Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2015 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_LIBARTBASE_BASE_ARRAY_SLICE_H_ |
| 18 | #define ART_LIBARTBASE_BASE_ARRAY_SLICE_H_ |
| 19 | |
| 20 | #include <ostream> |
| 21 | #include "bit_utils.h" |
| 22 | #include "casts.h" |
| 23 | #include "iteration_range.h" |
| 24 | #include "length_prefixed_array.h" |
| 25 | #include "stride_iterator.h" |
| 26 | |
| 27 | namespace art { |
| 28 | |
| 29 | // An ArraySlice is an abstraction over an array or a part of an array of a particular type. It does |
| 30 | // bounds checking and can be made from several common array-like structures in Art. |
| 31 | template <typename T> |
| 32 | class ArraySlice { |
| 33 | public: |
| 34 | using value_type = T; |
| 35 | using reference = T&; |
| 36 | using const_reference = const T&; |
| 37 | using pointer = T*; |
| 38 | using const_pointer = const T*; |
| 39 | using iterator = StrideIterator<T>; |
| 40 | using const_iterator = StrideIterator<const T>; |
| 41 | using reverse_iterator = std::reverse_iterator<iterator>; |
| 42 | using const_reverse_iterator = std::reverse_iterator<const_iterator>; |
| 43 | using difference_type = ptrdiff_t; |
| 44 | using size_type = size_t; |
| 45 | |
| 46 | // Create an empty array slice. |
| 47 | ArraySlice() : array_(nullptr), size_(0), element_size_(0) {} |
| 48 | |
| 49 | // Create an array slice of the first 'length' elements of the array, with each element being |
| 50 | // element_size bytes long. |
| 51 | ArraySlice(T* array, |
| 52 | size_t length, |
| 53 | size_t element_size = sizeof(T)) |
| 54 | : array_(array), |
| 55 | size_(dchecked_integral_cast<uint32_t>(length)), |
| 56 | element_size_(element_size) { |
| 57 | DCHECK(array_ != nullptr || length == 0); |
| 58 | } |
| 59 | |
| 60 | ArraySlice(LengthPrefixedArray<T>* lpa, |
| 61 | size_t element_size = sizeof(T), |
| 62 | size_t alignment = alignof(T)) |
| 63 | : ArraySlice( |
| 64 | lpa != nullptr && lpa->size() != 0 ? &lpa->At(0, element_size, alignment) : nullptr, |
| 65 | lpa != nullptr ? lpa->size() : 0, |
| 66 | element_size) {} |
| 67 | ArraySlice(const ArraySlice<T>&) = default; |
Fairphone ODM | 25c12f5 | 2023-12-15 17:24:06 +0800 | [diff] [blame] | 68 | ArraySlice(ArraySlice<T>&&) noexcept = default; |
Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame] | 69 | ArraySlice<T>& operator=(const ArraySlice<T>&) = default; |
Fairphone ODM | 25c12f5 | 2023-12-15 17:24:06 +0800 | [diff] [blame] | 70 | ArraySlice<T>& operator=(ArraySlice<T>&&) noexcept = default; |
Martin Stjernholm | c15e7e4 | 2020-12-02 22:50:53 +0000 | [diff] [blame] | 71 | |
| 72 | // Iterators. |
| 73 | iterator begin() { return iterator(&AtUnchecked(0), element_size_); } |
| 74 | const_iterator begin() const { return const_iterator(&AtUnchecked(0), element_size_); } |
| 75 | const_iterator cbegin() const { return const_iterator(&AtUnchecked(0), element_size_); } |
| 76 | StrideIterator<T> end() { return StrideIterator<T>(&AtUnchecked(size_), element_size_); } |
| 77 | const_iterator end() const { return const_iterator(&AtUnchecked(size_), element_size_); } |
| 78 | const_iterator cend() const { return const_iterator(&AtUnchecked(size_), element_size_); } |
| 79 | reverse_iterator rbegin() { return reverse_iterator(end()); } |
| 80 | const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); } |
| 81 | const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); } |
| 82 | reverse_iterator rend() { return reverse_iterator(begin()); } |
