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[Foundation] DataProtocol: Reimplement firstRange(of:in:)/lastRange(of:in:) to fix SR-10689.

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Cherry-pick from https://github.com/apple/swift-corelibs-foundation/pull/2499
This commit is contained in:
YOCKOW
2019-09-02 13:31:23 +09:00
parent bb1052ca3e
commit 1f32e2d957
1 changed files with 37 additions and 41 deletions
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78
stdlib/public/Darwin/Foundation/DataProtocol.swift
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@@ -142,60 +142,56 @@ extension DataProtocol {
return self.copyBytes(to: UnsafeMutableRawBufferPointer(start: ptr.baseAddress, count: ptr.count * MemoryLayout<DestinationType>.stride), from: range)
}
private func matches<D: DataProtocol>(_ data: D, from index: Index) -> Bool {
var haystackIndex = index
var needleIndex = data.startIndex
while true {
guard self[haystackIndex] == data[needleIndex] else { return false }
haystackIndex = self.index(after: haystackIndex)
needleIndex = data.index(after: needleIndex)
if needleIndex == data.endIndex {
// i.e. needle is found.
return true
} else if haystackIndex == endIndex {
return false
}
}
}
public func firstRange<D: DataProtocol, R: RangeExpression>(of data: D, in range: R) -> Range<Index>? where R.Bound == Index {
let r = range.relative(to: self)
let rangeCount = distance(from: r.lowerBound, to: r.upperBound)
if rangeCount < data.count {
let length = data.count
if length == 0 || length > distance(from: r.lowerBound, to: r.upperBound) {
return nil
}
var haystackIndex = r.lowerBound
let haystackEnd = index(r.upperBound, offsetBy: -data.count)
while haystackIndex < haystackEnd {
var compareIndex = haystackIndex
var needleIndex = data.startIndex
let needleEnd = data.endIndex
var matched = true
while compareIndex < haystackEnd && needleIndex < needleEnd {
if self[compareIndex] != data[needleIndex] {
matched = false
break
}
needleIndex = data.index(after: needleIndex)
compareIndex = index(after: compareIndex)
var position = r.lowerBound
while position < r.upperBound && distance(from: position, to: r.upperBound) >= length {
if matches(data, from: position) {
return position..<index(position, offsetBy: length)
}
if matched {
return haystackIndex..<compareIndex
}
haystackIndex = index(after: haystackIndex)
position = index(after: position)
}
return nil
}
public func lastRange<D: DataProtocol, R: RangeExpression>(of data: D, in range: R) -> Range<Index>? where R.Bound == Index {
let r = range.relative(to: self)
let rangeCount = distance(from: r.lowerBound, to: r.upperBound)
if rangeCount < data.count {
let length = data.count
if length == 0 || length > distance(from: r.lowerBound, to: r.upperBound) {
return nil
}
var haystackIndex = r.upperBound
let haystackStart = index(r.lowerBound, offsetBy: data.count)
while haystackIndex > haystackStart {
var compareIndex = haystackIndex
var needleIndex = data.endIndex
let needleStart = data.startIndex
var matched = true
while compareIndex > haystackStart && needleIndex > needleStart {
if self[compareIndex] != data[needleIndex] {
matched = false
break
}
needleIndex = data.index(before: needleIndex)
compareIndex = index(before: compareIndex)
var position = index(r.upperBound, offsetBy: -length)
while position >= r.lowerBound {
if matches(data, from: position) {
return position..<index(position, offsetBy: length)
}
if matched {
return compareIndex..<haystackIndex
}
haystackIndex = index(before: haystackIndex)
position = index(before: position)
}
return nil
}