1 files changed, 150 insertions, 0 deletions
diff --git a/libartbase/base/stride_iterator.h b/libartbase/base/stride_iterator.h
new file mode 100644
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+++ b/libartbase/base/stride_iterator.h
@@ -0,0 +1,150 @@
+/*
+ * 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_