1 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s 2 // expected-no-diagnostics 3 4 // Example bind 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 // Creation functions 93 template<typename T> 94 struct make_tuple_result { 95 typedef T type; 96 }; 97 98 template<typename T> 99 struct make_tuple_result<reference_wrapper<T> > { 100 typedef T& type; 101 }; 102 103 template<typename... Values> 104 tuple<typename make_tuple_result<Values>::type...> 105 make_tuple(const Values&... values) { 106 return tuple<typename make_tuple_result<Values>::type...>(values...); 107 } 108 109 template<typename... Values> 110 tuple<Values&...> tie(Values&... values) { 111 return tuple<Values&...>(values...); 112 } 113 114 // Helper classes 115 template<typename Tuple> struct tuple_size; 116 117 template<typename... Values> struct tuple_size<tuple<Values...> > { 118 static const int value = sizeof...(Values); 119 }; 120 121 template<int I, typename Tuple> struct tuple_element; 122 123 template<int I, typename Head, typename... Tail> 124 struct tuple_element<I, tuple<Head, Tail...> > { 125 typedef typename tuple_element<I-1, tuple<Tail...> >::type type; 126 }; 127 128 template<typename Head, typename... Tail> 129 struct tuple_element<0, tuple<Head, Tail...> > { 130 typedef Head type; 131 }; 132 133 // Element access 134 template<int I, typename Tuple> class get_impl; 135 template<int I, typename Head, typename... Values> 136 class get_impl<I, tuple<Head, Values...> > { 137 typedef typename tuple_element<I-1, tuple<Values...> >::type Element; 138 typedef typename add_reference<Element>::type RJ; 139 typedef typename add_const_reference<Element>::type PJ; 140 typedef get_impl<I-1, tuple<Values...> > Next; 141 public: 142 static RJ get(tuple<Head, Values...>& t) { return Next::get(t.tail()); } 143 static PJ get(const tuple<Head, Values...>& t) { return Next::get(t.tail()); } 144 }; 145 146 template<typename Head, typename... Values> 147 class get_impl<0, tuple<Head, Values...> > { 148 typedef typename add_reference<Head>::type RJ; 149 typedef typename add_const_reference<Head>::type PJ; 150 public: 151 static RJ get(tuple<Head, Values...>& t) { return t.head(); } 152 static PJ get(const tuple<Head, Values...>& t) { return t.head(); } 153 }; 154 155 template<int I, typename... Values> typename add_reference< 156 typename tuple_element<I, tuple<Values...> >::type >::type 157 get(tuple<Values...>& t) { 158 return get_impl<I, tuple<Values...> >::get(t); 159 } 160 161 template<int I, typename... Values> typename add_const_reference< 162 typename tuple_element<I, tuple<Values...> >::type >::type 163 get(const tuple<Values...>& t) { 164 return get_impl<I, tuple<Values...> >::get(t); 165 } 166 167 // Relational operators 168 inline bool operator==(const tuple<>&, const tuple<>&) { return true; } 169 170 template<typename T, typename... TTail, typename U, typename... UTail> 171 bool operator==(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) { 172 return t.head() == u.head() && t.tail() == u.tail(); 173 } 174 175 template<typename... TValues, typename... UValues> 176 bool operator!=(const tuple<TValues...>& t, const tuple<UValues...>& u) { 177 return !(t == u); 178 } 179 180 inline bool operator<(const tuple<>&, const tuple<>&) { return false; } 181 182 template<typename T, typename... TTail, typename U, typename... UTail> 183 bool operator<(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) { 184 return (t.head() < u.head() || (!(t.head() < u.head()) && t.tail() < u.tail())); 185 } 186 187 template<typename... TValues, typename... UValues> 188 bool operator>(const tuple<TValues...>& t, const tuple<UValues...>& u) { 189 return u < t; 190 } 191 192 template<typename... TValues, typename... UValues> 193 bool operator<=(const tuple<TValues...>& t, const tuple<UValues...>& u) { 194 return !(u < t); 195 } 196 197 template<typename... TValues, typename... UValues> 198 bool operator>=(const tuple<TValues...>& t, const tuple<UValues...>& u) { 199 return !(t < u); 200 } 201 202 // make_indices helper 203 template<int...> struct int_tuple {}; 204 // make_indexes impl is a helper for make_indexes 205 template<int I, typename IntTuple, typename... Types> struct make_indexes_impl; 206 207 template<int I, int... Indexes, typename T, typename... Types> 208 struct make_indexes_impl<I, int_tuple<Indexes...>, T, Types...> { 209 typedef typename make_indexes_impl<I+1, int_tuple<Indexes..., I>, Types...