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Refactor Throttle to use the same engine style as Debounce #290

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Refactor Throttle to use the same engine style as Debounce #290

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77 changes: 40 additions & 37 deletions ...yncAlgorithms/AsyncThrottleSequence.swift → ...thms/Throttle/AsyncThrottleSequence.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -12,19 +12,19 @@
extension AsyncSequence {
/// Create a rate-limited `AsyncSequence` by emitting values at most every specified interval.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public func throttle<C: Clock, Reduced>(for interval: C.Instant.Duration, clock: C, reducing: @Sendable @escaping (Reduced?, Element) async -> Reduced) -> AsyncThrottleSequence<Self, C, Reduced> {
public func throttle<C: Clock, Reduced>(for interval: C.Instant.Duration, clock: C, reducing: @Sendable @escaping (Reduced?, Element) async -> Reduced) -> AsyncThrottleSequence<Self, C, Reduced> where Self: Sendable {
AsyncThrottleSequence(self, interval: interval, clock: clock, reducing: reducing)
}

/// Create a rate-limited `AsyncSequence` by emitting values at most every specified interval.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public func throttle<Reduced>(for interval: Duration, reducing: @Sendable @escaping (Reduced?, Element) async -> Reduced) -> AsyncThrottleSequence<Self, ContinuousClock, Reduced> {
public func throttle<Reduced>(for interval: Duration, reducing: @Sendable @escaping (Reduced?, Element) async -> Reduced) -> AsyncThrottleSequence<Self, ContinuousClock, Reduced> where Self: Sendable {
throttle(for: interval, clock: .continuous, reducing: reducing)
}

/// Create a rate-limited `AsyncSequence` by emitting values at most every specified interval.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public func throttle<C: Clock>(for interval: C.Instant.Duration, clock: C, latest: Bool = true) -> AsyncThrottleSequence<Self, C, Element> {
public func throttle<C: Clock>(for interval: C.Instant.Duration, clock: C, latest: Bool = true) -> AsyncThrottleSequence<Self, C, Element> where Self: Sendable {
throttle(for: interval, clock: clock) { previous, element in
if latest {
return element
Expand All @@ -36,14 +36,14 @@ extension AsyncSequence {

/// Create a rate-limited `AsyncSequence` by emitting values at most every specified interval.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public func throttle(for interval: Duration, latest: Bool = true) -> AsyncThrottleSequence<Self, ContinuousClock, Element> {
public func throttle(for interval: Duration, latest: Bool = true) -> AsyncThrottleSequence<Self, ContinuousClock, Element> where Self: Sendable {
throttle(for: interval, clock: .continuous, latest: latest)
}
}

/// A rate-limited `AsyncSequence` by emitting values at most every specified interval.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public struct AsyncThrottleSequence<Base: AsyncSequence, C: Clock, Reduced> {
public struct AsyncThrottleSequence<Base: AsyncSequence & Sendable, C: Clock, Reduced> {
let base: Base
let interval: C.Instant.Duration
let clock: C
Expand All @@ -60,44 +60,47 @@ public struct AsyncThrottleSequence<Base: AsyncSequence, C: Clock, Reduced> {
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
extension AsyncThrottleSequence: AsyncSequence {
public typealias Element = Reduced

/// The iterator for an `AsyncThrottleSequence` instance.

public func makeAsyncIterator() -> Iterator {
let storage = ThrottleStorage(
base,
interval: interval,
clock: clock,
reducing: reducing
)
return Iterator(storage: storage)
}
}

@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
extension AsyncThrottleSequence {
public struct Iterator: AsyncIteratorProtocol {
var base: Base.AsyncIterator
var last: C.Instant?
let interval: C.Instant.Duration
let clock: C
let reducing: @Sendable (Reduced?, Base.Element) async -> Reduced
final class InternalClass: Sendable {
private let storage: ThrottleStorage<Base, C, Reduced>

fileprivate init(storage: ThrottleStorage<Base, C, Reduced>) {
self.storage = storage
}

deinit {
self.storage.iteratorDeinitialized()
}

func next() async rethrows -> Element? {
try await self.storage.next()
}
}

let internalClass: InternalClass

init(_ base: Base.AsyncIterator, interval: C.Instant.Duration, clock: C, reducing: @Sendable @escaping (Reduced?, Base.Element) async -> Reduced) {
self.base = base
self.interval = interval
self.clock = clock
self.reducing = reducing
fileprivate init(storage: ThrottleStorage<Base, C, Reduced>) {
self.internalClass = InternalClass(storage: storage)
}

public mutating func next() async rethrows -> Reduced? {
var reduced: Reduced?
let start = last ?? clock.now
repeat {
guard let element = try await base.next() else {
return nil
}
let reduction = await reducing(reduced, element)
let now = clock.now
if start.duration(to: now) >= interval || last == nil {
last = now
return reduction
} else {
reduced = reduction
}
} while true
public mutating func next() async rethrows -> Element? {
try await self.internalClass.next()
}
}

public func makeAsyncIterator() -> Iterator {
Iterator(base.makeAsyncIterator(), interval: interval, clock: clock, reducing: reducing)
}
}

@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
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