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| <!doctype html>
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| 
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| <title>CodeMirror: Scala mode</title>
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| <meta charset="utf-8"/>
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| <link rel=stylesheet href="../../doc/docs.css">
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| <div id=nav>
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|   <a href="https://codemirror.net"><h1>CodeMirror</h1><img id=logo src="../../doc/logo.png"></a>
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| 
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|   <ul>
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|     <li><a href="../../index.html">Home</a>
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|     <li><a href="../../doc/manual.html">Manual</a>
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|     <li><a href="https://github.com/codemirror/codemirror">Code</a>
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|   <ul>
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|     <li><a href="../index.html">Language modes</a>
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|     <li><a class=active href="#">Scala</a>
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|   </ul>
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| </div>
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| 
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| <article>
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| <h2>Scala mode</h2>
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| <form>
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| <textarea id="code" name="code">
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| 
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|   /*                     __                                               *\
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|   **     ________ ___   / /  ___     Scala API                            **
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|   **    / __/ __// _ | / /  / _ |    (c) 2003-2011, LAMP/EPFL             **
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|   **  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
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|   ** /____/\___/_/ |_/____/_/ | |                                         **
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|   **                          |/                                          **
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|   \*                                                                      */
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| 
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|   package scala.collection
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| 
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|   import generic._
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|   import mutable.{ Builder, ListBuffer }
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|   import annotation.{tailrec, migration, bridge}
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|   import annotation.unchecked.{ uncheckedVariance => uV }
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|   import parallel.ParIterable
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| 
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|   /** A template trait for traversable collections of type `Traversable[A]`.
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|    *  
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|    *  $traversableInfo
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|    *  @define mutability
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|    *  @define traversableInfo
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|    *  This is a base trait of all kinds of $mutability Scala collections. It
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|    *  implements the behavior common to all collections, in terms of a method
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|    *  `foreach` with signature:
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|    * {{{
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|    *     def foreach[U](f: Elem => U): Unit
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|    * }}}
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|    *  Collection classes mixing in this trait provide a concrete 
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|    *  `foreach` method which traverses all the
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|    *  elements contained in the collection, applying a given function to each.
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|    *  They also need to provide a method `newBuilder`
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|    *  which creates a builder for collections of the same kind.
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|    *  
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|    *  A traversable class might or might not have two properties: strictness
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|    *  and orderedness. Neither is represented as a type.
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|    *  
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|    *  The instances of a strict collection class have all their elements
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|    *  computed before they can be used as values. By contrast, instances of
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|    *  a non-strict collection class may defer computation of some of their
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|    *  elements until after the instance is available as a value.
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|    *  A typical example of a non-strict collection class is a
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|    *  <a href="../immutable/Stream.html" target="ContentFrame">
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|    *  `scala.collection.immutable.Stream`</a>.
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|    *  A more general class of examples are `TraversableViews`.
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|    *  
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|    *  If a collection is an instance of an ordered collection class, traversing
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|    *  its elements with `foreach` will always visit elements in the
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|    *  same order, even for different runs of the program. If the class is not
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|    *  ordered, `foreach` can visit elements in different orders for
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|    *  different runs (but it will keep the same order in the same run).'
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|    * 
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|    *  A typical example of a collection class which is not ordered is a
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|    *  `HashMap` of objects. The traversal order for hash maps will
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|    *  depend on the hash codes of its elements, and these hash codes might
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|    *  differ from one run to the next. By contrast, a `LinkedHashMap`
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|    *  is ordered because it's `foreach` method visits elements in the
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|    *  order they were inserted into the `HashMap`.
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|    *
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|    *  @author Martin Odersky
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|    *  @version 2.8
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|    *  @since   2.8
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|    *  @tparam A    the element type of the collection
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|    *  @tparam Repr the type of the actual collection containing the elements.
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|    *
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|    *  @define Coll Traversable
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|    *  @define coll traversable collection
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|    */
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|   trait TraversableLike[+A, +Repr] extends HasNewBuilder[A, Repr] 
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|                                       with FilterMonadic[A, Repr]
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|                                       with TraversableOnce[A]
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|                                       with GenTraversableLike[A, Repr]
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|                                       with Parallelizable[A, ParIterable[A]]
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|   {
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|     self =>
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| 
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|     import Traversable.breaks._
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| 
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|     /** The type implementing this traversable */
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|     protected type Self = Repr
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| 
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|     /** The collection of type $coll underlying this `TraversableLike` object.
