NSFileHandle Generator for for-loop

NSFileHandle+Generator

#!/usr/bin/env swift

import Foundation

public class _NSFileHandle_Generator: GeneratorType {
    private let fileHandle: NSFileHandle

    private var buffer = ""
    private var previousLine = ""
    private var newline: String?

    private init(fileHandle: NSFileHandle) {
        self.fileHandle = fileHandle
    }

    public func next() -> String? {
        if count(buffer) == 0 {
            if let nextString = fileHandle.availableString() {
                buffer = nextString
            } else {
                return nil
            }
        }

        if let range = buffer.rangeOfString("\n") {
            let line = buffer.substringWithRange(Range(start: buffer.startIndex,
                                                         end: range.startIndex))
            newline = previousLine + line
            buffer = buffer.substringWithRange(Range(start: advance(range.startIndex, 1),
                                                       end: buffer.endIndex))
        } else {
            previousLine = buffer
            buffer = ""
            return next()
        }

        return newline
    }
}

extension NSFileHandle: SequenceType {
    public func availableString() -> String? {
        let data: NSData = self.availableData
        if data.length == 0 {
            return nil
        }

        if let str = NSString(data: data, encoding: NSUTF8StringEncoding) {
            return str as String
        }

        return nil
    }

    public func generate() -> _NSFileHandle_Generator {
        return _NSFileHandle_Generator(fileHandle: self)
    }
}

func main(args: [String]) -> Int32 {
    let fileHandle = NSFileHandle(forReadingAtPath:args[1] as String)!
    for line in fileHandle {
        println(line)
    }

    return 0
}

let ret = main(Process.arguments)