1/*
2 * Copyright (C) 2012 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_SAFE_MAP_H_
18#define ART_RUNTIME_SAFE_MAP_H_
19
20#include <map>
21#include <memory>
22
23#include "base/allocator.h"
24#include "base/logging.h"
25
26namespace art {
27
28// Equivalent to std::map, but without operator[] and its bug-prone semantics (in particular,
29// the implicit insertion of a default-constructed value on failed lookups).
30template <typename K, typename V, typename Comparator = std::less<K>,
31          typename Allocator = TrackingAllocator<std::pair<const K, V>, kAllocatorTagSafeMap>>
32class SafeMap {
33 private:
34  typedef SafeMap<K, V, Comparator, Allocator> Self;
35
36 public:
37  typedef typename ::std::map<K, V, Comparator, Allocator>::key_compare key_compare;
38  typedef typename ::std::map<K, V, Comparator, Allocator>::value_compare value_compare;
39  typedef typename ::std::map<K, V, Comparator, Allocator>::allocator_type allocator_type;
40  typedef typename ::std::map<K, V, Comparator, Allocator>::iterator iterator;
41  typedef typename ::std::map<K, V, Comparator, Allocator>::const_iterator const_iterator;
42  typedef typename ::std::map<K, V, Comparator, Allocator>::size_type size_type;
43  typedef typename ::std::map<K, V, Comparator, Allocator>::key_type key_type;
44  typedef typename ::std::map<K, V, Comparator, Allocator>::value_type value_type;
45
46  SafeMap() = default;
47  explicit SafeMap(const key_compare& cmp, const allocator_type& allocator = allocator_type())
48    : map_(cmp, allocator) {
49  }
50
51  Self& operator=(const Self& rhs) {
52    map_ = rhs.map_;
53    return *this;
54  }
55
56  allocator_type get_allocator() const { return map_.get_allocator(); }
57  key_compare key_comp() const { return map_.key_comp(); }
58  value_compare value_comp() const { return map_.value_comp(); }
59
60  iterator begin() { return map_.begin(); }
61  const_iterator begin() const { return map_.begin(); }
62  iterator end() { return map_.end(); }
63  const_iterator end() const { return map_.end(); }
64
65  bool empty() const { return map_.empty(); }
66  size_type size() const { return map_.size(); }
67
68  void swap(Self& other) { map_.swap(other.map_); }
69  void clear() { map_.clear(); }
70  iterator erase(iterator it) { return map_.erase(it); }
71  size_type erase(const K& k) { return map_.erase(k); }
72
73  iterator find(const K& k) { return map_.find(k); }
74  const_iterator find(const K& k) const { return map_.find(k); }
75
76  iterator lower_bound(const K& k) { return map_.lower_bound(k); }
77  const_iterator lower_bound(const K& k) const { return map_.lower_bound(k); }
78
79  size_type count(const K& k) const { return map_.count(k); }
80
81  // Note that unlike std::map's operator[], this doesn't return a reference to the value.
82  V Get(const K& k) const {
83    const_iterator it = map_.find(k);
84    DCHECK(it != map_.end());
85    return it->second;
86  }
87
88  // Used to insert a new mapping.
89  iterator Put(const K& k, const V& v) {
90    std::pair<iterator, bool> result = map_.emplace(k, v);
91    DCHECK(result.second);  // Check we didn't accidentally overwrite an existing value.
92    return result.first;
93  }
94
95  // Used to insert a new mapping at a known position for better performance.
96  iterator PutBefore(iterator pos, const K& k, const V& v) {
97    // Check that we're using the correct position and the key is not in the map.
98    DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first));
99    DCHECK(pos == map_.begin() || map_.key_comp()((--iterator(pos))->first, k));
100    return map_.emplace_hint(pos, k, v);
101  }
102
103  // Used to insert a new mapping or overwrite an existing mapping. Note that if the value type
104  // of this container is a pointer, any overwritten pointer will be lost and if this container
105  // was the owner, you have a leak.
106  void Overwrite(const K& k, const V& v) {
107    std::pair<iterator, bool> result = map_.insert(std::make_pair(k, v));
108    if (!result.second) {
109      // Already there - update the value for the existing key
110      result.first->second = v;
111    }
112  }
113
114  bool Equals(const Self& rhs) const {
115    return map_ == rhs.map_;
116  }
117
118 private:
119  ::std::map<K, V, Comparator, Allocator> map_;
120};
121
122template <typename K, typename V, typename Comparator, typename Allocator>
123bool operator==(const SafeMap<K, V, Comparator, Allocator>& lhs,
124                const SafeMap<K, V, Comparator, Allocator>& rhs) {
125  return lhs.Equals(rhs);
126}
127
128template <typename K, typename V, typename Comparator, typename Allocator>
129bool operator!=(const SafeMap<K, V, Comparator, Allocator>& lhs,
130                const SafeMap<K, V, Comparator, Allocator>& rhs) {
131  return !(lhs == rhs);
132}
133
134template<class Key, class T, AllocatorTag kTag, class Compare = std::less<Key>>
135class AllocationTrackingSafeMap : public SafeMap<
136    Key, T, Compare, TrackingAllocator<std::pair<Key, T>, kTag>> {
137};
138
139}  // namespace art
140
141#endif  // ART_RUNTIME_SAFE_MAP_H_
142