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Diffstat (limited to 'src/library/scala/collection/immutable/FilteredTraversableInternal.scala')
| -rw-r--r-- | src/library/scala/collection/immutable/FilteredTraversableInternal.scala | 104 |
1 files changed, 0 insertions, 104 deletions
diff --git a/src/library/scala/collection/immutable/FilteredTraversableInternal.scala b/src/library/scala/collection/immutable/FilteredTraversableInternal.scala deleted file mode 100644 index 35585b7826..0000000000 --- a/src/library/scala/collection/immutable/FilteredTraversableInternal.scala +++ /dev/null @@ -1,104 +0,0 @@ -/* __ *\ -** ________ ___ / / ___ Scala API ** -** / __/ __// _ | / / / _ | (c) 2003-2013, LAMP/EPFL ** -** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** -** /____/\___/_/ |_/____/_/ | | ** -** |/ ** -\* */ - -package scala -package collection -package immutable - -import scala.annotation.tailrec - -/** - * Optimised filter functions for List - * n.b. this is an internal class to help maintain compatibility and should not be used directly. - */ -private[immutable] trait FilteredTraversableInternal[+A, +Repr <: AnyRef with TraversableLike[A, Repr]] extends TraversableLike[A, Repr] { - - // Optimized for List - - override def filter(p: A => Boolean): Self = filterImpl(p, isFlipped = false) - - override def filterNot(p: A => Boolean): Self = filterImpl(p, isFlipped = true) - - private[this] def filterImpl(p: A => Boolean, isFlipped: Boolean): Self = { - - // everything seen so far so far is not included - @tailrec def noneIn(l: Repr): Repr = { - if (l.isEmpty) - Nil.asInstanceOf[Repr] - else { - val h = l.head - val t = l.tail - if (p(h) != isFlipped) - allIn(l, t) - else - noneIn(t) - } - } - - // everything from 'start' is included, if everything from this point is in we can return the origin - // start otherwise if we discover an element that is out we must create a new partial list. - @tailrec def allIn(start: Repr, remaining: Repr): Repr = { - if (remaining.isEmpty) - start - else { - val x = remaining.head - if (p(x) != isFlipped) - allIn(start, remaining.tail) - else - partialFill(start, remaining) - } - } - - // we have seen elements that should be included then one that should be excluded, start building - def partialFill(origStart: Repr, firstMiss: Repr): Repr = { - val newHead = new ::(origStart.head, Nil) - var toProcess = origStart.tail - var currentLast = newHead - - // we know that all elements are :: until at least firstMiss.tail - while (!(toProcess eq firstMiss)) { - val newElem = new ::(toProcess.head, Nil) - currentLast.tl = newElem - currentLast = newElem - toProcess = toProcess.tail - } - - // at this point newHead points to a list which is a duplicate of all the 'in' elements up to the first miss. - // currentLast is the last element in that list. - - // now we are going to try and share as much of the tail as we can, only moving elements across when we have to. - var next = firstMiss.tail - var nextToCopy = next // the next element we would need to copy to our list if we cant share. - while (!next.isEmpty) { - // generally recommended is next.isNonEmpty but this incurs an extra method call. - val head: A = next.head - if (p(head) != isFlipped) { - next = next.tail - } else { - // its not a match - do we have outstanding elements? - while (!(nextToCopy eq next)) { - val newElem = new ::(nextToCopy.head, Nil) - currentLast.tl = newElem - currentLast = newElem - nextToCopy = nextToCopy.tail - } - nextToCopy = next.tail - next = next.tail - } - } - - // we have remaining elements - they are unchanged attach them to the end - if (!nextToCopy.isEmpty) - currentLast.tl = nextToCopy.asInstanceOf[List[A]] - - newHead.asInstanceOf[Repr] - } - - noneIn(repr) - } -}
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