70 lines
2.9 KiB
Java
70 lines
2.9 KiB
Java
|
|
/*
|
|
* Janino - An embedded Java[TM] compiler
|
|
*
|
|
* Copyright (c) 2001-2010, Arno Unkrig
|
|
* 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. The name of the author may not be used to endorse or promote products derived from this software without
|
|
* specific prior written permission.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 org.codehaus.janino.util.iterator;
|
|
|
|
import java.util.Iterator;
|
|
import java.util.NoSuchElementException;
|
|
|
|
import org.codehaus.janino.util.Producer;
|
|
|
|
/**
|
|
* An {@link Iterator} that iterates over all the objects produced by a delegate {@link Producer}.
|
|
*
|
|
* @param <T> The type of the products and the iterator elements
|
|
* @see Producer
|
|
*/
|
|
public
|
|
class ProducerIterator<T> implements Iterator<T> {
|
|
|
|
private final Producer<T> producer;
|
|
|
|
private static final Object UNKNOWN = new Object();
|
|
private static final Object AT_END = null;
|
|
private Object nextElement = ProducerIterator.UNKNOWN;
|
|
|
|
public
|
|
ProducerIterator(Producer<T> 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;
|
|
return result;
|
|
}
|
|
|
|
@Override public void
|
|
remove() { throw new UnsupportedOperationException("remove"); }
|
|
}
|