libcxx/test/std/utilities/function.objects/func.memfn/member_function_const.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 // <functional>
  10
  11 // template<Returnable R, class T, CopyConstructible... Args>
  12 //   unspecified mem_fn(R (T::* pm)(Args...) const);
  13
  14 #include <functional>
  15 #include <cassert>
  16
  17 #include "test_macros.h"
  18
  19 struct A
  20 {
  21     TEST_CONSTEXPR char test0() const {return 'a';}
  22     TEST_CONSTEXPR char test1(int) const {return 'b';}
  23     TEST_CONSTEXPR char test2(int, double) const {return 'c';}
  24 };
  25
  26 template <class F>
  27 TEST_CONSTEXPR_CXX20 bool
  28 test0(F f)
  29 {
  30     {
  31     A a;
  32     assert(f(a) == 'a');
  33     A* ap = &a;
  34     assert(f(ap) == 'a');
  35     const A* cap = &a;
  36     assert(f(cap) == 'a');
  37     const F& cf = f;
  38     assert(cf(ap) == 'a');
  39     }
  40     return true;
  41 }
  42
  43 template <class F>
  44 TEST_CONSTEXPR_CXX20 bool
  45 test1(F f)
  46 {
  47     {
  48     A a;
  49     assert(f(a, 1) == 'b');
  50     A* ap = &a;
  51     assert(f(ap, 2) == 'b');
  52     const A* cap = &a;
  53     assert(f(cap, 2) == 'b');
  54     const F& cf = f;
  55     assert(cf(ap, 2) == 'b');
  56     }
  57     return true;
  58 }
  59
  60 template <class F>
  61 TEST_CONSTEXPR_CXX20 bool
  62 test2(F f)
  63 {
  64     {
  65     A a;
  66     assert(f(a, 1, 2) == 'c');
  67     A* ap = &a;
  68     assert(f(ap, 2, 3.5) == 'c');
  69     const A* cap = &a;
  70     assert(f(cap, 2, 3.5) == 'c');
  71     const F& cf = f;
  72     assert(cf(ap, 2, 3.5) == 'c');
  73     }
  74     return true;
  75 }
  76
  77 int main(int, char**)
  78 {
  79     test0(std::mem_fn(&A::test0));
  80     test1(std::mem_fn(&A::test1));
  81     test2(std::mem_fn(&A::test2));
  82
  83 #if TEST_STD_VER >= 20
  84     static_assert(test0(std::mem_fn(&A::test0)));
  85     static_assert(test1(std::mem_fn(&A::test1)));
  86     static_assert(test2(std::mem_fn(&A::test2)));
  87 #endif
  88
  89     return 0;
  90 }