tdlight/tdutils/td/utils/MapNode.h

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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2022
//
// 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 <new>
namespace td {
template <class KeyT, class ValueT>
struct MapNode {
using first_type = KeyT;
using second_type = ValueT;
using public_key_type = KeyT;
using public_type = MapNode;
KeyT first{};
union {
ValueT second;
};
const KeyT &key() const {
return first;
}
MapNode &get_public() {
return *this;
}
MapNode() {
}
MapNode(KeyT key, ValueT value) : first(std::move(key)) {
new (&second) ValueT(std::move(value));
DCHECK(!empty());
}
MapNode(const MapNode &other) = delete;
MapNode &operator=(const MapNode &other) = delete;
MapNode(MapNode &&other) noexcept {
*this = std::move(other);
}
void operator=(MapNode &&other) noexcept {
DCHECK(empty());
DCHECK(!other.empty());
first = std::move(other.first);
other.first = KeyT{};
new (&second) ValueT(std::move(other.second));
other.second.~ValueT();
}
~MapNode() {
if (!empty()) {
second.~ValueT();
}
}
void copy_from(const MapNode &other) {
DCHECK(empty());
DCHECK(!other.empty());
first = other.first;
new (&second) ValueT(other.second);
}
bool empty() const {
return is_hash_table_key_empty(first);
}
void clear() {
DCHECK(!empty());
first = KeyT();
second.~ValueT();
DCHECK(empty());
}
template <class... ArgsT>
void emplace(KeyT key, ArgsT &&...args) {
DCHECK(empty());
first = std::move(key);
new (&second) ValueT(std::forward<ArgsT>(args)...);
DCHECK(!empty());
}
};
} // namespace td