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_RUNTIME_STRIDE_ITERATOR_H_
18 #define ART_RUNTIME_STRIDE_ITERATOR_H_
19 
20 #include <iterator>
21 
22 #include "base/logging.h"
23 
24 namespace art {
25 
26 template<typename T>
27 class StrideIterator : public std::iterator<std::forward_iterator_tag, T> {
28  public:
29   StrideIterator(const StrideIterator&) = default;
30   StrideIterator(StrideIterator&&) = default;
31   StrideIterator& operator=(const StrideIterator&) = default;
32   StrideIterator& operator=(StrideIterator&&) = default;
33 
StrideIterator(T * ptr,size_t stride)34   StrideIterator(T* ptr, size_t stride)
35       : ptr_(reinterpret_cast<uintptr_t>(ptr)),
36         stride_(stride) {}
37 
38   bool operator==(const StrideIterator& other) const {
39     DCHECK_EQ(stride_, other.stride_);
40     return ptr_ == other.ptr_;
41   }
42 
43   bool operator!=(const StrideIterator& other) const {
44     return !(*this == other);
45   }
46 
47   StrideIterator operator++() {  // Value after modification.
48     ptr_ += stride_;
49     return *this;
50   }
51 
52   StrideIterator operator++(int) {
53     StrideIterator<T> temp = *this;
54     ptr_ += stride_;
55     return temp;
56   }
57 
58   StrideIterator operator+(ssize_t delta) const {
59     StrideIterator<T> temp = *this;
60     temp += delta;
61     return temp;
62   }
63 
64   StrideIterator& operator+=(ssize_t delta) {
65     ptr_ += static_cast<ssize_t>(stride_) * delta;
66     return *this;
67   }
68 
69   T& operator*() const {
70     return *reinterpret_cast<T*>(ptr_);
71   }
72 
73   T* operator->() const {
74     return &**this;
75   }
76 
77  private:
78   uintptr_t ptr_;
79   // Not const for operator=.
80   size_t stride_;
81 };
82 
83 }  // namespace art
84 
85 #endif  // ART_RUNTIME_STRIDE_ITERATOR_H_
86