Commit 8ce2675b authored by Ruslan Arutyunyan's avatar Ruslan Arutyunyan Committed by Kent Ross
Browse files

[libc++][compare] Implement three_way_comparable[_with] concepts 

Implementation of `three_way_comparable` and `three_way_comparable_with` concepts from <compare> header.

Please note that I have temporarily removed `<compare>` header from `<utility>` due to cyclic dependency that prevents using `<concepts>` header in `<compare>` one.

I tried to quickly resolve those issues including applying suggestions from @cjdb and dive deeper by myself but the problem seems more complicated that we thought initially.

I am in progress to prepare the patch with resolving this cyclic dependency between headers but for now I decided to put all that I have to the review to unblock people that depend on that functionality. At first glance the patch with resolving cyclic dependency is not so small (unless I find the way to make it smaller and cleaner) so I don't want to mix everything to one review.

Reviewed By: ldionne, cjdb, #libc, Quuxplusone

Differential Revision: https://reviews.llvm.org/D103478
parent 1a88bd68

libcxx/include/CMakeLists.txt

+1 −0
Original line number Diff line number Diff line
@@ -103,6 +103,7 @@ set(files 
  __compare/common_comparison_category.h

  __compare/compare_three_way_result.h

  __compare/ordering.h

  __compare/three_way_comparable.h

  __concepts/arithmetic.h

  __concepts/assignable.h

  __concepts/boolean_testable.h

libcxx/include/__compare/three_way_comparable.h

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//===----------------------------------------------------------------------===//

//

// 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___COMPARE_THREE_WAY_COMPARABLE_H

#define _LIBCPP___COMPARE_THREE_WAY_COMPARABLE_H



#include <__compare/common_comparison_category.h>

#include <__compare/ordering.h>

#include <__concepts/common_reference_with.h>

#include <__concepts/equality_comparable.h>

#include <__concepts/same_as.h>

#include <__concepts/totally_ordered.h>

#include <__config>

#include <type_traits>



#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

#pragma GCC system_header

#endif



_LIBCPP_BEGIN_NAMESPACE_STD



#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) && !defined(_LIBCPP_HAS_NO_CONCEPTS)



template<class _Tp, class _Cat>

concept __compares_as =

  same_as<common_comparison_category_t<_Tp, _Cat>, _Cat>;



template<class _Tp, class _Cat = partial_ordering>

concept three_way_comparable =

  __weakly_equality_comparable_with<_Tp, _Tp> &&

  __partially_ordered_with<_Tp, _Tp> &&

  requires(__make_const_lvalue_ref<_Tp> __a, __make_const_lvalue_ref<_Tp> __b) {

    { __a <=> __b } -> __compares_as<_Cat>;

  };



template<class _Tp, class _Up, class _Cat = partial_ordering>

concept three_way_comparable_with =

  three_way_comparable<_Tp, _Cat> &&

  three_way_comparable<_Up, _Cat> &&

  common_reference_with<__make_const_lvalue_ref<_Tp>, __make_const_lvalue_ref<_Up>> &&

  three_way_comparable<common_reference_t<__make_const_lvalue_ref<_Tp>, __make_const_lvalue_ref<_Up>>, _Cat> &&

  __weakly_equality_comparable_with<_Tp, _Up> &&

  __partially_ordered_with<_Tp, _Up> &&

  requires(__make_const_lvalue_ref<_Tp> __t, __make_const_lvalue_ref<_Up> __u) {

    { __t <=> __u } -> __compares_as<_Cat>;

    { __u <=> __t } -> __compares_as<_Cat>;

  };



#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_SPACESHIP_OPERATOR) && !defined(_LIBCPP_HAS_NO_CONCEPTS)



_LIBCPP_END_NAMESPACE_STD



#endif // _LIBCPP___COMPARE_THREE_WAY_COMPARABLE_H

libcxx/include/compare

+7 −0
Original line number Diff line number Diff line
@@ -35,6 +35,12 @@ namespace std { 
  template<class... Ts>

    using common_comparison_category_t = typename common_comparison_category<Ts...>::type;



  // [cmp.concept], concept three_way_comparable

  template<class T, class Cat = partial_ordering>

    concept three_way_comparable = see below;

  template<class T, class U, class Cat = partial_ordering>

    concept three_way_comparable_with = see below;



  // [cmp.result], result of three-way comparison

  template<class T, class U = T> struct compare_three_way_result;
@@ -129,6 +135,7 @@ namespace std { 
#include <__compare/common_comparison_category.h>

#include <__compare/compare_three_way_result.h>

#include <__compare/ordering.h>

#include <__compare/three_way_comparable.h>

#include <__config>



#ifndef _LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER

libcxx/include/module.modulemap

+1 −0
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@@ -370,6 +370,7 @@ module std [system] { 
      module common_comparison_category { private header "__compare/common_comparison_category.h" }

      module compare_three_way_result   { private header "__compare/compare_three_way_result.h"   }

      module ordering                   { private header "__compare/ordering.h"                   }

      module three_way_comparable       { private header "__compare/three_way_comparable.h"       }

    }

  }

  module complex {

libcxx/test/libcxx/diagnostics/detail.headers/compare/three_way_comparable.module.verify.cpp

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// -*- 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

//

//===----------------------------------------------------------------------===//



// 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: '__compare/three_way_comparable.h'}}

#include <__compare/three_way_comparable.h>