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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_STRIDE_ITERATOR_H_
#define ART_LIBARTBASE_BASE_STRIDE_ITERATOR_H_
#include <iterator>
#include <android-base/logging.h>
namespace art {
template<typename T>
class StrideIterator : public std::iterator<std::random_access_iterator_tag, T> {
public:
using difference_type =
typename std::iterator<std::random_access_iterator_tag, T>::difference_type;
StrideIterator(const StrideIterator&) = default;
StrideIterator(StrideIterator&&) = default;
StrideIterator& operator=(const StrideIterator&) = default;
StrideIterator& operator=(StrideIterator&&) = default;
StrideIterator(T* ptr, size_t stride)
: ptr_(reinterpret_cast<uintptr_t>(ptr)),
stride_(stride) {}
bool operator==(const StrideIterator& other) const {
DCHECK_EQ(stride_, other.stride_);
return ptr_ == other.ptr_;
}
bool operator!=(const StrideIterator& other) const {
return !(*this == other);
}
StrideIterator& operator++() { // Value after modification.
ptr_ += stride_;
return *this;
}
StrideIterator operator++(int) {
StrideIterator<T> temp = *this;
++*this;
return temp;
}
StrideIterator& operator--() { // Value after modification.
ptr_ -= stride_;
return *this;
}
StrideIterator operator--(int) {
StrideIterator<T> temp = *this;
--*this;
return temp;
}
StrideIterator& operator+=(difference_type delta) {
ptr_ += static_cast<ssize_t>(stride_) * delta;
return *this;
}
StrideIterator operator+(difference_type delta) const {
StrideIterator<T> temp = *this;
temp += delta;
return temp;
}
StrideIterator& operator-=(difference_type delta) {
ptr_ -= static_cast<ssize_t>(stride_) * delta;
return *this;
}
StrideIterator operator-(difference_type delta) const {
StrideIterator<T> temp = *this;
temp -= delta;
return temp;
}
difference_type operator-(const StrideIterator& rhs) {
DCHECK_EQ(stride_, rhs.stride_);
DCHECK_EQ((ptr_ - rhs.ptr_) % stride_, 0u);
return (ptr_ - rhs.ptr_) / stride_;
}
T& operator*() const {
return *reinterpret_cast<T*>(ptr_);
}
T* operator->() const {
return &**this;
}
T& operator[](difference_type n) {
return *(*this + n);
}
private:
uintptr_t ptr_;
// Not const for operator=.
size_t stride_;
template <typename U>
friend bool operator<(const StrideIterator<U>& lhs, const StrideIterator<U>& rhs);
};
template <typename T>
StrideIterator<T> operator+(typename StrideIterator<T>::difference_type dist,
const StrideIterator<T>& it) {
return it + dist;
}
template <typename T>
bool operator<(const StrideIterator<T>& lhs, const StrideIterator<T>& rhs) {
DCHECK_EQ(lhs.stride_, rhs.stride_);
return lhs.ptr_ < rhs.ptr_;
}
template <typename T>
bool operator>(const StrideIterator<T>& lhs, const StrideIterator<T>& rhs) {
return rhs < lhs;
}
template <typename T>
bool operator<=(const StrideIterator<T>& lhs, const StrideIterator<T>& rhs) {
return !(rhs < lhs);
}
template <typename T>
bool operator>=(const StrideIterator<T>& lhs, const StrideIterator<T>& rhs) {
return !(lhs < rhs);
}
} // namespace art
#endif // ART_LIBARTBASE_BASE_STRIDE_ITERATOR_H_
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