ceph/src/test/common/test_backport14.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2017 Red Hat, Inc.
   7  *
   8  * Author: Casey Bodley <cbodley@redhat.com>
   9  *
  10  * This is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU Lesser General Public
  12  * License version 2.1, as published by the Free Software
  13  * Foundation.  See file COPYING.
  14  *
  15  */
  16
  17 #include "common/backport14.h" // include first: tests that header is standalone
  18 #include <gtest/gtest.h>
  19
  20 int int_func() { return 1; }
  21 bool bool_func0() { return true; }
  22 bool bool_func1(int a) { return true; }
  23 bool bool_func2(const std::string& a, int b) { return true; }
  24
  25 // given a callable and argument list, test that the result of ceph::not_fn
  26 // evaluates to false as both an lvalue and rvalue
  27 template <typename F, typename ...Args>
  28 void test_not(F&& fn, Args&&... args)
  29 {
  30   auto res = ceph::not_fn(std::forward<F>(fn));
  31   // test res as lvalue
  32   EXPECT_FALSE(res(std::forward<Args>(args)...));
  33   // test res as rvalue
  34   // note: this forwards args twice, but it's okay if none are rvalues
  35   EXPECT_FALSE(std::move(res)(std::forward<Args>(args)...));
  36 }
  37
  38 TEST(Backport14, not_fn)
  39 {
  40   // function pointers
  41   test_not(int_func);
  42   test_not(&int_func);
  43   test_not(bool_func0);
  44   test_not(&bool_func0);
  45   test_not(bool_func1, 5);
  46   test_not(bool_func2, "foo", 5);
  47
  48   // lambdas
  49   auto int_lambda = [] { return 1; };
  50   auto bool_lambda0 = [] { return true; };
  51   auto bool_lambda1 = [] (int a) { return true; };
  52   auto bool_lambda2 = [] (const std::string& a, int b) { return true; };
  53
  54   test_not(int_lambda);
  55   test_not(bool_lambda0);
  56   test_not(bool_lambda1, 5);
  57   test_not(bool_lambda2, "foo", 5);
  58
  59   // functors
  60   struct int_functor {
  61     int operator()() { return 1; }
  62   };
  63   test_not(int_functor{});
  64
  65   struct bool_functor {
  66     bool operator()() { return true; }
  67     bool operator()(int a) { return true; }
  68     bool operator()(const std::string& a, int b) { return true; }
  69   };
  70
  71   test_not(bool_functor{});
  72   test_not(bool_functor{}, 5);
  73   test_not(bool_functor{}, "foo", 5);
  74
  75   // lvalue-only overload
  76   struct lvalue_only_functor {
  77     bool operator()() & { return true; } // no overload for rvalue
  78   };
  79   auto lvalue_result = ceph::not_fn(lvalue_only_functor{});
  80   EXPECT_FALSE(lvalue_result());
  81   // should not compile:
  82   //   EXPECT_FALSE(std::move(lvalue_result)());
  83
  84   // rvalue-only overload
  85   struct rvalue_only_functor {
  86     bool operator()() && { return true; } // no overload for lvalue
  87   };
  88   EXPECT_FALSE(ceph::not_fn(rvalue_only_functor{})());
  89   auto lvalue_functor = rvalue_only_functor{};
  90   EXPECT_FALSE(ceph::not_fn(lvalue_functor)()); // lvalue functor, rvalue result
  91   // should not compile:
  92   //   auto lvalue_result2 = ceph::not_fn(rvalue_only_functor{});
  93   //   EXPECT_FALSE(lvalue_result2());
  94 }