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 using value_type = T; 44 using reference = T&; 45 using const_reference = const T&; 46 using pointer = T*; 47 using const_pointer = const T*; 48 using iterator = T*; 49 using const_iterator = const T*; 50 using reverse_iterator = std::reverse_iterator<iterator>; 51 using const_reverse_iterator = std::reverse_iterator<const_iterator>; 52 using difference_type = ptrdiff_t; 53 using size_type = size_t; 54 55 // Constructors. 56 ArrayRef()57 constexpr ArrayRef() 58 : array_(nullptr), size_(0u) { 59 } 60 61 template <size_t size> ArrayRef(T (& array)[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> ArrayRef(U (& array)[size])69 explicit constexpr ArrayRef(U (&array)[size]) 70 : array_(array), size_(size) { 71 } 72 ArrayRef(T * array_in,size_t size_in)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> ArrayRef(Vector & v)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> ArrayRef(const Vector & v)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. begin()113 iterator begin() { return array_; } begin()114 const_iterator begin() const { return array_; } cbegin()115 const_iterator cbegin() const { return array_; } end()116 iterator end() { return array_ + size_; } end()117 const_iterator end() const { return array_ + size_; } cend()118 const_iterator cend() const { return array_ + size_; } rbegin()119 reverse_iterator rbegin() { return reverse_iterator(end()); } rbegin()120 const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); } crbegin()121 const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); } rend()122 reverse_iterator rend() { return reverse_iterator(begin()); } rend()123 const_reverse_iterator rend() const { return const_reverse_iterator(begin()); } crend()124 const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); } 125 126 // Size. size()127 size_type size() const { return size_; } empty()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 front()142 reference front() { 143 DCHECK(!empty()); 144 return array_[0]; 145 } 146 front()147 const_reference front() const { 148 DCHECK(!empty()); 149 return array_[0]; 150 } 151 back()152 reference back() { 153 DCHECK(!empty()); 154 return array_[size_ - 1u]; 155 } 156 back()157 const_reference back() const { 158 DCHECK(!empty()); 159 return array_[size_ - 1u]; 160 } 161 data()162 value_type* data() { return array_; } data()163 const value_type* data() const { return array_; } 164 SubArray(size_type pos)165 ArrayRef SubArray(size_type pos) { 166 return SubArray(pos, size() - pos); 167 } 168 SubArray(size_type pos)169 ArrayRef<const T> SubArray(size_type pos) const { 170 return SubArray(pos, size() - pos); 171 } 172 SubArray(size_type pos,size_type length)173 ArrayRef SubArray(size_type pos, size_type length) { 174 DCHECK_LE(pos, size()); 175 DCHECK_LE(length, size() - pos); 176 return ArrayRef(data() + pos, length); 177 } 178 SubArray(size_type pos,size_type length)179 ArrayRef<const T> SubArray(size_type pos, size_type length) const { 180 DCHECK_LE(pos, size()); 181 DCHECK_LE(length, size() - pos); 182 return ArrayRef<const T>(data() + pos, length); 183 } 184 185 private: 186 T* array_; 187 size_t size_; 188 }; 189 190 template <typename T> 191 bool operator==(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) { 192 return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin()); 193 } 194 195 template <typename T> 196 bool operator!=(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) { 197 return !(lhs == rhs); 198 } 199 200 } // namespace art 201 202 203 #endif // ART_RUNTIME_BASE_ARRAY_REF_H_ 204