mirror of
https://github.com/google/promises
synced 2026-11-11 22:45:59 +05:45
36 lines
1.3 KiB
Swift
36 lines
1.3 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 Dispatch
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public extension Promise {
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/// Validates a fulfilled value or rejects the value if it can not be validated.
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/// - parameters:
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/// - queue: A queue to dispatch on.
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/// - predicate: An expression to validate.
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/// - returns: A new pending promise that gets either resolved with same resolution as `self` or
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/// rejected with `PromiseError.validationFailure` error.
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@discardableResult
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public func validate(
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on queue: DispatchQueue = .promises,
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_ predicate: @escaping (Value) -> Bool
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) -> Promise {
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return then { (value: Value) -> Value in
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guard predicate(value) else { throw PromiseError.validationFailure }
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return value
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}
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}
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}
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