Package no.digipost

Class DiggStreams

java.lang.Object

no.digipost.DiggStreams

public final class DiggStreams
extends Object

Utilities for working with Streams.

Method Summary

Modifier and Type	Method	Description
static <S,K,V> Stream<V>	streamByIndex(S source, IntStream indexes, ObjIntFunction<S,V> resolveValue)	Stream the elements from a container which allows access to the by through an int index, but does not itself offer any means for traversal/iteration/streaming.
static <S,K,V> Stream<V>	streamByIndex(S source, LongStream indexes, ObjLongFunction<S,V> resolveValue)	Stream the elements from a container which allows access to the by through a long index, but does not itself offer any means for traversal/iteration/streaming.
static <S,V> Stream<V>	streamByIntIndex(S source, int endExclusive, ObjIntFunction<S,V> resolveValue)	Stream the elements from a container which allows access to the elements by an int index, but does not itself offer any means for traversal/iteration/streaming.
static <S,K,V> Stream<V>	streamByKey(S source, Stream<K> keys, BiFunction<S,K,V> resolveValue)	Stream the elements from a container which allows access to the by through a key, but does not itself offer any means for traversal/iteration/streaming.
static <S,V> Stream<V>	streamByLongIndex(S source, long endExclusive, ObjLongFunction<S,V> resolveValue)	Stream the elements from a container which allows access to the elements by a long index, but does not itself offer any means for traversal/iteration/streaming.
static <P> Stream<P>	streamPages(int firstPageNum, IntFunction<P> resolvePage, Predicate<? super P> includeWhile)	Generate a stream of objects resolved from an incrementing int (page number), while a predicate is accepting the resolved objects.
static <P> Stream<P>	streamPages(IntFunction<P> resolvePage, Predicate<? super P> includeWhile)	Generate a stream of objects resolved from an incrementing int (page number), while a predicate is accepting the resolved objects.
static <E> Stream<E>	streamWhileNonEmpty(IntFunction<? extends Collection<E>> resolveCollection)	Stream elements retrieved from resolved collections while they are non-empty.

Methods inherited from class java.lang.Object

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

Method Detail

streamByIntIndex

public static final <S,V> Stream<V> streamByIntIndex(S source,
                                                           int endExclusive,
                                                           ObjIntFunction<S,V> resolveValue)

Stream the elements from a container which allows access to the elements by an int index, but does not itself offer any means for traversal/iteration/streaming. This method will stream all elements from index 0 up to, but not including, the given endExclusive index.

Type Parameters:

V - The type of the resolved elements yielded by the Stream.

S - The type of the source object which yields elements of type V by index.

Parameters:

source - The source object which yields the elements by an index

endExclusive - The end index. This is also effectively the resulting size of the stream

resolveValue - How to query the source object for each index. This can usually be a method reference like S::get or similar.

Returns:

the stream yielding the elements

streamByIndex

public static final <S,K,V> Stream<V> streamByIndex(S source,
                                                                IntStream indexes,
                                                                ObjIntFunction<S,V> resolveValue)

Stream the elements from a container which allows access to the by through an int index, but does not itself offer any means for traversal/iteration/streaming. This method will stream the elements with indexes from the given IntStream.

Type Parameters:

V - The type of the resolved elements yielded by the Stream.

S - The type of the source object which yields elements of type V by index.

Parameters:

source - The source object which yields the elements by an index

indexes - The indexes

resolveValue - How to query the source object for each index. This can usually be a method reference like S::get or similar.

Returns:

the stream yielding the elements

streamByLongIndex

public static final <S,V> Stream<V> streamByLongIndex(S source,
                                                            long endExclusive,
                                                            ObjLongFunction<S,V> resolveValue)

Stream the elements from a container which allows access to the elements by a long index, but does not itself offer any means for traversal/iteration/streaming. This method will stream all elements from index 0 up to, but not including, the given endExclusive index.

Type Parameters:

V - The type of the resolved elements yielded by the Stream.

S - The type of the source object which yields elements of type V by index.

Parameters:

source - The source object which yields the elements by an index

endExclusive - The end index. This is also effectively the resulting size of the stream

resolveValue - How to query the source object for each index. This can usually be a method reference like S::get or similar.

Returns:

the stream yielding the elements

streamByIndex

public static final <S,K,V> Stream<V> streamByIndex(S source,
                                                                LongStream indexes,
                                                                ObjLongFunction<S,V> resolveValue)

Stream the elements from a container which allows access to the by through a long index, but does not itself offer any means for traversal/iteration/streaming. This method will stream the elements with indexes from the given IntStream.

Type Parameters:

V - The type of the resolved elements yielded by the Stream.

S - The type of the source object which yields elements of type V by index.

Parameters:

source - The source object which yields the elements by an index

indexes - The indexes

resolveValue - How to query the source object for each index. This can usually be a method reference like S::get or similar.

Returns:

the stream yielding the elements

streamByKey

public static final <S,K,V> Stream<V> streamByKey(S source,
                                                              Stream<K> keys,
                                                              BiFunction<S,K,V> resolveValue)

Stream the elements from a container which allows access to the by through a key, but does not itself offer any means for traversal/iteration/streaming. This method will stream the elements with keys from the given Stream<K>.

Type Parameters:

V - The type of the resolved elements yielded by the Stream.

S - The type of the source object which yields elements of type V by key.

K - The type of the key used to query elements of type V.

Parameters:

source - The source object which yields the elements by a key

keys - The keys

resolveValue - How to query the source object for each key. This can usually be a method reference like S::get or similar.

Returns:

the stream yielding the elements

streamWhileNonEmpty

public static <E> Stream<E> streamWhileNonEmpty(IntFunction<? extends Collection<E>> resolveCollection)

Stream elements retrieved from resolved collections while they are non-empty. The first empty collection will end the stream.

Type Parameters:

E - The type of the elements in the resolved collections, and elements in the resulting stream

Parameters:

resolveCollection - a function accepting an int indicating the page number and returns a Collection with elements to include in the resulting stream

Returns:

the stream yielding the elements of the resolved collections

streamPages

public static <P> Stream<P> streamPages(IntFunction<P> resolvePage,
                                        Predicate<? super P> includeWhile)

Generate a stream of objects resolved from an incrementing int (page number), while a predicate is accepting the resolved objects. The first object not accepted by the predicate will end the stream.

Parameters:

resolvePage - a function accepting an int indicating the page number and returns a page to include in the resulting stream

includeWhile - the predicate accepting the objects to include in the stream

Returns:

the stream of the resolved objects

streamPages

public static <P> Stream<P> streamPages(int firstPageNum,
                                        IntFunction<P> resolvePage,
                                        Predicate<? super P> includeWhile)

Generate a stream of objects resolved from an incrementing int (page number), while a predicate is accepting the resolved objects. The first object not accepted by the predicate will end the stream.

Parameters:

firstPageNum - the initial page number

resolvePage - a function accepting an int indicating the page number and returns a page to include in the resulting stream

includeWhile - the predicate accepting the objects to include in the stream

Returns:

the stream of the resolved objects