38 lines
1.5 KiB
Swift
38 lines
1.5 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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typealias Catch = (Error) -> Void
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/// Creates a pending promise which eventually gets resolved with same resolution as `self`.
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/// If `self` is rejected, then `reject` block is executed asynchronously on the given queue.
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/// - parameters:
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/// - queue: A queue to invoke the `reject` block on.
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/// - reject: A block to handle the error that `self` was rejected with.
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/// - returns: A new pending promise.
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@discardableResult
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func `catch`(on queue: DispatchQueue = .promises, _ reject: @escaping Catch) -> Promise {
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let promise = Promise(objCPromise.__onQueue(queue, catch: {
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// Convert `NSError` to `PromiseError`, if applicable.
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let error = PromiseError($0) ?? $0
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return reject(error as NSError)
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}))
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// Keep Swift wrapper alive for chained promise until `ObjCPromise` counterpart is resolved.
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objCPromise.__addPendingObject(promise)
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return promise
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}
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}
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