Scala Library
scala.collection.mutable

class PriorityQueue
[source: scala/collection/mutable/PriorityQueue.scala]
@serializable

@cloneable

class PriorityQueue[A](implicit ord : Ordering[A])
extends ResizableArray[A] with Addable[A, PriorityQueue[A]] with Growable[A] with Cloneable[PriorityQueue[A]]
This class implements priority queues using a heap. To prioritize elements of type T there must be an implicit Ordering[T] available at creation. Martin: This class is utterly broken. It uses a resizable array as a heap, yet pretends to be a sequence via this same resizable array. Needless to say, order of elements is different in the two. So this class needs to be redesigned so that it uses the array only in its implementation, but implements a sequence interface separately.
Author
Matthias Zenger
Version
1.0, 03/05/2004
Since
1
Direct Known Subclasses:
PriorityQueueProxy, SynchronizedPriorityQueue
Values and Variables inherited from ResizableArray
array, size0
Method Summary
override def + (elem1 : A, elem2 : A, elems : A*) : PriorityQueue[A]
Add two or more elements to this set.
def + (elem : A) : PriorityQueue[A]
Creates a new collection with an additional element, unless the element is already present.
override def ++ (iter : Iterator[A]) : PriorityQueue[A]
Adds all elements provided by an iterator into the priority queue.
override def ++ (elems : Traversable[A]) : PriorityQueue[A]
Adds all elements provided by an Iterable object into the priority queue.
def += (elem : A) : PriorityQueue[A]
Inserts a single element into the priority queue.
def clear : Unit
Removes all elements from the queue. After this operation is completed, the queue will be empty.
override def clone : PriorityQueue[A]
This method clones the priority queue.
def dequeue : A
Returns the element with the highest priority in the queue, and removes this element from the queue.
def enqueue (elems : A*) : Unit
Adds all elements to the queue.
override def equals (obj : Any) : Boolean
This is utterly broken: Two priority queues of different length can still be equal! The method should be removed once PriotyQueue inserts correctly into the sequence class hierarchy.
protected def fixDown (as : Array[AnyRef], m : Int, n : Int) : Unit
protected def fixUp (as : Array[AnyRef], m : Int) : Unit
override def foreach [U](f : (A) => U) : Unit
Apply a function f to all elements of this iterable object.
override def hashCode : Int
The hashCode method always yields an error, since it is not safe to use mutable queues as keys in hash tables.
override def isEmpty : Boolean
Does this iterable contain no elements?
override def iterator : Iterator[A]
Returns an iterator which yields all the elements of the priority queue in descending priority order.
override def length : Int
Returns the length of this resizable array.
def max : A
Returns the element with the highest priority in the queue, or throws an error if there is no element contained in the queue.
override def repr : PriorityQueue[A]
override def toList : List[A]
Returns a list with all elements of this traversable object.
def toQueue : Queue[A]
Returns a regular queue containing the same elements.
override def toString : java.lang.String
Returns a textual representation of a queue as a string.
Methods inherited from Growable
+=, ++=, ++=
Methods inherited from ResizableArray
companion, initialSize, apply, update, copyToArray, reduceToSize, ensureSize, swap, copy
Methods inherited from IndexedSeqLike
thisCollection, toCollection, view, view
Methods inherited from IndexedSeqLike
forall, exists, find, foldLeft, foldRight, reduceLeft, reduceRight, zip, zipWithIndex, slice, head, tail, last, init, take, drop, takeRight, dropRight, splitAt, takeWhile, dropWhile, span, sameElements, lengthCompare, segmentLength, indexWhere, lastIndexWhere, reverse, reverseIterator, startsWith, endsWith
Methods inherited from SeqLike
size, isDefinedAt, prefixLength, indexWhere, findIndexOf, indexOf, indexOf, lastIndexOf, lastIndexOf, lastIndexWhere, reverseMap, reversedElements, startsWith, indexOfSeq, indexOfSeq, lastIndexOfSeq, lastIndexOfSeq, contains, union, diff, intersect, removeDuplicates, patch, updated, +:, :+, padTo, sortWith, sortWith, sortBy, toSeq, indices, findLastIndexOf, equalsWith, containsSlice, projection
Methods inherited from PartialFunction
orElse, andThen
Methods inherited from Function1
compose
