tdlight/tdutils/td/utils/Enumerator.h

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
//
// 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/common.h"
#include <limits>
#include <map>
#include <tuple>
namespace td {
template <class ValueT>
class Enumerator {
public:
using Key = int32;
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std::map<ValueT, int32> get_map() const {
return map_;
}
std::pair<Key, bool> next() {
if (!empty_id_.empty()) {
auto res = empty_id_.back();
empty_id_.pop_back();
return std::make_pair(res, true);
}
return std::make_pair((Key) (arr_.size() + 1), false);
}
void erase(Key key_y) {
empty_id_.push_back(key_y);
}
Key add(ValueT v) {
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auto next_id = next();
bool was_inserted;
decltype(map_.begin()) it;
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std::tie(it, was_inserted) = map_.emplace(std::move(v), next_id.first);
if (was_inserted && next_id.second) {
arr_[next_id.first - 1] = &it->first;
} else if (was_inserted) {
arr_.push_back(&it->first);
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} else if (next_id.second) {
empty_id_.push_back(next_id.first);
}
return it->second;
}
const ValueT &get(Key key) const {
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auto pos = static_cast<Key>(key - 1);
return *arr_[pos];
}
private:
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std::vector<Key> empty_id_;
std::map<ValueT, int32> map_;
std::vector<const ValueT *> arr_;
};
} // namespace td