69 lines
2.9 KiB
Swift
69 lines
2.9 KiB
Swift
//
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// Copyright (c) 2017 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 RxSwift
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public extension Sequence {
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/// Method which asynchronous transforms sequence using given transform closure
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/// and given number of concurrent operations
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///
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/// - Parameters:
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/// - concurrentOperationCount: Number of concurrent operations
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/// - qos: Target global dispatch queue, by quality of service class.
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/// - transform: Transform closure
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/// - Returns: Observable of array which contains transform return type
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func concurrentRxMap<R>(concurrentOperationCount: Int = ProcessInfo.processInfo.activeProcessorCount,
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qos: DispatchQoS = .default,
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transform: @escaping ((Iterator.Element) throws -> R)) -> Observable<[R]> {
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let operationsCount = Swift.max(1, concurrentOperationCount)
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let array = Array(self)
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let step = Int(ceil(Double(array.count) / Double(operationsCount)))
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let numberOfSlices = Int(ceil(Double(array.count) / Double(step)))
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let indexedRanges: [(idx: Int, range: CountableRange<Int>)] = (0..<numberOfSlices).map {
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let start = $0 * step
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let end = Swift.min(start + step, array.count)
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return ($0, start..<end)
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}
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let scheduler = ConcurrentDispatchQueueScheduler(qos: qos)
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return Observable.from(indexedRanges)
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.flatMap { indexedRange -> Observable<(idx: Int, results: [R])> in
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Observable.just(indexedRange)
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.observe(on: scheduler)
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.map { (idx: $0.idx, results: try array[$0.range].map(transform)) }
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}
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.toArray()
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.map { array -> [R] in
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array.sorted { $0.idx < $1.idx }
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.flatMap { $0.results }
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}
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.asObservable()
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}
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}
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