2 * Copyright (C) 2012 The Android Open Source Project
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 #ifndef ART_RUNTIME_SAFE_MAP_H_
18 #define ART_RUNTIME_SAFE_MAP_H_
22 #include <type_traits>
24 #include "base/allocator.h"
25 #include "base/logging.h"
29 // Equivalent to std::map, but without operator[] and its bug-prone semantics (in particular,
30 // the implicit insertion of a default-constructed value on failed lookups).
31 template <typename K, typename V, typename Comparator = std::less<K>,
32 typename Allocator = TrackingAllocator<std::pair<const K, V>, kAllocatorTagSafeMap>>
35 typedef SafeMap<K, V, Comparator, Allocator> Self;
38 typedef typename ::std::map<K, V, Comparator, Allocator>::key_compare key_compare;
39 typedef typename ::std::map<K, V, Comparator, Allocator>::value_compare value_compare;
40 typedef typename ::std::map<K, V, Comparator, Allocator>::allocator_type allocator_type;
41 typedef typename ::std::map<K, V, Comparator, Allocator>::iterator iterator;
42 typedef typename ::std::map<K, V, Comparator, Allocator>::const_iterator const_iterator;
43 typedef typename ::std::map<K, V, Comparator, Allocator>::size_type size_type;
44 typedef typename ::std::map<K, V, Comparator, Allocator>::key_type key_type;
45 typedef typename ::std::map<K, V, Comparator, Allocator>::value_type value_type;
48 SafeMap(const SafeMap&) = default;
49 explicit SafeMap(const key_compare& cmp, const allocator_type& allocator = allocator_type())
50 : map_(cmp, allocator) {
53 Self& operator=(const Self& rhs) {
58 allocator_type get_allocator() const { return map_.get_allocator(); }
59 key_compare key_comp() const { return map_.key_comp(); }
60 value_compare value_comp() const { return map_.value_comp(); }
62 iterator begin() { return map_.begin(); }
63 const_iterator begin() const { return map_.begin(); }
64 iterator end() { return map_.end(); }
65 const_iterator end() const { return map_.end(); }
67 bool empty() const { return map_.empty(); }
68 size_type size() const { return map_.size(); }
70 void swap(Self& other) { map_.swap(other.map_); }
71 void clear() { map_.clear(); }
72 iterator erase(iterator it) { return map_.erase(it); }
73 size_type erase(const K& k) { return map_.erase(k); }
75 iterator find(const K& k) { return map_.find(k); }
76 const_iterator find(const K& k) const { return map_.find(k); }
78 iterator lower_bound(const K& k) { return map_.lower_bound(k); }
79 const_iterator lower_bound(const K& k) const { return map_.lower_bound(k); }
81 size_type count(const K& k) const { return map_.count(k); }
83 // Note that unlike std::map's operator[], this doesn't return a reference to the value.
84 V Get(const K& k) const {
85 const_iterator it = map_.find(k);
86 DCHECK(it != map_.end());
90 // Used to insert a new mapping.
91 iterator Put(const K& k, const V& v) {
92 std::pair<iterator, bool> result = map_.emplace(k, v);
93 DCHECK(result.second); // Check we didn't accidentally overwrite an existing value.
96 iterator Put(const K& k, V&& v) {
97 std::pair<iterator, bool> result = map_.emplace(k, std::move(v));
98 DCHECK(result.second); // Check we didn't accidentally overwrite an existing value.
102 // Used to insert a new mapping at a known position for better performance.
103 iterator PutBefore(const_iterator pos, const K& k, const V& v) {
104 // Check that we're using the correct position and the key is not in the map.
105 DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first));
106 DCHECK(pos == map_.begin() || map_.key_comp()((--const_iterator(pos))->first, k));
107 return map_.emplace_hint(pos, k, v);
109 iterator PutBefore(const_iterator pos, const K& k, V&& v) {
110 // Check that we're using the correct position and the key is not in the map.
111 DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first));
112 DCHECK(pos == map_.begin() || map_.key_comp()((--const_iterator(pos))->first, k));
113 return map_.emplace_hint(pos, k, std::move(v));
116 // Used to insert a new mapping or overwrite an existing mapping. Note that if the value type
117 // of this container is a pointer, any overwritten pointer will be lost and if this container
118 // was the owner, you have a leak. Returns iterator pointing to the new or overwritten entry.
119 iterator Overwrite(const K& k, const V& v) {
120 std::pair<iterator, bool> result = map_.insert(std::make_pair(k, v));
121 if (!result.second) {
122 // Already there - update the value for the existing key
123 result.first->second = v;
128 template <typename CreateFn>
129 V GetOrCreate(const K& k, CreateFn create) {
130 static_assert(std::is_same<V, typename std::result_of<CreateFn()>::type>::value,
131 "Argument `create` should return a value of type V.");
132 auto lb = lower_bound(k);
133 if (lb != end() && !key_comp()(k, lb->first)) {
136 auto it = PutBefore(lb, k, create());
140 bool Equals(const Self& rhs) const {
141 return map_ == rhs.map_;
145 ::std::map<K, V, Comparator, Allocator> map_;
148 template <typename K, typename V, typename Comparator, typename Allocator>
149 bool operator==(const SafeMap<K, V, Comparator, Allocator>& lhs,
150 const SafeMap<K, V, Comparator, Allocator>& rhs) {
151 return lhs.Equals(rhs);
154 template <typename K, typename V, typename Comparator, typename Allocator>
155 bool operator!=(const SafeMap<K, V, Comparator, Allocator>& lhs,
156 const SafeMap<K, V, Comparator, Allocator>& rhs) {
157 return !(lhs == rhs);
160 template<class Key, class T, AllocatorTag kTag, class Compare = std::less<Key>>
161 class AllocationTrackingSafeMap : public SafeMap<
162 Key, T, Compare, TrackingAllocator<std::pair<const Key, T>, kTag>> {
167 #endif // ART_RUNTIME_SAFE_MAP_H_