46 lines
2.0 KiB
Swift
46 lines
2.0 KiB
Swift
//
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// Copyright (c) 2022 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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open class DependendAsyncOperation<Output, Failure: Error>: AsyncOperation<Output, Failure> {
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public var dependencyObservation: NSKeyValueObservation?
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public init<DependencyOutput, DependencyFailure: Error>(dependency: AsyncOperation<DependencyOutput, DependencyFailure>,
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resultObservation: @escaping (Result<DependencyOutput, DependencyFailure>) -> Result<Output, Failure>) {
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super.init()
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cancelOnCancellation(of: dependency)
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dependencyObservation = dependency.subscribe { [weak self] in
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self?.result = resultObservation($0)
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self?.state = .isReady
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}
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addDependency(dependency) // keeps strong reference to dependency as well
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state = nil // prevent start of current operation if result is not yet provided by dependency
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}
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}
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