Stream generators

[Paul Sandoz]

On Nov 30, 2012, at 6:41 PM, Joe Bowbeer <joe.bowbeer at gmail.com> wrote:

> My first impression is that there are a lot. Whether they carry their
> weight depends on how difficult it is to implement these directly.
> 

The following:

    <T> Stream<T> repeat(T t)
    <T> Stream<T> repeat(int n, T t)
    <T> Stream<T> repeatedly(Supplier<T> f)

all defer to:

    public static<T> Stream<T> repeatedly(final int n, final Supplier<T> f) {
        Objects.requireNonNull(f);

        if (n < 0) {
            InfiniteIterator<T> iterator = () -> f.get();
            return stream(new StreamSource.ForIterator<>(iterator), StreamOpFlag.IS_ORDERED);
        }
        else {
            final Iterator<T> repeatedly = new Iterator<T>() {
                int c = n;

                @Override
                public boolean hasNext() {
                    return c > 0;
                }

                @Override
                public T next() {
                    if (!hasNext()) {
                        throw new NoSuchElementException();
                    }

                    c--;
                    return f.get();
                }
            };

            return stream(new StreamSource.ForIterator<>(repeatedly), StreamOpFlag.IS_ORDERED);
        }
    }

Paul.