crossWith()

Cross every element of the input stream with every element of the given source, emitting them to the output stream as a Pair<INPUT, CROSS>.

Implementation Notes

This gather pairs up each element of the input stream with some source of other elements, which do not have to be of the same type. While it is possible to have the source of elements be empty, the resulting output stream would be too so it is not recommended (this condition is not checked). It is also possible for the source to be infinite, which would pair a single element from the input with whatever the source produces, which may make sense in a narrow set of cases (the implementation does not check for this condition).

Signatures

Note there are four possible types for the soruce of crossing elements.

crossWith(Iterator<CROSS> source)
crossWith(Iterable<CROSS> source)
crossWith(Stream<CROSS> source)
crossWith(CROSS... source)

source Must be non-null

Examples

Cross the input stream with an `Iterator`

final Stream<String> input = Stream.of("A", "B", "C");
final Iterator<Integer> cross = List.of(1, 2, 3).iterator();

input
    .gather(Gatherers4j.crossWith(cross))
    .toList();

// [
//    Pair("A", 1), Pair("A", 2), Pair("A", 3),
//    Pair("B", 1), Pair("B", 2), Pair("B", 3),
//    Pair("C", 1), Pair("C", 2), Pair("C", 3)
// ]

Cross the input stream with an `Iterable`

final Stream<String> input = Stream.of("A", "B", "C");
final Iterable<Integer> cross = List.of(1, 2, 3);   // `List` implements `Iterable`

input
    .gather(Gatherers4j.crossWith(cross))
    .toList();

// [
//    Pair("A", 1), Pair("A", 2), Pair("A", 3),
//    Pair("B", 1), Pair("B", 2), Pair("B", 3),
//    Pair("C", 1), Pair("C", 2), Pair("C", 3)
// ]

Cross the input stream with another `Stream`

final Stream<String> input = Stream.of("A", "B", "C");
final Stream<Integer> cross = Stream.of(1, 2, 3);

input
    .gather(Gatherers4j.crossWith(cross))
    .toList();

// [
//    Pair("A", 1), Pair("A", 2), Pair("A", 3),
//    Pair("B", 1), Pair("B", 2), Pair("B", 3),
//    Pair("C", 1), Pair("C", 2), Pair("C", 3)
// ]

Cross the input stream with a source provided as varargs

final Stream<String> input = Stream.of("A", "B", "C");

input
    .gather(Gatherers4j.crossWith(1, 2, 3))
    .toList();

// [
//    Pair("A", 1), Pair("A", 2), Pair("A", 3),
//    Pair("B", 1), Pair("B", 2), Pair("B", 3),
//    Pair("C", 1), Pair("C", 2), Pair("C", 3)
// ]