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* Copyright (C) 2012 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <map>
#include <memory>
#include "base/logging.h"
namespace art {
// Equivalent to std::map, but without operator[] and its bug-prone semantics (in particular,
// the implicit insertion of a default-constructed value on failed lookups).
template <typename K, typename V, typename Comparator = std::less<K>,
typename Allocator = std::allocator<std::pair<const K, V>>>
class SafeMap {
typedef SafeMap<K, V, Comparator, Allocator> Self;
typedef typename ::std::map<K, V, Comparator, Allocator>::key_compare key_compare;
typedef typename ::std::map<K, V, Comparator, Allocator>::allocator_type allocator_type;
typedef typename ::std::map<K, V, Comparator, Allocator>::iterator iterator;
typedef typename ::std::map<K, V, Comparator, Allocator>::const_iterator const_iterator;
typedef typename ::std::map<K, V, Comparator, Allocator>::size_type size_type;
typedef typename ::std::map<K, V, Comparator, Allocator>::value_type value_type;
SafeMap() = default;
explicit SafeMap(const key_compare& cmp, const allocator_type& allocator = allocator_type())
: map_(cmp, allocator) {
Self& operator=(const Self& rhs) {
map_ = rhs.map_;
return *this;
iterator begin() { return map_.begin(); }
const_iterator begin() const { return map_.begin(); }
iterator end() { return map_.end(); }
const_iterator end() const { return map_.end(); }
bool empty() const { return map_.empty(); }
size_type size() const { return map_.size(); }
void clear() { map_.clear(); }
void erase(iterator it) { map_.erase(it); }
size_type erase(const K& k) { return map_.erase(k); }
iterator find(const K& k) { return map_.find(k); }
const_iterator find(const K& k) const { return map_.find(k); }
iterator lower_bound(const K& k) { return map_.lower_bound(k); }
const_iterator lower_bound(const K& k) const { return map_.lower_bound(k); }
size_type count(const K& k) const { return map_.count(k); }
// Note that unlike std::map's operator[], this doesn't return a reference to the value.
V Get(const K& k) const {
const_iterator it = map_.find(k);
DCHECK(it != map_.end());
return it->second;
// Used to insert a new mapping.
void Put(const K& k, const V& v) {
std::pair<iterator, bool> result = map_.insert(std::make_pair(k, v));
DCHECK(result.second); // Check we didn't accidentally overwrite an existing value.
// Used to insert a new mapping or overwrite an existing mapping. Note that if the value type
// of this container is a pointer, any overwritten pointer will be lost and if this container
// was the owner, you have a leak.
void Overwrite(const K& k, const V& v) {
std::pair<iterator, bool> result = map_.insert(std::make_pair(k, v));
if (!result.second) {
// Already there - update the value for the existing key
result.first->second = v;
bool Equals(const Self& rhs) const {
return map_ == rhs.map_;
::std::map<K, V, Comparator, Allocator> map_;
template <typename K, typename V, typename Comparator>
bool operator==(const SafeMap<K, V, Comparator>& lhs, const SafeMap<K, V, Comparator>& rhs) {
return lhs.Equals(rhs);
template <typename K, typename V, typename Comparator>
bool operator!=(const SafeMap<K, V, Comparator>& lhs, const SafeMap<K, V, Comparator>& rhs) {
return !(lhs == rhs);
} // namespace art