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_COMPILER_UTILS_ARRAY_REF_H_ 18 #define ART_COMPILER_UTILS_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 private: 43 struct tag { }; 44 45 public: 46 typedef T value_type; 47 typedef T& reference; 48 typedef const T& const_reference; 49 typedef T* pointer; 50 typedef const T* const_pointer; 51 typedef T* iterator; 52 typedef const T* const_iterator; 53 typedef std::reverse_iterator<iterator> reverse_iterator; 54 typedef std::reverse_iterator<const_iterator> const_reverse_iterator; 55 typedef ptrdiff_t difference_type; 56 typedef size_t size_type; 57 58 // Constructors. 59 ArrayRef()60 constexpr ArrayRef() 61 : array_(nullptr), size_(0u) { 62 } 63 64 template <size_t size> ArrayRef(T (& array)[size])65 explicit constexpr ArrayRef(T (&array)[size]) 66 : array_(array), size_(size) { 67 } 68 69 template <typename U, size_t size> 70 explicit constexpr ArrayRef(U (&array)[size], 71 typename std::enable_if<std::is_same<T, const U>::value, tag>::type 72 t ATTRIBUTE_UNUSED = tag()) array_(array)73 : array_(array), size_(size) { 74 } 75 ArrayRef(T * array_in,size_t size_in)76 constexpr ArrayRef(T* array_in, size_t size_in) 77 : array_(array_in), size_(size_in) { 78 } 79 80 template <typename Vector, 81 typename = typename std::enable_if< 82 std::is_same<typename Vector::value_type, value_type>::value>::type> ArrayRef(Vector & v)83 explicit ArrayRef(Vector& v) 84 : array_(v.data()), size_(v.size()) { 85 } 86 87 template <typename Vector, 88 typename = typename std::enable_if< 89 std::is_same< 90 typename std::add_const<typename Vector::value_type>::type, 91 value_type>::value>::type> ArrayRef(const Vector & v)92 explicit ArrayRef(const Vector& v) 93 : array_(v.data()), size_(v.size()) { 94 } 95 96 ArrayRef(const ArrayRef&) = default; 97 98 // Assignment operators. 99 100 ArrayRef& operator=(const ArrayRef& other) { 101 array_ = other.array_; 102 size_ = other.size_; 103 return *this; 104 } 105 106 template <typename U> 107 typename std::enable_if<std::is_same<T, const U>::value, ArrayRef>::type& 108 operator=(const ArrayRef<U>& other) { 109 return *this = ArrayRef(other); 110 } 111 112 // Destructor. 113 ~ArrayRef() = default; 114 115 // Iterators. begin()116 iterator begin() { return array_; } begin()117 const_iterator begin() const { return array_; } cbegin()118 const_iterator cbegin() const { return array_; } end()119 iterator end() { return array_ + size_; } end()120 const_iterator end() const { return array_ + size_; } cend()121 const_iterator cend() const { return array_ + size_; } rbegin()122 reverse_iterator rbegin() { return reverse_iterator(end()); } rbegin()123 const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); } crbegin()124 const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); } rend()125 reverse_iterator rend() { return reverse_iterator(begin()); } rend()126 const_reverse_iterator rend() const { return const_reverse_iterator(begin()); } crend()127 const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); } 128 129 // Size. size()130 size_type size() const { return size_; } empty()131 bool empty() const { return size() == 0u; } 132 133 // Element access. NOTE: Not providing at(). 134 135 reference operator[](size_type n) { 136 DCHECK_LT(n, size_); 137 return array_[n]; 138 } 139 140 const_reference operator[](size_type n) const { 141 DCHECK_LT(n, size_); 142 return array_[n]; 143 } 144 front()145 reference front() { 146 DCHECK_NE(size_, 0u); 147 return array_[0]; 148 } 149 front()150 const_reference front() const { 151 DCHECK_NE(size_, 0u); 152 return array_[0]; 153 } 154 back()155 reference back() { 156 DCHECK_NE(size_, 0u); 157 return array_[size_ - 1u]; 158 } 159 back()160 const_reference back() const { 161 DCHECK_NE(size_, 0u); 162 return array_[size_ - 1u]; 163 } 164 data()165 value_type* data() { return array_; } data()166 const value_type* data() const { return array_; } 167 SubArray(size_type pos)168 ArrayRef SubArray(size_type pos) const { 169 return SubArray(pos, size_ - pos); 170 } SubArray(size_type pos,size_type length)171 ArrayRef SubArray(size_type pos, size_type length) const { 172 DCHECK_LE(pos, size()); 173 DCHECK_LE(length, size() - pos); 174 return ArrayRef(array_ + pos, length); 175 } 176 177 private: 178 T* array_; 179 size_t size_; 180 }; 181 182 template <typename T> 183 bool operator==(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) { 184 return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin()); 185 } 186 187 template <typename T> 188 bool operator!=(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) { 189 return !(lhs == rhs); 190 } 191 192 } // namespace art 193 194 195 #endif // ART_COMPILER_UTILS_ARRAY_REF_H_ 196