>::type type; 210 }; 211 212 template<int I, int... Indexes> 213 struct make_indexes_impl<I, int_tuple<Indexes...> > { 214 typedef int_tuple<Indexes...> type; 215 }; 216 217 template<typename... Types> 218 struct make_indexes : make_indexes_impl<0, int_tuple<>, Types...> { 219 }; 220 221 // Bind 222 template<typename T> struct is_bind_expression { 223 static const bool value = false; 224 }; 225 226 template<typename T> struct is_placeholder { 227 static const int value = 0; 228 }; 229 230 231 template<typename F, typename... BoundArgs> class bound_functor { 232 typedef typename make_indexes<BoundArgs...>::type indexes; 233 public: 234 typedef typename F::result_type result_type; 235 explicit bound_functor(const F& f, const BoundArgs&... bound_args) 236 : f(f), bound_args(bound_args...) { } template<typename... Args> 237 typename F::result_type operator()(Args&... args); 238 private: F f; 239 tuple<BoundArgs...> bound_args; 240 }; 241 242 template<typename F, typename... BoundArgs> 243 inline bound_functor<F, BoundArgs...> bind(const F& f, const BoundArgs&... bound_args) { 244 return bound_functor<F, BoundArgs...>(f, bound_args...); 245 } 246 247 template<typename F, typename ...BoundArgs> 248 struct is_bind_expression<bound_functor<F, BoundArgs...> > { 249 static const bool value = true; 250 }; 251 252 // enable_if helper 253 template<bool Cond, typename T = void> 254 struct enable_if; 255 256 template<typename T> 257 struct enable_if<true, T> { 258 typedef T type; 259 }; 260 261 template<typename T> 262 struct enable_if<false, T> { }; 263 264 // safe_tuple_element helper 265 template<int I, typename Tuple, typename = void> 266 struct safe_tuple_element { }; 267 268 template<int I, typename... Values> 269 struct safe_tuple_element<I, tuple<Values...>, 270 typename enable_if<(I >= 0 && I < tuple_size<tuple<Values...> >::value)>::type> { 271 typedef typename tuple_element<I, tuple<Values...> >::type type; 272 }; 273 274 // mu 275 template<typename Bound, typename... Args> 276 inline typename safe_tuple_element<is_placeholder<Bound>::value -1, 277 tuple<Args...> >::type 278 mu(Bound& bound_arg, const tuple<Args&...>& args) { 279 return get<is_placeholder<Bound>::value-1>(args); 280 } 281 282 template<typename T, typename... Args> 283 inline T& mu(reference_wrapper<T>& bound_arg, const tuple<Args&...>&) { 284 return bound_arg.get(); 285 } 286 287 template<typename F, int... Indexes, typename... Args> 288 inline typename F::result_type 289 unwrap_and_forward(F& f, int_tuple<Indexes...>, const tuple<Args&...>& args) { 290 return f(get<Indexes>(args)...); 291 } 292 293 template<typename Bound, typename... Args> 294 inline typename enable_if<is_bind_expression<Bound>::value, 295 typename Bound::result_type>::type 296 mu(Bound& bound_arg, const tuple<Args&...>& args) { 297 typedef typename make_indexes<Args...>::type Indexes; 298 return unwrap_and_forward(bound_arg, Indexes(), args); 299 } 300 301 template<typename T> 302 struct is_reference_wrapper { 303 static const bool value = false; 304 }; 305 306 template<typename T> 307 struct is_reference_wrapper<reference_wrapper<T>> { 308 static const bool value = true; 309 }; 310 311 template<typename Bound, typename... Args> 312 inline typename enable_if<(!is_bind_expression<Bound>::value 313 && !is_placeholder<Bound>::value 314 && !is_reference_wrapper<Bound>::value), 315 Bound&>::type 316 mu(Bound& bound_arg, const tuple<Args&...>&) { 317 return bound_arg; 318 } 319 320 template<typename F, typename... BoundArgs, int... Indexes, typename... Args> 321 typename F::result_type apply_functor(F& f, tuple<BoundArgs...>& bound_args, 322 int_tuple<Indexes...>, 323 const tuple<Args&...>& args) { 324 return f(mu(get<Indexes>(bound_args), args)...); 325 } 326 327 template<typename F, typename... BoundArgs> 328 template<typename... Args> 329 typename F::result_type bound_functor<F, BoundArgs...>::operator()(Args&... args) { 330 return apply_functor(f, bound_args, indexes(), tie(args...)); 331 } 332 333 template<int N> struct placeholder { }; 334 template<int N> 335 struct is_placeholder<placeholder<N>> { 336 static const int value = N; 337 }; 338 339 template<typename T> 340 struct plus { 341 typedef T result_type; 342 343 T operator()(T x, T y) { return x + y; } 344 }; 345 346 placeholder<1> _1; 347 348 // Test bind 349 void test_bind() { 350 int x = 17; 351 int y = 25; 352 bind(plus<int>(), x, _1)(y); 353 } 354
