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 using Self = SafeMap<K, V, Comparator, Allocator>; 35 using Impl = std::map<K, V, Comparator, Allocator>; 36 37 public: 38 using key_compare = typename Impl::key_compare; 39 using value_compare = typename Impl::value_compare; 40 using allocator_type = typename Impl::allocator_type; 41 using iterator = typename Impl::iterator; 42 using const_iterator = typename Impl::const_iterator; 43 using size_type = typename Impl::size_type; 44 using key_type = typename Impl::key_type; 45 using value_type = typename Impl::value_type; 46 using node_type = typename Impl::node_type; 47 using insert_return_type = typename Impl::insert_return_type; 48 49 SafeMap() = default; 50 SafeMap(const SafeMap&) = default; 51 SafeMap(SafeMap&&) noexcept = default; 52 explicit SafeMap(const key_compare& cmp, const allocator_type& allocator = allocator_type()) map_(cmp,allocator)53 : map_(cmp, allocator) { 54 } 55 56 Self& operator=(const Self& rhs) { 57 map_ = rhs.map_; 58 return *this; 59 } 60 get_allocator()61 allocator_type get_allocator() const { return map_.get_allocator(); } key_comp()62 key_compare key_comp() const { return map_.key_comp(); } value_comp()63 value_compare value_comp() const { return map_.value_comp(); } 64 begin()65 iterator begin() { return map_.begin(); } begin()66 const_iterator begin() const { return map_.begin(); } end()67 iterator end() { return map_.end(); } end()68 const_iterator end() const { return map_.end(); } 69 empty()70 bool empty() const { return map_.empty(); } size()71 size_type size() const { return map_.size(); } 72 swap(Self & other)73 void swap(Self& other) { map_.swap(other.map_); } clear()74 void clear() { map_.clear(); } 75 erase(const_iterator pos)76 iterator erase(const_iterator pos) { return map_.erase(pos); } erase(iterator pos)77 iterator erase(iterator pos) { return map_.erase(pos); } erase(iterator first,iterator last)78 iterator erase(iterator first, iterator last) { return map_.erase(first, last); } erase(const key_type & k)79 size_type erase(const key_type& k) { return map_.erase(k); } 80 extract(const_iterator pos)81 node_type extract(const_iterator pos) { return map_.extract(pos); } extract(const key_type & k)82 node_type extract(const key_type& k) { return map_.extract(k); } 83 insert(value_type && value)84 std::pair<iterator, bool> insert(value_type&& value) { return map_.insert(std::move(value)); } insert(node_type && node)85 insert_return_type insert(node_type&& node) { return map_.insert(std::move(node)); } insert(const_iterator hint,node_type && node)86 insert_return_type insert(const_iterator hint, node_type&& node) { 87 return map_.insert(hint, std::move(node)); 88 } 89 find(const Kv & k)90 template<typename Kv> iterator find(const Kv& k) { return map_.find(k); } find(const Kv & k)91 template<typename Kv> const_iterator find(const Kv& k) const { return map_.find(k); } 92 lower_bound(const Kv & k)93 template<typename Kv> iterator lower_bound(const Kv& k) { return map_.lower_bound(k); } lower_bound(const Kv & k)94 template<typename Kv> const_iterator lower_bound(const Kv& k) const { 95 return map_.lower_bound(k); 96 } 97 upper_bound(const Kv & k)98 template<typename Kv> iterator upper_bound(const Kv& k) { return map_.upper_bound(k); } upper_bound(const Kv & k)99 template<typename Kv> const_iterator upper_bound(const Kv& k) const { 100 return map_.upper_bound(k); 101 } 102 count(const Kv & k)103 template<typename Kv> size_type count(const Kv& k) const { return map_.count(k); } 104 105 // Note that unlike std::map's operator[], this doesn't return a reference to the value. Get(const K & k)106 V Get(const K& k) const { 107 const_iterator it = map_.find(k); 108 DCHECK(it != map_.end()); 109 return it->second; 110 } 111 112 // Used to insert a new mapping. Put(const K & k,const V & v)113 iterator Put(const K& k, const V& v) { 114 std::pair<iterator, bool> result = map_.emplace(k, v); 115 DCHECK(result.second); // Check we didn't accidentally overwrite an existing value. 