Merge pull request #18 from odersky/add-basetraits

Add base traits of collection hierarchy

Author: odersky

.gitignore

@@ -10,3 +10,4 @@ target/
 .history
 .DS_Store
 /tmp/
+/bin/

src/main/scala/strawman/collection/Iterable.scala

@@ -1,10 +1,10 @@
-package strawman.collection
+package strawman
+package collection
 
 import scala.annotation.unchecked.uncheckedVariance
 import scala.reflect.ClassTag
 import scala.{Int, Boolean, Array, Any, Unit, StringContext}
-import java.lang.String
-
+import java.lang.{String, UnsupportedOperationException}
 import strawman.collection.mutable.{ArrayBuffer, StringBuilder}
 
 /** Base trait for generic collections */
@@ -54,8 +54,10 @@ trait IterableOps[+A] extends Any {
   protected def coll: Iterable[A]
   private def iterator() = coll.iterator()
 
-  /** Apply `f` to each element for tis side effects */
-  def foreach(f: A => Unit): Unit = iterator().foreach(f)
+  /** Apply `f` to each element for its side effects
+   *  Note: [U] parameter needed to help scalac's type inference.
+   */
+  def foreach[U](f: A => U): Unit = iterator().foreach(f)
 
   /** Fold left */
   def foldLeft[B](z: B)(op: (B, A) => B): B = iterator().foldLeft(z)(op)
@@ -166,7 +168,10 @@ trait IterableMonoTransforms[+A, +Repr] extends Any {
   def drop(n: Int): Repr = fromIterableWithSameElemType(View.Drop(coll, n))
 
   /** The rest of the collection without its first element. */
-  def tail: Repr = drop(1)
+  def tail: Repr = {
+    if (coll.isEmpty) throw new UnsupportedOperationException
+    drop(1)
+  }
 }
 
 /** Transforms over iterables that can return collections of different element types.

src/main/scala/strawman/collection/IterableOnce.scala

@@ -1,6 +1,5 @@
-package strawman.collection
-
-import strawman.collection.mutable.Iterator
+package strawman
+package collection
 
 trait IterableOnce[+A] {
   /** Iterator can be used only once */

src/main/scala/strawman/collection/mutable/Iterator.scala renamed to src/main/scala/strawman/collection/Iterator.scala

@@ -1,17 +1,17 @@
-package strawman.collection.mutable
+package strawman.collection
 
 import scala.{Boolean, Int, Unit, Nothing, NoSuchElementException}
-import strawman.collection.{IndexedView, IterableOnce}
 
 /** A core Iterator class */
-trait Iterator[+A] { self =>
+trait Iterator[+A] extends IterableOnce[A] { self =>
   def hasNext: Boolean
   def next(): A
+  def iterator() = this
   def foldLeft[B](z: B)(op: (B, A) => B): B =
     if (hasNext) foldLeft(op(z, next()))(op) else z
   def foldRight[B](z: B)(op: (A, B) => B): B =
     if (hasNext) op(next(), foldRight(z)(op)) else z
-  def foreach(f: A => Unit): Unit =
+  def foreach[U](f: A => U): Unit =
     while (hasNext) f(next())
   def indexWhere(p: A => Boolean): Int = {
     var i = 0

src/main/scala/strawman/collection/Seq.scala

@@ -1,7 +1,6 @@
 package strawman.collection
 
 import scala.{Any, Boolean, Int, IndexOutOfBoundsException}
-import strawman.collection.mutable.Iterator
 import strawman.collection.immutable.{List, Nil}
 
 import scala.annotation.unchecked.uncheckedVariance
@@ -48,7 +47,6 @@ trait IndexedSeq[+A] extends Seq[A] { self =>
   }
 }
 
-
 /** Base trait for Seq operations */
 trait SeqLike[+A, +C[X] <: Seq[X]]
   extends IterableLike[A, C]

src/main/scala/strawman/collection/Set.scala

@@ -0,0 +1,4 @@
+package strawman
+package collection
+
+trait Set[A] extends Iterable[A] {}

src/main/scala/strawman/collection/View.scala

@@ -2,7 +2,6 @@ package strawman.collection
 
 import scala.{Int, Boolean, Nothing, annotation}
 import scala.Predef.intWrapper
-import strawman.collection.mutable.Iterator
 