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|      *  By default this is implemented as the `TraversableLike` object itself,
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|      *  but this can be overridden.
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|      */
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|     def repr: Repr = this.asInstanceOf[Repr]
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| 
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|     /** The underlying collection seen as an instance of `$Coll`.
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|      *  By default this is implemented as the current collection object itself,
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|      *  but this can be overridden.
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|      */
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|     protected[this] def thisCollection: Traversable[A] = this.asInstanceOf[Traversable[A]]
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| 
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|     /** A conversion from collections of type `Repr` to `$Coll` objects.
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|      *  By default this is implemented as just a cast, but this can be overridden.
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|      */
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|     protected[this] def toCollection(repr: Repr): Traversable[A] = repr.asInstanceOf[Traversable[A]]
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| 
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|     /** Creates a new builder for this collection type.
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|      */
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|     protected[this] def newBuilder: Builder[A, Repr]
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| 
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|     protected[this] def parCombiner = ParIterable.newCombiner[A]
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| 
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|     /** Applies a function `f` to all elements of this $coll.
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|      *  
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|      *    Note: this method underlies the implementation of most other bulk operations.
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|      *    It's important to implement this method in an efficient way.
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|      *  
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|      *
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|      *  @param  f   the function that is applied for its side-effect to every element.
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|      *              The result of function `f` is discarded.
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|      *              
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|      *  @tparam  U  the type parameter describing the result of function `f`. 
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|      *              This result will always be ignored. Typically `U` is `Unit`,
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|      *              but this is not necessary.
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|      *
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|      *  @usecase def foreach(f: A => Unit): Unit
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|      */
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|     def foreach[U](f: A => U): Unit
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| 
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|     /** Tests whether this $coll is empty.
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|      *
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|      *  @return    `true` if the $coll contain no elements, `false` otherwise.
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|      */
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|     def isEmpty: Boolean = {
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|       var result = true
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|       breakable {
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|         for (x <- this) {
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|           result = false
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|           break
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|         }
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|       }
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|       result
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|     }
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| 
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|     /** Tests whether this $coll is known to have a finite size.
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|      *  All strict collections are known to have finite size. For a non-strict collection
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|      *  such as `Stream`, the predicate returns `true` if all elements have been computed.
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|      *  It returns `false` if the stream is not yet evaluated to the end.
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|      *
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|      *  Note: many collection methods will not work on collections of infinite sizes. 
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|      *
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|      *  @return  `true` if this collection is known to have finite size, `false` otherwise.
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|      */
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|     def hasDefiniteSize = true
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| 
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|     def ++[B >: A, That](that: GenTraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
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|       val b = bf(repr)
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|       if (that.isInstanceOf[IndexedSeqLike[_, _]]) b.sizeHint(this, that.seq.size)
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|       b ++= thisCollection
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|       b ++= that.seq
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|       b.result
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|     }
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| 
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|     @bridge
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|     def ++[B >: A, That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That =
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|       ++(that: GenTraversableOnce[B])(bf)
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| 
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|     /** Concatenates this $coll with the elements of a traversable collection.
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|      *  It differs from ++ in that the right operand determines the type of the
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|      *  resulting collection rather than the left one.
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|      * 
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|      *  @param that   the traversable to append.
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|      *  @tparam B     the element type of the returned collection. 
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|      *  @tparam That  $thatinfo
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|      *  @param bf     $bfinfo
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|      *  @return       a new collection of type `That` which contains all elements
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|      *                of this $coll followed by all elements of `that`.
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|      * 
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|      *  @usecase def ++:[B](that: TraversableOnce[B]): $Coll[B]
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|      *  
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|      *  @return       a new $coll which contains all elements of this $coll
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|      *                followed by all elements of `that`.
