chromium/third_party/webrtc/rtc_base/unique_id_generator.h

/*
 *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef RTC_BASE_UNIQUE_ID_GENERATOR_H_
#define RTC_BASE_UNIQUE_ID_GENERATOR_H_

#include <limits>
#include <set>
#include <string>

#include "absl/strings/string_view.h"
#include "api/array_view.h"
#include "api/sequence_checker.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/system/no_unique_address.h"

namespace rtc {

// This class will generate numbers. A common use case is for identifiers.
// The generated numbers will be unique, in the local scope of the generator.
// This means that a generator will never generate the same number twice.
// The generator can also be initialized with a sequence of known ids.
// In such a case, it will never generate an id from that list.
// Recommendedations:
//  * Prefer unsigned types.
//  * Prefer larger types (uint8_t will run out quickly).
template <typename TIntegral>
class UniqueNumberGenerator { … };

// This class will generate unique ids. Ids are 32 bit unsigned integers.
// The generated ids will be unique, in the local scope of the generator.
// This means that a generator will never generate the same id twice.
// The generator can also be initialized with a sequence of known ids.
// In such a case, it will never generate an id from that list.
class UniqueRandomIdGenerator { … };

// This class will generate strings. A common use case is for identifiers.
// The generated strings will be unique, in the local scope of the generator.
// This means that a generator will never generate the same string twice.
// The generator can also be initialized with a sequence of known ids.
// In such a case, it will never generate an id from that list.
class UniqueStringGenerator { … };

template <typename TIntegral>
UniqueNumberGenerator<TIntegral>::UniqueNumberGenerator() : … { … }

template <typename TIntegral>
UniqueNumberGenerator<TIntegral>::UniqueNumberGenerator(
    ArrayView<TIntegral> known_ids)
    : … { … }

template <typename TIntegral>
UniqueNumberGenerator<TIntegral>::~UniqueNumberGenerator() { … }

template <typename TIntegral>
TIntegral UniqueNumberGenerator<TIntegral>::GenerateNumber() { … }

template <typename TIntegral>
bool UniqueNumberGenerator<TIntegral>::AddKnownId(TIntegral value) { … }
}  // namespace rtc

#endif  // RTC_BASE_UNIQUE_ID_GENERATOR_H_