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[Refactor] Remove ConcreteAsyncSequence #38

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Merged
merged 2 commits into from
Oct 6, 2025
Merged

[Refactor] Remove ConcreteAsyncSequence #38

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9612a02
[NFC] Remove ConcreteAsyncSequence
czechboy0 Oct 1, 2025
d776867
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czechboy0 Oct 6, 2025
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9 changes: 6 additions & 3 deletions Sources/Configuration/ConfigReader+internalHelpers.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -639,7 +639,8 @@ extension ConfigReader {
) async throws -> Return {
let absoluteKey = keyPrefix.appending(key)
return try await provider.watchValue(forKey: absoluteKey, type: type) { updates in
let mappedUpdates = ConcreteAsyncSequence(updates)
let mappedUpdates =
updates
.map { updateTuple in
let (providerResults, value) = mergingIsSecret(
isSecret,
Expand Down Expand Up @@ -715,7 +716,8 @@ extension ConfigReader {
) async throws -> Return {
let absoluteKey = keyPrefix.appending(key)
return try await provider.watchValue(forKey: absoluteKey, type: type) { updates in
let mappedUpdates = ConcreteAsyncSequence(updates)
let mappedUpdates =
updates
.map { updateTuple in
let (providerResults, value) = mergingIsSecret(
isSecret,
Expand Down Expand Up @@ -790,7 +792,8 @@ extension ConfigReader {
) async throws -> Return {
let absoluteKey = keyPrefix.appending(key)
return try await provider.watchValue(forKey: absoluteKey, type: type) { updates in
let mappedUpdates = ConcreteAsyncSequence(updates)
let mappedUpdates =
updates
.mapThrowing { updateTuple in
let (providerResults, value) = mergingIsSecret(
isSecret,
Expand Down
2 changes: 1 addition & 1 deletion Sources/Configuration/ConfigSnapshotReader.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -363,7 +363,7 @@ extension ConfigReader {
try await provider.watchSnapshot { updates in
try await updatesHandler(
ConfigUpdatesAsyncSequence(
ConcreteAsyncSequence(updates)
updates
.map { multiSnapshot in
ConfigSnapshotReader(
keyPrefix: keyPrefix,
Expand Down
4 changes: 2 additions & 2 deletions Sources/Configuration/MultiProvider.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -205,7 +205,7 @@ extension MultiProvider {
updatesHandler: { updateArrays in
try await body(
ConfigUpdatesAsyncSequence(
ConcreteAsyncSequence(updateArrays)
updateArrays
.map { array in
MultiSnapshot(snapshots: array)
}
Expand Down Expand Up @@ -302,7 +302,7 @@ extension MultiProvider {
updatesHandler: { updateArrays in
try await updatesHandler(
ConfigUpdatesAsyncSequence(
ConcreteAsyncSequence(updateArrays)
updateArrays
.map { array in
var results: [AccessEvent.ProviderResult] = []
for (providerIndex, lookupResult) in array.enumerated() {
Expand Down
2 changes: 1 addition & 1 deletion Sources/Configuration/Providers/Wrappers/KeyMappingProvider.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -109,7 +109,7 @@ extension KeyMappingProvider: ConfigProvider {
try await upstream.watchSnapshot { sequence in
try await updatesHandler(
ConfigUpdatesAsyncSequence(
ConcreteAsyncSequence(sequence)
sequence
.map { snapshot in
MappedKeySnapshot(mapKey: self.mapKey, upstream: self.upstream.snapshot())
}
Expand Down
65 changes: 0 additions & 65 deletions Sources/Configuration/Utilities/AsyncSequences.swift
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Expand Up @@ -55,71 +55,6 @@ extension ConfigUpdatesAsyncSequence: AsyncSequence {
}
}

