enhancement #20

5 files changed, 31 insertions, 31 deletions

diff --git a/src/compiler/scala/tools/nsc/matching/CodeFactory.scala b/src/compiler/scala/tools/nsc/matching/CodeFactory.scala
index c33e9f0e25..48d8297d5d 100644
--- a/src/compiler/scala/tools/nsc/matching/CodeFactory.scala
+++ b/src/compiler/scala/tools/nsc/matching/CodeFactory.scala
@@ -144,8 +144,8 @@ trait CodeFactory {
   final def seqHasLength(sel: Tree, ntpe: Type, i: Int) =
     typed(
       Equals(
-        Apply(Select(sel, ntpe.member(nme.length)), List()),
-        Literal(Constant(i))
+        Apply(Select(sel, ntpe.member(nme.lengthCompare)), List(Literal(Constant(i)))),
+        Literal(Constant(0))
       )
     )/*defs.Seq_length ?*/
 
@@ -153,8 +153,8 @@ trait CodeFactory {
    */
   final def seqLongerThan(sel:Tree, tpe:Type, i:Int) =
     GreaterThanOrEquals(
-      typed(Apply(Select(sel, tpe.member(nme.length)), List())),
-      typed(Literal(Constant(i))))
+      typed(Apply(Select(sel, tpe.member(nme.lengthCompare)), List(Literal(Constant(i))))),
+      typed(Literal(Constant(0))))
       //defs.Seq_length instead of tpe.member ?
 
   final def Not(arg:Tree) = arg match {
diff --git a/src/compiler/scala/tools/nsc/symtab/StdNames.scala b/src/compiler/scala/tools/nsc/symtab/StdNames.scala
index 51b76bd637..5cc4bd2542 100644
--- a/src/compiler/scala/tools/nsc/symtab/StdNames.scala
+++ b/src/compiler/scala/tools/nsc/symtab/StdNames.scala
@@ -292,6 +292,7 @@ trait StdNames {
     val java = newTermName("java")
     val lang = newTermName("lang")
     val length = newTermName("length")
+    val lengthCompare = newTermName("lengthCompare")
     val lift_ = newTermName("lift")
     val map = newTermName("map")
     val n = newTermName("n")
diff --git a/src/library/scala/List.scala b/src/library/scala/List.scala
index 9fd43f5140..8cc9e4e419 100644
--- a/src/library/scala/List.scala
+++ b/src/library/scala/List.scala
@@ -401,6 +401,15 @@ sealed abstract class List[+A] extends Seq[A] {
    */
   def head: A
 
+
+  /** returns length - l, without calling length
+   */
+  override def lengthCompare(l: Int) = {
+    if (isEmpty) 0 - l
+    else if (l <= 0) 1
+    else tail.lengthCompare(l - 1)
+  }
+
   /** Returns this list without its first element.
    *
    *  @return this list without its first element.
@@ -1210,32 +1219,8 @@ case object Nil extends List[Nothing] {
  *  @version 1.0, 15/07/2003
  */
 @SerialVersionUID(0L - 8476791151983527571L)
-final case class ::[B](private[scala] var hd: B, private[scala] var tl: List[B]) extends List[B] {
-  /* XXX: making hd a class-private var crashes the compiler. */
-  def head : B = hd
-  def tail : List[B] = tl
+final case class ::[B](hd: B, private[scala] var tl: List[B]) extends List[B] {
+  def head = hd
+  def tail = tl
   override def isEmpty: Boolean = false
-
-  import java.io._
-
-  private def writeObject(out : ObjectOutputStream) = {
-    val i = elements
-    while (i.hasNext) out.writeObject(i.next)
-    out.writeObject(ListSerializeEnd)
-  }
-  private def readObject(in : ObjectInputStream) : Unit = {
-    hd = in.readObject.asInstanceOf[B]
-    assert(hd != ListSerializeEnd)
-    var current : ::[B] = this
-    while (true) in.readObject match {
-    case ListSerializeEnd => current.tl = Nil; return
-    case a : Any =>
-      val list : ::[B] = new ::(a.asInstanceOf[B], Nil)
-      current.tl = list
-      current = list
-    }
-  }
 }
-/** Only used for list serialization */
-@SerialVersionUID(0L - 8476791151975527571L)
-private[scala] case object ListSerializeEnd
\ No newline at end of file
diff --git a/src/library/scala/Seq.scala b/src/library/scala/Seq.scala
index b78c3f9123..dd59ddfa81 100644
--- a/src/library/scala/Seq.scala
+++ b/src/library/scala/Seq.scala
@@ -156,6 +156,11 @@ trait Seq[+A] extends AnyRef with PartialFunction[Int, A] with Collection[A] {
    */
   def length: Int
 
+  /** Returns length - l. This method is used by matching streams against right-ignoring (...,_*) patterns.
+   *  Lazy sequences should override this method if length forces evaluation of the stream.
+   */
+  def lengthCompare(l: Int): Int = length - l
+
   /** should always be <code>length</code> */
   def size = length
 
diff --git a/src/library/scala/Stream.scala b/src/library/scala/Stream.scala
index 14bfd258d6..51c96b3f0c 100644
--- a/src/library/scala/Stream.scala
+++ b/src/library/scala/Stream.scala
@@ -196,6 +196,15 @@ trait Stream[+A] extends Seq.Projection[A] {
 
   /** The length of this stream */
   override def length: Int = if (isEmpty) 0 else tail.length + 1
+
+  /** returns length - l without calling length
+   */
+  override def lengthCompare(l: Int) = {
+    if (isEmpty) 0 - l
+    else if (l <= 0) 1
+    else tail.lengthCompare(l - 1)
+  }
+
   override def hasDefiniteSize = false