1 /* 2 * Copyright (C) 2014 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 ART_RUNTIME_BASE_ARRAY_REF_H_ 18 #define ART_RUNTIME_BASE_ARRAY_REF_H_ 19 20 #include <type_traits> 21 #include <vector> 22 23 #include "base/logging.h" 24 25 namespace art { 26 27 /** 28 * @brief A container that references an array. 29 * 30 * @details The template class ArrayRef provides a container that references 31 * an external array. This external array must remain alive while the ArrayRef 32 * object is in use. The external array may be a std::vector<>-backed storage 33 * or any other contiguous chunk of memory but that memory must remain valid, 34 * i.e. the std::vector<> must not be resized for example. 35 * 36 * Except for copy/assign and insert/erase/capacity functions, the interface 37 * is essentially the same as std::vector<>. Since we don't want to throw 38 * exceptions, at() is also excluded. 39 */ 40 template <typename T> 41 class ArrayRef { 42 public: 43 typedef T value_type; 44 typedef T& reference; 45 typedef const T& const_reference; 46 typedef T* pointer; 47 typedef const T* const_pointer; 48 typedef T* iterator; 49 typedef const T* const_iterator; 50 typedef std::reverse_iterator<iterator> reverse_iterator; 51 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 52 typedef ptrdiff_t difference_type; 53 typedef size_t size_type; 54 55 // Constructors. 56 57 constexpr ArrayRef() 58 : array_(nullptr), size_(0u) { 59 } 60 61 template <size_t size> 62 explicit constexpr ArrayRef(T (&array)[size]) 63 : array_(array), size_(size) { 64 } 65 66 template <typename U, 67 size_t size, 68 typename = typename std::enable_if<std::is_same<T, const U>::value>::type> 69 explicit constexpr ArrayRef(U (&array)[size]) 70 : array_(array), size_(size) { 71 } 72 73 constexpr ArrayRef(T* array_in, size_t size_in) 74 : array_(array_in), size_(size_in) { 75 } 76 77 template <typename Vector, 78 typename = typename std::enable_if< 79 std::is_same<typename Vector::value_type, value_type>::value>::type> 80 explicit ArrayRef(Vector& v) 81 : array_(v.data()), size_(v.size()) { 82 } 83 84 template <typename Vector, 85 typename = typename std::enable_if< 86 std::is_same< 87 typename std::add_const<typename Vector::value_type>::type, 88 value_type>::value>::type> 89 explicit ArrayRef(const Vector& v) 90 : array_(v.data()), size_(v.size()) { 91 } 92 93 ArrayRef(const ArrayRef&) = default; 94 95 // Assignment operators. 96 97 ArrayRef& operator=(const ArrayRef& other) { 98 array_ = other.array_; 99 size_ = other.size_; 100 return *this; 101 } 102 103 template <typename U> 104 typename std::enable_if<std::is_same<T, const U>::value, ArrayRef>::type& 105 operator=(const ArrayRef<U>& other) { 106 return *this = ArrayRef(other); 107 } 108 109 // Destructor. 110 ~ArrayRef() = default; 111 112 // Iterators. 113 iterator begin() { return array_; } 114 const_iterator begin() const { return array_; } 115 const_iterator cbegin() const { return array_; } 116 iterator end() { return array_ + size_; } 117 const_iterator end() const { return array_ + size_; } 118 const_iterator cend() const { return array_ + size_; } 119 reverse_iterator rbegin() { return reverse_iterator(end()); } 120 const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); } 121 const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); } 122 reverse_iterator rend() { return reverse_iterator(begin()); } 123 const_reverse_iterator rend() const { return const_reverse_iterator(begin()); } 124 const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); } 125 126 // Size. 127 size_type size() const { return size_; } 128 bool empty() const { return size() == 0u; } 129 130 // Element access. NOTE: Not providing at(). 131 132 reference operator[](size_type n) { 133 DCHECK_LT(n, size_); 134 return array_[n]; 135 } 136 137 const_reference operator[](size_type n) const { 138 DCHECK_LT(n, size_); 139 return array_[n]; 140 } 141 142 reference front() { 143 DCHECK_NE(size_, 0u); 144 return array_[0]; 145 } 146 147 const_reference front() const { 148 DCHECK_NE(size_, 0u); 149 return array_[0]; 150 } 151 152 reference back() { 153 DCHECK_NE(size_, 0u); 154 return array_[size_ - 1u]; 155 } 156 157 const_reference back() const { 158 DCHECK_NE(size_, 0u); 159 return array_[size_ - 1u]; 160 } 161 162 value_type* data() { return array_; } 163 const value_type* data() const { return array_; } 164 165 ArrayRef SubArray(size_type pos) { 166 return SubArray(pos, size() - pos); 167 } 168 ArrayRef<const T> SubArray(size_type pos) const { 169 return SubArray(pos, size() - pos); 170 } 171 ArrayRef SubArray(size_type pos, size_type length) { 172 DCHECK_LE(pos, size()); 173 DCHECK_LE(length, size() - pos); 174 return ArrayRef(data() + pos, length); 175 } 176 ArrayRef<const T> SubArray(size_type pos, size_type length) const { 177 DCHECK_LE(pos, size()); 178 DCHECK_LE(length, size() - pos); 179 return ArrayRef<const T>(data() + pos, length); 180 } 181 182 private: 183 T* array_; 184 size_t size_; 185 }; 186 187 template <typename T> 188 bool operator==(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) { 189 return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin()); 190 } 191 192 template <typename T> 193 bool operator!=(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) { 194 return !(lhs == rhs); 195 } 196 197 } // namespace art 198 199 200 #endif // ART_RUNTIME_BASE_ARRAY_REF_H_ 201
