Scala example source code file (JLineHistory.scala)

This example Scala source code file (JLineHistory.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

boolean, charsequence, compiler, history, int, jiterator, jlinefilehistory, jlinehistory, jlistiterator, nsc, simplehistory, unit

The JLineHistory.scala Scala example source code

/* NSC -- new Scala compiler
 * Copyright 2005-2013 LAMP/EPFL
 * @author Paul Phillips
 */

package scala.tools.nsc
package interpreter
package session

/** A straight scalification of the jline interface which mixes
 *  in the sparse jline-independent one too.
 */
trait JLineHistory extends JHistory with History {
  def size: Int
  def isEmpty: Boolean
  def index: Int
  def clear(): Unit
  def get(index: Int): CharSequence
  def add(line: CharSequence): Unit
  def replace(item: CharSequence): Unit

  def entries(index: Int): JListIterator[JEntry]
  def entries(): JListIterator[JEntry]
  def iterator: JIterator[JEntry]

  def current(): CharSequence
  def previous(): Boolean
  def next(): Boolean
  def moveToFirst(): Boolean
  def moveToLast(): Boolean
  def moveTo(index: Int): Boolean
  def moveToEnd(): Unit
}

object JLineHistory {
  class JLineFileHistory extends SimpleHistory with FileBackedHistory {
    override def add(item: CharSequence): Unit = {
      if (!isEmpty && last == item)
        repldbg("Ignoring duplicate entry '" + item + "'")
      else {
        super.add(item)
        addLineToFile(item)
      }
    }
    override def toString = "History(size = " + size + ", index = " + index + ")"
  }

  def apply(): JLineHistory = try new JLineFileHistory catch { case x: Exception => new SimpleHistory() }
}