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/None.h" 14 #include "llvm/ADT/SmallVector.h" 15 #include <vector> 16 17 namespace llvm { 18 19 /// ArrayRef - Represent a constant reference to an array (0 or more elements 20 /// consecutively in memory), i.e. a start pointer and a length. It allows 21 /// various APIs to take consecutive elements easily and conveniently. 22 /// 23 /// This class does not own the underlying data, it is expected to be used in 24 /// situations where the data resides in some other buffer, whose lifetime 25 /// extends past that of the ArrayRef. For this reason, it is not in general 26 /// safe to store an ArrayRef. 27 /// 28 /// This is intended to be trivially copyable, so it should be passed by 29 /// value. 30 template<typename T> 31 class ArrayRef { 32 public: 33 typedef const T *iterator; 34 typedef const T *const_iterator; 35 typedef size_t size_type; 36 37 typedef std::reverse_iterator<iterator> reverse_iterator; 38 39 private: 40 /// The start of the array, in an external buffer. 41 const T *Data; 42 43 /// The number of elements. 44 size_type Length; 45 46 public: 47 /// @name Constructors 48 /// @{ 49 50 /// Construct an empty ArrayRef. 51 /*implicit*/ ArrayRef() : Data(0), Length(0) {} 52 53 /// Construct an empty ArrayRef from None. 54 /*implicit*/ ArrayRef(NoneType) : Data(0), Length(0) {} 55 56 /// Construct an ArrayRef from a single element. 57 /*implicit*/ ArrayRef(const T &OneElt) 58 : Data(&OneElt), Length(1) {} 59 60 /// Construct an ArrayRef from a pointer and length. 61 /*implicit*/ ArrayRef(const T *data, size_t length) 62 : Data(data), Length(length) {} 63 64 /// Construct an ArrayRef from a range. 65 ArrayRef(const T *begin, const T *end) 66 : Data(begin), Length(end - begin) {} 67 68 /// Construct an ArrayRef from a SmallVector. This is templated in order to 69 /// avoid instantiating SmallVectorTemplateCommon<T> whenever we 70 /// copy-construct an ArrayRef. 71 template<typename U> 72 /*implicit*/ ArrayRef(const SmallVectorTemplateCommon<T, U> &Vec) 73 : Data(Vec.data()), Length(Vec.size()) { 74 } 75 76 /// Construct an ArrayRef from a std::vector. 77 template<typename A> 78 /*implicit*/ ArrayRef(const std::vector<T, A> &Vec) 79 : Data(Vec.empty() ? (T*)0 : &Vec[0]), Length(Vec.size()) {} 80 81 /// Construct an ArrayRef from a C array. 82 template <size_t N> 83 /*implicit*/ ArrayRef(const T (&Arr)[N]) 84 : Data(Arr), Length(N) {} 85 86 /// @} 87 /// @name Simple Operations 88 /// @{ 89 90 iterator begin() const { return Data; } 91 iterator end() const { return Data + Length; } 92 93 reverse_iterator rbegin() const { return reverse_iterator(end()); } 94 reverse_iterator rend() const { return reverse_iterator(begin()); } 95 96 /// empty - Check if the array is empty. 97 bool empty() const { return Length == 0; } 98 99 const T *data() const { return Data; } 100 101 /// size - Get the array size. 102 size_t size() const { return Length; } 103 104 /// front - Get the first element. 105 const T &front() const { 106 assert(!empty()); 107 return Data[0]; 108 } 109 110 /// back - Get the last element. 111 const T &back() const { 112 assert(!empty()); 113 return Data[Length-1]; 114 } 115 116 /// equals - Check for element-wise equality. 117 bool equals(ArrayRef RHS) const { 118 if (Length != RHS.Length) 119 return false; 120 for (size_type i = 0; i != Length; i++) 121 if (Data[i] != RHS.Data[i]) 122 return false; 123 return true; 124 } 125 126 /// slice(n) - Chop off the first N elements of the array. 127 ArrayRef<T> slice(unsigned N) const { 128 assert(N <= size() && "Invalid specifier"); 129 return ArrayRef<T>(data()+N, size()-N); 130 } 131 132 /// slice(n, m) - Chop off the first N elements of the array, and keep M 133 /// elements in the array. 134 ArrayRef<T> slice(unsigned N, unsigned M) const { 135 assert(N+M <= size() && "Invalid specifier"); 136 return ArrayRef<T>(data()+N, M); 137 } 138 139 /// @} 140 /// @name Operator Overloads 141 /// @{ 142 const T &operator[](size_t Index) const { 143 assert(Index < Length && "Invalid index!"); 144 return Data[Index]; 145 } 146 147 /// @} 148 /// @name Expensive Operations 149 /// @{ 150 std::vector<T> vec() const { 151 return std::vector<T>(Data, Data+Length); 152 } 153 154 /// @} 155 /// @name Conversion operators 156 /// @{ 157 operator std::vector<T>() const { 158 return std::vector<T>(Data, Data+Length); 159 } 160 161 /// @} 162 }; 163 164 /// MutableArrayRef - Represent a mutable reference to an array (0 or more 165 /// elements consecutively in memory), i.e. a start pointer and a length. It 166 /// allows various APIs to take and modify consecutive elements easily and 167 /// conveniently. 