libcxx/test/std/utilities/function.objects/comparisons/transparent.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11
  10 #include <functional>
  11 #include <string>
  12
  13 #include "test_macros.h"
  14
  15 template <class T>
  16 struct is_transparent
  17 {
  18 private:
  19     struct two {char lx; char lxx;};
  20     template <class U> static two test(...);
  21     template <class U> static char test(typename U::is_transparent* = 0);
  22 public:
  23     static const bool value = sizeof(test<T>(0)) == 1;
  24 };
  25
  26
  27 int main(int, char**)
  28 {
  29     static_assert ( !is_transparent<std::less<int>>::value, "" );
  30     static_assert ( !is_transparent<std::less<std::string>>::value, "" );
  31     static_assert (  is_transparent<std::less<void>>::value, "" );
  32     static_assert (  is_transparent<std::less<>>::value, "" );
  33
  34     static_assert ( !is_transparent<std::less_equal<int>>::value, "" );
  35     static_assert ( !is_transparent<std::less_equal<std::string>>::value, "" );
  36     static_assert (  is_transparent<std::less_equal<void>>::value, "" );
  37     static_assert (  is_transparent<std::less_equal<>>::value, "" );
  38
  39     static_assert ( !is_transparent<std::equal_to<int>>::value, "" );
  40     static_assert ( !is_transparent<std::equal_to<std::string>>::value, "" );
  41     static_assert (  is_transparent<std::equal_to<void>>::value, "" );
  42     static_assert (  is_transparent<std::equal_to<>>::value, "" );
  43
  44     static_assert ( !is_transparent<std::not_equal_to<int>>::value, "" );
  45     static_assert ( !is_transparent<std::not_equal_to<std::string>>::value, "" );
  46     static_assert (  is_transparent<std::not_equal_to<void>>::value, "" );
  47     static_assert (  is_transparent<std::not_equal_to<>>::value, "" );
  48
  49     static_assert ( !is_transparent<std::greater<int>>::value, "" );
  50     static_assert ( !is_transparent<std::greater<std::string>>::value, "" );
  51     static_assert (  is_transparent<std::greater<void>>::value, "" );
  52     static_assert (  is_transparent<std::greater<>>::value, "" );
  53
  54     static_assert ( !is_transparent<std::greater_equal<int>>::value, "" );
  55     static_assert ( !is_transparent<std::greater_equal<std::string>>::value, "" );
  56     static_assert (  is_transparent<std::greater_equal<void>>::value, "" );
  57     static_assert (  is_transparent<std::greater_equal<>>::value, "" );
  58
  59     return 0;
  60 }