62 lines
2.3 KiB
Swift
62 lines
2.3 KiB
Swift
// Copyright 2018 Google Inc. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at:
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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import Foundation
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public extension Promise {
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// swiftlint:disable:next type_name
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typealias Do<T> = () throws -> T
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/// Creates a pending promise to be resolved with the return value of `work` block which is
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/// executed asynchronously on the given `queue`.
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/// - parameters:
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/// - queue: A queue to invoke the `work` block on.
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/// - work: A block that returns a value used to resolve the new promise.
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convenience init<T>(on queue: DispatchQueue = .promises, _ work: @escaping Do<T>) {
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let objCPromise = ObjCPromise<AnyObject>.__onQueue(queue) {
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do {
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let resolution = try work()
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return type(of: resolution) is NSError.Type
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? resolution as! NSError : Promise<T>.asAnyObject(resolution)
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} catch let error {
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return error as NSError
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}
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}
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self.init(objCPromise)
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// Keep Swift wrapper alive for chained promise until `ObjCPromise` counterpart is resolved.
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objCPromise.__addPendingObject(self)
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}
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/// Creates a pending promise to be resolved with the same resolution as the promise returned from
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/// `work` block which is executed asynchronously on the given `queue`.
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/// - parameters:
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/// - queue: A queue to invoke the `work` block on.
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/// - work: A block that returns a promise used to resolve the new promise.
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convenience init<T>(
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on queue: DispatchQueue = .promises,
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_ work: @escaping Do<Promise<T>>
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) {
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let objCPromise = ObjCPromise<AnyObject>.__onQueue(queue) {
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do {
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return try work().objCPromise
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} catch let error {
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return error as NSError
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}
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}
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self.init(objCPromise)
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// Keep Swift wrapper alive for chained promise until `ObjCPromise` counterpart is resolved.
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objCPromise.__addPendingObject(self)
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}
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}
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