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/*
* Copyright 2018 Google
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_CORE_TARGET_ID_GENERATOR_H_
#define FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_CORE_TARGET_ID_GENERATOR_H_
#include "Firestore/core/src/firebase/firestore/model/types.h"
namespace firebase {
namespace firestore {
namespace core {
/** The set of all valid generators. */
enum class TargetIdGeneratorId { LocalStore = 0, SyncEngine = 1 };
/**
* Generates monotonically increasing integer IDs. There are separate generators
* for different scopes. While these generators will operate independently of
* each other, they are scoped, such that no two generators will ever produce
* the same ID. This is useful, because sometimes the backend may group IDs from
* separate parts of the client into the same ID space.
*
* Not thread-safe.
*/
class TargetIdGenerator {
public:
// Makes Objective-C++ code happy to provide a default ctor.
TargetIdGenerator() = default;
TargetIdGenerator(const TargetIdGenerator& value);
/**
* Creates and returns the TargetIdGenerator for the local store.
*
* @param after An ID to start at. Every call to NextId returns a larger id.
* @return An instance of TargetIdGenerator.
*/
static TargetIdGenerator LocalStoreTargetIdGenerator(model::TargetId after) {
return TargetIdGenerator(TargetIdGeneratorId::LocalStore, after);
}
/**
* Creates and returns the TargetIdGenerator for the sync engine.
*
* @param after An ID to start at. Every call to NextId returns a larger id.
* @return An instance of TargetIdGenerator.
*/
static TargetIdGenerator SyncEngineTargetIdGenerator(model::TargetId after) {
return TargetIdGenerator(TargetIdGeneratorId::SyncEngine, after);
}
TargetIdGeneratorId generator_id() {
return generator_id_;
}
model::TargetId NextId();
private:
TargetIdGenerator(TargetIdGeneratorId generator_id, model::TargetId after);
TargetIdGeneratorId generator_id_;
model::TargetId previous_id_;
static const int kReservedBits = 1;
};
} // namespace core
} // namespace firestore
} // namespace firebase
#endif // FIRESTORE_CORE_SRC_FIREBASE_FIRESTORE_CORE_TARGET_ID_GENERATOR_H_
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