Package com.googlecode.cqengine.resultset.connective

Class ResultSetIntersection<O>

java.lang.Object

com.googlecode.cqengine.resultset.ResultSet<O>

com.googlecode.cqengine.resultset.connective.ResultSetIntersection<O>

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<O>

public class ResultSetIntersection<O>
extends ResultSet<O>

A ResultSet which provides a view onto the intersection of other ResultSets.

Author:

Niall Gallagher

Constructor Summary

Constructors

Constructor	Description
ResultSetIntersection(Iterable<ResultSet<O>> resultSets, Query<O> query, QueryOptions queryOptions)
ResultSetIntersection(Iterable<ResultSet<O>> resultSets, Query<O> query, QueryOptions queryOptions, boolean indexMergeStrategyEnabled)

Method Summary

Modifier and Type	Method	Description
void	close()	Closes all of the underlying ResultSets.
boolean	contains(O object)	Returns true if the given object is contained in all underlying ResultSets.
int	getMergeCost()	Returns the merge cost from the underlying ResultSet with the lowest merge cost.
Query<O>	getQuery()	Returns the query for which this ResultSet provides results.
QueryOptions	getQueryOptions()	Returns the query options associated with the query.
int	getRetrievalCost()	Returns the retrieval cost from the underlying ResultSet which has the lowest merge cost.
Iterator<O>	iterator()	Returns an Iterator over objects matching the query for which this ResultSet was constructed.
boolean	matches(O object)	Similar to the ResultSet.contains(Object) method, but checks for logical containment in the ResultSet as opposed to physical containment in the ResultSet.
int	size()	Returns the number of objects which would be returned by this ResultSet if iterated.

Methods inherited from class com.googlecode.cqengine.resultset.ResultSet

isEmpty, isNotEmpty, spliterator, stream, uniqueResult

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach

Constructor Detail

ResultSetIntersection

public ResultSetIntersection(Iterable<ResultSet<O>> resultSets,
                             Query<O> query,
                             QueryOptions queryOptions)

ResultSetIntersection

public ResultSetIntersection(Iterable<ResultSet<O>> resultSets,
                             Query<O> query,
                             QueryOptions queryOptions,
                             boolean indexMergeStrategyEnabled)

Method Detail

iterator

public Iterator<O> iterator()

Description copied from class: ResultSet

Returns an Iterator over objects matching the query for which this ResultSet was constructed.

Specified by:

iterator in interface Iterable<O>

Specified by:

iterator in class ResultSet<O>

Returns:

An Iterator over objects matching the query for which this ResultSet was constructed

contains

public boolean contains(O object)

Returns true if the given object is contained in all underlying ResultSets.

Specified by:

contains in class ResultSet<O>

Parameters:

object - An object to check if contained

Returns:

true if the given object is contained in all underlying ResultSets, false if it is not contained in one or more ResultSets or if there are no underlying result sets

matches

public boolean matches(O object)

Description copied from class: ResultSet

Similar to the ResultSet.contains(Object) method, but checks for logical containment in the ResultSet as opposed to physical containment in the ResultSet. Determines if the given object would be contained in the ResultSet, by testing if the given object matches the query for which this ResultSet was generated, instead of actually checking if the object is contained in appropriate indexes.

This method will typically make the determination by evaluating the query on the given object on-the-fly without accessing indexes, however in some cases this method might delegate to the ResultSet.contains(Object) method to make the determination.

This method will perform better than ResultSet.contains(Object) in cases where querying indexes is more expensive than querying attributes, which is usually the case.

Specified by:

matches in class ResultSet<O>

Parameters:

object - The object to check for logical containment in this ResultSet

Returns:

True if this ResultSet logically contains the given object, false if it does not

size

public int size()

Description copied from class: ResultSet

Returns the number of objects which would be returned by this ResultSet if iterated.

Note that the cost of calling this method depends on the query for which it was constructed.

For simple queries where a single query is supplied and a matching index exists, or where several such simple queries are supplied and are connected using a simple Or query, calculating the size via this method will be cheaper than iterating through the ResultSet and counting the number of objects individually.

For more complex queries, where intersections must be performed or where no suitable indexes exist, calling this method can be non-trivial, but it will always be at least as cheap as iterating through the ResultSet and counting the number of objects individually.

Specified by:

size in class ResultSet<O>

Returns:

The number of objects which would be returned by this ResultSet if iterated

getRetrievalCost

public int getRetrievalCost()

Returns the retrieval cost from the underlying ResultSet which has the lowest merge cost.

Specified by:

getRetrievalCost in class ResultSet<O>

Returns:

the retrieval cost from the underlying ResultSet which has the lowest merge cost

getMergeCost

public int getMergeCost()

Returns the merge cost from the underlying ResultSet with the lowest merge cost.

Specified by:

getMergeCost in class ResultSet<O>

Returns:

the merge cost from the underlying ResultSet with the lowest merge cost

close

public void close()

Closes all of the underlying ResultSets.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Specified by:

close in class ResultSet<O>

getQuery

public Query<O> getQuery()

Description copied from class: ResultSet

Returns the query for which this ResultSet provides results.

Specified by:

getQuery in class ResultSet<O>

Returns:

The query for which this ResultSet provides results.

getQueryOptions

public QueryOptions getQueryOptions()

Description copied from class: ResultSet

Returns the query options associated with the query.

Specified by:

getQueryOptions in class ResultSet<O>

Returns:

The query options associated with the query.