1 //===--- ArrayRef.h - Array Reference Wrapper -------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef LLVM_ADT_ARRAYREF_H 11 #define LLVM_ADT_ARRAYREF_H 12 13 #include "llvm/ADT/Hashing.h" 14 #include "llvm/ADT/None.h" 15 #include "llvm/ADT/SmallVector.h" 16 #include <vector> 17 18 namespace llvm { 19 20 /// ArrayRef - Represent a constant reference to an array (0 or more elements 21 /// consecutively in memory), i.e. a start pointer and a length. It allows 22 /// various APIs to take consecutive elements easily and conveniently. 23 /// 24 /// This class does not own the underlying data, it is expected to be used in 25 /// situations where the data resides in some other buffer, whose lifetime 26 /// extends past that of the ArrayRef. For this reason, it is not in general 27 /// safe to store an ArrayRef. 28 /// 29 /// This is intended to be trivially copyable, so it should be passed by 30 /// value. 31 template<typename T> 32 class ArrayRef { 33 public: 34 typedef const T *iterator; 35 typedef const T *const_iterator; 36 typedef size_t size_type; 37 38 typedef std::reverse_iterator<iterator> reverse_iterator; 39 40 private: 41 /// The start of the array, in an external buffer. 42 const T *Data; 43 44 /// The number of elements. 45 size_type Length; 46 47 public: 48 /// @name Constructors 49 /// @{ 50 51 /// Construct an empty ArrayRef. 52 /*implicit*/ ArrayRef() : Data(nullptr), Length(0) {} 53 54 /// Construct an empty ArrayRef from None. 55 /*implicit*/ ArrayRef(NoneType) : Data(nullptr), Length(0) {} 56 57 /// Construct an ArrayRef from a single element. 58 /*implicit*/ ArrayRef(const T &OneElt) 59 : Data(&OneElt), Length(1) {} 60 61 /// Construct an ArrayRef from a pointer and length. 62 /*implicit*/ ArrayRef(const T *data, size_t length) 63 : Data(data), Length(length) {} 64 65 /// Construct an ArrayRef from a range. 66 ArrayRef(const T *begin, const T *end) 67 : Data(begin), Length(end - begin) {} 68 69 /// Construct an ArrayRef from a SmallVector. This is templated in order to 70 /// avoid instantiating SmallVectorTemplateCommon<T> whenever we 71 /// copy-construct an ArrayRef. 72 template<typename U> 73 /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec) 74 : Data(Vec.data()), Length(Vec.size()) { 75 } 76 77 /// Construct an ArrayRef from a std::vector. 78 template<typename A> 79 /*implicit*/ ArrayRef(const std::vector<T, A> &Vec) 80 : Data(Vec.data()), Length(Vec.size()) {} 81 82 /// Construct an ArrayRef from a C array. 83 template <size_t N> 84 /*implicit*/ LLVM_CONSTEXPR ArrayRef(const T (&Arr)[N]) 85 : Data(Arr), Length(N) {} 86 87 /// Construct an ArrayRef from a std::initializer_list. 88 /*implicit*/ ArrayRef(const std::initializer_list<T> &Vec) 89 : Data(Vec.begin() == Vec.end() ? (T*)nullptr : Vec.begin()), 90 Length(Vec.size()) {} 91 92 /// Construct an ArrayRef<const T*> from ArrayRef<T*>. This uses SFINAE to 93 /// ensure that only ArrayRefs of pointers can be converted. 94 template <typename U> 95 ArrayRef(const ArrayRef<U *> &A, 96 typename std::enable_if< 97 std::is_convertible<U *const *, T const *>::value>::type* = 0) 98 : Data(A.data()), Length(A.size()) {} 99 100 /// Construct an ArrayRef<const T*> from a SmallVector<T*>. This is 101 /// templated in order to avoid instantiating SmallVectorTemplateCommon<T> 102 /// whenever we copy-construct an ArrayRef. 103 template<typename U, typename DummyT> 104 /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<U*, DummyT> &Vec, 105 typename std::enable_if< 106 std::is_convertible<U *const *, 107 T const *>::value>::type* = 0) 108 : Data(Vec.data()), Length(Vec.size()) { 109 } 110 111 /// Construct an ArrayRef<const T*> from std::vector<T*>. This uses SFINAE 112 /// to ensure that only vectors of pointers can be converted. 