com.codepoetics.protonpack

Class StreamUtils

java.lang.Object

com.codepoetics.protonpack.StreamUtils

public final class StreamUtils
extends java.lang.Object

Utility class providing static methods for performing various operations on Streams.

Method Summary

Modifier and Type	Method and Description
static java.util.stream.LongStream	indices() Constructs an infinite (although in practice bounded by Long.MAX_VALUE) stream of longs 0, 1, 2, 3...
static <T> java.util.stream.Stream<T>	skipUntil(java.util.stream.Stream<T> source, java.util.function.Predicate<T> condition) Construct a stream which skips values from the source stream for as long as they do not meet the supplied condition, then streams every remaining value as soon as the first value is found which does meet the condition.
static <T> java.util.stream.Stream<T>	skipWhile(java.util.stream.Stream<T> source, java.util.function.Predicate<T> condition) Construct a stream which skips values from the source stream for as long as they meet the supplied condition, then streams every remaining value as soon as the first value is found which does not meet the condition.
static <T> java.util.stream.Stream<T>	takeUntil(java.util.stream.Stream<T> source, java.util.function.Predicate<T> condition) Construct a stream which takes values from the source stream until one of them meets the supplied condition, and then stops.
static <T> java.util.stream.Stream<T>	takeWhile(java.util.stream.Stream<T> source, java.util.function.Predicate<T> condition) Construct a stream which takes values from the source stream for as long as they meet the supplied condition, and stops as soon as a value is encountered which does not meet the condition.
static <T> java.util.stream.Stream<T>	unfold(T seed, java.util.function.Function<T,java.util.Optional<T>> generator) Construct a stream which takes the seed value and applies the generator to create the next value, feeding each new value back into the generator to create subsequent values.
static <L,R,O> java.util.stream.Stream<O>	zip(java.util.stream.Stream<L> lefts, java.util.stream.Stream<R> rights, java.util.function.BiFunction<L,R,O> combiner) Zip together the "left" and "right" streams until either runs out of values.
static <T> java.util.stream.Stream<Indexed<T>>	zipWithIndex(java.util.stream.Stream<T> source) Zip the source stream together with the stream of indices() to provide a stream of indexed values.

Methods inherited from class java.lang.Object

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

Method Detail

indices

public static java.util.stream.LongStream indices()

Constructs an infinite (although in practice bounded by Long.MAX_VALUE) stream of longs 0, 1, 2, 3... for use as indices.

Returns:

The stream of longs.

zipWithIndex

public static <T> java.util.stream.Stream<Indexed<T>> zipWithIndex(java.util.stream.Stream<T> source)

Zip the source stream together with the stream of indices() to provide a stream of indexed values.

Type Parameters:

T - The type over which the source stream streams.

Parameters:

source - The source stream.

Returns:

A stream of indexed values.

zip

public static <L,R,O> java.util.stream.Stream<O> zip(java.util.stream.Stream<L> lefts,
                                                     java.util.stream.Stream<R> rights,
                                                     java.util.function.BiFunction<L,R,O> combiner)

Zip together the "left" and "right" streams until either runs out of values. Each pair of values is combined into a single value using the supplied combiner function.

Type Parameters:

L - The type over which the "left" stream streams.

R - The type over which the "right" stream streams.

O - The type created by the combiner out of pairs of "left" and "right" values, over which the resulting stream streams.

Parameters:

lefts - The "left" stream to zip.

rights - The "right" stream to zip.

combiner - The function to combine "left" and "right" values.

Returns:

The constructed stream of zipped values.

takeWhile

public static <T> java.util.stream.Stream<T> takeWhile(java.util.stream.Stream<T> source,
                                                       java.util.function.Predicate<T> condition)

Construct a stream which takes values from the source stream for as long as they meet the supplied condition, and stops as soon as a value is encountered which does not meet the condition.

Type Parameters:

T - The type over which the stream streams.

Parameters:

source - The source stream.

condition - The condition to apply to elements of the source stream.

Returns:

The constructed stream.

takeUntil

public static <T> java.util.stream.Stream<T> takeUntil(java.util.stream.Stream<T> source,
                                                       java.util.function.Predicate<T> condition)

Construct a stream which takes values from the source stream until one of them meets the supplied condition, and then stops.

Type Parameters:

T - The type over which the stream streams.

Parameters:

source - The source stream.

condition - The condition to apply to elements of the source stream.

Returns:

The constructed stream.

skipWhile

public static <T> java.util.stream.Stream<T> skipWhile(java.util.stream.Stream<T> source,
                                                       java.util.function.Predicate<T> condition)

Construct a stream which skips values from the source stream for as long as they meet the supplied condition, then streams every remaining value as soon as the first value is found which does not meet the condition.

Type Parameters:

T - The type over which the stream streams.

Parameters:

source - The source stream.

condition - The condition to apply to elements of the source stream.

Returns:

The constructed stream.

skipUntil

public static <T> java.util.stream.Stream<T> skipUntil(java.util.stream.Stream<T> source,
                                                       java.util.function.Predicate<T> condition)

Construct a stream which skips values from the source stream for as long as they do not meet the supplied condition, then streams every remaining value as soon as the first value is found which does meet the condition.

Type Parameters:

T - The type over which the stream streams.

Parameters:

source - The source stream.

condition - The condition to apply to elements of the source stream.

Returns:

The constructed stream.

unfold

public static <T> java.util.stream.Stream<T> unfold(T seed,
                                                    java.util.function.Function<T,java.util.Optional<T>> generator)

Construct a stream which takes the seed value and applies the generator to create the next value, feeding each new value back into the generator to create subsequent values. If the generator returns Optional.empty(), then the stream has no more values.

Type Parameters:

T - The type over which the stream streams.

Parameters:

seed - The seed value.

generator - The generator to use to create new values.

Returns:

The constructed stream.