1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef CHRE_UTIL_DYNAMIC_VECTOR_H_ 18 #define CHRE_UTIL_DYNAMIC_VECTOR_H_ 19 20 #include <cstddef> 21 22 #include "chre/util/non_copyable.h" 23 24 namespace chre { 25 26 /** 27 * A container for storing a sequential array of elements. This container 28 * resizes dynamically using heap allocations. 29 */ 30 template<typename ElementType> 31 class DynamicVector : public NonCopyable { 32 public: 33 /** 34 * Random-access iterator that points to some element in the container. 35 */ 36 typedef ElementType* iterator; 37 typedef const ElementType* const_iterator; 38 39 typedef size_t size_type; 40 41 /** 42 * Default-constructs a dynamic vector. 43 */ 44 DynamicVector(); 45 46 /** 47 * Move-constructs a dynamic vector from another. The other dynamic vector is 48 * left in an empty state. 49 * 50 * @param other The other vector to move from. 51 */ 52 DynamicVector(DynamicVector<ElementType>&& other); 53 54 /** 55 * Move-constructs a dynamic vector from another. The other dynamic vector is 56 * left in an empty state. 57 */ 58 DynamicVector& operator=(DynamicVector<ElementType>&& other); 59 60 /** 61 * Destructs the objects and releases the memory owned by the vector. 62 */ 63 ~DynamicVector(); 64 65 /** 66 * Removes all elements from the vector, but does not change the capacity. 67 * All iterators and references are invalidated. 68 */ 69 void clear(); 70 71 /** 72 * Returns a pointer to the underlying buffer. Note that this should not be 73 * considered to be persistent as the vector will be moved and resized 74 * automatically. 75 * 76 * @return The pointer to the underlying buffer. 77 */ 78 ElementType *data(); 79 80 /** 81 * Returns a const pointer to the underlying buffer. Note that this should not 82 * be considered to be persistent as the vector will be moved and resized 83 * automatically. 84 * 85 * @return The const pointer to the underlying buffer. 86 */ 87 const ElementType *data() const; 88 89 /** 90 * Returns the current number of elements in the vector. 91 * 92 * @return The number of elements in the vector. 93 */ 94 size_type size() const; 95 96 /** 97 * Returns the maximum number of elements that can be stored in this vector 98 * without a resize operation. 99 * 100 * @return The capacity of the vector. 101 */ 102 size_type capacity() const; 103 104 /** 105 * Determines whether the vector is empty or not. 106 * 107 * @return true if the vector is empty. 108 */ 109 bool empty() const; 110 111 /** 112 * Erases the last element in the vector. Invalid to call on an empty vector. 113 * 114 * Invalidates any references to back() and end()/cend(). 115 */ 116 void pop_back(); 117 118 /** 119 * Copy- or move-constructs an element onto the back of the vector. If the 120 * vector requires a resize and that allocation fails this function will 121 * return false. All iterators and references are invalidated if the container 122 * has been resized. Otherwise, only the past-the-end iterator is invalidated. 123 * 124 * @param The element to push onto the vector. 125 * @return true if the element was pushed successfully. 126 */ 127 bool push_back(const ElementType& element); 128 bool push_back(ElementType&& element); 129 130 /** 131 * Constructs an element onto the back of the vector. All iterators and 132 * references are invalidated if the container has been resized. Otherwise, 133 * only the past-the-end iterator is invalidated. 134 * 135 * @param The arguments to the constructor 136 * @return true if the element is constructed successfully. 137 */ 138 template<typename... Args> 139 bool emplace_back(Args&&... args); 140 141 /** 142 * Obtains an element of the vector given an index. It is illegal to index 143 * this vector out of bounds and the user of the API must check the size() 144 * function prior to indexing this vector to ensure that they will not read 145 * out of bounds. 146 * 147 * @param The index of the element. 148 * @return The element. 149 */ 150 ElementType& operator[](size_type index); 151 152 /** 153 * Obtains a const element of the vector given an index. It is illegal to 154 * index this vector out of bounds and the user of the API must check the 155 * size() function prior to indexing this vector to ensure that they will not 156 * read out of bounds. 157 * 158 * @param The index of the element. 159 * @return The element. 160 */ 161 const ElementType& operator[](size_type index) const; 162 163 /** 164 * Compares two vectors for equality. It will compare the vector sizes and 165 * return false if those are different; if not, it will compare the contents 166 * of the vectors element-by-element. The operator == should be defined and 167 * meaningful for the vector's element type. 168 * 169 * @param Right-hand side vector to compared with. 170 * @return true if two vectors are equal, false otherwise. 