com.hazelcast.org.codehaus.commons.compiler.util.iterator.IteratorCollection Maven / Gradle / Ivy
/*
* 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. 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.commons.compiler.util.iterator;
import java.util.AbstractCollection;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import com.hazelcast.org.codehaus.commons.nullanalysis.Nullable;
/**
* A {@link java.util.Collection} that lazily reads its elements from an {@link java.util.Iterator}.
*
* In other words, you can call {@link #iterator()} as often as you want, but the {@link IteratorCollection} will
* iterate over its delegate only once.
*
*
* @param The element type of the iterator and the collection
*/
public
class IteratorCollection extends AbstractCollection {
/**
* The delegate.
*/
private final Iterator iterator;
/**
* Lazily-filled collection of the elements delivered by the delegate.
*/
private final List elements = new ArrayList();
public
IteratorCollection(Iterator iterator) { this.iterator = iterator; }
@Override public Iterator
iterator() {
return new Iterator() {
@Nullable private Iterator elementsIterator = IteratorCollection.this.elements.iterator();
@Override public T
next() {
Iterator ei = this.elementsIterator;
if (ei != null) {
if (ei.hasNext()) return ei.next();
this.elementsIterator = null;
}
T o = IteratorCollection.this.iterator.next();
IteratorCollection.this.elements.add(o);
return o;
}
@Override public boolean
hasNext() {
return (
(this.elementsIterator != null && this.elementsIterator.hasNext())
|| IteratorCollection.this.iterator.hasNext()
);
}
@Override public void
remove() { throw new UnsupportedOperationException(); }
};
}
@Override public int
size() {
int size = 0;
for (@SuppressWarnings("unused") Object o : this) ++size;
return size;
}
}