com.hazelcast.org.codehaus.janino.util.iterator.ProducerIterator Maven / Gradle / Ivy
/*
* Janino - An embedded Java[TM] com.hazelcast.com.iler
*
* Copyright (c) 2001-2010 Arno Unkrig. All rights reserved.
* Copyright (c) 2015-2016 TIBCO Software Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
* following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other materials provided with the distribution.
* 3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.hazelcast.org.codehaus.janino.util.iterator;
import java.util.Iterator;
import java.util.NoSuchElementException;
import com.hazelcast.org.codehaus.com.hazelcast.com.ons.nullanalysis.Nullable;
import com.hazelcast.org.codehaus.janino.util.Producer;
/**
* An {@link Iterator} that iterates over all the objects produced by a delegate {@link Producer}.
*
* @param The type of the products and the iterator elements
* @see Producer
*/
public
class ProducerIterator implements Iterator {
private final Producer producer;
private static final Object UNKNOWN = new Object();
@Nullable private static final Object AT_END = null;
@Nullable private Object nextElement = ProducerIterator.UNKNOWN;
public
ProducerIterator(Producer producer) { this.producer = producer; }
@Override public boolean
hasNext() {
if (this.nextElement == ProducerIterator.UNKNOWN) this.nextElement = this.producer.produce();
return this.nextElement != ProducerIterator.AT_END;
}
@Override public T
next() {
if (this.nextElement == ProducerIterator.UNKNOWN) this.nextElement = this.producer.produce();
if (this.nextElement == ProducerIterator.AT_END) throw new NoSuchElementException();
@SuppressWarnings("unchecked") T result = (T) this.nextElement;
this.nextElement = ProducerIterator.UNKNOWN;
assert result != null;
return result;
}
@Override public void
remove() { throw new UnsupportedOperationException("remove"); }
}