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_LIBARTBASE_BASE_SAFE_MAP_H_ 18 #define ART_LIBARTBASE_BASE_SAFE_MAP_H_ 19 20 #include <map> 21 #include <memory> 22 #include <type_traits> 23 24 #include <android-base/logging.h> 25 26 namespace 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). 30 template <typename K, typename V, typename Comparator = std::less<K>, 31 typename Allocator = std::allocator<std::pair<const K, V>>> 32 class 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 SafeMap(const SafeMap&) = default; 48 SafeMap(SafeMap&&) = default; 49 explicit SafeMap(const key_compare& cmp, const allocator_type& allocator = allocator_type()) 50 : map_(cmp, allocator) { 51 } 52 53 Self& operator=(const Self& rhs) { 54 map_ = rhs.map_; 55 return *this; 56 } 57 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(); } 61 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(); } 66 67 bool empty() const { return map_.empty(); } 68 size_type size() const { return map_.size(); } 69 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); } 74 75 iterator find(const K& k) { return map_.find(k); } 76 const_iterator find(const K& k) const { return map_.find(k); } 77 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); } 80 81 iterator upper_bound(const K& k) { return map_.upper_bound(k); } 82 const_iterator upper_bound(const K& k) const { return map_.upper_bound(k); } 83 84 size_type count(const K& k) const { return map_.count(k); } 85 86 // Note that unlike std::map's operator[], this doesn't return a reference to the value. 87 V Get(const K& k) const { 88 const_iterator it = map_.find(k); 89 DCHECK(it != map_.end()); 90 return it->second; 91 } 92 93 // Used to insert a new mapping. 94 iterator Put(const K& k, const V& v) { 95 std::pair<iterator, bool> result = map_.emplace(k, v); 96 DCHECK(result.second); // Check we didn't accidentally overwrite an existing value. 97 return result.first; 98 } 99 iterator Put(const K& k, V&& v) { 100 std::pair<iterator, bool> result = map_.emplace(k, std::move(v)); 101 DCHECK(result.second); // Check we didn't accidentally overwrite an existing value. 102 return result.first; 103 } 104 105 // Used to insert a new mapping at a known position for better performance. 106 iterator PutBefore(const_iterator pos, const K& k, const V& v) { 107 // Check that we're using the correct position and the key is not in the map. 108 DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first)); 109 DCHECK(pos == map_.begin() || map_.key_comp()((--const_iterator(pos))->first, k)); 110 return map_.emplace_hint(pos, k, v); 111 } 112 iterator PutBefore(const_iterator pos, const K& k, V&& v) { 113 // Check that we're using the correct position and the key is not in the map. 114 DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first)); 115 DCHECK(pos == map_.begin() || map_.key_comp()((--const_iterator(pos))->first, k)); 116 return map_.emplace_hint(pos, k, std::move(v)); 117 } 118 119 // Used to insert a new mapping or overwrite an existing mapping. Note that if the value type 120 // of this container is a pointer, any overwritten pointer will be lost and if this container 121 // was the owner, you have a leak. Returns iterator pointing to the new or overwritten entry. 122 iterator Overwrite(const K& k, const V& v) { 123 std::pair<iterator, bool> result = map_.insert(std::make_pair(k, v)); 124 if (!result.second) { 125 // Already there - update the value for the existing key 126 result.first->second = v; 127 } 128 return result.first; 129 } 130 131 template <typename CreateFn> 132 V GetOrCreate(const K& k, CreateFn create) { 133 static_assert(std::is_same<V, typename std::result_of<CreateFn()>::type>::value, 134 "Argument `create` should return a value of type V."); 135 auto lb = lower_bound(k); 136 if (lb != end() && !key_comp()(k, lb->first)) { 137 return lb->second; 138 } 139 auto it = PutBefore(lb, k, create()); 140 return it->second; 141 } 142 143 iterator FindOrAdd(const K& k, const V& v) { 144 iterator it = find(k); 145 return it == end() ? Put(k, v) : it; 146 } 147 148 iterator FindOrAdd(const K& k) { 149 iterator it = find(k); 150 return it == end() ? Put(k, V()) : it; 151 } 152 153 bool Equals(const Self& rhs) const { 154 return map_ == rhs.map_; 155 } 156 157 template <class... Args> 158 std::pair<iterator, bool> emplace(Args&&... args) { 159 return map_.emplace(std::forward<Args>(args)...); 160 } 161 162 private: 163 ::std::map<K, V, Comparator, Allocator> map_; 164 }; 165 166 template <typename K, typename V, typename Comparator, typename Allocator> 167 bool operator==(const SafeMap<K, V, Comparator, Allocator>& lhs, 168 const SafeMap<K, V, Comparator, Allocator>& rhs) { 169 return lhs.Equals(rhs); 170 } 171 172 template <typename K, typename V, typename Comparator, typename Allocator> 173 bool operator!=(const SafeMap<K, V, Comparator, Allocator>& lhs, 174 const SafeMap<K, V, Comparator, Allocator>& rhs) { 175 return !(lhs == rhs); 176 } 177 178 } // namespace art 179 180 #endif // ART_LIBARTBASE_BASE_SAFE_MAP_H_ 181
