89 lines
3.3 KiB
Swift
89 lines
3.3 KiB
Swift
//
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// Copyright (c) 2023 Touch Instinct
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the Software), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED AS IS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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//
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import Foundation
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private final class FlatMapAsyncOperation<Output, Failure: Error>: AsyncOperation<Output, Failure> {
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private var dependencyObservation: NSKeyValueObservation?
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private var flatMapObservation: NSKeyValueObservation?
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private let dependency: Operation
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private var flatMapDependency: AsyncOperation<Output, Failure>?
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init<DependencyOutput, DependencyFailure>(dependency: AsyncOperation<DependencyOutput, DependencyFailure>,
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flatMapOutput: ((DependencyOutput) -> AsyncOperation<Output, Failure>)?,
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flatMapFailure: ((DependencyFailure) -> AsyncOperation<Output, Failure>)?)
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where DependencyFailure: Error {
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self.dependency = dependency
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super.init()
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dependency.cancelOnCancellation(of: self)
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dependencyObservation = dependency.subscribe { [weak self] in
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switch $0 {
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case let .success(success):
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self?.flatMapDependency = flatMapOutput?(success)
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case let .failure(error):
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self?.flatMapDependency = flatMapFailure?(error)
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}
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if let self {
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self.flatMapDependency?.cancelOnCancellation(of: self)
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}
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self?.flatMapObservation = self?.flatMapDependency?.subscribe {
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self?.handle(result: $0)
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}
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self?.flatMapDependency?.start()
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}
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state = .isReady
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}
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override func start() {
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state = .isExecuting
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dependency.start()
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}
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}
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public extension AsyncOperation {
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func flatMap<NewOutput>(_ transform: @escaping (Output) -> AsyncOperation<NewOutput, Failure>)
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-> AsyncOperation<NewOutput, Failure> {
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FlatMapAsyncOperation(dependency: self,
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flatMapOutput: transform,
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flatMapFailure: { .just(failure: $0) })
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}
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func flatMapError<NewFailure>(_ transform: @escaping (Failure) -> AsyncOperation<Output, NewFailure>)
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-> AsyncOperation<Output, NewFailure> {
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FlatMapAsyncOperation(dependency: self,
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flatMapOutput: { .just(success: $0) },
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flatMapFailure: transform)
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}
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}
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