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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,112 @@ | ||
| // | ||
| // WithUnretained.swift | ||
| // CombineExt | ||
| // | ||
| // Created by Robert on 01/09/2021. | ||
| // Copyright © 2020 Combine Community. All rights reserved. | ||
| // | ||
|
|
||
| #if canImport(Combine) | ||
| import Combine | ||
|
|
||
| @available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *) | ||
| public extension Publisher { | ||
| /** | ||
| Provides an unretained, safe to use (i.e. not implicitly unwrapped), reference to an object along with the events published by the publisher. | ||
| In the case the provided object cannot be retained successfully, the publisher will complete. | ||
| - parameter obj: The object to provide an unretained reference on. | ||
| - parameter resultSelector: A function to combine the unretained referenced on `obj` and the value of the observable sequence. | ||
| - returns: A publisher that contains the result of `resultSelector` being called with an unretained reference on `obj` and the values of the upstream. | ||
| */ | ||
| func withUnretained<UnretainedObject: AnyObject, Output>(_ obj: UnretainedObject, resultSelector: @escaping (UnretainedObject, Self.Output) -> Output) -> Publishers.WithUnretained<UnretainedObject, Self, Output> { | ||
| Publishers.WithUnretained(unretainedObject: obj, upstream: self, resultSelector: resultSelector) | ||
| } | ||
|
|
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| /** | ||
| Provides an unretained, safe to use (i.e. not implicitly unwrapped), reference to an object along with the events published by the publisher. | ||
| In the case the provided object cannot be retained successfully, the publisher will complete. | ||
| - parameter obj: The object to provide an unretained reference on. | ||
| - returns: A publisher that publishes a sequence of tuples that contains both an unretained reference on `obj` and the values of the upstream. | ||
| */ | ||
| func withUnretained<UnretainedObject: AnyObject>(_ obj: UnretainedObject) -> Publishers.WithUnretained<UnretainedObject, Self, (UnretainedObject, Output)> { | ||
| Publishers.WithUnretained(unretainedObject: obj, upstream: self) { ($0, $1) } | ||
| } | ||
|
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| /// Attaches a subscriber with closure-based behavior. | ||
| /// | ||
| /// Use ``Publisher/sink(unretainedObject:receiveCompletion:receiveValue:)`` to observe values received by the publisher and process them using a closure you specify. | ||
| /// This method creates the subscriber and immediately requests an unlimited number of values, prior to returning the subscriber. | ||
| /// The return value should be held, otherwise the stream will be canceled. | ||
| /// | ||
| /// - parameter obj: The object to provide an unretained reference on. | ||
| /// - parameter receiveComplete: The closure to execute on completion. | ||
| /// - parameter receiveValue: The closure to execute on receipt of a value. | ||
| /// - Returns: A cancellable instance, which you use when you end assignment of the received value. Deallocation of the result will tear down the subscription stream. | ||
| func sink<UnretainedObject: AnyObject>(unretainedObject obj: UnretainedObject, receiveCompletion: @escaping ((Subscribers.Completion<Self.Failure>) -> Void), receiveValue: @escaping ((UnretainedObject, Self.Output) -> Void)) -> AnyCancellable { | ||
| withUnretained(obj) | ||
| .sink(receiveCompletion: receiveCompletion, receiveValue: receiveValue) | ||
| } | ||
| } | ||
|
|
||
| // MARK: - Publisher | ||
| @available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *) | ||
| public extension Publishers { | ||
| struct WithUnretained<UnretainedObject: AnyObject, Upstream: Publisher, Output>: Publisher { | ||
| public typealias Failure = Upstream.Failure | ||
|
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| private weak var unretainedObject: UnretainedObject? | ||
| private let upstream: Upstream | ||
| private let resultSelector: (UnretainedObject, Upstream.Output) -> Output | ||
|
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| public init(unretainedObject: UnretainedObject, upstream: Upstream, resultSelector: @escaping (UnretainedObject, Upstream.Output) -> Output) { | ||
| self.unretainedObject = unretainedObject | ||
| self.upstream = upstream | ||
| self.resultSelector = resultSelector | ||
| } | ||
|
|
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| public func receive<S: Combine.Subscriber>(subscriber: S) where Failure == S.Failure, Output == S.Input { | ||
| upstream.subscribe(Subscriber(unretainedObject: unretainedObject, downstream: subscriber, resultSelector: resultSelector)) | ||
| } | ||
| } | ||
| } | ||
|
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||
| // MARK: - Subscriber | ||
| @available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *) | ||
| private extension Publishers.WithUnretained { | ||
| class Subscriber<Downstream: Combine.Subscriber>: Combine.Subscriber where Downstream.Input == Output, Downstream.Failure == Failure { | ||
| typealias Input = Upstream.Output | ||
| typealias Failure = Downstream.Failure | ||
|
|
||
| private weak var unretainedObject: UnretainedObject? | ||
| private let downstream: Downstream | ||
| private let resultSelector: (UnretainedObject, Input) -> Output | ||
|
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| init(unretainedObject: UnretainedObject?, downstream: Downstream, resultSelector: @escaping (UnretainedObject, Input) -> Output) { | ||
| self.unretainedObject = unretainedObject | ||
| self.downstream = downstream | ||
| self.resultSelector = resultSelector | ||
| } | ||
|
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| func receive(subscription: Subscription) { | ||
| if unretainedObject == nil { return } | ||
| downstream.receive(subscription: subscription) | ||
| } | ||
|
