com.amazon.carbonado.cursor
Class UnionCursor<S>

java.lang.Object
  com.amazon.carbonado.cursor.AbstractCursor<S>
      com.amazon.carbonado.cursor.UnionCursor<S>

All Implemented Interfaces:

Cursor<S>

public class UnionCursor<S>
extends AbstractCursor<S>

Wraps two Cursors and performs a set union operation. In boolean logic, this is an or operation.

Both cursors must return results in the same order. Ordering is preserved by the union.

Author:

Brian S O'Neill

See Also:

IntersectionCursor, DifferenceCursor, SymmetricDifferenceCursor

Constructor Summary

UnionCursor(Cursor<S> left, Cursor<S> right, Comparator<S> order)

Method Summary

void	close() Call close to release any resources being held by this cursor.
boolean	hasNext() Returns true if this cursor has more elements.
S	next() Returns the next element from this cursor.

Methods inherited from class com.amazon.carbonado.cursor.AbstractCursor

copyInto, copyInto, skipNext, toList, toList

Methods inherited from class java.lang.Object

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

Constructor Detail

UnionCursor

public UnionCursor(Cursor<S> left,
                   Cursor<S> right,
                   Comparator<S> order)

Parameters:

left - cursor to wrap

right - cursor to wrap

order - describes sort ordering of wrapped cursors, which must be a total ordering

Method Detail

close

public void close()
           throws FetchException

Description copied from interface: Cursor

Call close to release any resources being held by this cursor. Further operations on this cursor will behave as if there are no results.

Throws:

FetchException

hasNext

public boolean hasNext()
                throws FetchException

Description copied from interface: Cursor

Returns true if this cursor has more elements. In other words, returns true if next would return an element rather than throwing an exception.

Throws:

FetchException - if storage layer throws an exception

next

public S next()
       throws FetchException

Description copied from interface: Cursor

Returns the next element from this cursor. This method may be called repeatedly to iterate through the results.

Throws:

FetchException - if storage layer throws an exception