 /** Concrete collection type: View */
 trait View[+A] extends Iterable[A] with IterableLike[A, View] {

src/main/scala/strawman/collection/immutable/Iterable.scala

@@ -0,0 +1,5 @@
+package strawman.collection.immutable
+import strawman.collection
+
+trait Iterable[+A] extends collection.Iterable[A]
+                      with collection.IterableLike[A, Iterable]

src/main/scala/strawman/collection/immutable/LazyList.scala

@@ -1,11 +1,11 @@
 package strawman.collection.immutable
 
 import scala.{Option, Some, None, Nothing, StringContext}
-import strawman.collection.{IterableFactory, Iterable, LinearSeq, SeqLike}
-import strawman.collection.mutable.Iterator
+import strawman.collection
+import strawman.collection.{IterableFactory, LinearSeq, SeqLike, Iterator}
 
 class LazyList[+A](expr: => LazyList.Evaluated[A])
-  extends LinearSeq[A] with SeqLike[A, LazyList] {
+  extends Seq[A] with SeqLike[A, LazyList] with LinearSeq[A] {
   private[this] var evaluated = false
   private[this] var result: LazyList.Evaluated[A] = _
 
@@ -23,7 +23,7 @@ class LazyList[+A](expr: => LazyList.Evaluated[A])
 
   def #:: [B >: A](elem: => B): LazyList[B] = new LazyList(Some((elem, this)))
 
-  def fromIterable[B](c: Iterable[B]): LazyList[B] = LazyList.fromIterable(c)
+  def fromIterable[B](c: collection.Iterable[B]): LazyList[B] = LazyList.fromIterable(c)
 
   override def className = "LazyList"
 
@@ -46,7 +46,7 @@ object LazyList extends IterableFactory[LazyList] {
     def unapply[A](s: LazyList[A]): Evaluated[A] = s.force
   }
 
-  def fromIterable[B](coll: Iterable[B]): LazyList[B] = coll match {
+  def fromIterable[B](coll: collection.Iterable[B]): LazyList[B] = coll match {
     case coll: LazyList[B] => coll
     case _ => fromIterator(coll.iterator())
   }

src/main/scala/strawman/collection/immutable/List.scala

@@ -3,17 +3,19 @@ package strawman.collection.immutable
 import scala.annotation.unchecked.uncheckedVariance
 import scala.Nothing
 import scala.Predef.???
-import strawman.collection.{Iterable, IterableFactory, IterableOnce, LinearSeq, SeqLike}
+import strawman.collection
+import strawman.collection.{IterableFactory, IterableOnce, LinearSeq, SeqLike}
 import strawman.collection.mutable.{Buildable, ListBuffer}
 
 
 /** Concrete collection type: List */
 sealed trait List[+A]
-  extends LinearSeq[A]
-    with SeqLike[A, List]
-    with Buildable[A, List[A]] {
+  extends Seq[A]
+     with SeqLike[A, List]
+     with LinearSeq[A]
+     with Buildable[A, List[A]] {
 
-  def fromIterable[B](c: Iterable[B]): List[B] = List.fromIterable(c)
+  def fromIterable[B](c: collection.Iterable[B]): List[B] = List.fromIterable(c)
 
   protected[this] def newBuilder = new ListBuffer[A].mapResult(_.toList)
 
@@ -48,8 +50,8 @@ case object Nil extends List[Nothing] {
 }
 
 object List extends IterableFactory[List] {
-  def fromIterable[B](coll: Iterable[B]): List[B] = coll match {
+  def fromIterable[B](coll: collection.Iterable[B]): List[B] = coll match {
     case coll: List[B] => coll
     case _ => ListBuffer.fromIterable(coll).toList
   }
-}
+}

src/main/scala/strawman/collection/immutable/Seq.scala

@@ -0,0 +1,9 @@
+package strawman.collection.immutable
+
+import strawman.collection
+
+trait Seq[+A] extends collection.Seq[A]
+                 with collection.SeqLike[A, Seq]
+                 with Iterable[A]
+
+