org.hypergraphdb.query.impl

Class PipedResult<Key,Value>

java.lang.Object

org.hypergraphdb.query.impl.PipedResult<Key,Value>

All Implemented Interfaces:

Iterator<Value>, HGSearchResult<Value>, TwoWayIterator<Value>, CloseMe

public class PipedResult<Key,Value>
extends Object
implements HGSearchResult<Value>

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

Constructors

Constructor and Description
PipedResult(HGSearchResult<Key> in, KeyBasedQuery<Key,Value> pipe, boolean own_in)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Free all system resources held up by the result set and invalidate it for further use.
Value	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.
Value	next()
Value	prev() Returns the previous element in this iteration.
void	remove()

Methods inherited from class java.lang.Object

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

Constructor Detail

PipedResult

public PipedResult(HGSearchResult<Key> in,
           KeyBasedQuery<Key,Value> 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 Value 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 if the next method was never invoked.

Specified by:

current in interface HGSearchResult<Value>

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<Value>

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<Value>

prev

public Value prev()

Description copied from interface: TwoWayIterator

Returns the previous element in this iteration.

Specified by:

prev in interface TwoWayIterator<Value>

remove

public void remove()

Specified by:

remove in interface Iterator<Value>

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<Value>

next

public Value next()

Specified by:

next in interface Iterator<Value>

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<Value>