dynamic_vector.h revision ea9fd91360a23da4652a5c51eb2e909ff765fe9e
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 24namespace chre { 25 26/** 27 * A container for storing a sequential array of elements. This container 28 * resizes dynamically using heap allocations. 29 */ 30template<typename ElementType> 31class DynamicVector : public NonCopyable { 32 public: 33 /** 34 * Destructs the objects and releases the memory owned by the vector. 35 */ 36 ~DynamicVector(); 37 38 /** 39 * Returns a pointer to the underlying buffer. Note that this should not be 40 * considered to be persistent as the vector will be moved and resized 41 * automatically. 42 * 43 * @return the pointer to the underlying buffer. 44 */ 45 ElementType *data(); 46 47 /** 48 * Returns a const pointer to the underlying buffer. Note that this should not 49 * be considered to be persistent as the vector will be moved and resized 50 * automatically. 51 * 52 * @return the const pointer to the underlying buffer. 53 */ 54 const ElementType *data() const; 55 56 /** 57 * Returns the current number of elements in the vector. 58 * 59 * @return the number of elements in the vector. 60 */ 61 size_t size() const; 62 63 /** 64 * Returns the maximum number of elements that can be stored in this vector 65 * without a resize operation. 66 * 67 * @return the capacity of the vector. 68 */ 69 size_t capacity() const; 70 71 /** 72 * Determines whether the vector is empty or not. 73 * 74 * @return Returns true if the vector is empty. 75 */ 76 bool empty() const; 77 78 /** 79 * Pushes an element onto the back of the vector. If the vector requires a 80 * resize and that allocation fails this function will return false. 81 * 82 * @param The element to push onto the vector. 83 * @return Returns true if the element was pushed successfully. 84 */ 85 bool push_back(const ElementType& element); 86 87 /** 88 * Constructs an element onto the back of the vector. It is illegal to 89 * construct an item onto a full vector. The user of the API must check the 90 * return of the full() function prior to constructing another element. 91 * 92 * @param The arguments to the constructor 93 */ 94 template<typename... Args> 95 bool emplace_back(Args&&... args); 96 97 /** 98 * Obtains an element of the vector given an index. It is illegal to index 99 * this vector out of bounds and the user of the API must check the size() 100 * function prior to indexing this vector to ensure that they will not read 101 * out of bounds. 102 * 103 * @param The index of the element. 104 * @return The element. 105 */ 106 ElementType& operator[](size_t index); 107 108 /** 109 * Obtains a const element of the vector given an index. It is illegal to 110 * index this vector out of bounds and the user of the API must check the 111 * size() function prior to indexing this vector to ensure that they will not 112 * read out of bounds. 113 * 114 * @param The index of the element. 115 * @return The element. 116 */ 117 const ElementType& operator[](size_t index) const; 118 119 /** 120 * Resizes the vector to a new capacity returning true if allocation was 121 * successful. If the new capacity is smaller than the current capacity, 122 * the operation is a no-op and true is returned. If a memory allocation 123 * fails, the contents of the vector are not modified and false is returned. 124 * This is intended to be similar to the reserve function of the std::vector. 125 * 126 * @param The new capacity of the vector. 127 * @return True if the resize operation was successful. 128 */ 129 bool reserve(size_t newCapacity); 130 131 /** 132 * Inserts an element into the vector at a given index. If a resize of the 133 * vector is required and the allocation fails, false will be returned. This 134 * will shift all vector elements after the given index one position backward 135 * in the list. The supplied index must be <= the size of the vector. It is 136 * not possible to have a sparse list of items. If the index is > the current 137 * size of the vector, false will be returned. 138 * 139 * @param index The index to insert an element at. 140 * @param element The element to insert. 141 * @return Whether or not the insert operation was successful. 142 */ 143 bool insert(size_t index, const ElementType& element); 144 145 /** 146 * Removes an element from the vector given an index. All elements are moved 147 * forward one position. The destructor is invoked. The index passed in must 148 * be less than the size() of the vector. If the index is greater than or 149 * equal to the size no operation is performed. 150 * 151 * @param index The index to remove an element at. 152 */ 153 void erase(size_t index); 154 155 private: 156 //! A pointer to the underlying data buffer. 157 ElementType *mData = nullptr; 158 159 //! The current size of the vector, as in the number of elements stored. 160 size_t mSize = 0; 161 162 //! The current capacity of the vector, as in the maximum number of elements 163 //! that can be stored. 164 size_t mCapacity = 0; 165 166 /** 167 * Prepares a vector to push one element onto the back. The vector may be 168 * resized if required. 169 * 170 * @return Whether or not the resize was successful. 171 */ 172 bool prepareForPush(); 173}; 174 175} // namespace chre 176 177#include "chre/util/dynamic_vector_impl.h" 178 179#endif // CHRE_UTIL_DYNAMIC_VECTOR_H_ 180