/// A concrete async sequence that wraps an existential async sequence.
///
/// This type provides a concrete implementation of `AsyncSequence` that wraps
/// an existential `any AsyncSequence`. It serves as a workaround for limitations
/// in Swift's type system where certain operations like `map` and other sequence
/// transformations don't work directly with existential async sequences.
///
/// ## Purpose
///
/// The Swift standard library's async sequence operations require concrete types
/// to function properly. When working with `any AsyncSequence`, these operations
/// are not available. This wrapper provides a concrete type that enables the use
/// of standard async sequence operations.
///
/// ## Usage
///
/// ```swift
/// let existentialSequence: any AsyncSequence<Int, Never> = someAsyncSequence
/// let concreteSequence = ConcreteAsyncSequence(existentialSequence)
///
/// // Now you can use standard async sequence operations
/// let mappedSequence = concreteSequence.map { $0 * 2 }
/// ```
package struct ConcreteAsyncSequence<Element: Sendable, Failure: Error> {

/// The upstream async sequence that this concrete sequence wraps.
///
/// This property holds the async sequence that provides the actual elements.
/// All operations on this concrete sequence are delegated to this upstream sequence.
var upstream: any AsyncSequence<Element, Failure>

/// Creates a new concrete async sequence wrapping the provided existential sequence.
///
/// - Parameter upstream: The async sequence to wrap.
package init(_ upstream: any AsyncSequence<Element, Failure>) {
self.upstream = upstream
}
}

extension ConcreteAsyncSequence: AsyncSequence {

/// An async iterator that wraps an existential async iterator.
///
/// This iterator provides the concrete implementation for iterating over
/// the wrapped existential async sequence. It delegates all operations
/// to the upstream iterator while maintaining type safety.
package struct Iterator: AsyncIteratorProtocol {

/// The upstream async iterator that provides the actual iteration logic.
var upstream: any AsyncIteratorProtocol<Element, Failure>

// swift-format-ignore: AllPublicDeclarationsHaveDocumentation
package mutating func next(
isolation actor: isolated (any Actor)?
) async throws(Failure) -> Element? {
try await upstream.next(isolation: actor)
}
}

// swift-format-ignore: AllPublicDeclarationsHaveDocumentation
package func makeAsyncIterator() -> Iterator {
Iterator(upstream: upstream.makeAsyncIterator())
}
}

// MARK: - AsyncSequence extensions

extension AsyncSequence where Failure == Never {
Expand Down
33 changes: 0 additions & 33 deletions Tests/ConfigurationTests/AsyncSequencesTests.swift
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Expand Up @@ -57,39 +57,6 @@ struct AsyncSequencesTests {
#expect(results == [1, 2])
}

// MARK: - ConcreteAsyncSequence tests

@Test func concreteAsyncSequenceWrapsExistentialSequence() async throws {
let values = [1, 2, 3, 4, 5]
let concreteSequence = ConcreteAsyncSequence(values.async)
let results = await concreteSequence.collect()
#expect(results == values)
}

@Test func concreteAsyncSequenceWithEmptySequence() async throws {
let concreteSequence = ConcreteAsyncSequence(([] as [Int]).async)
let results = await concreteSequence.collect()
#expect(results.isEmpty)
}

@Test func concreteAsyncSequencePropagatesErrors() async throws {
let throwingSequence = AsyncThrowingStream<Int, any Error> { continuation in
continuation.yield(1)
continuation.yield(2)
continuation.finish(throwing: TestError.upstreamFailed)
}
let concreteSequence = ConcreteAsyncSequence(throwingSequence)

var results: [Int] = []
let error = await #expect(throws: TestError.self) {
for try await value in concreteSequence {
results.append(value)
}
}
#expect(error == .upstreamFailed)
#expect(results == [1, 2])
}

// MARK: - mapThrowing Tests

@Test func mapThrowingSuccessfulTransformation() async throws {
Expand Down
4 changes: 2 additions & 2 deletions Tests/ConfigurationTests/MultiProviderTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -95,7 +95,7 @@ struct MultiProviderTests {
try await multiProvider.watchValue(forKey: key, type: type) { updates in
try await handler(
ConfigUpdatesAsyncSequence(
ConcreteAsyncSequence(updates)
updates
.map { update in
update.1.map { .init(encodedKey: "<not tested>", value: $0) }
}
Expand All @@ -116,7 +116,7 @@ struct MultiProviderTests {
try await multiProvider.watchSnapshot { updates in
try await updatesHandler(
ConfigUpdatesAsyncSequence(
ConcreteAsyncSequence(updates).map { $0 }
updates.map { $0 }
)
)
}
Expand Down
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