Scala example source code file (PagedSeqReader.scala)

This example Scala source code file (PagedSeqReader.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

eofch, eofch, int, int, offsetposition, pagedseq, pagedseq, pagedseqreader, pagedseqreader, position, reader

The Scala PagedSeqReader.scala source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2006-2011, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */


package scala.util.parsing.input

import scala.collection.immutable.PagedSeq

/** An object encapsulating basic character constants 
 *
 * @author Martin Odersky, Adriaan Moors
 */
object PagedSeqReader {
  final val EofCh = '\032'
}

/** A character array reader reads a stream of characters (keeping track of their positions) 
 * from an array.
 *
 * @param source the source sequence
 * @param offset  starting offset.
 *
 * @author Martin Odersky 
 */
class PagedSeqReader(seq: PagedSeq[Char], 
                     override val offset: Int) extends Reader[Char] {
  import PagedSeqReader._

  override lazy val source: java.lang.CharSequence = seq

  /** Construct a <code>PagedSeqReader with its first element at
   *  <code>source(0) and position (1,1).
   */
  def this(seq: PagedSeq[Char]) = this(seq, 0)

  /** Returns the first element of the reader, or EofCh if reader is at its end 
   */
  def first = 
    if (seq.isDefinedAt(offset)) seq(offset) else EofCh 

  /** Returns a PagedSeqReader consisting of all elements except the first 
   * 
   * @return If <code>atEnd is true, the result will be
   *         <code>this'; otherwise, it's a PagedSeqReader containing
   *         the rest of input.
   */
  def rest: PagedSeqReader =
    if (seq.isDefinedAt(offset)) new PagedSeqReader(seq, offset + 1)
    else this

  /** The position of the first element in the reader
   */
  def pos: Position = new OffsetPosition(source, offset)

  /** true iff there are no more elements in this reader (except for trailing
   *  EofCh's)
   */
  def atEnd = !seq.isDefinedAt(offset)
    
  /** Returns an abstract reader consisting of all elements except the first
   *  <code>n elements.
   */ 
  override def drop(n: Int): PagedSeqReader = 
    new PagedSeqReader(seq, offset + n)
}