92 lines
3.5 KiB
Java
92 lines
3.5 KiB
Java
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/*
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* Janino - An embedded Java[TM] compiler
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*
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* Copyright (c) 2001-2010, Arno Unkrig
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
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* following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the
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* following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
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* following disclaimer in the documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
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* THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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package org.codehaus.janino.util.iterator;
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import java.util.AbstractCollection;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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/**
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* A {@link java.util.Collection} that lazily reads its elements from an
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* {@link java.util.Iterator}.
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* <p>
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* In other words, you can call {@link #iterator()} as often as you want, but the
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* {@link IteratorCollection} will iterate over its delegate only once.
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*
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* @param <T> The element type of the iterator and the collection
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*/
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@SuppressWarnings({ "rawtypes", "unchecked" }) public
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class IteratorCollection<T> extends AbstractCollection<T> {
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/** The delegate. */
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private final Iterator<T> iterator;
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/** Lazily-filled collection of the elements delivered by the delegate. */
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private final List/*<T>*/ elements = new ArrayList();
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public
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IteratorCollection(Iterator iterator) { this.iterator = iterator; }
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@Override public Iterator<T>
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iterator() {
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return new Iterator/*<T>*/() {
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private Iterator/*<T>*/ elementsIterator = IteratorCollection.this.elements.iterator();
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@Override public Object
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next() {
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if (this.elementsIterator != null) {
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if (this.elementsIterator.hasNext()) return this.elementsIterator.next();
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this.elementsIterator = null;
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}
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Object o = IteratorCollection.this.iterator.next();
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IteratorCollection.this.elements.add(o);
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return o;
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}
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@Override public boolean
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hasNext() {
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return (
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(this.elementsIterator != null && this.elementsIterator.hasNext())
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|| IteratorCollection.this.iterator.hasNext()
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);
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}
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@Override public void
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remove() { throw new UnsupportedOperationException(); }
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};
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}
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@Override public int
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size() {
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int size = 0;
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for (@SuppressWarnings("unused") Object o : this) ++size;
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return size;
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}
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}
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