diff options
Diffstat (limited to 'src/library/scala/collection/mutable/PriorityQueue.scala')
| -rw-r--r-- | src/library/scala/collection/mutable/PriorityQueue.scala | 182 |
1 files changed, 176 insertions, 6 deletions
diff --git a/src/library/scala/collection/mutable/PriorityQueue.scala b/src/library/scala/collection/mutable/PriorityQueue.scala index 2562f60355..d5b7673c37 100644 --- a/src/library/scala/collection/mutable/PriorityQueue.scala +++ b/src/library/scala/collection/mutable/PriorityQueue.scala @@ -16,7 +16,7 @@ import generic._ * To prioritize elements of type A there must be an implicit * Ordering[A] available at creation. * - * Only the `dequeue` and `dequeueAll` methods will return methods in priority + * Only the `dequeue` and `dequeueAll` methods will return elements in priority * order (while removing elements from the heap). Standard collection methods * including `drop`, `iterator`, and `toString` will remove or traverse the heap * in whichever order seems most convenient. @@ -46,8 +46,7 @@ import generic._ * @define mayNotTerminateInf * @define willNotTerminateInf */ -@deprecatedInheritance("PriorityQueue is not intended to be subclassed due to extensive private implementation details.", "2.11.0") -class PriorityQueue[A](implicit val ord: Ordering[A]) +sealed class PriorityQueue[A](implicit val ord: Ordering[A]) extends AbstractIterable[A] with Iterable[A] with GenericOrderedTraversableTemplate[A, PriorityQueue] @@ -201,9 +200,7 @@ class PriorityQueue[A](implicit val ord: Ordering[A]) * @return A reversed priority queue. */ def reverse = { - val revq = new PriorityQueue[A]()(new scala.math.Ordering[A] { - def compare(x: A, y: A) = ord.compare(y, x) - }) + val revq = new PriorityQueue[A]()(ord.reverse) for (i <- 1 until resarr.length) revq += resarr(i) revq } @@ -266,3 +263,176 @@ object PriorityQueue extends OrderedTraversableFactory[PriorityQueue] { implicit def canBuildFrom[A](implicit ord: Ordering[A]): CanBuildFrom[Coll, A, PriorityQueue[A]] = new GenericCanBuildFrom[A] } + +/** This class servers as a proxy for priority queues. The + * elements of the queue have to be ordered in terms of the + * `Ordered[T]` class. + * + * @author Matthias Zenger + * @version 1.0, 03/05/2004 + * @since 1 + */ +@deprecated("Proxying is deprecated due to lack of use and compiler-level support.", "2.11.0") +sealed abstract class PriorityQueueProxy[A](implicit ord: Ordering[A]) extends PriorityQueue[A] + with Proxy +{ + def self: PriorityQueue[A] + + /** Creates a new iterator over all elements contained in this + * object. + * + * @return the new iterator + */ + override def iterator: Iterator[A] = self.iterator + + /** Returns the length of this priority queue. + */ + override def length: Int = self.length + + /** Checks if the queue is empty. + * + * @return true, iff there is no element in the queue. + */ + override def isEmpty: Boolean = self.isEmpty + + /** Inserts a single element into the priority queue. + * + * @param elem the element to insert + */ + override def +=(elem: A): this.type = { self += elem; this } + + /** Adds all elements provided by an iterator into the priority queue. + * + * @param it an iterator + */ + override def ++=(it: TraversableOnce[A]): this.type = { + self ++= it + this + } + + /** Adds all elements to the queue. + * + * @param elems the elements to add. + */ + override def enqueue(elems: A*): Unit = self ++= elems + + /** Returns the element with the highest priority in the queue, + * and removes this element from the queue. + * + * @return the element with the highest priority. + */ + override def dequeue(): A = self.dequeue() + + /** Returns the element with the highest priority in the queue, + * or throws an error if there is no element contained in the queue. + * + * @return the element with the highest priority. + */ + override def head: A = self.head + + /** Removes all elements from the queue. After this operation is completed, + * the queue will be empty. + */ + override def clear(): Unit = self.clear() + + /** Returns a regular queue containing the same elements. + */ + override def toQueue: Queue[A] = self.toQueue + + /** This method clones the priority queue. + * + * @return a priority queue with the same elements. + */ + override def clone(): PriorityQueue[A] = new PriorityQueueProxy[A] { + def self = PriorityQueueProxy.this.self.clone() + } +} + + +/** This class implements synchronized priority queues using a binary heap. + * The elements of the queue have to be ordered in terms of the `Ordered[T]` class. + * + * @tparam A type of the elements contained in this synchronized priority queue + * @param ord implicit ordering used to compared elements of type `A` + * + * @author Matthias Zenger + * @version 1.0, 03/05/2004 + * @since 1 + * @define Coll `SynchronizedPriorityQueue` + * @define coll synchronized priority queue + */ +@deprecated("Comprehensive synchronization via selective overriding of methods is inherently unreliable. Consider java.util.concurrent.ConcurrentSkipListSet as an alternative.", "2.11.0") +sealed class SynchronizedPriorityQueue[A](implicit ord: Ordering[A]) extends PriorityQueue[A] { + + /** Checks if the queue is empty. + * + * @return true, iff there is no element in the queue. + */ + override def isEmpty: Boolean = synchronized { super.isEmpty } + + /** Inserts a single element into the priority queue. + * + * @param elem the element to insert + */ + override def +=(elem: A): this.type = { + synchronized { + super.+=(elem) + } + this + } + + /** Adds all elements of a traversable object into the priority queue. + * + * @param xs a traversable object + */ + override def ++=(xs: TraversableOnce[A]): this.type = { + synchronized { + super.++=(xs) + } + this + } + + /** Adds all elements to the queue. + * + * @param elems the elements to add. + */ + override def enqueue(elems: A*): Unit = synchronized { super.++=(elems) } + + /** Returns the element with the highest priority in the queue, + * and removes this element from the queue. + * + * @return the element with the highest priority. + */ + override def dequeue(): A = synchronized { super.dequeue() } + + /** Returns the element with the highest priority in the queue, + * or throws an error if there is no element contained in the queue. + * + * @return the element with the highest priority. + */ + override def head: A = synchronized { super.head } + + /** Removes all elements from the queue. After this operation is completed, + * the queue will be empty. + */ + override def clear(): Unit = synchronized { super.clear() } + + /** Returns an iterator which yield all the elements of the priority + * queue in descending priority order. + * + * @return an iterator over all elements sorted in descending order. + */ + override def iterator: Iterator[A] = synchronized { super.iterator } + + /** Checks if two queues are structurally identical. + * + * @return true, iff both queues contain the same sequence of elements. + */ + override def equals(that: Any): Boolean = synchronized { super.equals(that) } + + /** Returns a textual representation of a queue as a string. + * + * @return the string representation of this queue. + */ + override def toString(): String = synchronized { super.toString() } +} |