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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,77 @@ | ||
| // | ||
| // PrefixWhileBehavior.swift | ||
| // CombineExt | ||
| // | ||
| // Created by Jasdev Singh on 29/12/2020. | ||
| // Copyright © 2020 Combine Community. All rights reserved. | ||
| // | ||
|
|
||
| #if canImport(Combine) | ||
| import Combine | ||
| import Foundation | ||
|
|
||
| /// Whether to include the first element that doesn’t pass | ||
| /// the `while` predicate passed to `Combine.Publisher.prefix(while:behavior:)`. | ||
| public enum PrefixWhileBehavior { | ||
| /// Include the first element that doesn’t pass the `while` predicate. | ||
| case inclusive | ||
|
|
||
| /// Exclude the first element that doesn’t pass the `while` predicate. | ||
| case exclusive | ||
| } | ||
|
|
||
| @available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *) | ||
| public extension Publisher { | ||
| /// An overload on `Publisher.prefix(while:)` that allows for inclusion of the first element that doesn’t pass the `while` predicate. | ||
| /// | ||
| /// - parameters: | ||
| /// - predicate: A closure that takes an element as its parameter and returns a Boolean value that indicates whether publishing should continue. | ||
| /// - behavior: Whether or not to include the first element that doesn’t pass `predicate`. | ||
| /// | ||
| /// - returns: A publisher that passes through elements until the predicate indicates publishing should finish — and optionally that first `predicate`-failing element. | ||
| func prefix( | ||
| while predicate: @escaping (Output) -> Bool, | ||
| behavior: PrefixWhileBehavior = .exclusive | ||
| ) -> AnyPublisher<Output, Failure> { | ||
| switch behavior { | ||
| case .exclusive: | ||
| return prefix(while: predicate) | ||
| .eraseToAnyPublisher() | ||
| case .inclusive: | ||
| return flatMap { next in | ||
| Just(PrefixInclusiveEvent.whileValueOrIncluded(next)) | ||
| .append(!predicate(next) ? [.end] : []) | ||
| .setFailureType(to: Failure.self) | ||
| } | ||
| .prefix(while: \.isWhileValueOrIncluded) | ||
| .compactMap(\.value) | ||
| .eraseToAnyPublisher() | ||
| } | ||
| } | ||
| } | ||
| #endif | ||
|
|
||
| // MARK: - Helpers | ||
|
|
||
| private enum PrefixInclusiveEvent<Output> { | ||
| case end | ||
| case whileValueOrIncluded(Output) | ||
|
|
||
| var isWhileValueOrIncluded: Bool { | ||
| switch self { | ||
| case .end: | ||
| return false | ||
| case .whileValueOrIncluded: | ||
| return true | ||
| } | ||
| } | ||
|
|
||
| var value: Output? { | ||
| switch self { | ||
| case .end: | ||
| return nil | ||
| case let .whileValueOrIncluded(inner): | ||
| return inner | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,166 @@ | ||
| // | ||
| // PrefixWhileBehaviorTests.swift | ||
| // CombineExt | ||
| // | ||
| // Created by Jasdev Singh on 29/12/2020. | ||
| // Copyright © 2020 Combine Community. All rights reserved. | ||
| // | ||
|
|
||
| #if !os(watchOS) | ||
| import Combine | ||
| import CombineExt | ||
| import XCTest | ||
|
|
||
| @available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *) | ||
| final class PrefixWhileBehaviorTests: XCTestCase { | ||
| private struct SomeError: Error, Equatable {} | ||
|
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| private var cancellable: AnyCancellable! | ||
|
|
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| func testExclusiveValueEventsWithFinished() { | ||
| let intSubject = PassthroughSubject<Int, Never>() | ||
|
|
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| var values = [Int]() | ||
| var completions = [Subscribers.Completion<Never>]() | ||
|
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| cancellable = intSubject | ||
| .prefix( | ||
| while: { $0 % 2 == 0 }, | ||
| behavior: .exclusive | ||
| ) | ||
| .sink( | ||
| receiveCompletion: { completions.append($0) }, | ||
| receiveValue: { values.append($0) } | ||
| ) | ||
|
|
||
| [0, 2, 4, 5] | ||
| .forEach(intSubject.send) | ||
|
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| XCTAssertEqual(values, [0, 2, 4]) | ||
| XCTAssertEqual(completions, [.finished]) | ||
| } | ||
|
|
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| func testExclusiveValueEventsWithError() { | ||