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|      */
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|     def ++:[B >: A, That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
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|       val b = bf(repr)
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|       if (that.isInstanceOf[IndexedSeqLike[_, _]]) b.sizeHint(this, that.size)
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|       b ++= that
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|       b ++= thisCollection
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|       b.result
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|     }
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| 
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|     /** This overload exists because: for the implementation of ++: we should reuse
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|      *  that of ++ because many collections override it with more efficient versions.
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|      *  Since TraversableOnce has no '++' method, we have to implement that directly,
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|      *  but Traversable and down can use the overload.
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|      */
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|     def ++:[B >: A, That](that: Traversable[B])(implicit bf: CanBuildFrom[Repr, B, That]): That =
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|       (that ++ seq)(breakOut)
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| 
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|     def map[B, That](f: A => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
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|       val b = bf(repr)
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|       b.sizeHint(this) 
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|       for (x <- this) b += f(x)
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|       b.result
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|     }
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| 
 | |
|     def flatMap[B, That](f: A => GenTraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
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|       val b = bf(repr)
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|       for (x <- this) b ++= f(x).seq
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|       b.result
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|     }
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| 
 | |
|     /** Selects all elements of this $coll which satisfy a predicate.
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|      *
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|      *  @param p     the predicate used to test elements.
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|      *  @return      a new $coll consisting of all elements of this $coll that satisfy the given
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|      *               predicate `p`. The order of the elements is preserved.
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|      */
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|     def filter(p: A => Boolean): Repr = {
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|       val b = newBuilder
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|       for (x <- this) 
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|         if (p(x)) b += x
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|       b.result
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|     }
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| 
 | |
|     /** Selects all elements of this $coll which do not satisfy a predicate.
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|      *
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|      *  @param p     the predicate used to test elements.
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|      *  @return      a new $coll consisting of all elements of this $coll that do not satisfy the given
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|      *               predicate `p`. The order of the elements is preserved.
 | |
|      */
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|     def filterNot(p: A => Boolean): Repr = filter(!p(_))
 | |
| 
 | |
|     def collect[B, That](pf: PartialFunction[A, B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
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|       val b = bf(repr)
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|       for (x <- this) if (pf.isDefinedAt(x)) b += pf(x)
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|       b.result
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|     }
 | |
| 
 | |
|     /** Builds a new collection by applying an option-valued function to all
 | |
|      *  elements of this $coll on which the function is defined.
 | |
|      *
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|      *  @param f      the option-valued function which filters and maps the $coll.
 | |
|      *  @tparam B     the element type of the returned collection.
 | |
|      *  @tparam That  $thatinfo
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|      *  @param bf     $bfinfo
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|      *  @return       a new collection of type `That` resulting from applying the option-valued function
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|      *                `f` to each element and collecting all defined results.
 | |
|      *                The order of the elements is preserved.
 | |
|      *
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|      *  @usecase def filterMap[B](f: A => Option[B]): $Coll[B]
 | |
|      *  
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|      *  @param pf     the partial function which filters and maps the $coll.
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|      *  @return       a new $coll resulting from applying the given option-valued function
 | |
|      *                `f` to each element and collecting all defined results.
 | |
|      *                The order of the elements is preserved.
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|     def filterMap[B, That](f: A => Option[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
 | |
|       val b = bf(repr)
 | |
|       for (x <- this) 
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|         f(x) match {
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|           case Some(y) => b += y
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|           case _ =>
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|         }
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|       b.result
 | |
|     }
 | |
|      */
 | |
| 
 | |
|     /** Partitions this $coll in two ${coll}s according to a predicate.
 | |
|      *
 | |
|      *  @param p the predicate on which to partition.
 | |
|      *  @return  a pair of ${coll}s: the first $coll consists of all elements that 
 | |
|      *           satisfy the predicate `p` and the second $coll consists of all elements
 | |
|      *           that don't. The relative order of the elements in the resulting ${coll}s
 | |
|      *           is the same as in the original $coll.
