ceph/src/Beast/test/core/empty_base_optimization.cpp

   1 //
   2 // Copyright (c) 2013-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
   3 //
   4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
   5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7
   8 // Test that header file is self-contained.
   9 #include <beast/core/detail/empty_base_optimization.hpp>
  10
  11 #include <beast/unit_test/suite.hpp>
  12
  13 namespace beast {
  14 namespace detail {
  15
  16 class empty_base_optimization_test
  17     : public beast::unit_test::suite
  18 {
  19 public:
  20     template<class T>
  21     class test1
  22         : private empty_base_optimization<T>
  23     {
  24         using Base = empty_base_optimization<T>;
  25         void* m_p;
  26     public:
  27         explicit test1 (T const& t)
  28             : Base (t)
  29         {}
  30
  31         T&       member()       {return Base::member();}
  32         T const& member() const {return Base::member();}
  33     };
  34
  35     template<class T>
  36     class test2
  37     {
  38         void* m_p;
  39         T m_t;
  40     public:
  41         explicit test2 (T const& t)
  42             : m_t (t)
  43         {}
  44
  45         T&       member()       {return m_t;}
  46         T const& member() const {return m_t;}
  47     };
  48
  49     struct Empty
  50     {
  51         operator bool() {return true;}
  52     };
  53
  54     static
  55     bool
  56     test_one()
  57     {
  58         test1<int> t1(1);
  59         test2<int> t2(2);
  60         static_assert(sizeof(t1) == sizeof(t2), "don't optimize for int");
  61         if(t1.member() != 1)
  62             return false;
  63         if(t2.member() != 2)
  64             return false;
  65         return true;
  66     }
  67
  68     static
  69     bool
  70     test_two()
  71     {
  72         test1<Empty> t1((Empty()));
  73         test2<Empty> t2((Empty()));
  74         static_assert(sizeof(t1) < sizeof(t2), "do optimize for Empty");
  75         if(t1.member() != true)
  76             return false;
  77         if(t2.member() != true)
  78             return false;
  79         return true;
  80     }
  81
  82     void
  83     run()
  84     {
  85         BEAST_EXPECT(test_one());
  86         BEAST_EXPECT(test_two());
  87         pass();
  88     }
  89 };
  90
  91 BEAST_DEFINE_TESTSUITE(empty_base_optimization,core,beast);
  92
  93 } // detail
  94 } // beast