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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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_LIBARTBASE_BASE_SAFE_MAP_H_
#define ART_LIBARTBASE_BASE_SAFE_MAP_H_
#include <map>
#include <memory>
#include <type_traits>
#include <android-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 {
private:
using Self = SafeMap<K, V, Comparator, Allocator>;
using Impl = std::map<K, V, Comparator, Allocator>;
public:
using key_compare = typename Impl::key_compare;
using value_compare = typename Impl::value_compare;
using allocator_type = typename Impl::allocator_type;
using iterator = typename Impl::iterator;
using const_iterator = typename Impl::const_iterator;
using size_type = typename Impl::size_type;
using key_type = typename Impl::key_type;
using value_type = typename Impl::value_type;
using node_type = typename Impl::node_type;
using insert_return_type = typename Impl::insert_return_type;
SafeMap() = default;
SafeMap(const SafeMap&) = default;
SafeMap(SafeMap&&) noexcept = default;
explicit SafeMap(const allocator_type& allocator) : map_(allocator) {}
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;
}
allocator_type get_allocator() const { return map_.get_allocator(); }
key_compare key_comp() const { return map_.key_comp(); }
value_compare value_comp() const { return map_.value_comp(); }
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 swap(Self& other) { map_.swap(other.map_); }
void clear() { map_.clear(); }
iterator erase(const_iterator pos) { return map_.erase(pos); }
iterator erase(iterator pos) { return map_.erase(pos); }
iterator erase(iterator first, iterator last) { return map_.erase(first, last); }
size_type erase(const key_type& k) { return map_.erase(k); }
node_type extract(const_iterator pos) { return map_.extract(pos); }
node_type extract(const key_type& k) { return map_.extract(k); }
std::pair<iterator, bool> insert(value_type&& value) { return map_.insert(std::move(value)); }
insert_return_type insert(node_type&& node) { return map_.insert(std::move(node)); }
insert_return_type insert(const_iterator hint, node_type&& node) {
return map_.insert(hint, std::move(node));
}
template<typename Kv> iterator find(const Kv& k) { return map_.find(k); }
template<typename Kv> const_iterator find(const Kv& k) const { return map_.find(k); }
template<typename Kv> iterator lower_bound(const Kv& k) { return map_.lower_bound(k); }
template<typename Kv> const_iterator lower_bound(const Kv& k) const {
return map_.lower_bound(k);
}
template<typename Kv> iterator upper_bound(const Kv& k) { return map_.upper_bound(k); }
template<typename Kv> const_iterator upper_bound(const Kv& k) const {
return map_.upper_bound(k);
}
template<typename Kv> size_type count(const Kv& 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.
iterator Put(const K& k, const V& v) {
std::pair<iterator, bool> result = map_.emplace(k, v);
DCHECK(result.second); // Check we didn't accidentally overwrite an existing value.
return result.first;
}
iterator Put(const K& k, V&& v) {
std::pair<iterator, bool> result = map_.emplace(k, std::move(v));
DCHECK(result.second); // Check we didn't accidentally overwrite an existing value.
return result.first;
}
// Used to insert a new mapping at a known position for better performance.
iterator PutBefore(const_iterator pos, const K& k, const V& v) {
// Check that we're using the correct position and the key is not in the map.
DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first));
DCHECK(pos == map_.begin() || map_.key_comp()((--const_iterator(pos))->first, k));
return map_.emplace_hint(pos, k, v);
}
iterator PutBefore(const_iterator pos, const K& k, V&& v) {
// Check that we're using the correct position and the key is not in the map.
DCHECK(pos == map_.end() || map_.key_comp()(k, pos->first));
DCHECK(pos == map_.begin() || map_.key_comp()((--const_iterator(pos))->first, k));
return map_.emplace_hint(pos, k, std::move(v));
}
// 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. Returns iterator pointing to the new or overwritten entry.
iterator 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;
}
return result.first;
}
template <typename CreateFn>
V& GetOrCreate(const K& k, CreateFn create) {
static_assert(std::is_same_v<V, std::invoke_result_t<CreateFn>>,
"Argument `create` should return a value of type V.");
auto lb = lower_bound(k);
if (lb != end() && !key_comp()(k, lb->first)) {
return lb->second;
}
auto it = PutBefore(lb, k, create());
return it->second;
}
iterator FindOrAdd(const K& k, const V& v) {
iterator it = find(k);
return it == end() ? Put(k, v) : it;
}
iterator FindOrAdd(const K& k) {
iterator it = find(k);
return it == end() ? Put(k, V()) : it;
}
bool Equals(const Self& rhs) const {
return map_ == rhs.map_;
}
template <class... Args>
std::pair<iterator, bool> emplace(Args&&... args) {
return map_.emplace(std::forward<Args>(args)...);
}
private:
Impl map_;
};
template <typename K, typename V, typename Comparator, typename Allocator>
bool operator==(const SafeMap<K, V, Comparator, Allocator>& lhs,
const SafeMap<K, V, Comparator, Allocator>& rhs) {
return lhs.Equals(rhs);
}
template <typename K, typename V, typename Comparator, typename Allocator>
bool operator!=(const SafeMap<K, V, Comparator, Allocator>& lhs,
const SafeMap<K, V, Comparator, Allocator>& rhs) {
return !(lhs == rhs);
}
} // namespace art
#endif // ART_LIBARTBASE_BASE_SAFE_MAP_H_
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