Methods inherited from IterableLike
elements, toIterable, zipAll, toStream, canEqual, first, firstOption
Methods inherited from GenericTraversableTemplate
newBuilder, genericBuilder, unzip, flatten, transpose
Methods inherited from TraversableLike
nonEmpty, hasDefiniteSize, ++, ++, map, flatMap, filter, filterNot, partialMap, remove, partition, groupBy, count, /:, :\, reduceLeftOption, reduceRightOption, sum, product, min, max, headOption, lastOption, copyToBuffer, copyToArray, toArray, toIndexedSeq, toSet, mkString, mkString, mkString, addString, addString, addString, stringPrefix, withFilter
Methods inherited from AnyRef
getClass, notify, notifyAll, wait, wait, wait, finalize, ==, !=, eq, ne, synchronized
Methods inherited from Any
==, !=, isInstanceOf, asInstanceOf
Method Details
override def length : Int
Returns the length of this resizable array.
Overrides
ResizableArray.length
override def isEmpty : Boolean
Does this iterable contain no elements?
override def repr : PriorityQueue[A]
Overrides
Addable.repr
override def foreach[U](f : (A) => U) : Unit
Apply a function f to all elements of this iterable object.
Parameters
f - A function that is applied for its side-effect to every element. The result (of arbitrary type U) of function `f` is discarded.
Notes
This method underlies the implementation of most other bulk operations. Implementing `foreach` with `iterator` is often suboptimal. So `foreach` should be overridden in concrete collection classes if a more efficient implementation is available.
Overrides
ResizableArray.foreach
protected def fixUp(as : Array[AnyRef], m : Int) : Unit
protected def fixDown(as : Array[AnyRef], m : Int, n : Int) : Unit
def +=(elem : A) : PriorityQueue[A]
Inserts a single element into the priority queue.
Parameters
elem - the element to insert
Overrides
Growable.+=
def +(elem : A) : PriorityQueue[A]
Creates a new collection with an additional element, unless the element is already present.
Parameters
elem - the element to be added
Returns
a fresh collection
Overrides
Addable.+
override def +(elem1 : A, elem2 : A, elems : A*) : PriorityQueue[A]
Add two or more elements to this set.
Parameters
elem1 - the first element.
kv2 - the second element.
kvs - the remaining elements.
Overrides
Addable.+
override def ++(elems : Traversable[A]) : PriorityQueue[A]
Adds all elements provided by an Iterable object into the priority queue.
Parameters
iter - an iterable object
Overrides
Addable.++
override def ++(iter : Iterator[A]) : PriorityQueue[A]
Adds all elements provided by an iterator into the priority queue.
Parameters
it - an iterator
Overrides
Addable.++
def enqueue(elems : A*) : Unit
Adds all elements to the queue.
Parameters
elems - the elements to add.
def dequeue : A
Returns the element with the highest priority in the queue, and removes this element from the queue.
Throws
Predef.NoSuchElementException -
Returns
the element with the highest priority.
def max : A
Returns the element with the highest priority in the queue, or throws an error if there is no element contained in the queue.
Returns
the element with the highest priority.
def clear : Unit
Removes all elements from the queue. After this operation is completed, the queue will be empty.
Overrides
Growable.clear
override def iterator : Iterator[A]
Returns an iterator which yields all the elements of the priority queue in descending priority order.
Returns
an iterator over all elements sorted in descending order.
override def equals(obj : Any) : Boolean
This is utterly broken: Two priority queues of different length can still be equal! The method should be removed once PriotyQueue inserts correctly into the sequence class hierarchy.
override def hashCode : Int
The hashCode method always yields an error, since it is not safe to use mutable queues as keys in hash tables.
Returns
never.
def toQueue : Queue[A]
Returns a regular queue containing the same elements.
override def toString : java.lang.String
Returns a textual representation of a queue as a string.
Returns
the string representation of this queue.
override def toList : List[A]
Returns a list with all elements of this traversable object.
Notes
Will not terminate for infinite-sized collections.
override def clone : PriorityQueue[A]
This method clones the priority queue.
Returns
a priority queue with the same elements.
Overrides
Cloneable.clone
Scala Library