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split out read-only RMap from PMap

This commit is contained in:
Mark Harrah 2010-08-10 08:39:30 -04:00
parent 9c8cf4451d
commit 6cada88fb3
1 changed files with 10 additions and 4 deletions
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14
util/collection/PMap.scala
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@ -5,12 +5,15 @@ package sbt
import Types._
trait PMap[K[_], V[_]] extends (K ~> V)
trait RMap[K[_], V[_]]
{
def apply[T](k: K[T]): V[T]
def get[T](k: K[T]): Option[V[T]]
def update[T](k: K[T], v: V[T]): Unit
def contains[T](k: K[T]): Boolean
}
trait PMap[K[_], V[_]] extends (K ~> V) with RMap[K,V]
{
def update[T](k: K[T], v: V[T]): Unit
def remove[T](k: K[T]): Option[V[T]]
def getOrUpdate[T](k: K[T], make: => V[T]): V[T]
}
@ -27,8 +30,11 @@ abstract class AbstractPMap[K[_], V[_]] extends PMap[K,V]
import collection.mutable.Map
/** Only suitable for K that is invariant in its parameter.
* Option and List keys are not, for example, because None <:< Option[String] and None <: Option[Int].*/
/**
* Only suitable for K that is invariant in its type parameter.
* Option and List keys are not suitable, for example,
* because None &lt;:&lt; Option[String] and None &lt;: Option[Int].
*/
class DelegatingPMap[K[_], V[_]](backing: Map[K[_], V[_]]) extends AbstractPMap[K,V]
{
def get[T](k: K[T]): Option[V[T]] = cast[T]( backing.get(k) )