ArrayRef.h revision 43ed63bc8310758d2a80deecb2e470f383ca5691
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 17namespace 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*/ LLVM_CONSTEXPR ArrayRef(const T (&Arr)[N]) 84 : Data(Arr), Length(N) {} 85 86#if LLVM_HAS_INITIALIZER_LISTS 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*)0 : Vec.begin()), 90 Length(Vec.size()) {} 91#endif 92 93 /// @} 94 /// @name Simple Operations 95 /// @{ 96 97 iterator begin() const { return Data; } 98 iterator end() const { return Data + Length; } 99 100 reverse_iterator rbegin() const { return reverse_iterator(end()); } 101 reverse_iterator rend() const { return reverse_iterator(begin()); } 102 103 /// empty - Check if the array is empty. 104 bool empty() const { return Length == 0; } 105 106 const T *data() const { return Data; } 107 108 /// size - Get the array size. 109 size_t size() const { return Length; } 110 111 /// front - Get the first element. 112 const T &front() const { 113 assert(!empty()); 114 return Data[0]; 115 } 116 117 /// back - Get the last element. 118 const T &back() const { 119 assert(!empty()); 120 return Data[Length-1]; 121 } 122 123 /// equals - Check for element-wise equality. 124 bool equals(ArrayRef RHS) const { 125 if (Length != RHS.Length) 126 return false; 127 for (size_type i = 0; i != Length; i++) 128 if (Data[i] != RHS.Data[i]) 129 return false; 130 return true; 131 } 132 133 /// slice(n) - Chop off the first N elements of the array. 134 ArrayRef<T> slice(unsigned N) const { 135 assert(N <= size() && "Invalid specifier"); 136 return ArrayRef<T>(data()+N, size()-N); 137 } 138 139 /// slice(n, m) - Chop off the first N elements of the array, and keep M 140 /// elements in the array. 141 ArrayRef<T> slice(unsigned N, unsigned M) const { 142 assert(N+M <= size() && "Invalid specifier"); 143 return ArrayRef<T>(data()+N, M); 144 } 145 146 /// @} 147 /// @name Operator Overloads 148 /// @{ 149 const T &operator[](size_t Index) const { 150 assert(Index < Length && "Invalid index!"); 151 return Data[Index]; 152 } 153 154 /// @} 155 /// @name Expensive Operations 156 /// @{ 157 std::vector<T> vec() const { 158 return std::vector<T>(Data, Data+Length); 159 } 160 161 /// @} 162 /// @name Conversion operators 163 /// @{ 164 operator std::vector<T>() const { 165 return std::vector<T>(Data, Data+Length); 166 } 167 168 /// @} 169 }; 170 171 /// MutableArrayRef - Represent a mutable reference to an array (0 or more 172 /// elements consecutively in memory), i.e. a start pointer and a length. It 173 /// allows various APIs to take and modify consecutive elements easily and 174 /// conveniently. 175 /// 176 /// This class does not own the underlying data, it is expected to be used in 177 /// situations where the data resides in some other buffer, whose lifetime 178 /// extends past that of the MutableArrayRef. For this reason, it is not in 179 /// general safe to store a MutableArrayRef. 180 /// 181 /// This is intended to be trivially copyable, so it should be passed by 182 /// value. 183 template<typename T> 184 class MutableArrayRef : public ArrayRef<T> { 185 public: 186 typedef T *iterator; 187 188 /// Construct an empty MutableArrayRef. 189 /*implicit*/ MutableArrayRef() : ArrayRef<T>() {} 190 191 /// Construct an empty MutableArrayRef from None. 192 /*implicit*/ MutableArrayRef(NoneType) : ArrayRef<T>() {} 193 194 /// Construct an MutableArrayRef from a single element. 195 /*implicit*/ MutableArrayRef(T &OneElt) : ArrayRef<T>(OneElt) {} 196 197 /// Construct an MutableArrayRef from a pointer and length. 