171 */ 172 bool operator==(const DynamicVector<ElementType>& other) const; 173 174 /** 175 * Resizes the vector to a new capacity returning true if allocation was 176 * successful. If the new capacity is smaller than the current capacity, 177 * the operation is a no-op and true is returned. If a memory allocation 178 * fails, the contents of the vector are not modified and false is returned. 179 * This is intended to be similar to the reserve function of the std::vector. 180 * All iterators and references are invalidated unless the container did not 181 * resize. 182 * 183 * @param The new capacity of the vector. 184 * @return true if the resize operation was successful. 185 */ 186 bool reserve(size_type newCapacity); 187 188 /** 189 * Resizes the vector to a new size. If the new capacity is smaller than the 190 * current size, the extraneous objects at the end are destructed. If the new 191 * capacity is larger than the current size, the new objects are 192 * default-constructed. 193 * 194 * @param size The new size of the vector. 195 * @return true if the resize operation was successful. 196 */ 197 bool resize(size_type newSize); 198 199 /** 200 * Inserts an element into the vector at a given index. If a resize of the 201 * vector is required and the allocation fails, false will be returned. This 202 * will shift all vector elements after the given index one position backward 203 * in the list. The supplied index must be <= the size of the vector. It is 204 * not possible to have a sparse list of items. If the index is > the current 205 * size of the vector, false will be returned. All iterators and references 206 * to and after the indexed element are invalidated. Iterators and references 207 * to before the indexed elements are unaffected if the container did not resize. 208 * 209 * @param index The index to insert an element at. 210 * @param element The element to insert. 211 * @return Whether or not the insert operation was successful. 212 */ 213 bool insert(size_type index, const ElementType& element); 214 bool insert(size_type index, ElementType&& element); 215 216 /** 217 * Similar to wrap(), except makes a copy of the supplied C-style array, 218 * maintaining ownership of the buffer within the DynamicVector container. The 219 * vector's capacity is increased if necessary to fit the given array, though 220 * note that this function will not cause the capacity to shrink. Upon 221 * successful reservation of necessary capacity, any pre-existing items in the 222 * vector are removed (via clear()), the supplied array is copied, and the 223 * vector's size is set to elementCount. All iterators and references are 224 * invalidated unless the container did not resize. 225 * 226 * This is essentially equivalent to calling these functions from std::vector: 227 * vector.clear(); 228 * vector.insert(vector.begin(), array, &array[elementCount]); 229 * 230 * This function is not valid to call on a vector where owns_data() is false. 231 * Use unwrap() first in that case. 232 * 233 * @param array Pointer to the start of an array 234 * @param elementCount Number of elements in the supplied array to copy 235 * 236 * @return true if capacity was reserved to fit the supplied array (or the 237 * vector already had sufficient capacity), and the supplied array was 238 * copied into the vector. If false, the vector is not modified. 239 */ 240 bool copy_array(const ElementType *array, size_type elementCount); 241 242 /** 243 * Removes an element from the vector given an index. All elements after the 244 * indexed one are moved forward one position. The destructor is invoked on 245 * on the invalid item left at the end of the vector. The index passed in 246 * must be less than the size() of the vector. If the index is greater than or 247 * equal to the size no operation is performed. All iterators and references 248 * to and after the indexed element are invalidated. 249 * 250 * @param index The index to remove an element at. 251 */ 252 void erase(size_type index); 253 254 /** 255 * Searches the vector for an element. 256 * 257 * @param element The element to comare against. 258 * @return The index of the element found. If the return is equal to size() 259 * then the element was not found. 