org.hypergraphdb.query.impl
Class PipedResult

java.lang.Object
  org.hypergraphdb.query.impl.PipedResult

All Implemented Interfaces:

java.util.Iterator, HGSearchResult, TwoWayIterator, CloseMe

public class PipedResult
extends java.lang.Object
implements HGSearchResult

A piped query result takes the output of a query, in the form of a HGSearchResult instance and uses it as input to a "pipe" query.

Such a result may be used to implement various query operators (e.g. union, intersection) when one of the operands is an indexed set and can be queried directly by a key.

Author:

Borislav Iordanov

Field Summary

Fields inherited from interface org.hypergraphdb.HGSearchResult

EMPTY

Constructor Summary

PipedResult(HGSearchResult in, KeyBasedQuery pipe, boolean own_in)

Method Summary

void	close() Free all system resources held up by the result set and invalidate it for further use.
java.lang.Object	current() Returns the current element in the result set.
boolean	hasNext()
boolean	hasPrev() Return true if there is a previous element in the current iteration state and false otherwise.
boolean	isOrdered() Return true if the elements in this search result are in ordered and false otherwise.
java.lang.Object	next()
java.lang.Object	prev() Returns the previous element in this iteration.
void	remove()

Methods inherited from class java.lang.Object

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

Constructor Detail

PipedResult

public PipedResult(HGSearchResult in,
                   KeyBasedQuery pipe,
                   boolean own_in)

Parameters:

in - The input query result, can't be null.

pipe - The pipe query, can't be null.

own_in - Specifies whether to close the input result object when this object is closed.

Method Detail

current

public java.lang.Object current()

Description copied from interface: HGSearchResult

Returns the current element in the result set. If there is no current element, java.util.NoSuchElementException is thrown. There is no current element in one of two cases: either the result set is empty or the next method was never invoked.

Specified by:

current in interface HGSearchResult

Returns:

The current element in a HGSearchResult.

close

public void close()

Description copied from interface: HGSearchResult

Free all system resources held up by the result set and invalidate it for further use.

Specified by:

close in interface HGSearchResult

Specified by:

close in interface CloseMe

hasPrev

public boolean hasPrev()

Description copied from interface: TwoWayIterator

Return true if there is a previous element in the current iteration state and false otherwise. After the iterator has been initialized, the value of hasPrev will always be false.

Specified by:

hasPrev in interface TwoWayIterator

prev

public java.lang.Object prev()

Description copied from interface: TwoWayIterator

Returns the previous element in this iteration.

Specified by:

prev in interface TwoWayIterator

remove

public void remove()

Specified by:

remove in interface java.util.Iterator

hasNext

public boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator

next

public java.lang.Object next()

Specified by:

next in interface java.util.Iterator

isOrdered

public boolean isOrdered()

Description copied from interface: HGSearchResult

Return true if the elements in this search result are in ordered and false otherwise. It is assumed that when elements are ordered, they are instances of java.lang.Comparable

Specified by:

isOrdered in interface HGSearchResult