XCActivityLogTokenyizer.swift

//
//  XCActivityLogTokenyizer.swift
//  XCActivityLogParser
//
//  Created by Vorobyov Semyon on 15.07.2023.
//

import Foundation

// Let's take a simple tokenizer for converting the SLF0 format into tokens.
// 
// https://medium.com/@vorobyov.semyon.ana/lets-parse-xcode-logs-dea4e5fb1de4
// https://habr.com/ru/articles/749554/

enum Token {
    case integer(Int)
    case double(Double)
    case null
    case string(String)
    case array(Int)
    case class_name(String)
    case class_instance(Int)
}

guard
    let fileHandle = FileHandle(forReadingAtPath: "test_log")
else { fatalError("Can't open file") }

// Skip SLF0 header
_ = try? fileHandle.read(upToCount: 4)

var tokens = [Token]()

var current_side_value = ""
while let data = try? fileHandle.read(upToCount: 1), let char = String(data: data, encoding: .ascii) {
    switch char {
    case "#":
        guard let value = Int(current_side_value) else { break }
        tokens.append(.integer(value))
        current_side_value = ""
    case "^":
        guard let value = UInt64(current_side_value, radix: 16) else { break }
        let double =  Double(bitPattern: value.byteSwapped)
        tokens.append(.double(double))
        current_side_value = ""
    case "-":
        tokens.append(.null)
        current_side_value = ""
    case "\"":
        guard
            let count = Int(current_side_value),
            let stringData = try? fileHandle.read(upToCount: count), let value = String(data: stringData, encoding: .ascii)
        else {
            tokens.append(.string(""))
            current_side_value = ""
            break
        }
        tokens.append(.string(value))
        current_side_value = ""
    case "(":
        guard let value = Int(current_side_value) else { break }
        tokens.append(.array(value))
        current_side_value = ""
    case "%":
        guard
            let count = Int(current_side_value),
            let stringData = try? fileHandle.read(upToCount: count), let value = String(data: stringData, encoding: .ascii)
        else { break }
        tokens.append(.class_name(value))
        current_side_value = ""
    case "@":
        guard let value = Int(current_side_value) else { break }
        tokens.append(.class_instance(value))
        current_side_value = ""
    default:
        current_side_value.append(char)
    }
    
}

fileHandle.closeFile()

tokens.forEach { token in
    print(token)
}