 | |
|      */
 | |
|     def partition(p: A => Boolean): (Repr, Repr) = {
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|       val l, r = newBuilder
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|       for (x <- this) (if (p(x)) l else r) += x
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|       (l.result, r.result)
 | |
|     }
 | |
| 
 | |
|     def groupBy[K](f: A => K): immutable.Map[K, Repr] = {
 | |
|       val m = mutable.Map.empty[K, Builder[A, Repr]]
 | |
|       for (elem <- this) {
 | |
|         val key = f(elem)
 | |
|         val bldr = m.getOrElseUpdate(key, newBuilder)
 | |
|         bldr += elem
 | |
|       }
 | |
|       val b = immutable.Map.newBuilder[K, Repr]
 | |
|       for ((k, v) <- m)
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|         b += ((k, v.result))
 | |
| 
 | |
|       b.result
 | |
|     }
 | |
| 
 | |
|     /** Tests whether a predicate holds for all elements of this $coll.
 | |
|      *
 | |
|      *  $mayNotTerminateInf
 | |
|      *
 | |
|      *  @param   p     the predicate used to test elements.
 | |
|      *  @return        `true` if the given predicate `p` holds for all elements
 | |
|      *                 of this $coll, otherwise `false`.
 | |
|      */
 | |
|     def forall(p: A => Boolean): Boolean = {
 | |
|       var result = true
 | |
|       breakable {
 | |
|         for (x <- this)
 | |
|           if (!p(x)) { result = false; break }
 | |
|       }
 | |
|       result
 | |
|     }
 | |
| 
 | |
|     /** Tests whether a predicate holds for some of the elements of this $coll.
 | |
|      *
 | |
|      *  $mayNotTerminateInf
 | |
|      *
 | |
|      *  @param   p     the predicate used to test elements.
 | |
|      *  @return        `true` if the given predicate `p` holds for some of the
 | |
|      *                 elements of this $coll, otherwise `false`.
 | |
|      */
 | |
|     def exists(p: A => Boolean): Boolean = {
 | |
|       var result = false
 | |
|       breakable {
 | |
|         for (x <- this)
 | |
|           if (p(x)) { result = true; break }
 | |
|       }
 | |
|       result
 | |
|     }
 | |
| 
 | |
|     /** Finds the first element of the $coll satisfying a predicate, if any.
 | |
|      * 
 | |
|      *  $mayNotTerminateInf
 | |
|      *  $orderDependent
 | |
|      *
 | |
|      *  @param p    the predicate used to test elements.
 | |
|      *  @return     an option value containing the first element in the $coll
 | |
|      *              that satisfies `p`, or `None` if none exists.
 | |
|      */
 | |
|     def find(p: A => Boolean): Option[A] = {
 | |
|       var result: Option[A] = None
 | |
|       breakable {
 | |
|         for (x <- this)
 | |
|           if (p(x)) { result = Some(x); break }
 | |
|       }
 | |
|       result
 | |
|     }
 | |
| 
 | |
|     def scan[B >: A, That](z: B)(op: (B, B) => B)(implicit cbf: CanBuildFrom[Repr, B, That]): That = scanLeft(z)(op)
 | |
| 
 | |
|     def scanLeft[B, That](z: B)(op: (B, A) => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
 | |
|       val b = bf(repr)
 | |
|       b.sizeHint(this, 1)
 | |
|       var acc = z
 | |
|       b += acc
 | |
|       for (x <- this) { acc = op(acc, x); b += acc }
 | |
|       b.result
 | |
|     }
 | |
| 
 | |
|     @migration(2, 9,
 | |
|       "This scanRight definition has changed in 2.9.\n" +
 | |
|       "The previous behavior can be reproduced with scanRight.reverse."
 | |
|     )
 | |
|     def scanRight[B, That](z: B)(op: (A, B) => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
 | |
|       var scanned = List(z)
 | |
|       var acc = z
 | |
|       for (x <- reversed) {
 | |
|         acc = op(x, acc)
 | |
|         scanned ::= acc
 | |
|       }
 | |
|       val b = bf(repr)
 | |
|       for (elem <- scanned) b += elem
 | |
|       b.result
 | |
|     }
 | |
| 
 | |
|     /** Selects the first element of this $coll.
 | |
|      *  $orderDependent
 | |
|      *  @return  the first element of this $coll.
 | |
|      *  @throws `NoSuchElementException` if the $coll is empty.
