Vladimir Marko | 089142c | 2014-06-05 10:57:05 +0100 | [diff] [blame^] | 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 | template <typename T, bool ok> struct ArrayRefHelper; |
| 28 | |
| 29 | /** |
| 30 | * @brief A container that references an array. |
| 31 | * |
| 32 | * @details The template class ArrayRef provides a container that references |
| 33 | * an external array. This external array must remain alive while the ArrayRef |
| 34 | * object is in use. The external array may be a std::vector<>-backed storage |
| 35 | * or any other contiguous chunk of memory but that memory must remain valid, |
| 36 | * i.e. the std::vector<> must not be resized for example. |
| 37 | * |
| 38 | * Except for copy/assign and insert/erase/capacity functions, the interface |
| 39 | * is essentially the same as std::vector<>. Since we don't want to throw |
| 40 | * exceptions, at() is also excluded. |
| 41 | */ |
| 42 | template <typename T> |
| 43 | class ArrayRef { |
| 44 | public: |
| 45 | typedef T value_type; |
| 46 | typedef T& reference; |
| 47 | typedef const T& const_reference; |
| 48 | typedef T* pointer; |
| 49 | typedef const T* const_pointer; |
| 50 | typedef T* iterator; |
| 51 | typedef const T* const_iterator; |
| 52 | typedef std::reverse_iterator<iterator> reverse_iterator; |
| 53 | typedef std::reverse_iterator<const_iterator> const_reverse_iterator; |
| 54 | typedef ptrdiff_t difference_type; |
| 55 | typedef size_t size_type; |
| 56 | |
| 57 | // Constructors. |
| 58 | |
| 59 | constexpr ArrayRef() |
| 60 | : array_(nullptr), size_(0u) { |
| 61 | } |
| 62 | |
| 63 | template <size_t size> |
| 64 | constexpr ArrayRef(T (&array)[size]) |
| 65 | : array_(array), size_(size) { |
| 66 | } |
| 67 | |
| 68 | template <typename U, size_t size> |
| 69 | constexpr ArrayRef(U (&array)[size], |
| 70 | typename ArrayRefHelper<T, std::is_same<T, const U>::value>::tag t = tag()) |
| 71 | : array_(array), size_(size) { |
| 72 | } |
| 73 | |
| 74 | constexpr ArrayRef(T* array, size_t size) |
| 75 | : array_(array), size_(size) { |
| 76 | } |
| 77 | |
| 78 | template <typename U> |
| 79 | constexpr ArrayRef(U* array, size_t size, |
| 80 | typename ArrayRefHelper<T, std::is_same<T, const U>::value>::tag t = tag()) |
| 81 | : array_(array), size_(size) { |
| 82 | } |
| 83 | |
| 84 | explicit ArrayRef(std::vector<T>& v) |
| 85 | : array_(v.data()), size_(v.size()) { |
| 86 | } |
| 87 | |
| 88 | template <typename U> |
| 89 | ArrayRef(const std::vector<U>& v, |
| 90 | typename ArrayRefHelper<T, std::is_same<T, const U>::value>::tag t = tag()) |
| 91 | : array_(v.data()), size_(v.size()) { |
| 92 | } |
| 93 | |
| 94 | // Assignment operators. |
| 95 | |
| 96 | ArrayRef& operator=(const ArrayRef& other) { |
| 97 | array_ = other.array_; |
| 98 | size_ = other.size_; |
| 99 | return *this; |
| 100 | } |
| 101 | |
| 102 | template <typename U> |
| 103 | typename ArrayRefHelper<T, std::is_same<T, const U>::value>::type& |
| 104 | operator=(const ArrayRef<U>& other) { |
| 105 | return *this = ArrayRef(other); |
| 106 | } |
| 107 | |
| 108 | // Destructor. |
| 109 | ~ArrayRef() = default; |
| 110 | |
| 111 | // Iterators. |
| 112 | iterator begin() { return array_; } |
| 113 | const_iterator begin() const { return array_; } |
| 114 | const_iterator cbegin() const { return array_; } |
| 115 | iterator end() { return array_ + size_; } |
| 116 | const_iterator end() const { return array_ + size_; } |
| 117 | const_iterator cend() const { return array_ + size_; } |
| 118 | reverse_iterator rbegin() { return reverse_iterator(end()); } |
| 119 | const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); } |
| 120 | const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); } |
| 121 | reverse_iterator rend() { return reverse_iterator(begin()); } |
| 122 | const_reverse_iterator rend() const { return const_reverse_iterator(begin()); } |
| 123 | const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); } |
| 124 | |
| 125 | // Size. |
| 126 | size_type size() const { return size_; } |
| 127 | bool empty() const { return size() == 0u; } |
| 128 | |
| 129 | // Element access. NOTE: Not providing at(). |
| 130 | |
| 131 | reference operator[](size_type n) { |
| 132 | DCHECK_LT(n, size_); |
| 133 | return array_[n]; |
| 134 | } |
| 135 | |
| 136 | const_reference operator[](size_type n) const { |
| 137 | DCHECK_LT(n, size_); |
| 138 | return array_[n]; |
| 139 | } |
| 140 | |
| 141 | reference front() { |
| 142 | DCHECK_NE(size_, 0u); |
| 143 | return array_[0]; |
| 144 | } |
| 145 | |
| 146 | const_reference front() const { |
| 147 | DCHECK_NE(size_, 0u); |
| 148 | return array_[0]; |
| 149 | } |
| 150 | |
| 151 | reference back() { |
| 152 | DCHECK_NE(size_, 0u); |
| 153 | return array_[size_ - 1u]; |
| 154 | } |
| 155 | |
| 156 | const_reference back() const { |
| 157 | DCHECK_NE(size_, 0u); |
| 158 | return array_[size_ - 1u]; |
| 159 | } |
| 160 | |
| 161 | value_type* data() { return array_; } |
| 162 | const value_type* data() const { return array_; } |
| 163 | |
| 164 | private: |
| 165 | struct tag { }; |
| 166 | friend struct ArrayRefHelper<T, true>; |
| 167 | |
| 168 | T* array_; |
| 169 | size_t size_; |
| 170 | }; |
| 171 | |
| 172 | template <typename T> struct ArrayRefHelper<T, true> { |
| 173 | typedef typename ArrayRef<T>::tag tag; |
| 174 | typedef ArrayRef<T> type; |
| 175 | }; |
| 176 | |
| 177 | template <typename T> struct ArrayRefHelper<T, false> { |
| 178 | // SFINAE: No "tag" or "type" typedef. |
| 179 | }; |
| 180 | |
| 181 | } // namespace art |
| 182 | |
| 183 | |
| 184 | #endif // ART_COMPILER_UTILS_ARRAY_REF_H_ |