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//
// LogEntryParser.swift
// MullvadVPN
//
// Created by pronebird on 18/08/2020.
// Copyright © 2020 Mullvad VPN AB. All rights reserved.
//
#if DEBUG
import Foundation
import Logging
struct ParsedLogEntry {
let timestamp: Date
let level: Logger.Level
let module: String
let message: String
}
class LogEntryParser {
/// Date formatter used for decoding the timestamp
private let dateFormatter = CustomFormatLogHandler.makeDateFormatter()
/// Parse a log entry in the following format:
/// [<DATE>][<MODULE>][<LOG_LEVEL>] <MESSAGE>
func parse(_ str: String) -> ParsedLogEntry? {
let ranges = Self.stringRangesWithinSquareBrackets(string: str, maxResults: 3)
guard ranges.count == 3 else {
return nil
}
let strings = ranges.map { String(str[$0]) }
guard let timestamp = dateFormatter.date(from: strings[0]),
let logLevel = Logger.Level(rawValue: strings[2]) else {
return nil
}
// Extract the log message following the log level
let startIndex = str.index(ranges.last!.upperBound, offsetBy: 1, limitedBy: str.endIndex)
let message = startIndex.map({ (startIndex) -> String in
return str[startIndex..<str.endIndex].trimmingCharacters(in: .whitespaces)
}) ?? ""
return ParsedLogEntry(
timestamp: timestamp,
level: logLevel,
module: strings[1],
message: message
)
}
/// Find consecutive ranges of strings within square brackets.
private static func stringRangesWithinSquareBrackets(string: String, maxResults: Int) -> [Range<String.Index>] {
var results = [Range<String.Index>]()
var maybeStartIndex: String.Index?
guard maxResults > 0 else { return results }
loop: for (offset, char) in string.enumerated() {
switch char {
case "[":
if maybeStartIndex == nil {
maybeStartIndex = string.index(string.startIndex, offsetBy: offset + 1, limitedBy: string.endIndex)
} else {
// out of order
break loop
}
case "]":
if let startIndex = maybeStartIndex {
maybeStartIndex = nil
let endIndex = string.index(string.startIndex, offsetBy: offset)
results.append((startIndex..<endIndex))
if results.count >= maxResults {
// done
break loop
}
} else {
// out of order
break loop
}
default:
continue
}
}
return results
}
}
#endif
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