 | |
|      */
 | |
|     def head: A = {
 | |
|       var result: () => A = () => throw new NoSuchElementException
 | |
|       breakable {
 | |
|         for (x <- this) {
 | |
|           result = () => x
 | |
|           break
 | |
|         }
 | |
|       }
 | |
|       result()
 | |
|     }
 | |
| 
 | |
|     /** Optionally selects the first element.
 | |
|      *  $orderDependent
 | |
|      *  @return  the first element of this $coll if it is nonempty, `None` if it is empty.
 | |
|      */
 | |
|     def headOption: Option[A] = if (isEmpty) None else Some(head)
 | |
| 
 | |
|     /** Selects all elements except the first.
 | |
|      *  $orderDependent
 | |
|      *  @return  a $coll consisting of all elements of this $coll
 | |
|      *           except the first one.
 | |
|      *  @throws `UnsupportedOperationException` if the $coll is empty.
 | |
|      */ 
 | |
|     override def tail: Repr = {
 | |
|       if (isEmpty) throw new UnsupportedOperationException("empty.tail")
 | |
|       drop(1)
 | |
|     }
 | |
| 
 | |
|     /** Selects the last element.
 | |
|       * $orderDependent
 | |
|       * @return The last element of this $coll.
 | |
|       * @throws NoSuchElementException If the $coll is empty.
 | |
|       */
 | |
|     def last: A = {
 | |
|       var lst = head
 | |
|       for (x <- this)
 | |
|         lst = x
 | |
|       lst
 | |
|     }
 | |
| 
 | |
|     /** Optionally selects the last element.
 | |
|      *  $orderDependent
 | |
|      *  @return  the last element of this $coll$ if it is nonempty, `None` if it is empty.
 | |
|      */
 | |
|     def lastOption: Option[A] = if (isEmpty) None else Some(last)
 | |
| 
 | |
|     /** Selects all elements except the last.
 | |
|      *  $orderDependent
 | |
|      *  @return  a $coll consisting of all elements of this $coll
 | |
|      *           except the last one.
 | |
|      *  @throws `UnsupportedOperationException` if the $coll is empty.
 | |
|      */
 | |
|     def init: Repr = {
 | |
|       if (isEmpty) throw new UnsupportedOperationException("empty.init")
 | |
|       var lst = head
 | |
|       var follow = false
 | |
|       val b = newBuilder
 | |
|       b.sizeHint(this, -1)
 | |
|       for (x <- this.seq) {
 | |
|         if (follow) b += lst
 | |
|         else follow = true
 | |
|         lst = x
 | |
|       }
 | |
|       b.result
 | |
|     }
 | |
| 
 | |
|     def take(n: Int): Repr = slice(0, n)
 | |
| 
 | |
|     def drop(n: Int): Repr = 
 | |
|       if (n <= 0) {
 | |
|         val b = newBuilder
 | |
|         b.sizeHint(this)
 | |
|         b ++= thisCollection result
 | |
|       }
 | |
|       else sliceWithKnownDelta(n, Int.MaxValue, -n)
 | |
| 
 | |
|     def slice(from: Int, until: Int): Repr = sliceWithKnownBound(math.max(from, 0), until)
 | |
| 
 | |
|     // Precondition: from >= 0, until > 0, builder already configured for building.
