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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Async Algorithms open source project
//
// Copyright (c) 2022 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
extension AsyncSequence {
/// Returns a new `AsyncSequence` that iterates over every non-nil element from the
/// original `AsyncSequence`.
///
/// Produces the same result as `c.compactMap { $0 }`.
///
/// - Returns: An `AsyncSequence` where the element is the unwrapped original
/// element and iterates over every non-nil element from the original
/// `AsyncSequence`.
@inlinable
public func compacted<Unwrapped>() -> AsyncCompactedSequence<Self, Unwrapped>
where Element == Unwrapped? {
AsyncCompactedSequence(self)
}
}
/// An `AsyncSequence` that iterates over every non-nil element from the original
/// `AsyncSequence`.
@frozen
public struct AsyncCompactedSequence<Base: AsyncSequence, Element>: AsyncSequence
where Base.Element == Element? {
@usableFromInline
let base: Base
@inlinable
init(_ base: Base) {
self.base = base
}
/// The iterator for an `AsyncCompactedSequence` instance.
@frozen
public struct Iterator: AsyncIteratorProtocol {
@usableFromInline
var base: Base.AsyncIterator
@inlinable
init(_ base: Base.AsyncIterator) {
self.base = base
}
@inlinable
public mutating func next() async rethrows -> Element? {
while let wrapped = try await base.next() {
guard let some = wrapped else { continue }
return some
}
return nil
}
}
@inlinable
public func makeAsyncIterator() -> Iterator {
Iterator(base.makeAsyncIterator())
}
}
extension AsyncCompactedSequence: Sendable where Base: Sendable, Base.Element: Sendable { }
@available(*, unavailable)
extension AsyncCompactedSequence.Iterator: Sendable { }
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