mirror of
https://github.com/firebase/firebase-ios-sdk
synced 2026-11-09 22:36:01 +05:45
45 lines
1.5 KiB
Swift
45 lines
1.5 KiB
Swift
/*
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* Copyright 2026 Google LLC
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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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*/
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extension Sequence {
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/// The elements in order, keeping only the first with each `key`.
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func uniqued<Key: Hashable>(by key: (Element) -> Key) -> [Element] {
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var seen = Set<Key>()
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return filter { seen.insert(key($0)).inserted }
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}
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}
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extension Sequence where Element: Hashable {
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/// The elements in order, keeping only the first of each.
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func uniqued() -> [Element] {
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uniqued(by: { $0 })
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}
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}
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extension Sequence where Element: Sequence, Element.Element: Equatable {
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/// Returns a flat array containing the unique elements of the nested sequences in order.
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///
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/// Only needs `Equatable`, unlike `uniqued()`: privacy manifests union `NSDictionary` entries,
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/// which should compare by value without relying on how they hash.
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func union() -> [Element.Element] {
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joined().reduce(into: []) { result, element in
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if !result.contains(element) {
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result.append(element)
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}
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}
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}
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}
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