Akka/Scala example source code file (Address.scala)

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

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

Akka tags/keywords

actor, address, akka, annotation, collection, int, list, none, option, pathutils, some, string, uri, urisyntaxexception

The Address.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */
package akka.actor
import java.net.URI
import java.net.URISyntaxException
import java.net.MalformedURLException
import scala.annotation.tailrec
import scala.collection.immutable

/**
 * The address specifies the physical location under which an Actor can be
 * reached. Examples are local addresses, identified by the ActorSystem’s
 * name, and remote addresses, identified by protocol, host and port.
 *
 * This class is final to allow use as a case class (copy method etc.); if
 * for example a remote transport would want to associate additional
 * information with an address, then this must be done externally.
 */
@SerialVersionUID(1L)
final case class Address private (protocol: String, system: String, host: Option[String], port: Option[Int]) {
  // Please note that local/non-local distinction must be preserved:
  // host.isDefined == hasGlobalScope
  // host.isEmpty == hasLocalScope
  // hasLocalScope == !hasGlobalScope

  def this(protocol: String, system: String) = this(protocol, system, None, None)
  def this(protocol: String, system: String, host: String, port: Int) = this(protocol, system, Option(host), Some(port))

  /**
   * Returns true if this Address is only defined locally. It is not safe to send locally scoped addresses to remote
   * hosts. See also [[akka.actor.Address#hasGlobalScope]].
   */
  def hasLocalScope: Boolean = host.isEmpty

  /**
   * Returns true if this Address is usable globally. Unlike locally defined addresses ([[akka.actor.Address#hasLocalScope]])
   * addresses of global scope are safe to sent to other hosts, as they globally and uniquely identify an addressable
   * entity.
   */
  def hasGlobalScope: Boolean = host.isDefined

  // store hashCode
  @transient override lazy val hashCode: Int = scala.util.hashing.MurmurHash3.productHash(this)

  /**
   * Returns the canonical String representation of this Address formatted as:
   *
   * <protocol>://<system>@<host>:<port>
   */
  @transient
  override lazy val toString: String = {
    val sb = (new java.lang.StringBuilder(protocol)).append("://").append(system)

    if (host.isDefined) sb.append('@').append(host.get)
    if (port.isDefined) sb.append(':').append(port.get)

    sb.toString
  }

  /**
   * Returns a String representation formatted as:
   *
   * <system>@<host>:<port>
   */
  def hostPort: String = toString.substring(protocol.length + 3)
}

object Address {
  /**
   * Constructs a new Address with the specified protocol and system name
   */
  def apply(protocol: String, system: String) = new Address(protocol, system)

  /**
   * Constructs a new Address with the specified protocol, system name, host and port
   */
  def apply(protocol: String, system: String, host: String, port: Int) = new Address(protocol, system, Some(host), Some(port))
}

private[akka] trait PathUtils {
  protected def split(s: String, fragment: String): List[String] = {
    @tailrec
    def rec(pos: Int, acc: List[String]): List[String] = {
      val from = s.lastIndexOf('/', pos - 1)
      val sub = s.substring(from + 1, pos)
      val l =
        if ((fragment ne null) && acc.isEmpty) sub + "#" + fragment :: acc
        else sub :: acc
      if (from == -1) l else rec(from, l)
    }
    rec(s.length, Nil)
  }
}

/**
 * Extractor for so-called “relative actor paths” as in “relative URI”, not in
 * “relative to some actor”. Examples:
 *
 *  * "grand/child"
 *  * "/user/hello/world"
 */
object RelativeActorPath extends PathUtils {
  def unapply(addr: String): Option[immutable.Seq[String]] = {
    try {
      val uri = new URI(addr)
      if (uri.isAbsolute) None
      else Some(split(uri.getRawPath, uri.getRawFragment))
    } catch {
      case _: URISyntaxException ⇒ None
    }
  }
}

/**
 * This object serves as extractor for Scala and as address parser for Java.
 */
object AddressFromURIString {
  def unapply(addr: String): Option[Address] = try unapply(new URI(addr)) catch { case _: URISyntaxException ⇒ None }

  def unapply(uri: URI): Option[Address] =
    if (uri eq null) None
    else if (uri.getScheme == null || (uri.getUserInfo == null && uri.getHost == null)) None
    else if (uri.getUserInfo == null) { // case 1: “akka://system”
      if (uri.getPort != -1) None
      else Some(Address(uri.getScheme, uri.getHost))
    } else { // case 2: “akka://system@host:port”
      if (uri.getHost == null || uri.getPort == -1) None
      else Some(
        if (uri.getUserInfo == null) Address(uri.getScheme, uri.getHost)
        else Address(uri.getScheme, uri.getUserInfo, uri.getHost, uri.getPort))
    }

  /**
   * Try to construct an Address from the given String or throw a java.net.MalformedURLException.
   */
  def apply(addr: String): Address = addr match {
    case AddressFromURIString(address) ⇒ address
    case _                             ⇒ throw new MalformedURLException(addr)
  }

  /**
   * Java API: Try to construct an Address from the given String or throw a java.net.MalformedURLException.
   */
  def parse(addr: String): Address = apply(addr)
}

/**
 * Given an ActorPath it returns the Address and the path elements if the path is well-formed
 */
object ActorPathExtractor extends PathUtils {
  def unapply(addr: String): Option[(Address, immutable.Iterable[String])] =
    try {
      val uri = new URI(addr)
      uri.getRawPath match {
        case null ⇒ None
        case path ⇒ AddressFromURIString.unapply(uri).map((_, split(path, uri.getRawFragment).drop(1)))
      }
    } catch {
      case _: URISyntaxException ⇒ None
    }
}