113 template<typename U, typename A> 114 ArrayRef(const std::vector<U *, A> &Vec, 115 typename std::enable_if< 116 std::is_convertible<U *const *, T const *>::value>::type* = 0) 117 : Data(Vec.data()), Length(Vec.size()) {} 118 119 /// @} 120 /// @name Simple Operations 121 /// @{ 122 123 iterator begin() const { return Data; } 124 iterator end() const { return Data + Length; } 125 126 reverse_iterator rbegin() const { return reverse_iterator(end()); } 127 reverse_iterator rend() const { return reverse_iterator(begin()); } 128 129 /// empty - Check if the array is empty. 130 bool empty() const { return Length == 0; } 131 132 const T *data() const { return Data; } 133 134 /// size - Get the array size. 135 size_t size() const { return Length; } 136 137 /// front - Get the first element. 138 const T &front() const { 139 assert(!empty()); 140 return Data[0]; 141 } 142 143 /// back - Get the last element. 144 const T &back() const { 145 assert(!empty()); 146 return Data[Length-1]; 147 } 148 149 // copy - Allocate copy in Allocator and return ArrayRef<T> to it. 150 template <typename Allocator> ArrayRef<T> copy(Allocator &A) { 151 T *Buff = A.template Allocate<T>(Length); 152 std::uninitialized_copy(begin(), end(), Buff); 153 return ArrayRef<T>(Buff, Length); 154 } 155 156 /// equals - Check for element-wise equality. 157 bool equals(ArrayRef RHS) const { 158 if (Length != RHS.Length) 159 return false; 160 return std::equal(begin(), end(), RHS.begin()); 161 } 162 163 /// slice(n) - Chop off the first N elements of the array. 164 ArrayRef<T> slice(unsigned N) const { 165 assert(N <= size() && "Invalid specifier"); 166 return ArrayRef<T>(data()+N, size()-N); 167 } 168 169 /// slice(n, m) - Chop off the first N elements of the array, and keep M 170 /// elements in the array. 171 ArrayRef<T> slice(unsigned N, unsigned M) const { 172 assert(N+M <= size() && "Invalid specifier"); 173 return ArrayRef<T>(data()+N, M); 174 } 175 176 // \brief Drop the last \p N elements of the array. 177 ArrayRef<T> drop_back(unsigned N = 1) const { 178 assert(size() >= N && "Dropping more elements than exist"); 179 return slice(0, size() - N); 180 } 181 182 /// @} 183 /// @name Operator Overloads 184 /// @{ 185 const T &operator[](size_t Index) const { 186 assert(Index < Length && "Invalid index!"); 187 return Data[Index]; 188 } 189 190 /// @} 191 /// @name Expensive Operations 192 /// @{ 193 std::vector<T> vec() const { 194 return std::vector<T>(Data, Data+Length); 195 } 196 197 /// @} 198 /// @name Conversion operators 199 /// @{ 200 operator std::vector<T>() const { 201 return std::vector<T>(Data, Data+Length); 202 } 203 204 /// @} 205 }; 206 207 /// MutableArrayRef - Represent a mutable reference to an array (0 or more 208 /// elements consecutively in memory), i.e. a start pointer and a length. It 209 /// allows various APIs to take and modify consecutive elements easily and 210 /// conveniently. 211 /// 212 /// This class does not own the underlying data, it is expected to be used in 213 /// situations where the data resides in some other buffer, whose lifetime 214 /// extends past that of the MutableArrayRef. For this reason, it is not in 215 /// general safe to store a MutableArrayRef. 216 /// 217 /// This is intended to be trivially copyable, so it should be passed by 218 /// value. 219 template<typename T> 220 class MutableArrayRef : public ArrayRef<T> { 221 public: 222 typedef T *iterator; 223 224 typedef std::reverse_iterator<iterator> reverse_iterator; 225 226 /// Construct an empty MutableArrayRef. 227 /*implicit*/ MutableArrayRef() : ArrayRef<T>() {} 228 229 /// Construct an empty MutableArrayRef from None. 230 /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {} 231 232 /// Construct an MutableArrayRef from a single element. 233 /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {} 234 235 /// Construct an MutableArrayRef from a pointer and length. 236 /*implicit*/ MutableArrayRef(T *data, size_t length) 237 : ArrayRef<T>(data, length) {} 238 239 /// Construct an MutableArrayRef from a range. 240 MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {} 241 242 /// Construct an MutableArrayRef from a SmallVector. 243 /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec) 244 : ArrayRef<T>(Vec) {} 245 246 /// Construct a MutableArrayRef from a std::vector. 