Package com.stardog.stark.query

Interface QueryResult<T>

All Superinterfaces:

java.lang.AutoCloseable, CloseableIterator<T>, java.util.Iterator<T>

All Known Subinterfaces:

BooleanQueryResult, GraphQueryResult, PathQueryResult, SelectQueryResult

All Known Implementing Classes:

AsyncGraphQueryResult, AsyncSelectQueryResult, IteratorAsBooleanQueryResult, IteratorAsGraphQueryResult, IteratorAsPathQueryResult, IteratorAsTupleQueryResult, PathsAsTupleQueryResult, TuplesAsPathQueryResult

public interface QueryResult<T>
extends CloseableIterator<T>

The results of executing a Query

Since:

1.0

Version:

1.0

Author:

Michael Grove

Nested Class Summary

Nested classes/interfaces inherited from interface com.complexible.common.base.CloseableIterator

CloseableIterator.AbstractCloseableIterator<T>, CloseableIterator.DelegatingCloseableIterator<T>, CloseableIterator.EmptyCloseableIterator<T>

Method Summary

Modifier and Type	Method	Description
void	close()	Close the query results and return any resources in use back to the system.
boolean	hasNext()
default Options	metadata()	Return any metadata associated with the query results, such as runtime, number of results, etc.
T	next()
default java.util.stream.Stream<T>	stream()	Return the results as a Stream.

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Method Detail

metadata

@Nonnull
default Options metadata()

Return any metadata associated with the query results, such as runtime, number of results, etc.

Returns:

the metadata

close

void close()

Close the query results and return any resources in use back to the system. This *must* be called on all result sets to avoid resource leaks.

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface CloseableIterator<T>

Throws:

java.lang.RuntimeException - if there was a fatal error while closing

Implementation Requirements:

Once closed, a result cannot be re-used. Additionally, close is idempotent.

hasNext

boolean hasNext()

Specified by:

hasNext in interface java.util.Iterator<T>

Implementation Requirements:

A closed result set should return `false`

next

T next()

Specified by:

next in interface java.util.Iterator<T>

Throws:

java.lang.IllegalStateException - if the results have been closed

stream

default java.util.stream.Stream<T> stream()

Return the results as a Stream. The `Stream` *must be* closed when no longer in use so that the results are closed. Optionally, the caller can close the results directly after using the `Stream`.

Returns:

the results as a stream

Throws:

java.lang.IllegalStateException - Obtaining the stream, or iterating through the stream can throw this exception of the underlying results are closed at any time.

Implementation Notes:

The underlying `Stream` is `Spliterator.IMMUTABLE | Spliterator.NONNULL` and *NOT* parallel. Additionally, the `Stream` uses ClosingSpliterator to *auto-close* these results when the last item is iterated over in an effort to help users who are forgetful about closing Streams since that is not common.