Scala example source code file (bug3636.scala)

This example Scala source code file (bug3636.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

ctxnlocal, impl, instant, proctxn, proctxn, t, t, transition, txn, txn, txnlocal, txnlocal, unit

The Scala bug3636.scala source code

class CTxnLocal[ T ] {
    def set( x: T )( implicit t: Txn ) {}
    def get( implicit t: Txn ) : T = null.asInstanceOf[ T ]
    def initialValue( t: Txn ) : T = null.asInstanceOf[ T ]
}

trait Txn
    
trait ProcTxn {
    def ccstm: Txn
}
    
trait TxnLocal[ @specialized T ] {
   def apply()( implicit tx: ProcTxn ) : T
   def set( v: T )( implicit tx: ProcTxn ) : Unit
   def swap( v: T )( implicit tx: ProcTxn ) : T
   def transform( f: T => T )( implicit tx: ProcTxn ) : Unit
}

object TxnLocal {
   def apply[ @specialized T ] : TxnLocal[ T ] = new Impl( new CTxnLocal[ T ])
   def apply[ @specialized T ]( initValue: => T ) : TxnLocal[ T ] = new Impl( new CTxnLocal[ T ] {
      override def initialValue( tx: Txn ): T = initValue
   })

   private class Impl[ T ]( c: CTxnLocal[ T ]) extends TxnLocal[ T ] {
      def apply()( implicit tx: ProcTxn ) : T = c.get( tx.ccstm )
      def set( v: T )( implicit tx: ProcTxn ) : Unit = c.set( v )( tx.ccstm )
      def swap( v: T )( implicit tx: ProcTxn ) : T = {
         // currently not implemented in CTxnLocal
         val oldV = apply
         set( v )
         oldV
      }
      def transform( f: T => T )( implicit tx: ProcTxn ) {
         set( f( apply ))
      }
   }
}


object Transition {
   private val currentRef = TxnLocal[ Transition ]( Instant )
   def current( implicit tx: ProcTxn ) : Transition = currentRef()
}

sealed abstract class Transition
case object Instant extends Transition