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tdlib-fork/tddb/td/db/SeqKeyValue.h

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2018
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#pragma once
#include "td/utils/Slice.h"
#include <unordered_map>
namespace td {
class SeqKeyValue {
public:
using SeqNo = uint64;
SeqKeyValue() = default;
SeqKeyValue(SeqKeyValue &&) = default;
SeqKeyValue &operator=(SeqKeyValue &&) = default;
SeqKeyValue(const SeqKeyValue &) = delete;
SeqKeyValue &operator=(const SeqKeyValue &) = delete;
~SeqKeyValue() = default;
SeqNo set(Slice key, Slice value) {
auto it_ok = map_.insert({key.str(), value.str()});
if (!it_ok.second) {
if (it_ok.first->second == value) {
return 0;
}
it_ok.first->second = value.str();
}
return next_seq_no();
}
SeqNo erase(const string &key) {
auto it = map_.find(key);
if (it == map_.end()) {
return 0;
}
map_.erase(it);
return next_seq_no();
}
SeqNo seq_no() const {
return current_id_ + 1;
}
string get(const string &key) const {
auto it = map_.find(key);
if (it == map_.end()) {
return string();
}
return it->second;
}
template <class F>
void foreach (const F &f) {
for (auto &it : map_) {
f(it.first, it.second);
}
}
size_t size() const {
return map_.size();
}
void reset_seq_no() {
current_id_ = 0;
}
std::unordered_map<string, string> get_all() const {
return map_;
}
private:
std::unordered_map<string, string> map_;
SeqNo current_id_ = 0;
SeqNo next_seq_no() {
return ++current_id_;
}
};
} // namespace td