Reader.scala

import scala.util.parsing.input.Reader
import scala.util.parsing.input.CharArrayReader.EofCh
import scala.util.parsing.input.Position

case class ByteOffsetPosition(offset: Int) extends Position {
  final val line = 1 
  def column = offset + 1
  def lineContents: String = ""
} 

class ByteReader (val bytes: Array[Byte], override val offset: Int = 0) extends Reader[Byte] {
  def this(reader: Reader[_]) = this(reader.source.toString.getBytes, 0)
  def this(bytes: Seq[Byte]) = this(bytes.toArray, 0)
  def this(str: String) = this(str.getBytes, 0)
  																							
  def first: Byte = if (offset < bytes.length) bytes(offset) else EofCh.toByte
  def rest: ByteReader = if (offset < bytes.length) new ByteReader(bytes, offset + 1) else this
  def pos: Position = ByteOffsetPosition(offset)
  def atEnd = offset >= bytes.length
 
  def byteAt(n: Int) = bytes(n)
  def length = bytes.length - offset
 
  override def drop(n: Int): ByteReader = new ByteReader(bytes, offset + n)
  def take(n: Int): Seq[Byte] = bytes drop offset take n
 
  override def toString = "ByteReader(%d / %d)".format(offset, bytes.length)
}