BufferedReader, but better

PushbackBufferedStream.scala

import java.io

import collection.mutable

class PushbackBufferedStream(in: io.InputStream, lineSize: Int = 30, bufSize: Int = 4096)
		extends io.PushbackInputStream(in, bufSize) {
	def readLine(): String = {
		val read_buf = new Array[Byte](bufSize)
		val line_buf = new mutable.ArrayBuffer[Byte](lineSize * 2)
		def loop(sz: Int): Unit = {
			val r = read(read_buf, 0, sz)
			val buf = read_buf.slice(0, r)
			var index = buf.indexOf('\n')
			if (index == -1) {
				line_buf ++= buf
				return loop(bufSize)
			}
			if (index == 0)
				return ()
			line_buf ++= buf.slice(0, index)
			// +1 to skip '\n'
			unread(buf, index + 1, r - (index + 1))
		}
		loop(if (pos == bufSize) bufSize else bufSize - pos)
		if (line_buf.size == 0)
			return ""
		var upto = line_buf.size-1
		if (line_buf(upto) != '\r')
			upto += 1
		return new String(line_buf.slice(0, upto).toArray)
	}
}