clang/test/CXX/temp/temp.decls/temp.variadic/example-tuple.cpp

   1 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
   2 // expected-no-diagnostics
   3
   4 // Example tuple implementation from the variadic templates proposal,
   5 // ISO C++ committee document number N2080.
   6
   7 // Helper type traits
   8 template<typename T>
   9 struct add_reference {
  10   typedef T &type;
  11 };
  12
  13 template<typename T>
  14 struct add_reference<T&> {
  15   typedef T &type;
  16 };
  17
  18 template<typename T>
  19 struct add_const_reference {
  20   typedef T const &type;
  21 };
  22
  23 template<typename T>
  24 struct add_const_reference<T&> {
  25   typedef T &type;
  26 };
  27
  28 template<typename T, typename U>
  29 struct is_same {
  30   static const bool value = false;
  31 };
  32
  33 template<typename T>
  34 struct is_same<T, T> {
  35   static const bool value = true;
  36 };
  37
  38 template<typename T>
  39 class reference_wrapper {
  40   T *ptr;
  41
  42 public:
  43   reference_wrapper(T& t) : ptr(&t) { }
  44   operator T&() const { return *ptr; }
  45 };
  46
  47 template<typename T> reference_wrapper<T> ref(T& t) {
  48   return reference_wrapper<T>(t);
  49 }
  50 template<typename T> reference_wrapper<const T> cref(const T& t) {
  51   return reference_wrapper<const T>(t);
  52 }
  53
  54 template<typename... Values> class tuple;
  55
  56 // Basis case: zero-length tuple
  57 template<> class tuple<> { };
  58
  59 template<typename Head, typename... Tail>
  60 class tuple<Head, Tail...> : private tuple<Tail...> {
  61   typedef tuple<Tail...> inherited;
  62
  63 public:
  64   tuple() { }
  65   // implicit copy-constructor is okay
  66
  67   // Construct tuple from separate arguments.
  68   tuple(typename add_const_reference<Head>::type v,
  69         typename add_const_reference<Tail>::type... vtail)
  70     : m_head(v), inherited(vtail...) { }
  71
  72   // Construct tuple from another tuple.
  73   template<typename... VValues> tuple(const tuple<VValues...>& other)
  74     : m_head(other.head()), inherited(other.tail()) { }
  75
  76   template<typename... VValues> tuple&
  77   operator=(const tuple<VValues...>& other) {
  78     m_head = other.head();
  79     tail() = other.tail();
  80     return *this;
  81   }
  82
  83   typename add_reference<Head>::type head() { return m_head; }
  84   typename add_reference<const Head>::type head() const { return m_head; }
  85   inherited& tail() { return *this; }
  86   const inherited& tail() const { return *this; }
  87
  88 protected:
  89   Head m_head;
  90 };
  91
  92 void test_tuple() {
  93   tuple<> t0a;
  94   tuple<> t0b(t0a);
  95   t0a = t0b;
  96
  97   tuple<int> t1a;
  98   tuple<int> t1b(17);
  99   tuple<int> t1c(t1b);
 100   t1a = t1b;
 101
 102   tuple<float> t1d(3.14159);
 103   tuple<float> t1e(t1d);
 104   t1d = t1e;
 105
 106   int i;
 107   float f;
 108   double d;
 109   tuple<int*, float*, double*> t3a(&i, &f, &d);
 110 }
 111
 112 // Creation functions
 113 template<typename T>
 114 struct make_tuple_result {
 115   typedef T type;
 116 };
 117
 118 template<typename T>
 119 struct make_tuple_result<reference_wrapper<T> > {
 120   typedef T& type;
 121 };
 122
 123 template<typename... Values>
 124 tuple<typename make_tuple_result<Values>::type...>
 125 make_tuple(const Values&... values) {
 126   return tuple<typename make_tuple_result<Values>::type...>(values...);
 127 }
 128
 129 template<typename... Values>
 130 tuple<Values&...> tie(Values&... values) {
 131   return tuple<Values&...>(values...);
 132 }
 133
 134 template<typename T> const T *addr(const T& ref) { return &ref; }
 135 void test_creation_functions() {
 136   int i;
 137   float f;
 138   double d;
 139   const tuple<int, float&, const double&> *t3p = addr(make_tuple(i, ref(f), cref(d)));
 140   const tuple<int&, float&, double&> *t3q = addr(tie(i, f, d));
 141 }
 142
 143 // Helper classes
 144 template<typename Tuple> struct tuple_size;
 145
 146 template<typename... Values> struct tuple_size<tuple<Values...> > {
 147   static const int value = sizeof...(Values);
 148 };
 149
 150 int check_tuple_size_0[tuple_size<tuple<> >::value == 0? 1 : -1];
 151 int check_tuple_size_1[tuple_size<tuple<int>>::value == 1? 1 : -1];
