4 out of 5 spelling bee champs say: Traversable

1 files changed, 213 insertions, 0 deletions

diff --git a/src/library/scala/collection/Traversable.scala b/src/library/scala/collection/Traversable.scala
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+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2003-2009, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+// $Id: Traversable.scala 15188 2008-05-24 15:01:02Z stepancheg $
+package scala.collection
+
+// import immutable.{List, Stream, Nil}
+import mutable.{Buffer, ArrayBuffer, ListBuffer}
+import util.control.Breaks._
+import generic._
+
+/** A template trait for traversable collections.
+ *
+ *  Collection classes mixing in this trait provide a method
+ *  <code>foreach</code> which traverses all the
+ *  elements contained in the collection, applying a given procedure to each.
+ *  They also provide a method `newBuilder`
+ *  which creates a builder for collections of the same kind.
+ *
+ *  @author Martin Odersky
+ *  @version 2.8
+ */
+trait Traversable[+A] extends TraversableTemplate[A, Traversable[A]] {
+  protected[this] def newBuilder = Traversable.newBuilder
+  def traversableBuilder[B]: Builder[B, Traversable[B], Any] = Traversable.newBuilder[B]
+
+  /* The following methods are inherited from TraversableTemplate
+   *
+  override def isEmpty: Boolean
+  override def size: Int
+  override def hasDefiniteSize
+  override def ++[B >: A, That](that: Traversable[B])(implicit bf: BuilderFactory[B, That, Traversable[A]]): That
+  override def ++[B >: A, That](that: Iterator[B])(implicit bf: BuilderFactory[B, That, Traversable[A]]): That
+  override def map[B, That](f: A => B)(implicit bf: BuilderFactory[B, That, Traversable[A]]): That
+  override def flatMap[B, That](f: A => Traversable[B])(implicit bf: BuilderFactory[B, That, Traversable[A]]): That
+  override def filter(p: A => Boolean): Traversable[A]
+  override def remove(p: A => Boolean): Traversable[A]
+  override def partition(p: A => Boolean): (Traversable[A], Traversable[A])
+  override def groupBy[K](f: A => K): Map[K, Traversable[A]]
+  override def foreach(f: A => Unit): Unit
+  override def forall(p: A => Boolean): Boolean
+  override def exists(p: A => Boolean): Boolean
+  override def count(p: A => Boolean): Int
+  override def find(p: A => Boolean): Option[A]
+  override def foldLeft[B](z: B)(op: (B, A) => B): B
+  override def /: [B](z: B)(op: (B, A) => B): B
+  override def foldRight[B](z: B)(op: (A, B) => B): B
+  override def :\ [B](z: B)(op: (A, B) => B): B
+  override def reduceLeft[B >: A](op: (B, A) => B): B
+  override def reduceLeftOpt[B >: A](op: (B, A) => B): Option[B]
+  override def reduceRight[B >: A](op: (A, B) => B): B
+  override def reduceRightOpt[B >: A](op: (A, B) => B): Option[B]
+  override def head: A
+  override def headOption: Option[A]
+  override def tail: Traversable[A]
+  override def last: A
+  override def lastOption: Option[A]
+  override def init: Traversable[A]
+  override def take(n: Int): Traversable[A]
+  override def drop(n: Int): Traversable[A]
+  override def slice(from: Int, until: Int): Traversable[A]
+  override def takeWhile(p: A => Boolean): Traversable[A]
+  override def dropWhile(p: A => Boolean): Traversable[A]
+  override def span(p: A => Boolean): (Traversable[A], Traversable[A])
+  override def splitAt(n: Int): (Traversable[A], Traversable[A])
+  override def copyToBuffer[B >: A](dest: Buffer[B])
+  override def copyToArray[B >: A](xs: Array[B], start: Int, len: Int)
+  override def copyToArray[B >: A](xs: Array[B], start: Int)
+  override def toArray[B >: A]: Array[B]
+  override def toList: List[A]
+  override def toIterable: Iterable[A]
+  override def toSequence: Sequence[A]
+  override def toStream: Stream[A]
+//  override def sortWith(lt : (A,A) => Boolean): Traversable[A]
+  override def mkString(start: String, sep: String, end: String): String
+  override def mkString(sep: String): String
+  override def mkString: String
+  override def addString(b: StringBuilder, start: String, sep: String, end: String): StringBuilder
+  override def addString(b: StringBuilder, sep: String): StringBuilder
+  override def addString(b: StringBuilder): StringBuilder
+  override def toString
+  override def stringPrefix : String
+  override def view
+  override def view(from: Int, until: Int): TraversableView[A, Traversable[A]]
+  */
+}
+
+/** Factory methods and utilities for instances of type Traversable */
+object Traversable extends TraversableFactory[Traversable] { self =>
+
+  type Coll = Traversable[_]
+  implicit def builderFactory[A]: BuilderFactory[A, Traversable[A], Coll] = new BuilderFactory[A, Traversable[A], Coll] { def apply(from: Coll) = from.traversableBuilder[A] }
+  def newBuilder[A]: Builder[A, Traversable[A], Any] = immutable.Traversable.newBuilder[A]
+
+  /** A wrapper class which adds `min` and `max` methods to iterables of an element type that has an Ordering.
