95 lines
2.6 KiB
Swift
95 lines
2.6 KiB
Swift
/*
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* Copyright 2022 The Yorkie Authors. All rights reserved.
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*
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* Licensed under the Apache License, Version 2.0 (the "License")
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import Foundation
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/**
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* `Checkpoint` is used to determine the changes sent and received by the
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* client. This is immutable.
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*
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**/
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struct Checkpoint: Equatable {
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/**
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* `InitialCheckpoint` is the initial value of the checkpoint.
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*/
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static let initial = Checkpoint(serverSeq: 0, clientSeq: 0)
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private var serverSeq: Int64
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private var clientSeq: UInt32
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init(serverSeq: Int64, clientSeq: UInt32) {
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self.serverSeq = serverSeq
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self.clientSeq = clientSeq
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}
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/**
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* `increaseClientSeq` creates a new instance with increased client sequence.
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*/
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func increasedClientSeq(by value: UInt32) -> Checkpoint {
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if value == 0 {
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return self
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} else {
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return Checkpoint(serverSeq: self.serverSeq, clientSeq: self.clientSeq + value)
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}
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}
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/**
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* `forward` creates a new instance with the given checkpoint if it is
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* greater than the values of internal properties.
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*/
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mutating func forward(other: Checkpoint) {
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if self == other {
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return
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}
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self.serverSeq = max(self.serverSeq, other.serverSeq)
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self.clientSeq = max(self.clientSeq, other.clientSeq)
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}
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/**
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* `getServerSeqAsString` returns the server seq of this checkpoint as a
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* string.
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*/
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func getServerSeqAsString() -> String {
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return "\(self.serverSeq)"
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}
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/**
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* `getClientSeq` returns the client seq of this checkpoint.
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*/
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func getClientSeq() -> UInt32 {
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return self.clientSeq
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}
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/**
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* `getServerSeq` returns the server seq of this checkpoint.
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*/
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func getServerSeq() -> Int64 {
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return self.serverSeq
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}
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/**
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* `structureAsString` returns a string containing the meta data of this
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* checkpoint.
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*/
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var structureAsString: String {
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return "serverSeq=\(self.serverSeq), clientSeq=\(self.clientSeq)"
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}
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static func == (lhs: Self, rhs: Self) -> Bool {
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lhs.clientSeq == rhs.clientSeq && lhs.serverSeq == rhs.serverSeq
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}
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}
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