scala.sys.PropImpl.scala Maven / Gradle / Ivy
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala
package sys
import scala.collection.mutable
/** The internal implementation of scala.sys.Prop.
*/
private[sys] class PropImpl[+T](val key: String, valueFn: String => T) extends Prop[T] {
def value: T = if (isSet) valueFn(get) else zero
def isSet = underlying contains key
def set(newValue: String): String = {
val old = if (isSet) get else null
underlying(key) = newValue
old
}
def setValue[T1 >: T](newValue: T1): T = {
val old = value
if (newValue == null) set(null)
else set("" + newValue)
old
}
def get: String =
if (isSet) underlying.getOrElse(key, "")
else ""
def clear(): Unit = underlying -= key
def option: Option[T] = if (isSet) Some(value) else None
def or[T1 >: T](alt: => T1): T1 = if (isSet) value else alt
/** The underlying property map, in our case always sys.props */
protected def underlying: mutable.Map[String, String] = scala.sys.props
protected def zero: T = null.asInstanceOf[T]
private def getString = if (isSet) "currently: " + get else "unset"
override def toString = "%s (%s)".format(key, getString)
}
private[sys] abstract class CreatorImpl[+T](f: String => T) extends Prop.Creator[T] {
def apply(key: String): Prop[T] = new PropImpl[T](key, f)
}