001/************************************************************************
002 * Licensed under Public Domain (CC0)                                    *
003 *                                                                       *
004 * To the extent possible under law, the person who associated CC0 with  *
005 * this code has waived all copyright and related or neighboring         *
006 * rights to this code.                                                  *
007 *                                                                       *
008 * You should have received a copy of the CC0 legalcode along with this  *
009 * work. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.*
010 ************************************************************************/
011
012package org.reactivestreams.tck.support;
013
014import java.util.Collections;
015import java.util.Iterator;
016import java.util.concurrent.Executor;
017import org.reactivestreams.Subscription;
018import org.reactivestreams.Subscriber;
019import org.reactivestreams.Publisher;
020import org.reactivestreams.example.unicast.AsyncIterablePublisher;
021
022public class HelperPublisher<T> extends AsyncIterablePublisher<T> {
023  
024    public HelperPublisher(final int from, final int to, final Function<Integer, T> create, final Executor executor) {
025        super(new Iterable<T>() {
026          { if(from > to) throw new IllegalArgumentException("from must be equal or greater than to!"); }
027          @Override public Iterator<T> iterator() {
028            return new Iterator<T>() {
029              private int at = from;
030              @Override public boolean hasNext() { return at < to; }
031              @Override public T next() {
032                if (!hasNext()) return Collections.<T>emptyList().iterator().next();
033                else try {
034                  return create.apply(at++);
035                } catch (Throwable t) {
036                  throw new IllegalStateException(String.format("Failed to create element for id %d!", at - 1), t);
037                }
038              }
039              @Override public void remove() { throw new UnsupportedOperationException(); }
040            };
041          }
042        }, executor);
043    }
044}