Play Framework/Scala example source code file (PlayInteractionMode.scala)

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

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

Play Framework tags/keywords

closeable, consolereader, none, not, play, play framework, playinteractionmode, playnonblockinginteractionmode, some, stopping, t, unit

The PlayInteractionMode.scala Play Framework example source code

/*
 * Copyright (C) 2009-2013 Typesafe Inc. <http://www.typesafe.com>
 */
package play

import java.io.Closeable

import jline.console.ConsoleReader

trait PlayInteractionMode {
  /**
   * This is our means of blocking a `play run` call until
   *  the user has denoted, via some interface (console or GUI) that
   *  play should no longer be running.
   */
  def waitForCancel(): Unit

  /**
   * Enables and disables console echo (or does nothing if no console).
   * This ensures console echo is enabled on exception thrown in the
   * given code block.
   */
  def doWithoutEcho(f: => Unit): Unit
  // TODO - Hooks for messages that print to screen?
}

/**
 * Marker trait to signify a non blocking interaction mode.
 *
 * This is provided, rather than adding a new flag to PlayInteractionMode, to preserve binary compatibility.
 */
trait PlayNonBlockingInteractionMode extends PlayInteractionMode {
  def waitForCancel() = ()
  def doWithoutEcho(f: => Unit) = f

  /**
   * Start the server, if not already started
   *
   * @param server A callback to start the server, that returns a closeable to stop it
   */
  def start(server: => Closeable): Unit

  /**
   * Stop the server started by the last start request, if such a server exists
   */
  def stop(): Unit
}

/**
 * Default behavior for interaction mode is to
 *  wait on jline.
 */
object PlayConsoleInteractionMode extends PlayInteractionMode {

  private def withConsoleReader[T](f: ConsoleReader => T): T = {
    val consoleReader = new ConsoleReader
    try f(consoleReader) finally consoleReader.shutdown()
  }
  private def waitForKey(): Unit = {
    withConsoleReader { consoleReader =>
      def waitEOF(): Unit = {
        consoleReader.readCharacter() match {
          case 4 | -1 =>
          // Note: we have to listen to -1 for jline2, for some reason...
          // STOP on Ctrl-D or EOF.
          case 11 =>
            consoleReader.clearScreen(); waitEOF()
          case 10 =>
            println(); waitEOF()
          case x => waitEOF()
        }
      }
      doWithoutEcho(waitEOF())
    }
  }
  def doWithoutEcho(f: => Unit): Unit = {
    withConsoleReader { consoleReader =>
      val terminal = consoleReader.getTerminal
      terminal.setEchoEnabled(false)
      try f finally terminal.restore()
    }
  }
  override def waitForCancel(): Unit = waitForKey()

  override def toString = "Console Interaction Mode"
}

/**
 * Simple implementation of the non blocking interaction mode that simply stores the current application in a static
 * variable.
 */
object StaticPlayNonBlockingInteractionMode extends PlayNonBlockingInteractionMode {
  private var current: Option[Closeable] = None

  /**
   * Start the server, if not already started
   *
   * @param server A callback to start the server, that returns a closeable to stop it
   */
  def start(server: => Closeable) = synchronized {
    current match {
      case Some(_) => println("Not starting server since one is already started")
      case None =>
        println("Starting server")
        current = Some(server)
    }
  }

  /**
   * Stop the server started by the last start request, if such a server exists
   */
  def stop() = synchronized {
    current match {
      case Some(server) =>
        println("Stopping server")
        server.close()
        current = None
      case None => println("Not stopping server since none is started")
    }
  }
}