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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2023 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
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
extension BidirectionalCollection where Index == String.Index {
internal func _alignIndex(roundingDown i: Index) -> Index {
index(i, offsetBy: 0)
}
internal func _alignIndex(roundingUp i: Index) -> Index {
let truncated = _alignIndex(roundingDown: i)
guard i > truncated && truncated < endIndex else { return truncated }
return index(after: truncated)
}
internal func _boundaryAlignedRange(_ r: some RangeExpression<Index>) -> Range<Index> {
let range = r.relative(to: self)
return _alignIndex(roundingDown: range.lowerBound)..<_alignIndex(roundingUp: range.upperBound)
}
internal func _checkRange(_ r: Range<Index>) -> Range<Index>? {
guard r.lowerBound >= startIndex, r.upperBound <= endIndex else {
return nil
}
return r
}
}
extension BidirectionalCollection {
func _trimmingCharacters(while predicate: (Element) -> Bool) -> SubSequence {
var idx = startIndex
while idx < endIndex && predicate(self[idx]) {
formIndex(after: &idx)
}
let startOfNonTrimmedRange = idx // Points at the first char not in the set
guard startOfNonTrimmedRange != endIndex else {
return self[endIndex...]
}
let beforeEnd = index(before: endIndex)
guard startOfNonTrimmedRange < beforeEnd else {
return self[startOfNonTrimmedRange ..< endIndex]
}
var backIdx = beforeEnd
// No need to bound-check because we've already trimmed from the beginning, so we'd definitely break off of this loop before `backIdx` rewinds before `startIndex`
while predicate(self[backIdx]) {
formIndex(before: &backIdx)
}
return self[startOfNonTrimmedRange ... backIdx]
}
// Equal to calling `index(&idx, offsetBy: -other.count)` with just one loop
func _index<S: BidirectionalCollection>(_ index: Index, backwardsOffsetByCountOf other: S) -> Index? {
var idx = index
var otherIdx = other.endIndex
while otherIdx > other.startIndex {
guard idx > startIndex else {
// other.count > self.count: bail
return nil
}
other.formIndex(before: &otherIdx)
formIndex(before: &idx)
}
return idx
}
package func _range<S: BidirectionalCollection>(of other: S, anchored: Bool, backwards: Bool) -> Range<Index>? where S.Element == Element, Element : Equatable {
var result: Range<Index>? = nil
var fromLoc: Index
var toLoc: Index
if backwards {
guard let idx = _index(endIndex, backwardsOffsetByCountOf: other) else {
// other.count > string.count: bail
return nil
}
fromLoc = idx
toLoc = anchored ? fromLoc : startIndex
} else {
fromLoc = startIndex
if anchored {
toLoc = fromLoc
} else {
guard let idx = _index(endIndex, backwardsOffsetByCountOf: other) else {
return nil
}
toLoc = idx
}
}
let delta = fromLoc <= toLoc ? 1 : -1
while true {
var str1Index = fromLoc
var str2Index = other.startIndex
while str2Index < other.endIndex && str1Index < endIndex {
if self[str1Index] != other[str2Index] {
break
}
formIndex(after: &str1Index)
other.formIndex(after: &str2Index)
}
if str2Index == other.endIndex {
result = fromLoc..<str1Index
break
}
if fromLoc == toLoc {
break
}
formIndex(&fromLoc, offsetBy: delta)
}
return result
}
}
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