//
// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2026
//
// 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 <cstddef>
#include <type_traits>
#include <utility>

namespace td {

// const-correct and compiler-friendly (g++ RAM and CPU usage 10 times less than for std::unique_ptr)
// replacement for std::unique_ptr
template <class T>
class unique_ptr final {
 public:
  using pointer = T *;
  using element_type = T;

  unique_ptr() noexcept = default;
  unique_ptr(const unique_ptr &) = delete;
  unique_ptr &operator=(const unique_ptr &) = delete;
  unique_ptr(unique_ptr &&other) noexcept : ptr_(other.release()) {
  }
  unique_ptr &operator=(unique_ptr &&other) noexcept {
    reset(other.release());
    return *this;
  }
  ~unique_ptr() {
    reset();
  }

  unique_ptr(std::nullptr_t) noexcept {
  }
  explicit unique_ptr(T *ptr) noexcept : ptr_(ptr) {
  }
  template <class S, class = std::enable_if_t<std::is_base_of<T, S>::value>>
  unique_ptr(unique_ptr<S> &&other) noexcept : ptr_(static_cast<S *>(other.release())) {
  }
  template <class S, class = std::enable_if_t<std::is_base_of<T, S>::value>>
  unique_ptr &operator=(unique_ptr<S> &&other) noexcept {
    reset(static_cast<T *>(other.release()));
    return *this;
  }
  void reset(T *new_ptr = nullptr) noexcept {
    static_assert(sizeof(T) > 0, "Can't destroy unique_ptr with incomplete type");
    delete ptr_;
    ptr_ = new_ptr;
  }
  T *release() noexcept {
    auto res = ptr_;
    ptr_ = nullptr;
    return res;
  }
  T *get() noexcept {
    return ptr_;
  }
  const T *get() const noexcept {
    return ptr_;
  }
  T *operator->() noexcept {
    return ptr_;
  }
  const T *operator->() const noexcept {
    return ptr_;
  }
  T &operator*() noexcept {
    return *ptr_;
  }
  const T &operator*() const noexcept {
    return *ptr_;
  }
  explicit operator bool() const noexcept {
    return ptr_ != nullptr;
  }

 private:
  T *ptr_{nullptr};
};

template <class T>
bool operator==(std::nullptr_t, const unique_ptr<T> &p) {
  return !p;
}
template <class T>
bool operator==(const unique_ptr<T> &p, std::nullptr_t) {
  return !p;
}
template <class T>
bool operator!=(std::nullptr_t, const unique_ptr<T> &p) {
  return static_cast<bool>(p);
}
template <class T>
bool operator!=(const unique_ptr<T> &p, std::nullptr_t) {
  return static_cast<bool>(p);
}

template <class T>
bool operator==(const unique_ptr<T> &lhs, const unique_ptr<T> &rhs) {
  if (lhs == nullptr) {
    return rhs == nullptr;
  }
  if (rhs == nullptr) {
    return false;
  }
  return *lhs == *rhs;
}

template <class T>
bool operator!=(const unique_ptr<T> &lhs, const unique_ptr<T> &rhs) {
  return !(lhs == rhs);
}

template <class Type, class... Args>
unique_ptr<Type> make_unique(Args &&...args) {
  return unique_ptr<Type>(new Type(std::forward<Args>(args)...));
}

}  // namespace td
