1 /*

     2  * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  */

    23 

    24 package org.reactivestreams.tck.flow.support;

    25 

    26 import java.util.Collections;

    27 import java.util.Iterator;

    28 import java.util.concurrent.Executor;

    29 

    30 import org.reactivestreams.example.unicast.AsyncIterablePublisher;

    31 

    32 public class HelperPublisher<T> extends AsyncIterablePublisher<T> {

    33 

    34     public HelperPublisher(final int from, final int to, final Function<Integer, T> create, final Executor executor) {

    35         super(new Iterable<T>() {

    36           { if(from > to) throw new IllegalArgumentException("from must be equal or greater than to!"); }

    37           @Override public Iterator<T> iterator() {

    38             return new Iterator<T>() {

    39               private int at = from;

    40               @Override public boolean hasNext() { return at < to; }

    41               @Override public T next() {

    42                 if (!hasNext()) return Collections.<T>emptyList().iterator().next();

    43                 else try {

    44                   return create.apply(at++);

    45                 } catch (Throwable t) {

    46                   throw new IllegalStateException(String.format("Failed to create element for id %d!", at - 1), t);

    47                 }

    48               }

    49               @Override public void remove() { throw new UnsupportedOperationException(); }

    50             };

    51           }

    52         }, executor);

    53     }

    54 }