BitMap.scala

object BitMap {
  final val Bytes = Array( 128, 64, 32, 16, 8, 4, 2, 1 )

  def apply( bytes : Seq[Byte] ) : BitMap = new BitMap(bytes : _*)

}

/**
 *
 * Implements a bit map where you can check which bits are set and which are not.
 *
 * @param bytes
 */

class BitMap( bytes : Byte * ) extends IndexedSeq[(Int,Boolean)] {

  val length = bytes.length * 8

  /**
   *
   * Returns true if the bit at the given index is set, false if it is not.
   *
   * @param index the bit position, starts at 0
   * @return
   */

  def isSet( index : Int ) : Boolean = {
    val quotient = index / 8
    val remainder = index % 8

    (bytes(quotient) & BitMap.Bytes(remainder)) != 0
  }


  override def foreach[U](f: ((Int, Boolean)) => U) {
    var currentIndex = 0
    for ( byte <- bytes ) {
      var x = 0
      while ( x < BitMap.Bytes.length ) {
        f( currentIndex, (byte & BitMap.Bytes(x)) != 0 )
        x += 1
        currentIndex += 1
      }
    }
  }

  def apply(idx: Int): (Int, Boolean) = (idx,this.isSet(idx))

  override def toString: String = this.map( entry => if ( entry._2 ) '1' else '0' ).mkString("")
}