247 /*implicit*/ MutableArrayRef(std::vector<T> &Vec) 248 : ArrayRef<T>(Vec) {} 249 250 /// Construct an MutableArrayRef from a C array. 251 template <size_t N> 252 /*implicit*/ LLVM_CONSTEXPR MutableArrayRef(T (&Arr)[N]) 253 : ArrayRef<T>(Arr) {} 254 255 T *data() const { return const_cast<T*>(ArrayRef<T>::data()); } 256 257 iterator begin() const { return data(); } 258 iterator end() const { return data() + this->size(); } 259 260 reverse_iterator rbegin() const { return reverse_iterator(end()); } 261 reverse_iterator rend() const { return reverse_iterator(begin()); } 262 263 /// front - Get the first element. 264 T &front() const { 265 assert(!this->empty()); 266 return data()[0]; 267 } 268 269 /// back - Get the last element. 270 T &back() const { 271 assert(!this->empty()); 272 return data()[this->size()-1]; 273 } 274 275 /// slice(n) - Chop off the first N elements of the array. 276 MutableArrayRef<T> slice(unsigned N) const { 277 assert(N <= this->size() && "Invalid specifier"); 278 return MutableArrayRef<T>(data()+N, this->size()-N); 279 } 280 281 /// slice(n, m) - Chop off the first N elements of the array, and keep M 282 /// elements in the array. 283 MutableArrayRef<T> slice(unsigned N, unsigned M) const { 284 assert(N+M <= this->size() && "Invalid specifier"); 285 return MutableArrayRef<T>(data()+N, M); 286 } 287 288 MutableArrayRef<T> drop_back(unsigned N) const { 289 assert(this->size() >= N && "Dropping more elements than exist"); 290 return slice(0, this->size() - N); 291 } 292 293 /// @} 294 /// @name Operator Overloads 295 /// @{ 296 T &operator[](size_t Index) const { 297 assert(Index < this->size() && "Invalid index!"); 298 return data()[Index]; 299 } 300 }; 301 302 /// @name ArrayRef Convenience constructors 303 /// @{ 304 305 /// Construct an ArrayRef from a single element. 306 template<typename T> 307 ArrayRef<T> makeArrayRef(const T &OneElt) { 308 return OneElt; 309 } 310 311 /// Construct an ArrayRef from a pointer and length. 312 template<typename T> 313 ArrayRef<T> makeArrayRef(const T *data, size_t length) { 314 return ArrayRef<T>(data, length); 315 } 316 317 /// Construct an ArrayRef from a range. 318 template<typename T> 319 ArrayRef<T> makeArrayRef(const T *begin, const T *end) { 320 return ArrayRef<T>(begin, end); 321 } 322 323 /// Construct an ArrayRef from a SmallVector. 324 template <typename T> 325 ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) { 326 return Vec; 327 } 328 329 /// Construct an ArrayRef from a SmallVector. 330 template <typename T, unsigned N> 331 ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) { 332 return Vec; 333 } 334 335 /// Construct an ArrayRef from a std::vector. 336 template<typename T> 337 ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) { 338 return Vec; 339 } 340 341 /// Construct an ArrayRef from an ArrayRef (no-op) (const) 342 template <typename T> ArrayRef<T> makeArrayRef(const ArrayRef<T> &Vec) { 343 return Vec; 344 } 345 346 /// Construct an ArrayRef from an ArrayRef (no-op) 347 template <typename T> ArrayRef<T> &makeArrayRef(ArrayRef<T> &Vec) { 348 return Vec; 349 } 350 351 /// Construct an ArrayRef from a C array. 352 template<typename T, size_t N> 353 ArrayRef<T> makeArrayRef(const T (&Arr)[N]) { 354 return ArrayRef<T>(Arr); 355 } 356 357 /// @} 358 /// @name ArrayRef Comparison Operators 359 /// @{ 360 361 template<typename T> 362 inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) { 363 return LHS.equals(RHS); 364 } 365 366 template<typename T> 367 inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) { 368 return !(LHS == RHS); 369 } 370 371 /// @} 372 373 // ArrayRefs can be treated like a POD type. 374 template <typename T> struct isPodLike; 375 template <typename T> struct isPodLike<ArrayRef<T> > { 376 static const bool value = true; 377 }; 378 379 template <typename T> hash_code hash_value(ArrayRef<T> S) { 380 return hash_combine_range(S.begin(), S.end()); 381 } 382 } 383 384 #endif 385
