46 lines
1.0 KiB
C++
46 lines
1.0 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#pragma once
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#include "td/utils/common.h"
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#include <limits>
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#include <map>
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#include <tuple>
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namespace td {
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template <class ValueT>
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class Enumerator {
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public:
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using Key = int32;
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Key add(ValueT v) {
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CHECK(arr_.size() < static_cast<size_t>(std::numeric_limits<int32>::max() - 1));
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int32 next_id = static_cast<int32>(arr_.size() + 1);
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bool was_inserted;
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decltype(map_.begin()) it;
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std::tie(it, was_inserted) = map_.emplace(std::move(v), next_id);
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if (was_inserted) {
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arr_.push_back(&it->first);
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}
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return it->second;
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}
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const ValueT &get(Key key) const {
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auto pos = static_cast<size_t>(key - 1);
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CHECK(pos < arr_.size());
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return *arr_[pos];
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}
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private:
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std::map<ValueT, int32> map_;
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std::vector<const ValueT *> arr_;
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};
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} // namespace td
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