 | |
|     private[this] def sliceInternal(from: Int, until: Int, b: Builder[A, Repr]): Repr = {
 | |
|       var i = 0
 | |
|       breakable {
 | |
|         for (x <- this.seq) {
 | |
|           if (i >= from) b += x
 | |
|           i += 1
 | |
|           if (i >= until) break
 | |
|         }
 | |
|       }
 | |
|       b.result
 | |
|     }
 | |
|     // Precondition: from >= 0
 | |
|     private[scala] def sliceWithKnownDelta(from: Int, until: Int, delta: Int): Repr = {
 | |
|       val b = newBuilder
 | |
|       if (until <= from) b.result
 | |
|       else {
 | |
|         b.sizeHint(this, delta)
 | |
|         sliceInternal(from, until, b)
 | |
|       }
 | |
|     }
 | |
|     // Precondition: from >= 0
 | |
|     private[scala] def sliceWithKnownBound(from: Int, until: Int): Repr = {
 | |
|       val b = newBuilder
 | |
|       if (until <= from) b.result
 | |
|       else {
 | |
|         b.sizeHintBounded(until - from, this)      
 | |
|         sliceInternal(from, until, b)
 | |
|       }
 | |
|     }
 | |
| 
 | |
|     def takeWhile(p: A => Boolean): Repr = {
 | |
|       val b = newBuilder
 | |
|       breakable {
 | |
|         for (x <- this) {
 | |
|           if (!p(x)) break
 | |
|           b += x
 | |
|         }
 | |
|       }
 | |
|       b.result
 | |
|     }
 | |
| 
 | |
|     def dropWhile(p: A => Boolean): Repr = {
 | |
|       val b = newBuilder
 | |
|       var go = false
 | |
|       for (x <- this) {
 | |
|         if (!p(x)) go = true
 | |
|         if (go) b += x
 | |
|       }
 | |
|       b.result
 | |
|     }
 | |
| 
 | |
|     def span(p: A => Boolean): (Repr, Repr) = {
 | |
|       val l, r = newBuilder
 | |
|       var toLeft = true
 | |
|       for (x <- this) {
 | |
|         toLeft = toLeft && p(x)
 | |
|         (if (toLeft) l else r) += x
 | |
|       }
 | |
|       (l.result, r.result)
 | |
|     }
 | |
| 
 | |
|     def splitAt(n: Int): (Repr, Repr) = {
 | |
|       val l, r = newBuilder
 | |
|       l.sizeHintBounded(n, this)
 | |
|       if (n >= 0) r.sizeHint(this, -n)
 | |
|       var i = 0
 | |
|       for (x <- this) {
 | |
|         (if (i < n) l else r) += x
 | |
|         i += 1
 | |
|       }
 | |
|       (l.result, r.result)
 | |
|     }
 | |
| 
 | |
|     /** Iterates over the tails of this $coll. The first value will be this
 | |
|      *  $coll and the final one will be an empty $coll, with the intervening
 | |
|      *  values the results of successive applications of `tail`.
 | |
|      *
 | |
|      *  @return   an iterator over all the tails of this $coll
 | |
|      *  @example  `List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)`
 | |
|      */  
 | |
|     def tails: Iterator[Repr] = iterateUntilEmpty(_.tail)
 | |
| 
 | |
|     /** Iterates over the inits of this $coll. The first value will be this
 | |
|      *  $coll and the final one will be an empty $coll, with the intervening
 | |
|      *  values the results of successive applications of `init`.
 | |
|      *
 | |
|      *  @return  an iterator over all the inits of this $coll
 | |
|      *  @example  `List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)`
 | |
|      */
 | |
|     def inits: Iterator[Repr] = iterateUntilEmpty(_.init)
 | |
| 
 | |
|     /** Copies elements of this $coll to an array.
 | |
|      *  Fills the given array `xs` with at most `len` elements of
 | |
|      *  this $coll, starting at position `start`.
 | |
|      *  Copying will stop once either the end of the current $coll is reached,
 | |
|      *  or the end of the array is reached, or `len` elements have been copied.
 | |
|      *
 | |
|      *  $willNotTerminateInf
 | |
|      * 
 | |
|      *  @param  xs     the array to fill.
 | |
|      *  @param  start  the starting index.
 | |
|      *  @param  len    the maximal number of elements to copy.
 | |
|      *  @tparam B      the type of the elements of the array. 
 | |
|      * 
 | |
|      *
 | |
|      *  @usecase def copyToArray(xs: Array[A], start: Int, len: Int): Unit
 | |
|      */
 | |
|     def copyToArray[B >: A](xs: Array[B], start: Int, len: Int) {
 | |
|       var i = start
 | |
|       val end = (start + len) min xs.length
 | |
|       breakable {
 | |
|         for (x <- this) {
 | |
|           if (i >= end) break
 | |
|           xs(i) = x
 | |
|           i += 1
 | |
|         }
 | |
|       }
 | |
|     }
 | |
| 
 | |
|     def toTraversable: Traversable[A] = thisCollection
 | |
|     def toIterator: Iterator[A] = toStream.iterator
 | |
|     def toStream: Stream[A] = toBuffer.toStream
 | |
| 
 | |
|     /** Converts this $coll to a string.
