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//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2023
//
// 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 "td/utils/Span.h"
#include <utility>
namespace td {
template <class T>
class VectorQueue {
public:
template <class S>
void push(S &&s) {
vector_.emplace_back(std::forward<S>(s));
}
template <class... Args>
void emplace(Args &&...args) {
vector_.emplace_back(std::forward<Args>(args)...);
}
T pop() {
try_shrink();
return std::move(vector_[read_pos_++]);
}
template <class RndT>
T pop_rand(RndT &rnd) {
auto i = rnd() % size();
std::swap(vector_[i], vector_[read_pos_]);
return pop();
}
void pop_n(size_t n) {
read_pos_ += n;
try_shrink();
}
const T &front() const {
return vector_[read_pos_];
}
T &front() {
return vector_[read_pos_];
}
const T &back() const {
return vector_.back();
}
T &back() {
return vector_.back();
}
bool empty() const {
return size() == 0;
}
size_t size() const {
return vector_.size() - read_pos_;
}
const T *data() const {
return vector_.data() + read_pos_;
}
T *data() {
return vector_.data() + read_pos_;
}
Span<T> as_span() const {
return {data(), size()};
}
MutableSpan<T> as_mutable_span() {
return {vector_.data() + read_pos_, size()};
}
private:
vector<T> vector_;
size_t read_pos_{0};
void try_shrink() {
if (read_pos_ * 2 > vector_.size() && read_pos_ > 4) {
vector_.erase(vector_.begin(), vector_.begin() + read_pos_);
read_pos_ = 0;
}
}
};
} // namespace td
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