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223 lines
6.1 KiB
223 lines
6.1 KiB
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_LIBARTBASE_BASE_ARRAY_REF_H_
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#define ART_LIBARTBASE_BASE_ARRAY_REF_H_
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#include <type_traits>
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#include <vector>
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#include <android-base/logging.h>
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namespace art {
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/**
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* @brief A container that references an array.
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*
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* @details The template class ArrayRef provides a container that references
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* an external array. This external array must remain alive while the ArrayRef
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* object is in use. The external array may be a std::vector<>-backed storage
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* or any other contiguous chunk of memory but that memory must remain valid,
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* i.e. the std::vector<> must not be resized for example.
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*
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* Except for copy/assign and insert/erase/capacity functions, the interface
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* is essentially the same as std::vector<>. Since we don't want to throw
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* exceptions, at() is also excluded.
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*/
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template <typename T>
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class ArrayRef {
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public:
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using value_type = T;
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using reference = T&;
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using const_reference = const T&;
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using pointer = T*;
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using const_pointer = const T*;
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using iterator = T*;
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using const_iterator = const T*;
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using reverse_iterator = std::reverse_iterator<iterator>;
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using const_reverse_iterator = std::reverse_iterator<const_iterator>;
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using difference_type = ptrdiff_t;
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using size_type = size_t;
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// Constructors.
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constexpr ArrayRef()
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: array_(nullptr), size_(0u) {
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}
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template <size_t size>
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explicit constexpr ArrayRef(T (&array)[size])
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: array_(array), size_(size) {
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}
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template <typename U,
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size_t size,
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typename = typename std::enable_if<std::is_same<T, const U>::value>::type>
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explicit constexpr ArrayRef(U (&array)[size])
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: array_(array), size_(size) {
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}
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constexpr ArrayRef(T* array, size_t size)
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: array_(array), size_(size) {
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}
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template <typename Vector,
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typename = typename std::enable_if<
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std::is_same<typename Vector::value_type, value_type>::value>::type>
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explicit ArrayRef(Vector& v)
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: array_(v.data()), size_(v.size()) {
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}
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template <typename Vector,
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typename = typename std::enable_if<
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std::is_same<
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typename std::add_const<typename Vector::value_type>::type,
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value_type>::value>::type>
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explicit ArrayRef(const Vector& v)
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: array_(v.data()), size_(v.size()) {
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}
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ArrayRef(const ArrayRef&) = default;
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// Assignment operators.
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ArrayRef& operator=(const ArrayRef& other) {
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array_ = other.array_;
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size_ = other.size_;
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return *this;
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}
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template <typename U>
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typename std::enable_if<std::is_same<T, const U>::value, ArrayRef>::type&
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operator=(const ArrayRef<U>& other) {
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return *this = ArrayRef(other);
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}
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template <typename U>
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static ArrayRef Cast(const ArrayRef<U>& src) {
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return ArrayRef(reinterpret_cast<const T*>(src.data()),
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src.size() * sizeof(T) / sizeof(U));
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}
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// Destructor.
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~ArrayRef() = default;
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// Iterators.
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iterator begin() { return array_; }
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const_iterator begin() const { return array_; }
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const_iterator cbegin() const { return array_; }
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iterator end() { return array_ + size_; }
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const_iterator end() const { return array_ + size_; }
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const_iterator cend() const { return array_ + size_; }
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reverse_iterator rbegin() { return reverse_iterator(end()); }
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const_reverse_iterator rbegin() const { return const_reverse_iterator(end()); }
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const_reverse_iterator crbegin() const { return const_reverse_iterator(cend()); }
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reverse_iterator rend() { return reverse_iterator(begin()); }
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const_reverse_iterator rend() const { return const_reverse_iterator(begin()); }
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const_reverse_iterator crend() const { return const_reverse_iterator(cbegin()); }
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// Size.
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size_type size() const { return size_; }
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bool empty() const { return size() == 0u; }
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// Element access. NOTE: Not providing at().
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reference operator[](size_type n) {
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DCHECK_LT(n, size_);
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return array_[n];
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}
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const_reference operator[](size_type n) const {
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DCHECK_LT(n, size_);
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return array_[n];
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}
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reference front() {
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DCHECK(!empty());
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return array_[0];
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}
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const_reference front() const {
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DCHECK(!empty());
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return array_[0];
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}
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reference back() {
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DCHECK(!empty());
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return array_[size_ - 1u];
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}
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const_reference back() const {
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DCHECK(!empty());
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return array_[size_ - 1u];
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}
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value_type* data() { return array_; }
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const value_type* data() const { return array_; }
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ArrayRef SubArray(size_type pos) {
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return SubArray(pos, size() - pos);
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}
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ArrayRef<const T> SubArray(size_type pos) const {
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return SubArray(pos, size() - pos);
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}
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ArrayRef SubArray(size_type pos, size_type length) {
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DCHECK_LE(pos, size());
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DCHECK_LE(length, size() - pos);
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return ArrayRef(data() + pos, length);
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}
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ArrayRef<const T> SubArray(size_type pos, size_type length) const {
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DCHECK_LE(pos, size());
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DCHECK_LE(length, size() - pos);
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return ArrayRef<const T>(data() + pos, length);
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}
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private:
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T* array_;
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size_t size_;
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};
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template <typename T>
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bool operator==(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) {
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return lhs.size() == rhs.size() && std::equal(lhs.begin(), lhs.end(), rhs.begin());
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}
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template <typename T>
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bool operator!=(const ArrayRef<T>& lhs, const ArrayRef<T>& rhs) {
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return !(lhs == rhs);
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}
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template<typename T>
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std::ostream& operator<<(std::ostream& os, const ArrayRef<T>& ts) {
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bool first = true;
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os << "[";
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for (const T& t : ts) {
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if (!first) { os << ", "; }
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first = false;
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os << t;
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}
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os << "]";
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return os;
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}
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} // namespace art
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#endif // ART_LIBARTBASE_BASE_ARRAY_REF_H_
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