tdlight/td/telegram/SetWithPosition.h

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//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2024
//
// 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/algorithm.h"
#include "td/utils/common.h"
#include <algorithm>
#include <set>
#include <utility>
namespace td {
template <class T>
class FastSetWithPosition {
public:
std::vector<T> get_some_elements() const {
std::vector<T> res;
res.reserve(4);
if (!checked_.empty()) {
res.push_back(*checked_.begin());
res.push_back(*checked_.rbegin());
}
if (!not_checked_.empty()) {
res.push_back(*not_checked_.begin());
res.push_back(*not_checked_.rbegin());
}
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td::unique(res);
if (res.size() > 2) {
res.erase(res.begin() + 1, res.end() - 1);
}
return res;
}
bool add(T x) {
if (checked_.count(x) != 0) {
return false;
}
return not_checked_.insert(x).second;
}
bool remove(T x) {
return checked_.erase(x) != 0 || not_checked_.erase(x) != 0;
}
bool has_next() const {
return !not_checked_.empty();
}
void reset_position() {
if (not_checked_.empty()) {
not_checked_ = std::move(checked_);
} else {
not_checked_.insert(checked_.begin(), checked_.end());
}
reset_to_empty(checked_);
}
T next() {
CHECK(has_next());
auto it = not_checked_.begin();
auto res = *it;
not_checked_.erase(it);
checked_.insert(res);
return res;
}
void merge(FastSetWithPosition &&other) {
if (this == &other) {
return;
}
if (size() < other.size()) {
std::swap(*this, other);
}
for (auto x : other.checked_) {
not_checked_.erase(x);
checked_.insert(x);
}
for (auto x : other.not_checked_) {
if (checked_.count(x) != 0) {
continue;
}
not_checked_.insert(x);
}
}
size_t size() const {
return checked_.size() + not_checked_.size();
}
bool empty() const {
return size() == 0;
}
private:
std::set<T> checked_;
std::set<T> not_checked_;
};
template <class T>
class SetWithPosition {
public:
std::vector<T> get_some_elements() const {
if (fast_) {
return fast_->get_some_elements();
}
if (has_value_) {
return {value_};
}
return {};
}
bool add(T x) {
if (fast_) {
return fast_->add(x);
}
if (!has_value_) {
value_ = x;
has_value_ = true;
is_checked_ = false;
return true;
}
if (value_ == x) {
return false;
}
make_fast();
return fast_->add(x);
}
bool remove(T x) {
if (fast_) {
return fast_->remove(x);
}
if (has_value_ && value_ == x) {
has_value_ = false;
is_checked_ = false;
return true;
}
return false;
}
bool has_next() const {
if (fast_) {
return fast_->has_next();
}
return has_value_ && !is_checked_;
}
void reset_position() {
if (fast_) {
fast_->reset_position();
return;
}
is_checked_ = false;
}
T next() {
CHECK(has_next());
if (fast_) {
return fast_->next();
}
is_checked_ = true;
return value_;
}
void merge(SetWithPosition &&other) {
if (this == &other) {
return;
}
if (size() < other.size()) {
std::swap(*this, other);
}
if (other.size() == 0) {
return;
}
if (other.fast_ == nullptr && fast_ == nullptr && value_ == other.value_) {
is_checked_ |= other.is_checked_;
other.value_ = T();
other.has_value_ = false;
other.is_checked_ = false;
return;
}
make_fast();
other.make_fast();
fast_->merge(std::move(*other.fast_));
reset_to_empty(other);
}
size_t size() const {
if (fast_) {
return fast_->size();
}
return static_cast<size_t>(has_value_);
}
bool empty() const {
if (fast_) {
return false;
}
return !has_value_;
}
private:
T value_{};
bool has_value_{false};
bool is_checked_{false};
unique_ptr<FastSetWithPosition<T>> fast_;
void make_fast() {
if (fast_) {
return;
}
fast_ = make_unique<FastSetWithPosition<T>>();
CHECK(has_value_);
fast_->add(value_);
if (is_checked_) {
fast_->next();
}
}
};
} // namespace td