================
--- /dev/null
+++ libcxx/test/std/containers/container.adaptors/stack/compare.three_way.pass.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <stack>
+
+// template<class T, three_­way_­comparable Container>
+//   compare_three_way_result_t<Container>
+//     operator<=>(const stack<T, Container>& x, const stack<T, Container>& y);
+
+#include <cassert>
+#include <deque>
+#include <list>
+#include <stack>
+#include <vector>
+
+#include "test_container_comparisons.h"
+
+int main(int, char**) {
+  assert((test_ordered_container_adaptor_spaceship<std::stack, std::deque>()));
+  assert((test_ordered_container_adaptor_spaceship<std::stack, std::list>()));
+  // assert((test_ordered_container_adaptor_spaceship<std::stack, std::vector>())); # Not yet supported
+  // `std::stack` is not constexpr, so no `static_assert` test here.
+  return 0;
+}
Index: libcxx/include/stack
===================================================================
--- libcxx/include/stack
+++ libcxx/include/stack
@@ -89,6 +89,9 @@
   bool operator>=(const stack<T, Container>& x, const stack<T, Container>& y);
 template <class T, class Container>
   bool operator<=(const stack<T, Container>& x, const stack<T, Container>& y);
+template<class T, three_­way_­comparable Container>
+  compare_three_way_result_t<Container>
+    operator<=>(const stack<T, Container>& x, const stack<T, Container>& y); // since C++20
 
 template <class T, class Container>
   void swap(stack<T, Container>& x, stack<T, Container>& y)
@@ -266,6 +269,15 @@
     friend
     bool
     operator< (const stack<T1, _C1>& __x, const stack<T1, _C1>& __y);
+
+#if _LIBCPP_STD_VER >= 20
+
+    template<class T1, three_way_comparable _C1>
+    friend
+    compare_three_way_result_t<_C1>
+    operator<=>(const stack<T1, _C1>& __x, const stack<T1, _C1>& __y);
+
+#endif
 };
 
 #if _LIBCPP_STD_VER >= 17
@@ -346,6 +358,18 @@
     return !(__y < __x);
 }
 
+#if _LIBCPP_STD_VER >= 20
+
+template<class _Tp, three_way_comparable _Container>
+inline _LIBCPP_HIDE_FROM_ABI
+compare_three_way_result_t<_Container>
+operator<=>(const stack<_Tp, _Container>& __x, const stack<_Tp, _Container>& __y)
+{
+    return __x.c <=> __y.c;
+}
+
+#endif
+
 template <class _Tp, class _Container>
 inline _LIBCPP_INLINE_VISIBILITY
 __enable_if_t<__is_swappable<_Container>::value, void>
Index: libcxx/docs/Status/SpaceshipProjects.csv
===================================================================
--- libcxx/docs/Status/SpaceshipProjects.csv
+++ libcxx/docs/Status/SpaceshipProjects.csv
@@ -45,7 +45,7 @@
 | `[associative.set.syn] <https://wg21.link/associative.set.syn>`_ (`general <https://wg21.link/container.opt.reqmts>`_),"| multiset
 | set",[expos.only.func],Unassigned,|Not Started|
 | `[queue.ops] <https://wg21.link/queue.ops>`_,| queue,None,Unassigned,|Not Started|
-| `[stack.ops] <https://wg21.link/stack.ops>`_,| stack,None,Unassigned,|Not Started|
+| `[stack.ops] <https://wg21.link/stack.ops>`_,| `stack <>`_,None,Hristo Hristov,|Complete|
 | `[reverse.iter.cmp] <https://wg21.link/reverse.iter.cmp>`_,| `reverse_iterator <https://reviews.llvm.org/D113695>`_,None,Mikhail Maltsev,|Complete|
 | `[move.iter.op.comp] <https://wg21.link/move.iter.op.comp>`_,| `move_iterator <https://reviews.llvm.org/D117656>`_,None,Arthur O'Dwyer,|Complete|
 | `[counted.iter.cmp] <https://wg21.link/counted.iter.cmp>`_,| `counted_iterator <https://reviews.llvm.org/D106205>`_,None,Zoe Carver,|Complete|


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