| let intSubject = PassthroughSubject<Int, SomeError>() | ||
|
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| var values = [Int]() | ||
| var completions = [Subscribers.Completion<SomeError>]() | ||
|
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| cancellable = intSubject | ||
| .prefix( | ||
| while: { $0 % 2 == 0 }, | ||
| behavior: .exclusive | ||
| ) | ||
| .sink( | ||
| receiveCompletion: { completions.append($0) }, | ||
| receiveValue: { values.append($0) } | ||
| ) | ||
|
|
||
| [0, 2, 4] | ||
| .forEach(intSubject.send) | ||
|
|
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| intSubject.send(completion: .failure(.init())) | ||
|
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| XCTAssertEqual(values, [0, 2, 4]) | ||
| XCTAssertEqual(completions, [.failure(.init())]) | ||
| } | ||
|
|
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| func testInclusiveValueEventsWithStopElement() { | ||
| let intSubject = PassthroughSubject<Int, Never>() | ||
|
|
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| var values = [Int]() | ||
| var completions = [Subscribers.Completion<Never>]() | ||
|
|
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| cancellable = intSubject | ||
| .prefix( | ||
| while: { $0 % 2 == 0 }, | ||
| behavior: .inclusive | ||
| ) | ||
| .sink( | ||
| receiveCompletion: { completions.append($0) }, | ||
| receiveValue: { values.append($0) } | ||
| ) | ||
|
|
||
| [0, 2, 4, 5] | ||
| .forEach(intSubject.send) | ||
|
|
||
| XCTAssertEqual(values, [0, 2, 4, 5]) | ||
| XCTAssertEqual(completions, [.finished]) | ||
| } | ||
|
|
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| func testInclusiveValueEventsWithErrorAfterStopElement() { | ||
| let intSubject = PassthroughSubject<Int, SomeError>() | ||
|
|
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| var values = [Int]() | ||
| var completions = [Subscribers.Completion<SomeError>]() | ||
|
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| cancellable = intSubject | ||
| .prefix( | ||
| while: { $0 % 2 == 0 }, | ||
| behavior: .inclusive | ||
| ) | ||
| .sink( | ||
| receiveCompletion: { completions.append($0) }, | ||
| receiveValue: { values.append($0) } | ||
| ) | ||
|
|
||
| [0, 2, 4, 5] | ||
| .forEach(intSubject.send) | ||
|
|
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| intSubject.send(completion: .failure(.init())) | ||
|
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| XCTAssertEqual(values, [0, 2, 4, 5]) | ||
| XCTAssertEqual(completions, [.finished]) | ||
| } | ||
|
|
||
| func testInclusiveValueEventsWithErrorBeforeStop() { | ||
| let intSubject = PassthroughSubject<Int, SomeError>() | ||
|
|
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| var values = [Int]() | ||
| var completions = [Subscribers.Completion<SomeError>]() | ||
|
|
||
| cancellable = intSubject | ||
| .prefix( | ||
| while: { $0 % 2 == 0 }, | ||
| behavior: .inclusive | ||
| ) | ||
| .sink( | ||
| receiveCompletion: { completions.append($0) }, | ||
| receiveValue: { values.append($0) } | ||
| ) | ||
|
|
||
| [0, 2, 4] | ||
| .forEach(intSubject.send) | ||
|
|
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| intSubject.send(completion: .failure(.init())) | ||
|
|
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| XCTAssertEqual(values, [0, 2, 4]) | ||
| XCTAssertEqual(completions, [.failure(.init())]) | ||
| } | ||
|
|
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| func testInclusiveEarlyCompletion() { | ||
| let intSubject = PassthroughSubject<Int, SomeError>() | ||
|
|
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| var values = [Int]() | ||
| var completions = [Subscribers.Completion<SomeError>]() | ||
|
|
||
| cancellable = intSubject | ||
| .prefix( | ||
| while: { $0 % 2 == 0 }, | ||
| behavior: .inclusive | ||
| ) | ||
| .sink( | ||
| receiveCompletion: { completions.append($0) }, | ||
| receiveValue: { values.append($0) } | ||
| ) | ||
|
|
||
| [0, 2, 4] | ||
| .forEach(intSubject.send) | ||
|
|
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| intSubject.send(completion: .finished) | ||
|
|
||
| XCTAssertEqual(values, [0, 2, 4]) | ||
| XCTAssertEqual(completions, [.finished]) | ||
| } | ||
| } | ||
| #endif |