116 return result.first; 117 } Put(const K & k,V && v)118 iterator Put(const K& k, V&& v) { 119 std::pair<iterator, bool> result = map_.emplace(k, std::move(v)); 120 DCHECK(result.second); // Check we didn't accidentally overwrite an existing value. 121 return result.first; 122 } 123 124 // Used to insert a new mapping at a known position for better performance. PutBefore(const_iterator pos,const K & k,const V & v)125 iterator PutBefore(const_iterator pos, const K& k, const V& v) { 126 // Check that we're using the correct position and the key is not in the map. 127 DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first)); 128 DCHECK(pos == map_.begin() || map_.key_comp()((--const_iterator(pos))->first, k)); 129 return map_.emplace_hint(pos, k, v); 130 } PutBefore(const_iterator pos,const K & k,V && v)131 iterator PutBefore(const_iterator pos, const K& k, V&& v) { 132 // Check that we're using the correct position and the key is not in the map. 133 DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first)); 134 DCHECK(pos == map_.begin() || map_.key_comp()((--const_iterator(pos))->first, k)); 135 return map_.emplace_hint(pos, k, std::move(v)); 136 } 137 138 // Used to insert a new mapping or overwrite an existing mapping. Note that if the value type 139 // of this container is a pointer, any overwritten pointer will be lost and if this container 140 // was the owner, you have a leak. Returns iterator pointing to the new or overwritten entry. Overwrite(const K & k,const V & v)141 iterator Overwrite(const K& k, const V& v) { 142 std::pair<iterator, bool> result = map_.insert(std::make_pair(k, v)); 143 if (!result.second) { 144 // Already there - update the value for the existing key 145 result.first->second = v; 146 } 147 return result.first; 148 } 149 150 template <typename CreateFn> GetOrCreate(const K & k,CreateFn create)151 V& GetOrCreate(const K& k, CreateFn create) { 152 static_assert(std::is_same_v<V, std::result_of_t<CreateFn()>>, 153 "Argument `create` should return a value of type V."); 154 auto lb = lower_bound(k); 155 if (lb != end() && !key_comp()(k, lb->first)) { 156 return lb->second; 157 } 158 auto it = PutBefore(lb, k, create()); 159 return it->second; 160 } 161 FindOrAdd(const K & k,const V & v)162 iterator FindOrAdd(const K& k, const V& v) { 163 iterator it = find(k); 164 return it == end() ? Put(k, v) : it; 165 } 166 FindOrAdd(const K & k)167 iterator FindOrAdd(const K& k) { 168 iterator it = find(k); 169 return it == end() ? Put(k, V()) : it; 170 } 171 Equals(const Self & rhs)172 bool Equals(const Self& rhs) const { 173 return map_ == rhs.map_; 174 } 175 176 template <class... Args> emplace(Args &&...args)177 std::pair<iterator, bool> emplace(Args&&... args) { 178 return map_.emplace(std::forward<Args>(args)...); 179 } 180 181 private: 182 Impl map_; 183 }; 184 185 template <typename K, typename V, typename Comparator, typename Allocator> 186 bool operator==(const SafeMap<K, V, Comparator, Allocator>& lhs, 187 const SafeMap<K, V, Comparator, Allocator>& rhs) { 188 return lhs.Equals(rhs); 189 } 190 191 template <typename K, typename V, typename Comparator, typename Allocator> 192 bool operator!=(const SafeMap<K, V, Comparator, Allocator>& lhs, 193 const SafeMap<K, V, Comparator, Allocator>& rhs) { 194 return !(lhs == rhs); 195 } 196 197 } // namespace art 198 199 #endif // ART_LIBARTBASE_BASE_SAFE_MAP_H_ 200