+   */
+  class ComparableTraversableOps[A](self: Traversable[A], cmp: Ordering[A]) {
+
+    /** Returns the minimal element of the wrapped iterable `self` with respect to the given ordering `cmp` */
+    def min: A = {
+      require(!self.isEmpty, "min(<empty>)")
+      var acc = self.head
+      for (x <- self)
+        if (cmp.lt(x, acc)) acc = x
+      acc
+    }
+
+    /** Returns the maximal element of the wrapped iterable `self` with respect to the given ordering `cmp` */
+    def max: A = {
+      require(!self.isEmpty, "max(<empty>)")
+      var acc = self.head
+      for (x <- self)
+        if (cmp.gt(x, acc)) acc = x
+      acc
+    }
+  }
+
+  /** A wrapper class which adds `sum` and `product` methods to iterables of an element type that is `Numeric`.
+   */
+  class NumericTraversableOps[A](self: Traversable[A], num: Numeric[A]) {
+
+    /** Returns the sum of all elements of the wrapped iterable `self` with respect to the numeric operations in `num` */
+    def sum: A = {
+      var acc = num.zero
+      for (x <- self) acc = num.plus(acc, x)
+      acc
+    }
+
+    /** Returns the product of all elements of the wrapped iterable `self` with respect to the numeric operations in `num` */
+    def product: A = {
+      var acc = num.one
+      for (x <- self) acc = num.times(acc, x)
+      acc
+    }
+  }
+
+  /** A wrapper class which adds `flatten` and `transpose` methods to iterables or iterable element type`.
+   */
+  class TraversableTraversableOps[This <: Traversable[Traversable[A]], A](self: This) {
+
+    /** Returns the concatenation of all elements of the wrapped iterable `self` */
+    def flatten[That](implicit bf: BuilderFactory[A, That, This]): That = {
+      val b = bf(self)
+      for (xs <- self)
+        b ++= xs
+      b.result
+    }
+
+    /** Returns the transposition of the wrapped iterable `self`: rows become columns and columns become rows.
+     */
+    def transpose[Row, That](implicit bf: BuilderFactory[A, Row, This], bbf: BuilderFactory[Row, That, This]): That = {
+      val bs: Array[Builder[A, Row, This]] = self.head.map(_ => bf(self))(Traversable.builderFactory[Builder[A, Row, This]]).toArray
+      for (xs <- self) {
+        var i = 0
+        for (x <- xs) {
+          bs(i) += x
+          i += 1
+        }
+      }
+      val bb = bbf(self)
+      for (b <- bs) bb += b.result
+      bb.result
+    }
+  }
+
+  /** A wrapper class which adds an `unzip` method to iterable whose elements are pairs.
+  	*/
+  class PairTraversableOps[This <: Traversable[(A1, A2)], A1, A2](self: This) {
+
+    /** Returns a pair of iterables consisting of the first, respectively second, component of all
+     *  elements in the wrapped iterable `self`.
+     */
+    def unzip[That1, That2](implicit bf1: BuilderFactory[A1, That1, This], bf2: BuilderFactory[A2, That2, This]): (That1, That2) = {
+      val b1 = bf1(self)
+      val b2 = bf2(self)
+      for ((x1, x2) <- self) {
+        b1 += x1
+        b2 += x2
+      }
+      (b1.result, b2.result)
+    }
+  }
+
+  /** Implicit wrapper conversion of iterables with elements admitting comparison.
+   *  @see ComparableTraversableOps
+   */
+  implicit def comparableTraversableWrapper[A](self: Traversable[A])(implicit cmp: Ordering[A]) =
+    new ComparableTraversableOps(self, cmp)
+
+  /** Implicit wrapper conversion of iterables with numeric elements.
+   *  @see NumericTraversableOps
+   */
+  implicit def numericTraversableWrapper[A](self: Traversable[A])(implicit num: Numeric[A]) =
+    new NumericTraversableOps(self, num)
+
+  /** Implicit wrapper conversion of iterables with iterable elements.
+   *  @see TraversableTraversableOps
+   */
+  implicit def traversableTraversableWrapper[This <: Traversable[Traversable[A]], A](self: This) =
+    new TraversableTraversableOps[This, A](self) // !!! error if type parameters are omitted
+
+  /** Implicit wrapper conversion of iterables with pairs as elements.
+   *  @see PairTraversableOps
+   */
+  implicit def pairTraversableWrapper[This <: Traversable[(A1, A2)], A1, A2](self: This) =
+    new PairTraversableOps[This, A1, A2](self)
+}
+