260 */ 261 size_type find(const ElementType& element) const; 262 263 /** 264 * Swaps the location of two elements stored in the vector. The indices 265 * passed in must be less than the size() of the vector. If the index is 266 * greater than or equal to the size, no operation is performed. All 267 * iterators and references to these two indexed elements are invalidated. 268 * 269 * @param index0 The index of the first element 270 * @param index1 The index of the second element 271 */ 272 void swap(size_type index0, size_type index1); 273 274 /** 275 * Wraps an existing C-style array so it can be used as a DynamicVector. A 276 * reference to the supplied array is kept, as opposed to making a copy. The 277 * caller retains ownership of the memory. Calling code must therefore ensure 278 * that the lifetime of the supplied array is at least as long as that of this 279 * vector, and that the memory is released after this vector is destructed, as 280 * the vector will not attempt to free the memory itself. 281 * 282 * Once a vector wraps another buffer, it cannot be resized except through 283 * another call to wrap(). However, elements can be erased to make room for 284 * adding new elements. 285 * 286 * Destruction of elements within a wrapped array remains the responsibility 287 * of the calling code. While the vector may invoke the element destructor as 288 * a result of explicit calls to functions like erase() or clear(), it will 289 * not destruct elements remaining in the array when the vector is destructed. 290 * Therefore, special care must be taken when wrapping an array of elements 291 * that have a non-trivial destructor. 292 * 293 * @param array Pointer to a pre-allocated array 294 * @param elementCount Number of elements in the array (NOT the array's size 295 * in bytes); will become the vector's size() and capacity() 296 */ 297 void wrap(ElementType *array, size_type elementCount); 298 299 300 /** 301 * Returns a vector that is wrapping an array to the newly-constructed state, 302 * with capacity equal to 0, and owns_data() is true. 303 */ 304 void unwrap(); 305 306 /** 307 * @return false if this vector is wrapping an array passed in via wrap() 308 */ 309 bool owns_data() const; 310 311 /** 312 * Returns a reference to the first element in the vector. It is illegal to 313 * call this on an empty vector. 314 * 315 * @return The first element in the vector. 316 */ 317 ElementType& front(); 318 319 /** 320 * Returns a const reference to the first element in the vector. It is illegal 321 * to call this on an empty vector. 322 * 323 * @return The first element in the vector. 324 */ 325 const ElementType& front() const; 326 327 /** 328 * Returns a reference to the last element in the vector. It is illegal to 329 * call this on an empty vector. 330 * 331 * @return The last element in the vector. 332 */ 333 ElementType& back(); 334 335 /** 336 * Returns a const reference to the last element in the vector. It is illegal 337 * to call this on an empty vector. 338 * 339 * @return The last element in the vector. 340 */ 341 const ElementType& back() const; 342 343 /** 344 * Prepares a vector to push a minimum of one element onto the back. The 345 * vector may be resized if required. The capacity of the vector increases 346 * with the growth policy of this vector (doubles for each resize for now). 347 * 348 * @return Whether or not the resize was successful. 349 */ 350 bool prepareForPush(); 351 352 /** 353 * @return A random-access iterator to the beginning. 354 */ 355 typename DynamicVector<ElementType>::iterator begin(); 356 typename DynamicVector<ElementType>::const_iterator begin() const; 357 typename DynamicVector<ElementType>::const_iterator cbegin() const; 358 359 /** 360 * @return A random-access iterator to the end. 361 */ 362 typename DynamicVector<ElementType>::iterator end(); 363 typename DynamicVector<ElementType>::const_iterator end() const; 364 typename DynamicVector<ElementType>::const_iterator cend() const; 365 366 private: 367 //! A pointer to the underlying data buffer. 368 ElementType *mData = nullptr; 369 370 //! The current size of the vector, as in the number of elements stored. 371 size_t mSize = 0; 372 373 //! The current capacity of the vector, as in the maximum number of elements 374 //! that can be stored. 375 size_t mCapacity = 0; 376 377 //! Set to true when the buffer (mData) was supplied via wrap() 378 bool mDataIsWrapped = false; 379 380 /** 381 * Prepares the vector for insertion - upon successful return, the memory at 382 * the given index will be allocated but uninitialized 383 * 384 * @param index 385 * @return true 386 */ 387 bool prepareInsert(size_t index); 388 }; 389 390 } // namespace chre 391 392 #include "chre/util/dynamic_vector_impl.h" 393 394 #endif // CHRE_UTIL_DYNAMIC_VECTOR_H_ 395
