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