168 /// 169 /// This class does not own the underlying data, it is expected to be used in 170 /// situations where the data resides in some other buffer, whose lifetime 171 /// extends past that of the MutableArrayRef. For this reason, it is not in 172 /// general safe to store a MutableArrayRef. 173 /// 174 /// This is intended to be trivially copyable, so it should be passed by 175 /// value. 176 template<typename T> 177 class MutableArrayRef : public ArrayRef<T> { 178 public: 179 typedef T *iterator; 180 181 /// Construct an empty MutableArrayRef. 182 /*implicit*/ MutableArrayRef() : ArrayRef<T>() {} 183 184 /// Construct an empty MutableArrayRef from None. 185 /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {} 186 187 /// Construct an MutableArrayRef from a single element. 188 /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {} 189 190 /// Construct an MutableArrayRef from a pointer and length. 191 /*implicit*/ MutableArrayRef(T *data, size_t length) 192 : ArrayRef<T>(data, length) {} 193 194 /// Construct an MutableArrayRef from a range. 195 MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {} 196 197 /// Construct an MutableArrayRef from a SmallVector. 198 /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec) 199 : ArrayRef<T>(Vec) {} 200 201 /// Construct a MutableArrayRef from a std::vector. 202 /*implicit*/ MutableArrayRef(std::vector<T> &Vec) 203 : ArrayRef<T>(Vec) {} 204 205 /// Construct an MutableArrayRef from a C array. 206 template <size_t N> 207 /*implicit*/ MutableArrayRef(T (&Arr)[N]) 208 : ArrayRef<T>(Arr) {} 209 210 T *data() const { return const_cast<T*>(ArrayRef<T>::data()); } 211 212 iterator begin() const { return data(); } 213 iterator end() const { return data() + this->size(); } 214 215 /// front - Get the first element. 216 T &front() const { 217 assert(!this->empty()); 218 return data()[0]; 219 } 220 221 /// back - Get the last element. 222 T &back() const { 223 assert(!this->empty()); 224 return data()[this->size()-1]; 225 } 226 227 /// slice(n) - Chop off the first N elements of the array. 228 MutableArrayRef<T> slice(unsigned N) const { 229 assert(N <= this->size() && "Invalid specifier"); 230 return MutableArrayRef<T>(data()+N, this->size()-N); 231 } 232 233 /// slice(n, m) - Chop off the first N elements of the array, and keep M 234 /// elements in the array. 235 MutableArrayRef<T> slice(unsigned N, unsigned M) const { 236 assert(N+M <= this->size() && "Invalid specifier"); 237 return MutableArrayRef<T>(data()+N, M); 238 } 239 240 /// @} 241 /// @name Operator Overloads 242 /// @{ 243 T &operator[](size_t Index) const { 244 assert(Index < this->size() && "Invalid index!"); 245 return data()[Index]; 246 } 247 }; 248 249 /// @name ArrayRef Convenience constructors 250 /// @{ 251 252 /// Construct an ArrayRef from a single element. 253 template<typename T> 254 ArrayRef<T> makeArrayRef(const T &OneElt) { 255 return OneElt; 256 } 257 258 /// Construct an ArrayRef from a pointer and length. 259 template<typename T> 260 ArrayRef<T> makeArrayRef(const T *data, size_t length) { 261 return ArrayRef<T>(data, length); 262 } 263 264 /// Construct an ArrayRef from a range. 265 template<typename T> 266 ArrayRef<T> makeArrayRef(const T *begin, const T *end) { 267 return ArrayRef<T>(begin, end); 268 } 269 270 /// Construct an ArrayRef from a SmallVector. 271 template <typename T> 272 ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) { 273 return Vec; 274 } 275 276 /// Construct an ArrayRef from a SmallVector. 277 template <typename T, unsigned N> 278 ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) { 279 return Vec; 280 } 281 282 /// Construct an ArrayRef from a std::vector. 283 template<typename T> 284 ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) { 285 return Vec; 286 } 287 288 /// Construct an ArrayRef from a C array. 289 template<typename T, size_t N> 290 ArrayRef<T> makeArrayRef(const T (&Arr)[N]) { 291 return ArrayRef<T>(Arr); 292 } 293 294 /// @} 295 /// @name ArrayRef Comparison Operators 296 /// @{ 297 298 template<typename T> 299 inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) { 300 return LHS.equals(RHS); 301 } 302 303 template<typename T> 304 inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) { 305 return !(LHS == RHS); 306 } 307 308 /// @} 309 310 // ArrayRefs can be treated like a POD type. 311 template <typename T> struct isPodLike; 312 template <typename T> struct isPodLike<ArrayRef<T> > { 313 static const bool value = true; 314 }; 315 } 316 317 #endif 318
