Package org.apache.myfaces.util.lang
Class PriorityQueue<T>
java.lang.Object
org.apache.myfaces.util.lang.PriorityQueue<T>
A PriorityQueue maintains a partial ordering of its elements such that the
 least element can always be found in constant time.  Put()'s and pop()'s
 require log(size) time.
 
NOTE: This class will pre-allocate a full array of
 length maxSize+1 if instantiated via the
 PriorityQueue(int,boolean) constructor with
 prepopulate set to true.
 
 lucene.internal
 see org.apache.lucene.util.PriorityQueue
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Constructor SummaryConstructors
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Method SummaryModifier and TypeMethodDescriptionfinal TAdds an Object to a PriorityQueue in log(size) time.final voidclear()Removes all entries from the PriorityQueue.protected final Object[]This method returns the internal heap array as Object[].protected TThis method can be overridden by extending classes to return a sentinel object which will be used by thePriorityQueue(int,boolean)constructor to fill the queue, so that the code which uses that queue can always assume it's full and only change the top without attempting to insert any new object.
 Those sentinel values should always compare worse than any non-sentinel value (i.e.,lessThan(T, T)should always favor the non-sentinel values).
 By default, this method returns false, which means the queue will not be filled with sentinel values.insertWithOverflow(T element) Adds an Object to a PriorityQueue in log(size) time.protected abstract booleanDetermines the ordering of objects in this priority queue.final Tpop()Removes and returns the least element of the PriorityQueue in log(size) time.final intsize()Returns the number of elements currently stored in the PriorityQueue.final Ttop()Returns the least element of the PriorityQueue in constant time.final TShould be called when the Object at top changes values.
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Constructor Details- 
PriorityQueuepublic PriorityQueue(int maxSize) 
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PriorityQueuepublic PriorityQueue(int maxSize, boolean prepopulate) 
 
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Method Details- 
lessThanDetermines the ordering of objects in this priority queue. Subclasses must define this one method.- Returns:
- trueiff parameter a is less than parameter b.
 
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getSentinelObjectThis method can be overridden by extending classes to return a sentinel object which will be used by thePriorityQueue(int,boolean)constructor to fill the queue, so that the code which uses that queue can always assume it's full and only change the top without attempting to insert any new object.
 Those sentinel values should always compare worse than any non-sentinel value (i.e.,lessThan(T, T)should always favor the non-sentinel values).
 By default, this method returns false, which means the queue will not be filled with sentinel values. Otherwise, the value returned will be used to pre-populate the queue. Adds sentinel values to the queue.
 If this method is extended to return a non-null value, then the following usage pattern is recommended:// extends getSentinelObject() to return a non-null value. PriorityQueue<MyObject> pq = new MyQueue<MyObject>(numHits); // save the 'top' element, which is guaranteed to not be null. MyObject pqTop = pq.top(); <...> // now in order to add a new element, which is 'better' than top (after // you've verified it is better), it is as simple as: pqTop.change(). pqTop = pq.updateTop();NOTE: if this method returns a non-null value, it will be called by thePriorityQueue(int,boolean)constructorsize()times, relying on a new object to be returned and will not check if it's null again. Therefore you should ensure any call to this method creates a new instance and behaves consistently, e.g., it cannot return null if it previously returned non-null.- Returns:
- the sentinel object to use to pre-populate the queue, or null if sentinel objects are not supported.
 
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addAdds an Object to a PriorityQueue in log(size) time. If one tries to add more objects than maxSize from initialize anArrayIndexOutOfBoundsExceptionis thrown.- Returns:
- the new 'top' element in the queue.
 
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insertWithOverflowAdds an Object to a PriorityQueue in log(size) time. It returns the object (if any) that was dropped off the heap because it was full. This can be the given parameter (in case it is smaller than the full heap's minimum, and couldn't be added), or another object that was previously the smallest value in the heap and now has been replaced by a larger one, or null if the queue wasn't yet full with maxSize elements.
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topReturns the least element of the PriorityQueue in constant time.
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popRemoves and returns the least element of the PriorityQueue in log(size) time.
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updateTopShould be called when the Object at top changes values. Still log(n) worst case, but it's at least twice as fast topq.top().change(); pq.updateTop(); instead ofo = pq.pop(); o.change(); pq.push(o); - Returns:
- the new 'top' element.
 
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sizepublic final int size()Returns the number of elements currently stored in the PriorityQueue.
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clearpublic final void clear()Removes all entries from the PriorityQueue.
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getHeapArrayThis method returns the internal heap array as Object[]. lucene.internal
 
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