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Made the code leaner, and removed a few unnecessary self references. 

Signed-off-by: Adam Rocska <adam.rocska@adams.solutions>
This commit is contained in:
Adam Rocska 2020-05-01 14:51:09 +02:00
parent 379b3d576c
commit 322234151a
1 changed files with 17 additions and 22 deletions
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39
Sources/MaxMindDBReader/DataExtensions/IndexOfData.swift
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@ -5,25 +5,25 @@ extension Data {
fileprivate func boyerMoore(data: Data, from: Index) -> Index? {
let patternLength = data.count
precondition(patternLength > 0, "Pattern can't be empty.")
precondition(self.count >= patternLength, "Pattern can't be >= than the Data to search in.")
precondition(self.indices.contains(from), "Index from which to start the lookup must be contained in the Data.")
precondition(count >= patternLength, "Pattern can't be >= than the Data to search in.")
precondition(indices.contains(from), "Index from which to start the lookup must be contained in the Data.")
var skipTable = [UInt8: Int]()
for (i, byte) in data.enumerated() {
skipTable[byte] = patternLength - i - 1
}
let lastIndexOfSelf = self.endIndex
let lastIndexOfSelf = endIndex
let lastIndexOfData = data.index(before: data.endIndex)
let lastByteOfData = data.last
var i = self.index(from, offsetBy: patternLength - 1, limitedBy: lastIndexOfSelf) ?? lastIndexOfSelf
var i = index(from, offsetBy: patternLength - 1, limitedBy: lastIndexOfSelf) ?? lastIndexOfSelf
func reverseMatch() -> Index? {
var dataIndex = lastIndexOfData
var selfIndex = i
while dataIndex > data.startIndex {
selfIndex = self.index(before: selfIndex)
dataIndex = self.index(before: dataIndex)
selfIndex = index(before: selfIndex)
dataIndex = index(before: dataIndex)
if self[selfIndex] != data[dataIndex] { return nil }
}
return selfIndex
@ -36,9 +36,9 @@ extension Data {
if let foundIndex = reverseMatch() {
return foundIndex
}
i = self.index(after: i)
i = index(after: i)
} else {
i = self.index(
i = index(
i,
offsetBy: skipTable[byte] ?? patternLength,
limitedBy: lastIndexOfSelf
@ -49,7 +49,7 @@ extension Data {
}
func index(of data: Data) -> Index? {
return boyerMoore(data: data, from: self.startIndex)
return boyerMoore(data: data, from: startIndex)
}
func index(of data: Data, from: Index) -> Index? {
@ -57,23 +57,18 @@ extension Data {
}
func lastIndex(of data: Data) -> Index? {
return lastIndex(of: data, from: self.startIndex)
return lastIndex(of: data, from: startIndex)
}
func lastIndex(of data: Data, from: Index) -> Index? {
var lastIndexOfData: Index? = from
while lastIndexOfData != nil {
let upcomingIndex = self.index(after: lastIndexOfData!)
if !self.indices.contains(upcomingIndex) { return lastIndexOfData == from ? nil : lastIndexOfData }
guard let currentIndexOfData = index(
of: data,
from: upcomingIndex
) else {
break
}
lastIndexOfData = currentIndexOfData
var last: Index? = from
while last != nil {
let next = index(after: last!)
if !indices.contains(next) { break }
guard let current = index(of: data, from: next) else { break }
last = current
}
return lastIndexOfData == from ? nil : lastIndexOfData
return last == from ? nil : last
}
}