org.openimaj.util.stream

Interface Stream<T>

Type Parameters:

T - The type of data item in the stream

All Superinterfaces:

Iterable<T>, Iterator<T>

All Known Subinterfaces:

StreamingDataset<INSTANCE>

All Known Implementing Classes:

AbstractIRCStreamDataset, AbstractStream, AbstractTwitterSearchDataset, AbstractTwitterStatusesFilterDataset, AbstractTwitterStreamDataset, BasicIRCStreamDataset, BlockingDroppingBufferedStream, BufferedReaderStream, CollectionStream, ContextRoundRobinTwitterSearchAPIDataset, ContextStreamCombiner, MetaPayloadStreamCombiner, RoundRobinStreamCombiner, RoundRobinTwitterSearchAPIDataset, StreamCombiner, TwitterSearchDataset, TwitterStreamDataset, TwitterStreamFilterDataset, WikipediaEditsDataset

public interface Stream<T>
extends Iterator<T>, Iterable<T>

Interface describing a stream of data items. Streams are sequences of items supporting both sequential and parallel bulk operations. Streams support lazy transformative operations (transforming a stream to another stream) such as filter(Predicate) and map(Function), and consuming operations, such as forEach(Operation) and Iterator.next().

Streams may be either bounded or infinite in length. Once an item has been extracted from a stream, it is said to be consumed and is no longer available for operations on the stream.

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

Method Summary

Methods

Modifier and Type	Method and Description
Stream<T>	filter(Predicate<T> filter) Transform the stream by creating a view that consists of only the items that match the given Predicate.
void	forEach(Operation<T> op) Apply the given Operation to each item in the stream.
int	forEach(Operation<T> operation, int limit) Apply the given Operation to each item in the stream.
void	forEach(Operation<T> operation, Predicate<T> stopPredicate) Apply the given Operation to each item in the stream.
<R> Stream<R>	map(Function<T,R> mapper) Transform the stream by creating a new stream that transforms the items in this stream with the given Function.
<R> Stream<R>	map(MultiFunction<T,R> mapper) Transform the stream by creating a new stream that transforms the items in this stream with the given Function.
void	parallelForEach(Operation<T> op) Apply the given Operation to each item in the stream, making use of multiple threads.
void	parallelForEach(Operation<T> op, ThreadPoolExecutor pool) Apply the given Operation to each item in the stream, making use of multiple threads.
<R> Stream<R>	transform(Function<Stream<T>,Stream<R>> transform) Transform the stream using the given function to transform the items in this stream.

Methods inherited from interface java.util.Iterator

hasNext, next, remove

Methods inherited from interface java.lang.Iterable

iterator

Method Detail

forEach

void forEach(Operation<T> op)

Apply the given Operation to each item in the stream. Items are presented to the Operation in the order they appear in the stream.

Note: for an unbounded stream, this method will never return unless some form of exception is raised.

Parameters:

op - the Operation to apply

forEach

void forEach(Operation<T> operation,
           Predicate<T> stopPredicate)

Apply the given Operation to each item in the stream. Items are presented to the Operation in the order they appear in the stream. The given Predicate can be used to stop processing of the stream once some condition is met.

Note: for an unbounded stream, this method will never return unless some form of exception is raised or the condition of the stopPredicate is met.

Parameters:

operation - the Operation to apply

stopPredicate - a predicate representing a condition that once met causes processing to stop

forEach

int forEach(Operation<T> operation,
          int limit)

Apply the given Operation to each item in the stream. Items are presented to the Operation in the order they appear in the stream. The given Predicate can be used to stop processing of the stream once some condition is met.

Note: for an unbounded stream, this method will never return unless some form of exception is raised or the condition of the stopPredicate is met.

Parameters:

operation - the Operation to apply

limit - the number of items to read from the stream

Returns:

the number of items read

parallelForEach

void parallelForEach(Operation<T> op)

Apply the given Operation to each item in the stream, making use of multiple threads. The order in which operations are performed on the stream is not guaranteed.

This method is intended to be a shortcut to calling Parallel.forEachUnpartitioned(Iterator, Operation).

Note: for an unbounded stream, this method will never return unless some form of exception is raised.

Parameters:

op - the Operation to apply

parallelForEach

void parallelForEach(Operation<T> op,
                   ThreadPoolExecutor pool)

Apply the given Operation to each item in the stream, making use of multiple threads. The order in which operations are performed on the stream is not guaranteed.

This method is intended to be a shortcut to calling Parallel.forEachUnpartitioned(Iterator, Operation, ThreadPoolExecutor).

Note: for an unbounded stream, this method will never return unless some form of exception is raised.

Parameters:

op - the Operation to apply

pool - the thread pool.

filter

Stream<T> filter(Predicate<T> filter)

Transform the stream by creating a view that consists of only the items that match the given Predicate.

Parameters:

filter - the predicate

Returns:

a new stream consisting of the matched items from this stream

map

<R> Stream<R> map(Function<T,R> mapper)

Transform the stream by creating a new stream that transforms the items in this stream with the given Function.

Parameters:

mapper - the function to apply

Returns:

a new stream with transformed items from this stream

map

<R> Stream<R> map(MultiFunction<T,R> mapper)

Transform the stream by creating a new stream that transforms the items in this stream with the given Function.

Parameters:

mapper - the function to apply

Returns:

a new stream with transformed items from this stream

transform

<R> Stream<R> transform(Function<Stream<T>,Stream<R>> transform)

Transform the stream using the given function to transform the items in this stream.

Parameters:

transform - the transform function

Returns:

a new stream with transformed items from this stream