| 83 | const_reverse_iterator rend() const { return const_reverse_iterator(begin()); } |
| 84 | const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); } |
| 85 | |
| 86 | // Size. |
| 87 | size_type size() const { return size_; } |
| 88 | bool empty() const { return size() == 0u; } |
| 89 | |
| 90 | // Element access. NOTE: Not providing at() and data(). |
| 91 | |
| 92 | reference operator[](size_t index) { |
| 93 | DCHECK_LT(index, size_); |
| 94 | return AtUnchecked(index); |
| 95 | } |
| 96 | |
| 97 | const_reference operator[](size_t index) const { |
| 98 | DCHECK_LT(index, size_); |
| 99 | return AtUnchecked(index); |
| 100 | } |
| 101 | |
| 102 | reference front() { |
| 103 | DCHECK(!empty()); |
| 104 | return (*this)[0]; |
| 105 | } |
| 106 | |
| 107 | const_reference front() const { |
| 108 | DCHECK(!empty()); |
| 109 | return (*this)[0]; |
| 110 | } |
| 111 | |
| 112 | reference back() { |
| 113 | DCHECK(!empty()); |
| 114 | return (*this)[size_ - 1u]; |
| 115 | } |
| 116 | |
| 117 | const_reference back() const { |
| 118 | DCHECK(!empty()); |
| 119 | return (*this)[size_ - 1u]; |
| 120 | } |
| 121 | |
| 122 | ArraySlice<T> SubArray(size_type pos) { |
| 123 | return SubArray(pos, size() - pos); |
| 124 | } |
| 125 | |
| 126 | ArraySlice<const T> SubArray(size_type pos) const { |
| 127 | return SubArray(pos, size() - pos); |
| 128 | } |
| 129 | |
| 130 | ArraySlice<T> SubArray(size_type pos, size_type length) { |
| 131 | DCHECK_LE(pos, size()); |
| 132 | DCHECK_LE(length, size() - pos); |
| 133 | return ArraySlice<T>(&AtUnchecked(pos), length, element_size_); |
| 134 | } |
| 135 | |
| 136 | ArraySlice<const T> SubArray(size_type pos, size_type length) const { |
| 137 | DCHECK_LE(pos, size()); |
| 138 | DCHECK_LE(length, size() - pos); |
| 139 | return ArraySlice<const T>(&AtUnchecked(pos), length, element_size_); |
| 140 | } |
| 141 | |
| 142 | size_t ElementSize() const { |
| 143 | return element_size_; |
| 144 | } |
| 145 | |
| 146 | bool Contains(const T* element) const { |
| 147 | return &AtUnchecked(0) <= element && element < &AtUnchecked(size_) && |
| 148 | ((reinterpret_cast<uintptr_t>(element) - |
| 149 | reinterpret_cast<uintptr_t>(&AtUnchecked(0))) % element_size_) == 0; |
| 150 | } |
| 151 | |
| 152 | size_t OffsetOf(const T* element) const { |
| 153 | DCHECK(Contains(element)); |
| 154 | // Since it's possible element_size_ != sizeof(T) we cannot just use pointer arithmatic |
| 155 | uintptr_t base_ptr = reinterpret_cast<uintptr_t>(&AtUnchecked(0)); |
| 156 | uintptr_t obj_ptr = reinterpret_cast<uintptr_t>(element); |
| 157 | return (obj_ptr - base_ptr) / element_size_; |
| 158 | } |
| 159 | |
| 160 | private: |
| 161 | T& AtUnchecked(size_t index) { |
| 162 | return *reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(array_) + index * element_size_); |
| 163 | } |
| 164 | |
| 165 | const T& AtUnchecked(size_t index) const { |
| 166 | return *reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(array_) + index * element_size_); |
| 167 | } |
| 168 | |
| 169 | T* array_; |
| 170 | size_t size_; |
| 171 | size_t element_size_; |
| 172 | }; |
| 173 | |
| 174 | template<typename T> |
| 175 | std::ostream& operator<<(std::ostream& os, const ArraySlice<T>& ts) { |
| 176 | bool first = true; |
| 177 | os << "["; |
| 178 | for (const T& t : ts) { |
| 179 | if (!first) { os << ", "; } |
| 180 | first = false; |
| 181 | os << t; |
| 182 | } |
| 183 | os << "]"; |
| 184 | return os; |
| 185 | } |
| 186 | |
| 187 | } // namespace art |
| 188 | |
| 189 | #endif // ART_LIBARTBASE_BASE_ARRAY_SLICE_H_ |