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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
//
//===----------------------------------------------------------------------===//
/// A collection searcher that naively searches the input by repeatedly trying to consume it using the underlying consumer.
struct ConsumerSearcher<Consumer: CollectionConsumer> {
let consumer: Consumer
}
extension ConsumerSearcher: StatelessCollectionSearcher {
typealias Searched = Consumer.Consumed
func search(
_ searched: Searched,
in range: Range<Searched.Index>
) -> Range<Searched.Index>? {
var start = range.lowerBound
while true {
if let end = consumer.consuming(searched, in: start..<range.upperBound) {
return start..<end
} else if start == range.upperBound {
return nil
} else {
searched.formIndex(after: &start)
}
}
}
}
extension ConsumerSearcher: BackwardCollectionSearcher,
BackwardStatelessCollectionSearcher
where Consumer: BidirectionalCollectionConsumer
{
typealias BackwardSearched = Consumer.Consumed
func searchBack(
_ searched: BackwardSearched,
in range: Range<Searched.Index>
) -> Range<Searched.Index>? {
var end = range.upperBound
while true {
if let start = consumer.consumingBack(
searched, in: range.lowerBound..<end) {
return start..<end
} else if end == searched.startIndex {
return nil
} else {
searched.formIndex(before: &end)
}
}
}
}
extension ConsumerSearcher: MatchingCollectionSearcher,
MatchingStatelessCollectionSearcher
where Consumer: MatchingCollectionConsumer
{
typealias Match = Consumer.Match
func matchingSearch(
_ searched: Searched,
in range: Range<Searched.Index>
) -> (range: Range<Searched.Index>, match: Consumer.Match)? {
var start = range.lowerBound
while true {
if let (end, value) = consumer.matchingConsuming(
searched,
in: start..<range.upperBound
) {
return (start..<end, value)
} else if start == range.upperBound {
return nil
} else {
searched.formIndex(after: &start)
}
}
}
}
extension ConsumerSearcher: BackwardMatchingCollectionSearcher,
BackwardMatchingStatelessCollectionSearcher
where Consumer: BidirectionalMatchingCollectionConsumer
{
typealias Match = Consumer.Match
func matchingSearchBack(
_ searched: BackwardSearched,
in range: Range<Searched.Index>
) -> (range: Range<Searched.Index>, match: Match)? {
var end = range.upperBound
while true {
if let (start, value) = consumer.matchingConsumingBack(
searched, in: range.lowerBound..<end) {
return (start..<end, value)
} else if end == searched.startIndex {
return nil
} else {
searched.formIndex(before: &end)
}
}
}
}
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