198 /*implicit*/ MutableArrayRef(T *data, size_t length) 199 : ArrayRef<T>(data, length) {} 200 201 /// Construct an MutableArrayRef from a range. 202 MutableArrayRef(T *begin, T *end) : ArrayRef<T>(begin, end) {} 203 204 /// Construct an MutableArrayRef from a SmallVector. 205 /*implicit*/ MutableArrayRef(SmallVectorImpl<T> &Vec) 206 : ArrayRef<T>(Vec) {} 207 208 /// Construct a MutableArrayRef from a std::vector. 209 /*implicit*/ MutableArrayRef(std::vector<T> &Vec) 210 : ArrayRef<T>(Vec) {} 211 212 /// Construct an MutableArrayRef from a C array. 213 template <size_t N> 214 /*implicit*/ MutableArrayRef(T (&Arr)[N]) 215 : ArrayRef<T>(Arr) {} 216 217 T *data() const { return const_cast<T*>(ArrayRef<T>::data()); } 218 219 iterator begin() const { return data(); } 220 iterator end() const { return data() + this->size(); } 221 222 /// front - Get the first element. 223 T &front() const { 224 assert(!this->empty()); 225 return data()[0]; 226 } 227 228 /// back - Get the last element. 229 T &back() const { 230 assert(!this->empty()); 231 return data()[this->size()-1]; 232 } 233 234 /// slice(n) - Chop off the first N elements of the array. 235 MutableArrayRef<T> slice(unsigned N) const { 236 assert(N <= this->size() && "Invalid specifier"); 237 return MutableArrayRef<T>(data()+N, this->size()-N); 238 } 239 240 /// slice(n, m) - Chop off the first N elements of the array, and keep M 241 /// elements in the array. 242 MutableArrayRef<T> slice(unsigned N, unsigned M) const { 243 assert(N+M <= this->size() && "Invalid specifier"); 244 return MutableArrayRef<T>(data()+N, M); 245 } 246 247 /// @} 248 /// @name Operator Overloads 249 /// @{ 250 T &operator[](size_t Index) const { 251 assert(Index < this->size() && "Invalid index!"); 252 return data()[Index]; 253 } 254 }; 255 256 /// @name ArrayRef Convenience constructors 257 /// @{ 258 259 /// Construct an ArrayRef from a single element. 260 template<typename T> 261 ArrayRef<T> makeArrayRef(const T &OneElt) { 262 return OneElt; 263 } 264 265 /// Construct an ArrayRef from a pointer and length. 266 template<typename T> 267 ArrayRef<T> makeArrayRef(const T *data, size_t length) { 268 return ArrayRef<T>(data, length); 269 } 270 271 /// Construct an ArrayRef from a range. 272 template<typename T> 273 ArrayRef<T> makeArrayRef(const T *begin, const T *end) { 274 return ArrayRef<T>(begin, end); 275 } 276 277 /// Construct an ArrayRef from a SmallVector. 278 template <typename T> 279 ArrayRef<T> makeArrayRef(const SmallVectorImpl<T> &Vec) { 280 return Vec; 281 } 282 283 /// Construct an ArrayRef from a SmallVector. 284 template <typename T, unsigned N> 285 ArrayRef<T> makeArrayRef(const SmallVector<T, N> &Vec) { 286 return Vec; 287 } 288 289 /// Construct an ArrayRef from a std::vector. 290 template<typename T> 291 ArrayRef<T> makeArrayRef(const std::vector<T> &Vec) { 292 return Vec; 293 } 294 295 /// Construct an ArrayRef from a C array. 296 template<typename T, size_t N> 297 ArrayRef<T> makeArrayRef(const T (&Arr)[N]) { 298 return ArrayRef<T>(Arr); 299 } 300 301 /// @} 302 /// @name ArrayRef Comparison Operators 303 /// @{ 304 305 template<typename T> 306 inline bool operator==(ArrayRef<T> LHS, ArrayRef<T> RHS) { 307 return LHS.equals(RHS); 308 } 309 310 template<typename T> 311 inline bool operator!=(ArrayRef<T> LHS, ArrayRef<T> RHS) { 312 return !(LHS == RHS); 313 } 314 315 /// @} 316 317 // ArrayRefs can be treated like a POD type. 318 template <typename T> struct isPodLike; 319 template <typename T> struct isPodLike<ArrayRef<T> > { 320 static const bool value = true; 321 }; 322} 323 324#endif 325