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High performance primitives and utility library.
/*
* Copyright 2014 - 2016 Real Logic Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.agrona.collections;
import java.util.AbstractCollection;
import java.util.Collection;
import java.util.Iterator;
import java.util.function.Function;
/**
* An unmodifiable view of a collection that maps each element in an underlying
* collection into a view.
*
* @param The type of the view.
* @param The type of the underlying element.
*/
public class UnmodifiableCollectionView extends AbstractCollection
{
private final ReusableIterator iterator = new ReusableIterator();
private final Function viewer;
private final Collection elements;
public UnmodifiableCollectionView(final Function viewer, final Collection elements)
{
this.viewer = viewer;
this.elements = elements;
}
/**
* {@inheritDoc}
*/
public int size()
{
return elements.size();
}
/**
* {@inheritDoc}
*/
public Iterator iterator()
{
return iterator.reset();
}
private class ReusableIterator implements Iterator
{
private Iterator delegate;
public boolean hasNext()
{
return delegate.hasNext();
}
public V next()
{
return viewer.apply(delegate.next());
}
private ReusableIterator reset()
{
delegate = elements.iterator();
return this;
}
}
}