macOS client store and API
This commit is contained in:
Ian Gulliver
@@ -0,0 +1,222 @@
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import AppKit
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import Foundation
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import Network
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private let staleAfter: TimeInterval = 40
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private let retryAfter: Duration = .seconds(2)
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private let checkEvery: Duration = .seconds(5)
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private enum Frame: Sendable {
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case open
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case ping
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case ready
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case event(id: Int64?, ByreEvent)
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}
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@MainActor
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final class EventStream {
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private let api: API
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private let lead: Bool
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private let onEvent: (ByreEvent) -> Void
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private let onState: (Bool) -> Void
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private let onReady: () -> Void
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private var last: Int64
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private var heard = Date()
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private var reading: Task<Void, Never>?
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private var retry: Task<Void, Never>?
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private var checker: Task<Void, Never>?
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private var generation = 0
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private let monitor = NWPathMonitor()
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private var online: Bool?
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private var activeObserver: (any NSObjectProtocol)?
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init(api: API, after: Int64, lead: Bool, onEvent: @escaping (ByreEvent) -> Void, onState: @escaping (Bool) -> Void, onReady: @escaping () -> Void) {
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self.api = api
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self.lead = lead
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self.onEvent = onEvent
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self.onState = onState
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self.onReady = onReady
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last = after
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checker = Task { [weak self] in
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while !Task.isCancelled {
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try? await Task.sleep(for: checkEvery)
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self?.check()
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}
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}
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monitor.pathUpdateHandler = { [weak self] path in
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let up = path.status == .satisfied
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Task { @MainActor in
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self?.pathChanged(up)
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}
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}
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monitor.start(queue: .main)
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activeObserver = NotificationCenter.default.addObserver(forName: NSApplication.didBecomeActiveNotification, object: nil, queue: .main) { [weak self] _ in
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MainActor.assumeIsolated {
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self?.check()
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}
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}
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connect()
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}
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func stop() {
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generation += 1
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checker?.cancel()
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retry?.cancel()
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reading?.cancel()
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monitor.cancel()
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if let activeObserver {
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NotificationCenter.default.removeObserver(activeObserver)
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}
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activeObserver = nil
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}
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private func pathChanged(_ up: Bool) {
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let was = online
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online = up
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if was == false && up {
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connect()
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}
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}
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private func check() {
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if Date().timeIntervalSince(heard) < staleAfter {
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return
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}
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onState(false)
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connect()
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}
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private func connect() {
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retry?.cancel()
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reading?.cancel()
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generation += 1
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let gen = generation
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heard = Date()
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var query = [URLQueryItem(name: "after", value: String(last))]
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if lead {
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query.append(URLQueryItem(name: "lead", value: "true"))
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}
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var request = URLRequest(url: api.url("/api/events", query))
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request.setValue("text/event-stream", forHTTPHeaderField: "Accept")
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let session = api.session
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reading = Task.detached { [weak self] in
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do {
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try await Self.read(session, request) { frame in
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self?.receive(frame, gen)
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}
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await self?.failed(gen)
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} catch {
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await self?.failed(gen)
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}
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}
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}
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private func receive(_ frame: Frame, _ gen: Int) {
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guard gen == generation else {
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return
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}
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heard = Date()
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switch frame {
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case .open:
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onState(true)
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case .ping:
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break
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case .ready:
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onReady()
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case .event(let id, let ev):
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if let id, id > last {
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last = id
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}
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if ev.seq > last {
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last = ev.seq
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}
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onEvent(ev)
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}
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}
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private func failed(_ gen: Int) {
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guard gen == generation else {
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return
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}
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onState(false)
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retry = Task { [weak self] in
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try? await Task.sleep(for: retryAfter)
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if !Task.isCancelled && self?.generation == gen {
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self?.connect()
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}
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}
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}
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nonisolated private static func read(_ session: URLSession, _ request: URLRequest, _ deliver: @escaping @MainActor @Sendable (Frame) -> Void) async throws {
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let (bytes, response) = try await session.bytes(for: request)
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let code = (response as! HTTPURLResponse).statusCode
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if code != 200 {
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throw ApiError(status: code, message: "\(code) \(HTTPURLResponse.localizedString(forStatusCode: code))")
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}
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await deliver(.open)
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let decoder = jsonDecoder()
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var line: [UInt8] = []
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var afterCR = false
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var kind = ""
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var data: [String] = []
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var id: Int64?
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for try await byte in bytes {
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if byte == 0x0A && afterCR {
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afterCR = false
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continue
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}
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afterCR = byte == 0x0D
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if byte != 0x0A && byte != 0x0D {
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line.append(byte)
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continue
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}
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let text = String(decoding: line, as: UTF8.self)
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line.removeAll(keepingCapacity: true)
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if !text.isEmpty {
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if text.hasPrefix(":") {
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continue
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}
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let colon = text.firstIndex(of: ":") ?? text.endIndex
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let field = String(text[..<colon])
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var value = colon == text.endIndex ? "" : String(text[text.index(after: colon)...])
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if value.hasPrefix(" ") {
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value.removeFirst()
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}
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switch field {
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case "event":
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kind = value
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case "data":
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data.append(value)
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case "id":
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id = Int64(value)
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default:
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break
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}
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continue
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}
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defer {
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kind = ""
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data = []
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id = nil
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}
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if data.isEmpty {
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continue
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}
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switch kind {
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case "ping":
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await deliver(.ping)
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case "ready":
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await deliver(.ready)
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case "", "message":
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do {
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let ev = try decoder.decode(ByreEvent.self, from: Data(data.joined(separator: "\n").utf8))
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await deliver(.event(id: id, ev))
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} catch {
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log.error("decode event: \(String(describing: error), privacy: .public)")
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}
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default:
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break
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}
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}
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}
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}
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