Created
September 24, 2012 22:00
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Boolean Logic in Pure Scala
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package booleanlogic | |
sealed abstract class Boolean { | |
def ifTrue[T](doWhenTrue: => T): Option[T] | |
def &&(other: => Boolean): Boolean | |
def &(other: Boolean): Boolean | |
def ||(other: => Boolean): Boolean | |
def |(other: Boolean): Boolean | |
def ^(other: Boolean): Boolean | |
def unary_! : Boolean | |
} | |
case object true1 extends Boolean { | |
override def ifTrue[T](doWhenTrue: => T): Option[T] = Some(doWhenTrue) | |
override def &&(other: => Boolean): Boolean = other | |
override def &(other: Boolean): Boolean = other | |
override def ||(other: => Boolean): Boolean = this | |
override def |(other: Boolean): Boolean = this | |
override def ^(other: Boolean): Boolean = !other | |
override def unary_! : Boolean = false1 | |
} | |
case object false1 extends Boolean { | |
override def ifTrue[T](doWhenTrue: => T): Option[T] = None | |
override def &&(other: => Boolean): Boolean = this | |
override def &(other: Boolean): Boolean = this | |
override def ||(other: => Boolean): Boolean = other | |
override def |(other: Boolean): Boolean = other | |
override def ^(other: Boolean): Boolean = other | |
override def unary_! : Boolean = true1 | |
} | |
object Conditional { | |
def if1[T](boolean: Boolean)(doWhenTrue: => T): IfResult[T] = { | |
val resultOfIfTrue = boolean.ifTrue(doWhenTrue) | |
return new IfResult(boolean, resultOfIfTrue) | |
} | |
class IfResult[T] private[Conditional] (boolean: Boolean, resultOfIfTrue: Option[T]) { | |
def elseif(boolean: Boolean)(doWhenTrue: => T): IfResult[T] = { | |
val ifResultIfAlreadyTrue = resultOfIfTrue.map(_=> this) | |
return ifResultIfAlreadyTrue.getOrElse(new IfResult(boolean, boolean.ifTrue(doWhenTrue))) | |
} | |
def else1(doWhenFalse: => T): T = { | |
return resultOfIfTrue.getOrElse(doWhenFalse) | |
} | |
} | |
} |
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