 | |
|      *
 | |
|      *  @return   a string representation of this collection. By default this
 | |
|      *            string consists of the `stringPrefix` of this $coll,
 | |
|      *            followed by all elements separated by commas and enclosed in parentheses.
 | |
|      */
 | |
|     override def toString = mkString(stringPrefix + "(", ", ", ")")
 | |
| 
 | |
|     /** Defines the prefix of this object's `toString` representation.
 | |
|      *
 | |
|      *  @return  a string representation which starts the result of `toString`
 | |
|      *           applied to this $coll. By default the string prefix is the
 | |
|      *           simple name of the collection class $coll.
 | |
|      */
 | |
|     def stringPrefix : String = {
 | |
|       var string = repr.asInstanceOf[AnyRef].getClass.getName
 | |
|       val idx1 = string.lastIndexOf('.' : Int)
 | |
|       if (idx1 != -1) string = string.substring(idx1 + 1)
 | |
|       val idx2 = string.indexOf('$')
 | |
|       if (idx2 != -1) string = string.substring(0, idx2)
 | |
|       string
 | |
|     }
 | |
| 
 | |
|     /** Creates a non-strict view of this $coll.
 | |
|      * 
 | |
|      *  @return a non-strict view of this $coll.
 | |
|      */
 | |
|     def view = new TraversableView[A, Repr] {
 | |
|       protected lazy val underlying = self.repr
 | |
|       override def foreach[U](f: A => U) = self foreach f
 | |
|     }
 | |
| 
 | |
|     /** Creates a non-strict view of a slice of this $coll.
 | |
|      *
 | |
|      *  Note: the difference between `view` and `slice` is that `view` produces
 | |
|      *        a view of the current $coll, whereas `slice` produces a new $coll.
 | |
|      * 
 | |
|      *  Note: `view(from, to)` is equivalent to `view.slice(from, to)`
 | |
|      *  $orderDependent
 | |
|      * 
 | |
|      *  @param from   the index of the first element of the view
 | |
|      *  @param until  the index of the element following the view
 | |
|      *  @return a non-strict view of a slice of this $coll, starting at index `from`
 | |
|      *  and extending up to (but not including) index `until`.
 | |
|      */
 | |
|     def view(from: Int, until: Int): TraversableView[A, Repr] = view.slice(from, until)
 | |
| 
 | |
|     /** Creates a non-strict filter of this $coll.
 | |
|      *
 | |
|      *  Note: the difference between `c filter p` and `c withFilter p` is that
 | |
|      *        the former creates a new collection, whereas the latter only
 | |
|      *        restricts the domain of subsequent `map`, `flatMap`, `foreach`,
 | |
|      *        and `withFilter` operations.
 | |
|      *  $orderDependent
 | |
|      * 
 | |
|      *  @param p   the predicate used to test elements.
 | |
|      *  @return    an object of class `WithFilter`, which supports
 | |
|      *             `map`, `flatMap`, `foreach`, and `withFilter` operations.
 | |
|      *             All these operations apply to those elements of this $coll which
 | |
|      *             satisfy the predicate `p`.
 | |
|      */
 | |
|     def withFilter(p: A => Boolean): FilterMonadic[A, Repr] = new WithFilter(p)
 | |
| 
 | |
|     /** A class supporting filtered operations. Instances of this class are
 | |
|      *  returned by method `withFilter`.
 | |
|      */
 | |
|     class WithFilter(p: A => Boolean) extends FilterMonadic[A, Repr] {
 | |
| 
 | |
|       /** Builds a new collection by applying a function to all elements of the
 | |
|        *  outer $coll containing this `WithFilter` instance that satisfy predicate `p`.
 | |
|        *
 | |
|        *  @param f      the function to apply to each element.
 | |
|        *  @tparam B     the element type of the returned collection.
 | |
|        *  @tparam That  $thatinfo
 | |
|        *  @param bf     $bfinfo
 | |
|        *  @return       a new collection of type `That` resulting from applying
 | |
|        *                the given function `f` to each element of the outer $coll
 | |
|        *                that satisfies predicate `p` and collecting the results.
