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/* __ *\
** ________ ___ / / ___ Scala API **
** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL **
** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ **
** /____/\___/_/ |_/____/_/ | | **
** |/ **
\* */
package scala
package sys
import scala.language.implicitConversions
/** A few additional conveniences for Boolean properties.
*/
trait BooleanProp extends Prop[Boolean] {
/** The semantics of value are determined at Prop creation. See methods
* `valueIsTrue` and `keyExists` in object BooleanProp for examples.
*
* @return true if the current String is considered true, false otherwise
*/
def value: Boolean
/** Alter this property so that `value` will be true. */
def enable(): Unit
/** Alter this property so that `value` will be false. */
def disable(): Unit
/** Toggle the property between enabled and disabled states. */
def toggle(): Unit
}
object BooleanProp {
private[sys]
class BooleanPropImpl(key: String, valueFn: String => Boolean) extends PropImpl(key, valueFn) with BooleanProp {
override def setValue[T1 >: Boolean](newValue: T1): Boolean = newValue match {
case x: Boolean if !x => val old = value ; clear() ; old
case x => super.setValue(newValue)
}
def enable() = this setValue true
def disable() = this.clear()
def toggle() = if (value) disable() else enable()
}
private[sys]
class ConstantImpl(val key: String, val value: Boolean) extends BooleanProp {
val isSet = value
def set(newValue: String) = "" + value
def setValue[T1 >: Boolean](newValue: T1): Boolean = value
def get: String = "" + value
val clear, enable, disable, toggle = ()
def option = if (isSet) Some(value) else None
protected def zero = false
}
/** The java definition of property truth is that the key be in the map and
* the value be equal to the String "true", case insensitively. This method
* creates a BooleanProp instance which adheres to that definition.
*
* @return A BooleanProp which acts like java's Boolean.getBoolean
*/
def valueIsTrue[T](key: String): BooleanProp = new BooleanPropImpl(key, _.toLowerCase == "true")
/** As an alternative, this method creates a BooleanProp which is true
* if the key exists in the map. This way -Dfoo.bar is enough to be
* considered true.
*
* @return A BooleanProp with a liberal truth policy
*/
def keyExists[T](key: String): BooleanProp = new BooleanPropImpl(key, _ => true)
/** A constant true or false property which ignores all method calls.
*/
def constant(key: String, isOn: Boolean): BooleanProp = new ConstantImpl(key, isOn)
implicit def booleanPropAsBoolean(b: BooleanProp): Boolean = b.value
}
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