 152 int check_tuple_size_2[tuple_size<tuple<float, double>>::value == 2? 1 : -1];
 153 int check_tuple_size_3[tuple_size<tuple<char, unsigned char, signed char>>::value == 3? 1 : -1];
 154
 155 template<int I, typename Tuple> struct tuple_element;
 156
 157 template<int I, typename Head, typename... Tail>
 158 struct tuple_element<I, tuple<Head, Tail...> > {
 159   typedef typename tuple_element<I-1, tuple<Tail...> >::type type;
 160 };
 161
 162 template<typename Head, typename... Tail>
 163 struct tuple_element<0, tuple<Head, Tail...> > {
 164   typedef Head type;
 165 };
 166
 167 int check_tuple_element_0[is_same<tuple_element<0, tuple<int&, float, double>>::type,
 168                                   int&>::value? 1 : -1];
 169
 170 int check_tuple_element_1[is_same<tuple_element<1, tuple<int&, float, double>>::type,
 171                                   float>::value? 1 : -1];
 172
 173 int check_tuple_element_2[is_same<tuple_element<2, tuple<int&, float, double>>::type,
 174                                   double>::value? 1 : -1];
 175
 176 // Element access
 177 template<int I, typename Tuple> class get_impl;
 178 template<int I, typename Head, typename... Values>
 179 class get_impl<I, tuple<Head, Values...> > {
 180   typedef typename tuple_element<I-1, tuple<Values...> >::type Element;
 181   typedef typename add_reference<Element>::type RJ;
 182   typedef typename add_const_reference<Element>::type PJ;
 183   typedef get_impl<I-1, tuple<Values...> > Next;
 184 public:
 185   static RJ get(tuple<Head, Values...>& t) { return Next::get(t.tail()); }
 186   static PJ get(const tuple<Head, Values...>& t) { return Next::get(t.tail()); }
 187 };
 188
 189 template<typename Head, typename... Values>
 190 class get_impl<0, tuple<Head, Values...> > {
 191   typedef typename add_reference<Head>::type RJ;
 192   typedef typename add_const_reference<Head>::type PJ;
 193 public:
 194   static RJ get(tuple<Head, Values...>& t) { return t.head(); }
 195   static PJ get(const tuple<Head, Values...>& t) { return t.head(); }
 196 };
 197
 198 template<int I, typename... Values> typename add_reference<
 199 typename tuple_element<I, tuple<Values...> >::type >::type
 200 get(tuple<Values...>& t) {
 201   return get_impl<I, tuple<Values...> >::get(t);
 202 }
 203
 204 template<int I, typename... Values> typename add_const_reference<
 205 typename tuple_element<I, tuple<Values...> >::type >::type
 206 get(const tuple<Values...>& t) {
 207   return get_impl<I, tuple<Values...> >::get(t);
 208 }
 209
 210 void test_element_access(tuple<int*, float*, double*&> t3) {
 211   int i;
 212   float f;
 213   double d;
 214   get<0>(t3) = &i;
 215   get<1>(t3) = &f;
 216   get<2>(t3) = &d;
 217 }
 218
 219 // Relational operators
 220 inline bool operator==(const tuple<>&, const tuple<>&) { return true; }
 221
 222 template<typename T, typename... TTail, typename U, typename... UTail>
 223 bool operator==(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) {
 224   return t.head() == u.head() && t.tail() == u.tail();
 225 }
 226
 227 template<typename... TValues, typename... UValues>
 228 bool operator!=(const tuple<TValues...>& t, const tuple<UValues...>& u) {
 229   return !(t == u);
 230 }
 231
 232 inline bool operator<(const tuple<>&, const tuple<>&) { return false; }
 233
 234 template<typename T, typename... TTail, typename U, typename... UTail>
 235 bool operator<(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) {
 236   return (t.head() < u.head() || (!(t.head() < u.head()) && t.tail() < u.tail()));
 237 }
 238
 239 template<typename... TValues, typename... UValues>
 240 bool operator>(const tuple<TValues...>& t, const tuple<UValues...>& u) {
 241   return u < t;
 242 }
 243
 244 template<typename... TValues, typename... UValues>
 245 bool operator<=(const tuple<TValues...>& t, const tuple<UValues...>& u) {
 246   return !(u < t);
 247 }
 248
 249 template<typename... TValues, typename... UValues>
 250 bool operator>=(const tuple<TValues...>& t, const tuple<UValues...>& u) {
 251   return !(t < u);
 252 }
 253
 254 void test_relational_operators(tuple<int*, float*, double*> t3) {
 255   (void)(t3 == t3);
 256   (void)(t3 != t3);
 257   (void)(t3 < t3);
 258   (void)(t3 <= t3);
 259   (void)(t3 >= t3);
 260   (void)(t3 > t3);
 261 };