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/logging.h" 24 25 namespace art { 26 27 // Equivalent to std::map, but without operator[] and its bug-prone semantics (in particular, 28 // the implicit insertion of a default-constructed value on failed lookups). 29 template <typename K, typename V, typename Comparator = std::less<K>, 30 typename Allocator = std::allocator<std::pair<const K, V> > > 31 class SafeMap { 32 private: 33 typedef SafeMap<K, V, Comparator, Allocator> Self; 34 35 public: 36 typedef typename ::std::map<K, V, Comparator>::iterator iterator; 37 typedef typename ::std::map<K, V, Comparator>::const_iterator const_iterator; 38 typedef typename ::std::map<K, V, Comparator>::size_type size_type; 39 typedef typename ::std::map<K, V, Comparator>::value_type value_type; 40 41 Self& operator=(const Self& rhs) { 42 map_ = rhs.map_; 43 return *this; 44 } 45 begin()46 iterator begin() { return map_.begin(); } begin()47 const_iterator begin() const { return map_.begin(); } end()48 iterator end() { return map_.end(); } end()49 const_iterator end() const { return map_.end(); } 50 empty()51 bool empty() const { return map_.empty(); } size()52 size_type size() const { return map_.size(); } 53 clear()54 void clear() { map_.clear(); } erase(iterator it)55 void erase(iterator it) { map_.erase(it); } erase(const K & k)56 size_type erase(const K& k) { return map_.erase(k); } 57 find(const K & k)58 iterator find(const K& k) { return map_.find(k); } find(const K & k)59 const_iterator find(const K& k) const { return map_.find(k); } 60 count(const K & k)61 size_type count(const K& k) const { return map_.count(k); } 62 63 // Note that unlike std::map's operator[], this doesn't return a reference to the value. Get(const K & k)64 V Get(const K& k) const { 65 const_iterator it = map_.find(k); 66 DCHECK(it != map_.end()); 67 return it->second; 68 } 69 70 // Used to insert a new mapping. Put(const K & k,const V & v)71 void Put(const K& k, const V& v) { 72 std::pair<iterator, bool> result = map_.insert(std::make_pair(k, v)); 73 DCHECK(result.second); // Check we didn't accidentally overwrite an existing value. 74 } 75 76 // Used to insert a new mapping or overwrite an existing mapping. Note that if the value type 77 // of this container is a pointer, any overwritten pointer will be lost and if this container 78 // was the owner, you have a leak. Overwrite(const K & k,const V & v)79 void Overwrite(const K& k, const V& v) { 80 std::pair<iterator, bool> result = map_.insert(std::make_pair(k, v)); 81 if (!result.second) { 82 // Already there - update the value for the existing key 83 result.first->second = v; 84 } 85 } 86 Equals(const Self & rhs)87 bool Equals(const Self& rhs) const { 88 return map_ == rhs.map_; 89 } 90 91 private: 92 ::std::map<K, V, Comparator, Allocator> map_; 93 }; 94 95 template <typename K, typename V, typename Comparator> 96 bool operator==(const SafeMap<K, V, Comparator>& lhs, const SafeMap<K, V, Comparator>& rhs) { 97 return lhs.Equals(rhs); 98 } 99 100 template <typename K, typename V, typename Comparator> 101 bool operator!=(const SafeMap<K, V, Comparator>& lhs, const SafeMap<K, V, Comparator>& rhs) { 102 return !(lhs == rhs); 103 } 104 105 } // namespace art 106 107 #endif // ART_RUNTIME_SAFE_MAP_H_ 108