xxl.cursors
Class Merger

java.lang.Object
  |
  +--xxl.cursors.Merger

public class Merger

extends java.lang.Object

implements Cursor

A Merger-object serializes inputs with respect to a given comparator.

Field Summary

protected Cursor[]	cursors
protected Cursor	minCursor
protected Queue	queue The queue used to merge inputs.

Constructor Summary

Merger(java.util.Iterator[] iterators)
Creates a new Merger.

Merger(java.util.Iterator[] iterators, java.util.Comparator comparator)
Creates a new Merger.

Merger(java.util.Iterator[] iterators, Queue queue)
Creates a new Merger.

Merger(java.util.Iterator iterator0, java.util.Iterator iterator1)
Creates a new Merger for two input-iterators.

Merger(java.util.Iterator iterator0, java.util.Iterator iterator1, java.util.Comparator comparator)
Creates a new Merger for two input-iterators.

Merger(java.util.Iterator iterator0, java.util.Iterator iterator1, Queue queue)
Creates a new Merger for two input-iterators.

Method Summary

void	close() Closes the Cursor.
boolean	hasNext() Returns true if the iteration has more elements.
java.lang.Object	next() Returns the next element in the iteration.
java.lang.Object	peek() Shows the next element in the iteration without removing it.
void	remove() Removes from the underlying collection the last element returned by the iterator (optional operation).
void	reset() Resets the Cursor to its initial state.
boolean	supportsPeek() Returns true if the peek operation is supported by this PeekIterator (Always returns true).
void	update(java.lang.Object object) Replaces the object that was returned by the last call to next() or peek().

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

queue

protected Queue queue

The queue used to merge inputs.

minCursor

protected Cursor minCursor

cursors

protected Cursor[] cursors

Constructor Detail

Merger

public Merger(java.util.Iterator[] iterators,
              Queue queue)

Creates a new Merger.

Parameters:

iterators - input-iterators to be merged

queue - Queue used for merging

Merger

public Merger(java.util.Iterator[] iterators,
              java.util.Comparator comparator)

Creates a new Merger.

Parameters:

iterators - input-iterators to be merged

comparator - Comparator used to create the queue for merging

Merger

public Merger(java.util.Iterator[] iterators)

Creates a new Merger.

Parameters:

iterators - the Iterator pointing to the input-iterators

Merger

public Merger(java.util.Iterator iterator0,
              java.util.Iterator iterator1,
              Queue queue)

Creates a new Merger for two input-iterators.

Parameters:

iterator0 - input-iterator 0

iterator0 - input-iterator 1

queue - the Queue used for merging

Merger

public Merger(java.util.Iterator iterator0,
              java.util.Iterator iterator1,
              java.util.Comparator comparator)

Creates a new Merger for two input-iterators.

Parameters:

iterator0 - input-iterator 0

iterator0 - input-iterator 1

comparator - the Comparator used to create the Heap for merging

Merger

public Merger(java.util.Iterator iterator0,
              java.util.Iterator iterator1)

Creates a new Merger for two input-iterators.

Parameters:

iterator0 - input-iterator 0

iterator0 - input-iterator 1

Method Detail

close

public void close()

Closes the Cursor. Signals the cursor to cleanup resources, close files, etc. After a call to close() calls to methods like next() or peek() are not guarantied to yield proper results.

Specified by:

close in interface Cursor

hasNext

public boolean hasNext()

Returns true if the iteration has more elements.

Specified by:

hasNext in interface Cursor

Returns:

true if the iterator has more elements.

next

public java.lang.Object next()
                      throws java.util.NoSuchElementException

Returns the next element in the iteration.

Specified by:

next in interface Cursor

Returns:

the next element in the iteration.

Throws:

java.util.NoSuchElementException - iteration has no more elements.

peek

public java.lang.Object peek()
                      throws java.util.NoSuchElementException

Shows the next element in the iteration without removing it.

Specified by:

peek in interface Cursor

Returns:

the next element in the iteration.

Throws:

java.util.NoSuchElementException - iteration has no more elements.

java.lang.UnsupportedOperationException - if the peek operation is not supported by this PeekIterator.

remove

public void remove()
            throws java.lang.UnsupportedOperationException,
                   java.lang.IllegalStateException

Removes from the underlying collection the last element returned by the iterator (optional operation).

Specified by:

remove in interface Cursor

Throws:

java.lang.IllegalStateException - if the next method has not yet been called, or the remove method has already been called after the last call to the next method.

java.lang.UnsupportedOperationException - if the remove operation is not supported by this PeekIterator.

reset

public void reset()
           throws java.lang.UnsupportedOperationException

Resets the Cursor to its initial state.

Specified by:

reset in interface Cursor

supportsPeek

public boolean supportsPeek()

Returns true if the peek operation is supported by this PeekIterator (Always returns true).

Specified by:

supportsPeek in interface Cursor

Returns:

true if the peek operation is supported by this PeekIterator.

update

public void update(java.lang.Object object)
            throws java.lang.UnsupportedOperationException

Replaces the object that was returned by the last call to next() or peek(). This operation must not be called after a call to hasNext(). It should follow a call to next() or peek().

Specified by:

update in interface Cursor

Parameters:

object - the object that replaces the object returned by the last call to next() or peek()