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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Async Algorithms open source project
//
// Copyright (c) 2021 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
extension AsyncSequence {
/// Creates an asynchronous sequence that creates chunks of a given `RangeReplaceableCollection` type of a given count or when a signal `AsyncSequence` produces an element.
public func chunks<Signal, Collected: RangeReplaceableCollection>(ofCount count: Int, or signal: Signal, into: Collected.Type) -> AsyncChunksOfCountOrSignalSequence<Self, Collected, Signal> where Collected.Element == Element {
AsyncChunksOfCountOrSignalSequence(self, count: count, signal: signal)
}
/// Creates an asynchronous sequence that creates chunks of a given count or when a signal `AsyncSequence` produces an element.
public func chunks<Signal>(ofCount count: Int, or signal: Signal) -> AsyncChunksOfCountOrSignalSequence<Self, [Element], Signal> {
chunks(ofCount: count, or: signal, into: [Element].self)
}
/// Creates an asynchronous sequence that creates chunks of a given `RangeReplaceableCollection` type when a signal `AsyncSequence` produces an element.
public func chunked<Signal, Collected: RangeReplaceableCollection>(by signal: Signal, into: Collected.Type) -> AsyncChunksOfCountOrSignalSequence<Self, Collected, Signal> where Collected.Element == Element {
AsyncChunksOfCountOrSignalSequence(self, count: nil, signal: signal)
}
/// Creates an asynchronous sequence that creates chunks when a signal `AsyncSequence` produces an element.
public func chunked<Signal>(by signal: Signal) -> AsyncChunksOfCountOrSignalSequence<Self, [Element], Signal> {
chunked(by: signal, into: [Element].self)
}
/// Creates an asynchronous sequence that creates chunks of a given `RangeReplaceableCollection` type of a given count or when an `AsyncTimerSequence` fires.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public func chunks<C: Clock, Collected: RangeReplaceableCollection>(ofCount count: Int, or timer: AsyncTimerSequence<C>, into: Collected.Type) -> AsyncChunksOfCountOrSignalSequence<Self, Collected, AsyncTimerSequence<C>> where Collected.Element == Element {
AsyncChunksOfCountOrSignalSequence(self, count: count, signal: timer)
}
/// Creates an asynchronous sequence that creates chunks of a given count or when an `AsyncTimerSequence` fires.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public func chunks<C: Clock>(ofCount count: Int, or timer: AsyncTimerSequence<C>) -> AsyncChunksOfCountOrSignalSequence<Self, [Element], AsyncTimerSequence<C>> {
chunks(ofCount: count, or: timer, into: [Element].self)
}
/// Creates an asynchronous sequence that creates chunks of a given `RangeReplaceableCollection` type when an `AsyncTimerSequence` fires.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public func chunked<C: Clock, Collected: RangeReplaceableCollection>(by timer: AsyncTimerSequence<C>, into: Collected.Type) -> AsyncChunksOfCountOrSignalSequence<Self, Collected, AsyncTimerSequence<C>> where Collected.Element == Element {
AsyncChunksOfCountOrSignalSequence(self, count: nil, signal: timer)
}
/// Creates an asynchronous sequence that creates chunks when an `AsyncTimerSequence` fires.
@available(macOS 13.0, iOS 16.0, watchOS 9.0, tvOS 16.0, *)
public func chunked<C: Clock>(by timer: AsyncTimerSequence<C>) -> AsyncChunksOfCountOrSignalSequence<Self, [Element], AsyncTimerSequence<C>> {
chunked(by: timer, into: [Element].self)
}
}
/// An `AsyncSequence` that chunks elements into collected `RangeReplaceableCollection` instances by either count or a signal from another `AsyncSequence`.
public struct AsyncChunksOfCountOrSignalSequence<Base: AsyncSequence, Collected: RangeReplaceableCollection, Signal: AsyncSequence>: AsyncSequence, Sendable where Collected.Element == Base.Element, Base: Sendable, Signal: Sendable, Base.Element: Sendable, Signal.Element: Sendable {
public typealias Element = Collected
enum Either {
case element(Base.Element)
case terminal
case signal
}
/// The iterator for a `AsyncChunksOfCountOrSignalSequence` instance.
public struct Iterator: AsyncIteratorProtocol {
typealias EitherMappedBase = AsyncMapSequence<Base, Either>
typealias EitherMappedSignal = AsyncMapSequence<Signal, Either>
typealias ChainedBase = AsyncChain2Sequence<EitherMappedBase, AsyncSyncSequence<[Either]>>
typealias Merged = AsyncMerge2Sequence<ChainedBase, EitherMappedSignal>
let count: Int?
var iterator: Merged.AsyncIterator
var terminated = false
init(iterator: Merged.AsyncIterator, count: Int?) {
self.count = count
self.iterator = iterator
}
public mutating func next() async rethrows -> Collected? {
guard !terminated else {
return nil
}
var result: Collected?
while let next = try await iterator.next() {
switch next {
case .element(let element):
if result == nil {
result = Collected()
}
result!.append(element)
if result?.count == count {
return result
}
case .terminal:
terminated = true
return result
case .signal:
if result != nil {
return result
}
}
}
return result
}
}
let base: Base
let signal: Signal
let count: Int?
init(_ base: Base, count: Int?, signal: Signal) {
if let count = count {
precondition(count > 0)
}
self.base = base
self.count = count
self.signal = signal
}
public func makeAsyncIterator() -> Iterator {
return Iterator(iterator: merge(chain(base.map { Either.element($0) }, [.terminal].async), signal.map { _ in Either.signal }).makeAsyncIterator(), count: count)
}
}
@available(*, unavailable)
extension AsyncChunksOfCountOrSignalSequence.Iterator: Sendable { }
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