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| func receive(_ input: Input) -> Subscribers.Demand { | ||
| guard let unretainedObject = unretainedObject else { return .none } | ||
| return downstream.receive(resultSelector(unretainedObject, input)) | ||
| } | ||
|
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| func receive(completion: Subscribers.Completion<Failure>) { | ||
| if unretainedObject == nil { | ||
| return downstream.receive(completion: .finished) | ||
| } | ||
| downstream.receive(completion: completion) | ||
| } | ||
| } | ||
| } | ||
| #endif |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,140 @@ | ||
| // | ||
| // WithUnretainedTests.swift | ||
| // CombineExtTests | ||
| // | ||
| // Created by Robert on 02/09/2021. | ||
| // | ||
|
|
||
| #if !os(watchOS) | ||
| import XCTest | ||
| import Foundation | ||
| import Combine | ||
| import CombineExt | ||
|
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| @available(OSX 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *) | ||
| final class WithUnretainedTests: XCTestCase { | ||
| fileprivate var testClass: TestClass! | ||
| var subscription: AnyCancellable? | ||
| var values: [String] = [] | ||
|
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| enum WithUnretainedTestsError: Swift.Error { | ||
| case someError | ||
| } | ||
|
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| override func setUp() { | ||
| super.setUp() | ||
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| testClass = TestClass() | ||
| values = [] | ||
| } | ||
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| override func tearDown() { | ||
| subscription?.cancel() | ||
| subscription = nil | ||
| } | ||
|
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| func testObjectAttached() { | ||
| let testClassId = testClass.id | ||
| var completed = false | ||
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| let correctValues = [ | ||
| "\(testClassId), 1", | ||
| "\(testClassId), 2", | ||
| "\(testClassId), 3", | ||
| "\(testClassId), 5", | ||
| "\(testClassId), 8" | ||
| ] | ||
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| let inputArr = [1, 2, 3, 5, 8] | ||
|
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| subscription = Publishers.Sequence<[Int], WithUnretainedTestsError>(sequence: inputArr) | ||
| .withUnretained(self.testClass) | ||
| .map { "\($0.id), \($1)" } | ||
| .sink(receiveCompletion: { _ in completed = true }, | ||
| receiveValue: { self.values.append($0) }) | ||
|
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| XCTAssertEqual(values, correctValues) | ||
| XCTAssertTrue(completed) | ||
| } | ||
|
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| func testObjectDeallocatesWithEmptyPublisher() { | ||
| subscription = Empty<Int, WithUnretainedTestsError>() | ||
| .withUnretained(self.testClass) | ||
| .sink(receiveCompletion: { _ in }, receiveValue: { _ in }) | ||
|
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| // Confirm the object can be deallocated | ||
| XCTAssertTrue(testClass != nil) | ||
| testClass = nil | ||
| XCTAssertTrue(testClass == nil) | ||
| } | ||
|
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| func testObjectDeallocates() { | ||
| let inputArr = [1, 2, 3, 5, 8] | ||
|
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| subscription = Publishers.Sequence<[Int], WithUnretainedTestsError>(sequence: inputArr) | ||
| .withUnretained(self.testClass) | ||
| .sink(receiveCompletion: { _ in }, receiveValue: { _ in }) | ||
|
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| // Confirm the object can be deallocated | ||
| XCTAssertTrue(testClass != nil) | ||
| testClass = nil | ||
| XCTAssertTrue(testClass == nil) | ||
| } | ||
|
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| func testObjectDeallocatesSequenceCompletes() { | ||
| let testClassId = testClass.id | ||
| var completed = false | ||
|
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| let correctValues = [ | ||
| "\(testClassId), 1", | ||
| "\(testClassId), 2", | ||
| "\(testClassId), 3" | ||
| ] | ||
|
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| let inputArr = [1, 2, 3] | ||
| subscription = Publishers.Sequence<[Int], WithUnretainedTestsError>(sequence: inputArr) | ||
| .withUnretained(self.testClass) | ||
| .handleEvents(receiveOutput: { _, value in | ||
| // Release the object in the middle of the sequence | ||
| // to confirm it properly terminates the sequence | ||
| if value == 3 { | ||
| self.testClass = nil | ||
| } | ||
| }) | ||
| .map { "\($0.id), \($1)" } | ||
| .sink(receiveCompletion: { _ in completed = true }, | ||
| receiveValue: { self.values.append($0) }) | ||
|
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| XCTAssertEqual(values, correctValues) | ||
| XCTAssertTrue(completed) | ||
| } | ||
|
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| func testResultsSelector() { | ||
| let testClassId = testClass.id | ||
| var completed = false | ||
|
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| let inputArr = [(1, "a"), (2, "b"), (3, "c"), (5, "d"), (8, "e")] | ||
|
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| let correctValues = [ | ||
| "\(testClassId), 1, a", | ||
| "\(testClassId), 2, b", | ||
| "\(testClassId), 3, c", | ||
| "\(testClassId), 5, d", | ||
| "\(testClassId), 8, e" | ||
| ] | ||
|
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| subscription = Publishers.Sequence<[(Int, String)], WithUnretainedTestsError>(sequence: inputArr) | ||
| .withUnretained(self.testClass) { ($0, $1.0, $1.1) } | ||
| .map { "\($0.id), \($1), \($2)" } | ||
| .sink(receiveCompletion: { _ in completed = true }, | ||
| receiveValue: { self.values.append($0) }) | ||
|
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| XCTAssertEqual(values, correctValues) | ||
| XCTAssertTrue(completed) | ||
| } | ||
| } | ||
|
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| private class TestClass { | ||
| let id: String = UUID().uuidString | ||
| } | ||
| #endif |