a fast, functional PartialFunction implementation

runtime.AbstractPartialFunction provides a default implementation
for the new-style partial function. In principle this class is only
subclassed by compiler-generated partial functions arising from matches.

Either
 - the apply method (old-style partialfun) or
 - the applyOrElse method (current scheme)
must be overridden, and the isDefinedAt method implemented.
The applyOrElse method implementation is provided to ease the
transition from the old scheme, since starr still generates
old-style PartialFunctions, but locker's library has the
new AbstractPartialFunction.

Thus, this implementation is intended as a drop-in replacement for the
old partial function, and does not require changes to the compiler.
(compiler patches, both for old and new-style pattern matching, follow)

- runtime.AbstractPartialFunction is based on PartialFunction.WithDefault
Original version of FunctionWithDefault by Odersky
(http://article.gmane.org/gmane.comp.lang.scala.internals/4032)
- better performance for OrElse#applyOrElse, OrElse#lift, PF.cond
- new combinator methods: PF#run, PF#runWith, PF.apply

authored by @pavelpavlov, refactored by @adriaanm, review by @paulp

1 files changed, 6 insertions, 6 deletions

diff --git a/src/compiler/scala/tools/cmd/FromString.scala b/src/compiler/scala/tools/cmd/FromString.scala
index e4504702d4..3792c26c34 100644
--- a/src/compiler/scala/tools/cmd/FromString.scala
+++ b/src/compiler/scala/tools/cmd/FromString.scala
@@ -14,9 +14,9 @@ import scala.reflect.OptManifest
  *  example instances are in the companion object, but in general
  *  either IntFromString will suffice or you'll want custom transformers.
  */
-abstract class FromString[+T](implicit m: OptManifest[T]) extends scala.runtime.AbstractPartialFunction[String, T] {
+abstract class FromString[+T](implicit m: OptManifest[T]) extends PartialFunction[String, T] {
   def apply(s: String): T
-  def _isDefinedAt(s: String): Boolean = true
+  def isDefinedAt(s: String): Boolean = true
   def zero: T = apply("")
 
   def targetString: String = m.toString
@@ -30,20 +30,20 @@ object FromString {
   /** Path related stringifiers.
    */
   val ExistingFile: FromString[File] = new FromString[File] {
-    override def _isDefinedAt(s: String) = toFile(s).isFile
+    override def isDefinedAt(s: String) = toFile(s).isFile
     def apply(s: String): File =
       if (isDefinedAt(s)) toFile(s)
       else cmd.runAndExit(println("'%s' is not an existing file." format s))
   }
   val ExistingDir: FromString[Directory] = new FromString[Directory] {
-    override def _isDefinedAt(s: String) = toDir(s).isDirectory
+    override def isDefinedAt(s: String) = toDir(s).isDirectory
     def apply(s: String): Directory =
       if (isDefinedAt(s)) toDir(s)
       else cmd.runAndExit(println("'%s' is not an existing directory." format s))
   }
   def ExistingDirRelativeTo(root: Directory) = new FromString[Directory] {
     private def resolve(s: String) = toDir(s) toAbsoluteWithRoot root toDirectory
-    override def _isDefinedAt(s: String) = resolve(s).isDirectory
+    override def isDefinedAt(s: String) = resolve(s).isDirectory
     def apply(s: String): Directory =
       if (isDefinedAt(s)) resolve(s)
       else cmd.runAndExit(println("'%s' is not an existing directory." format resolve(s)))
@@ -65,7 +65,7 @@ object FromString {
   /** Implicit as the most likely to be useful as-is.
    */
   implicit val IntFromString: FromString[Int] = new FromString[Int] {
-    override def _isDefinedAt(s: String)  = safeToInt(s).isDefined
+    override def isDefinedAt(s: String)   = safeToInt(s).isDefined
     def apply(s: String)                  = safeToInt(s).get
     def safeToInt(s: String): Option[Int] = try Some(java.lang.Integer.parseInt(s)) catch { case _: NumberFormatException => None }
   }