Scala Scanner

Scanner.scala

import java.io._
import java.nio.file.{Files, Path}
import java.util.StringTokenizer

import scala.io.Codec

/**
 * Scala implementation of a faster java.util.Scanner
 * See: http://codeforces.com/blog/entry/21125
 * All next methods throw NoSuchElementException when !hasNext
 */
class Scanner(reader: LineNumberReader) extends Iterator[String] with AutoCloseable {
  def this(reader: BufferedReader) = this(new LineNumberReader(reader))
  def this(reader: Reader) = this(new BufferedReader(reader))
  def this(inputStream: InputStream)(implicit codec: Codec) = this(new InputStreamReader(inputStream, codec.charSet))
  def this(path: Path)(implicit codec: Codec) = this(Files.newBufferedReader(path, codec.charSet))
  def this(file: File)(implicit codec: Codec) = this(file.toPath)(codec)
  def this(str: String) = this(new StringReader(str))

  val lines = Iterator.continually(reader.readLine()).takeWhile(_ != null)

  private[this] val tokenizers = lines.map(new StringTokenizer(_)).filter(_.hasMoreTokens)
  private[this] var current: Option[StringTokenizer] = None

  @inline private[this] def tokenizer(): Option[StringTokenizer] = current.find(_.hasMoreTokens) orElse {
    current = if (tokenizers.hasNext) Some(tokenizers.next()) else None
    current
  }

  /**
   * Unlike Java's scanner which returns till end of current line, this actually returns the next line
   * @see tillEndOfLine() if you want the Java behaviour
   */
  def nextLine(): String = {
    current = None   // reset
    lines.next()
  }
  def lineNumber(): Int = reader.getLineNumber
  def till(delim: String): String = tokenizer().get.nextToken(delim)
  def tillEndOfLine() = till("\n\r")
  def nextString(): String = next()
  def nextChar(): Char = next().ensuring(_.length == 1).head
  def nextBoolean(): Boolean = next().toBoolean
  def nextByte(radix: Int = 10): Byte = java.lang.Byte.parseByte(next(), radix)
  def nextShort(radix: Int = 10): Short = java.lang.Short.parseShort(next(), radix)
  def nextInt(radix: Int = 10): Int = java.lang.Integer.parseInt(next(), radix)
  def nextLong(radix: Int = 10): Long = java.lang.Long.parseLong(next(), radix)
  def nextBigInt(radix: Int = 10): BigInt = BigInt(next(), radix)
  def nextFloat(): Float = next().toFloat
  def nextDouble(): Double = next().toDouble
  def nextBigDecimal(): BigDecimal = BigDecimal(next())
  override def next() = tokenizer().get.nextToken()
  override def hasNext = tokenizer().nonEmpty
  override def close() = reader.close()
}