libstdc++-v3/testsuite/18_support/comparisons/algorithms/partial_order.cc

   1 // Copyright (C) 2019-2023 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-do run { target c++20 } }
  19
  20 #include <compare>
  21 #include <limits>
  22 #include <testsuite_hooks.h>
  23
  24 using std::partial_order;
  25 using std::partial_ordering;
  26
  27 void
  28 test01()
  29 {
  30   const int one = 1, two = 2;
  31
  32   static_assert( partial_order(one, two) == partial_ordering::less );
  33   static_assert( partial_order(one, one) == partial_ordering::equivalent );
  34   static_assert( partial_order(two, one) == partial_ordering::greater );
  35   static_assert( noexcept(partial_order(1, 1)) );
  36 }
  37
  38 constexpr partial_ordering different_cv_quals(int i, const int j)
  39 {
  40   return partial_order(i, j);
  41 }
  42
  43 void
  44 test02()
  45 {
  46   const int fortytwo = 42, nines = 999, lots = 1000;
  47   static_assert( different_cv_quals(fortytwo, nines) == partial_ordering::less );
  48   static_assert( different_cv_quals(-nines, -nines) == partial_ordering::equivalent );
  49   static_assert( different_cv_quals(-nines, -lots) == partial_ordering::greater );
  50 }
  51
  52 void
  53 test03()
  54 {
  55   constexpr double zero = 0.0;
  56   static_assert( partial_order(zero, zero) == partial_ordering::equivalent );
  57   static_assert( partial_order(-zero, -zero) == partial_ordering::equivalent );
  58   static_assert( partial_order(-zero, zero) == partial_ordering::equivalent );
  59   static_assert( partial_order(zero, -zero) == partial_ordering::equivalent );
  60   static_assert( noexcept(partial_order(zero, 1.0)) );
  61   static_assert( partial_order(0.0, 1.0) == std::partial_ordering::less );
  62
  63   constexpr double min = std::numeric_limits<double>::lowest();
  64   constexpr double max = std::numeric_limits<double>::max();
  65   constexpr double nan = std::numeric_limits<double>::quiet_NaN();
  66   constexpr double inf = std::numeric_limits<double>::infinity();
  67   constexpr double denorm = std::numeric_limits<double>::denorm_min();
  68   constexpr double smallest = std::numeric_limits<double>::min();
  69   constexpr double epsilon = std::numeric_limits<double>::epsilon();
  70   static_assert( partial_order(denorm, smallest) == partial_ordering::less );
  71   static_assert( partial_order(denorm, 0.0) == partial_ordering::greater );
  72   // FIXME: these should all use static_assert.  See PR88173.
  73   VERIFY( partial_order(0.0, nan) == partial_ordering::unordered );
  74   VERIFY( partial_order(nan, nan) == partial_ordering::unordered );
  75   VERIFY( partial_order(nan, 0.0) == partial_ordering::unordered );
  76   VERIFY( partial_order(-nan, 0.0) == partial_ordering::unordered );
  77   VERIFY( partial_order(-nan, min) == partial_ordering::unordered );
  78   static_assert( partial_order(-inf, min) == partial_ordering::less );
  79   VERIFY( partial_order(-nan, -inf) == partial_ordering::unordered );
  80   VERIFY( partial_order(-inf, -nan) == partial_ordering::unordered );
  81   static_assert( partial_order(max, inf) == partial_ordering::less );
  82   static_assert( partial_order(inf, max) == partial_ordering::greater );
  83   VERIFY( partial_order(inf, nan) == partial_ordering::unordered );
  84   static_assert( partial_order(1.0, 1.0+epsilon) == partial_ordering::less );
  85 }
  86
  87 namespace N
  88 {
  89   struct X { int i; };
  90
  91   constexpr partial_ordering operator<=>(X l, X r)
  92   {
  93     if (l.i < 0 && r.i < 0)
  94       return partial_ordering::equivalent;
  95     return r.i <=> l.i;
  96   }
  97
  98   constexpr bool operator==(X l, X r) { return std::is_eq(l <=> r); }
  99
 100   static_assert(std::three_way_comparable<X>);
 101 }
 102
 103 void
 104 test04()
 105 {
 106   using N::X;
 107   X one{1};
 108   X negone{-1};
 109
 110   // FIXME: these should all use static_assert
 111   VERIFY( partial_order(one, X{1}) == partial_ordering::equivalent );
 112   VERIFY( partial_order(negone, X{-2}) == partial_ordering::equivalent );
 113   VERIFY( partial_order(one, X{2}) == partial_ordering::greater );
 114   static_assert( !noexcept(partial_order(X{1}, X{2})) );
 115 }
 116
 117 int main()
 118 {
 119   test01();
 120   test02();
 121   test03();
 122   test04();
 123 }