ceph/src/boost/libs/type_traits/test/enable_if_test.cpp

   1 /*
   2 Copyright 2018 Glen Joseph Fernandes
   3 (glenjofe@gmail.com)
   4
   5 Distributed under the Boost Software License,
   6 Version 1.0. (See accompanying file LICENSE_1_0.txt
   7 or copy at http://www.boost.org/LICENSE_1_0.txt)
   8 */
   9 #include <boost/type_traits/enable_if.hpp>
  10 #include "test.hpp"
  11
  12 template<bool B>
  13 struct Constant {
  14     enum {
  15         value = B
  16     };
  17 };
  18
  19 template<class T>
  20 struct Check
  21     : Constant<false> { };
  22
  23 template<>
  24 struct Check<long>
  25     : Constant<true> { };
  26
  27 class Construct {
  28 public:
  29     template<class T>
  30     Construct(T, typename boost::enable_if_<Check<T>::value>::type* = 0)
  31         : value_(true) { }
  32     template<class T>
  33     Construct(T, typename boost::enable_if_<!Check<T>::value>::type* = 0)
  34         : value_(false) { }
  35     bool value() const {
  36         return value_;
  37     }
  38 private:
  39     bool value_;
  40 };
  41
  42 template<class T, class E = void>
  43 struct Specialize;
  44
  45 template<class T>
  46 struct Specialize<T, typename boost::enable_if_<Check<T>::value>::type>
  47     : Constant<true> { };
  48
  49 template<class T>
  50 struct Specialize<T, typename boost::enable_if_<!Check<T>::value>::type>
  51     : Constant<false> { };
  52
  53 template<class T>
  54 typename boost::enable_if_<Check<T>::value, bool>::type Returns(T)
  55 {
  56     return true;
  57 }
  58
  59 template<class T>
  60 typename boost::enable_if_<!Check<T>::value, bool>::type Returns(T)
  61 {
  62     return false;
  63 }
  64
  65 #if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
  66 template<class T>
  67 boost::enable_if_t<Check<T>::value, bool> Alias(T)
  68 {
  69     return true;
  70 }
  71
  72 template<class T>
  73 boost::enable_if_t<!Check<T>::value, bool> Alias(T)
  74 {
  75     return false;
  76 }
  77 #endif
  78
  79 TT_TEST_BEGIN(enable_if)
  80
  81 BOOST_CHECK(!Construct(1).value());
  82 BOOST_CHECK(Construct(1L).value());
  83 BOOST_CHECK(!Specialize<int>::value);
  84 BOOST_CHECK(Specialize<long>::value);
  85 BOOST_CHECK(!Returns(1));
  86 BOOST_CHECK(Returns(1L));
  87 #if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
  88 BOOST_CHECK(!Alias(1));
  89 BOOST_CHECK(Alias(1L));
  90 #endif
  91
  92 TT_TEST_END