 | |
|        *
 | |
|        *  @usecase def map[B](f: A => B): $Coll[B] 
 | |
|        *  
 | |
|        *  @return       a new $coll resulting from applying the given function
 | |
|        *                `f` to each element of the outer $coll that satisfies
 | |
|        *                predicate `p` and collecting the results.
 | |
|        */
 | |
|       def map[B, That](f: A => B)(implicit bf: CanBuildFrom[Repr, B, That]): That = {
 | |
|         val b = bf(repr)
 | |
|         for (x <- self) 
 | |
|           if (p(x)) b += f(x)
 | |
|         b.result
 | |
|       }
 | |
| 
 | |
|       /** Builds a new collection by applying a function to all elements of the
 | |
|        *  outer $coll containing this `WithFilter` instance that satisfy
 | |
|        *  predicate `p` and concatenating the results. 
 | |
|        *
 | |
|        *  @param f      the function to apply to each element.
 | |
|        *  @tparam B     the element type of the returned collection.
 | |
|        *  @tparam That  $thatinfo
 | |
|        *  @param bf     $bfinfo
 | |
|        *  @return       a new collection of type `That` resulting from applying
 | |
|        *                the given collection-valued function `f` to each element
 | |
|        *                of the outer $coll that satisfies predicate `p` and
 | |
|        *                concatenating the results.
 | |
|        *
 | |
|        *  @usecase def flatMap[B](f: A => TraversableOnce[B]): $Coll[B]
 | |
|        * 
 | |
|        *  @return       a new $coll resulting from applying the given collection-valued function
 | |
|        *                `f` to each element of the outer $coll that satisfies predicate `p` and concatenating the results.
 | |
|        */
 | |
|       def flatMap[B, That](f: A => GenTraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That = {
 | |
|         val b = bf(repr)
 | |
|         for (x <- self) 
 | |
|           if (p(x)) b ++= f(x).seq
 | |
|         b.result
 | |
|       }
 | |
| 
 | |
|       /** Applies a function `f` to all elements of the outer $coll containing
 | |
|        *  this `WithFilter` instance that satisfy predicate `p`.
 | |
|        *
 | |
|        *  @param  f   the function that is applied for its side-effect to every element.
 | |
|        *              The result of function `f` is discarded.
 | |
|        *              
 | |
|        *  @tparam  U  the type parameter describing the result of function `f`. 
 | |
|        *              This result will always be ignored. Typically `U` is `Unit`,
 | |
|        *              but this is not necessary.
 | |
|        *
 | |
|        *  @usecase def foreach(f: A => Unit): Unit
 | |
|        */   
 | |
|       def foreach[U](f: A => U): Unit = 
 | |
|         for (x <- self) 
 | |
|           if (p(x)) f(x)
 | |
| 
 | |
|       /** Further refines the filter for this $coll.
 | |
|        *
 | |
|        *  @param q   the predicate used to test elements.
 | |
|        *  @return    an object of class `WithFilter`, which supports
 | |
|        *             `map`, `flatMap`, `foreach`, and `withFilter` operations.
 | |
|        *             All these operations apply to those elements of this $coll which
 | |
|        *             satisfy the predicate `q` in addition to the predicate `p`.
 | |
|        */
 | |
|       def withFilter(q: A => Boolean): WithFilter = 
 | |
|         new WithFilter(x => p(x) && q(x))
 | |
|     }
 | |
| 
 | |
|     // A helper for tails and inits.
 | |
|     private def iterateUntilEmpty(f: Traversable[A @uV] => Traversable[A @uV]): Iterator[Repr] = {
 | |
|       val it = Iterator.iterate(thisCollection)(f) takeWhile (x => !x.isEmpty)
 | |
|       it ++ Iterator(Nil) map (newBuilder ++= _ result)
 | |
|     }
 | |
|   }
 | |
| 
 | |
| 
 | |
| </textarea>
 | |
| </form>
 | |
| 
 | |
|     <script>
 | |
|       var editor = CodeMirror.fromTextArea(document.getElementById("code"), {
 | |
|         lineNumbers: true,
 | |
|         matchBrackets: true,
 | |
|         theme: "ambiance",
 | |
|         mode: "text/x-scala"
 | |
|       });
 | |
|     </script>
 | |
|   </article>
 |