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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2021-2022 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
//
//===----------------------------------------------------------------------===//
protocol CollectionConsumer {
associatedtype Consumed: Collection
func consuming(
_ consumed: Consumed,
in range: Range<Consumed.Index>
) -> Consumed.Index?
}
extension CollectionConsumer {
func consuming(_ consumed: Consumed) -> Consumed.Index? {
consuming(consumed, in: consumed.startIndex..<consumed.endIndex)
}
// TODO: `@discardableResult`?
/// Returns `true` if the consume was successful.
func consume(_ consumed: inout Consumed) -> Bool
where Consumed.SubSequence == Consumed
{
guard let index = consuming(consumed) else { return false }
consumed = consumed[index...]
return true
}
}
// MARK: Consuming from the back
protocol BidirectionalCollectionConsumer: CollectionConsumer
where Consumed: BidirectionalCollection
{
func consumingBack(
_ consumed: Consumed,
in range: Range<Consumed.Index>
) -> Consumed.Index?
}
extension BidirectionalCollectionConsumer {
func consumingBack(_ consumed: Consumed) -> Consumed.Index? {
consumingBack(consumed, in: consumed.startIndex..<consumed.endIndex)
}
func consumeBack(_ consumed: inout Consumed) -> Bool
where Consumed.SubSequence == Consumed
{
guard let index = consumingBack(consumed) else { return false }
consumed = consumed[..<index]
return true
}
}
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