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+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_LIBARTBASE_BASE_ARRAY_SLICE_H_
+#define ART_LIBARTBASE_BASE_ARRAY_SLICE_H_
+
+#include "base/bit_utils.h"
+#include "base/casts.h"
+#include "base/iteration_range.h"
+#include "stride_iterator.h"
+
+namespace art {
+
+// An ArraySlice is an abstraction over an array or a part of an array of a particular type. It does
+// bounds checking and can be made from several common array-like structures in Art.
+template <typename T>
+class ArraySlice {
+ public:
+ using value_type = T;
+ using reference = T&;
+ using const_reference = const T&;
+ using pointer = T*;
+ using const_pointer = const T*;
+ using iterator = StrideIterator<T>;
+ using const_iterator = StrideIterator<const T>;
+ using reverse_iterator = std::reverse_iterator<iterator>;
+ using const_reverse_iterator = std::reverse_iterator<const_iterator>;
+ using difference_type = ptrdiff_t;
+ using size_type = size_t;
+
+ // Create an empty array slice.
+ ArraySlice() : array_(nullptr), size_(0), element_size_(0) {}
+
+ // Create an array slice of the first 'length' elements of the array, with each element being
+ // element_size bytes long.
+ ArraySlice(T* array,
+ size_t length,
+ size_t element_size = sizeof(T))
+ : array_(array),
+ size_(dchecked_integral_cast<uint32_t>(length)),
+ element_size_(element_size) {
+ DCHECK(array_ != nullptr || length == 0);
+ }
+
+ // Iterators.
+ iterator begin() { return iterator(&AtUnchecked(0), element_size_); }
+ const_iterator begin() const { return const_iterator(&AtUnchecked(0), element_size_); }
+ const_iterator cbegin() const { return const_iterator(&AtUnchecked(0), element_size_); }
+ StrideIterator<T> end() { return StrideIterator<T>(&AtUnchecked(size_), element_size_); }
+ const_iterator end() const { return const_iterator(&AtUnchecked(size_), element_size_); }
+ const_iterator cend() const { return const_iterator(&AtUnchecked(size_), element_size_); }
+ reverse_iterator rbegin() { return reverse_iterator(end()); }
+ const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
+ const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); }
+ reverse_iterator rend() { return reverse_iterator(begin()); }
+ const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
+ const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); }
+
+ // Size.
+ size_type size() const { return size_; }
+ bool empty() const { return size() == 0u; }
+
+ // Element access. NOTE: Not providing at() and data().
+
+ reference operator[](size_t index) {
+ DCHECK_LT(index, size_);
+ return AtUnchecked(index);
+ }
+
+ const_reference operator[](size_t index) const {
+ DCHECK_LT(index, size_);
+ return AtUnchecked(index);
+ }
+
+ reference front() {
+ DCHECK(!empty());
+ return (*this)[0];
+ }
+
+ const_reference front() const {
+ DCHECK(!empty());
+ return (*this)[0];
+ }
+
+ reference back() {
+ DCHECK(!empty());
+ return (*this)[size_ - 1u];
+ }
+
+ const_reference back() const {
+ DCHECK(!empty());
+ return (*this)[size_ - 1u];
+ }
+
+ ArraySlice<T> SubArray(size_type pos) {
+ return SubArray(pos, size() - pos);
+ }
+
+ ArraySlice<const T> SubArray(size_type pos) const {
+ return SubArray(pos, size() - pos);
+ }
+
+ ArraySlice<T> SubArray(size_type pos, size_type length) {
+ DCHECK_LE(pos, size());
+ DCHECK_LE(length, size() - pos);
+ return ArraySlice<T>(&AtUnchecked(pos), length, element_size_);
+ }
+
+ ArraySlice<const T> SubArray(size_type pos, size_type length) const {
+ DCHECK_LE(pos, size());
+ DCHECK_LE(length, size() - pos);
+ return ArraySlice<const T>(&AtUnchecked(pos), length, element_size_);
+ }
+
+ size_t ElementSize() const {
+ return element_size_;
+ }
+
+ bool Contains(const T* element) const {
+ return &AtUnchecked(0) <= element && element < &AtUnchecked(size_);
+ }
+
+ private:
+ T& AtUnchecked(size_t index) {
+ return *reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(array_) + index * element_size_);
+ }
+
+ const T& AtUnchecked(size_t index) const {
+ return *reinterpret_cast<T*>(reinterpret_cast<uintptr_t>(array_) + index * element_size_);
+ }
+
+ T* array_;
+ size_t size_;
+ size_t element_size_;
+};
+
+} // namespace art
+
+#endif // ART_LIBARTBASE_BASE_ARRAY_SLICE_H_