68 lines
1.7 KiB
Java
68 lines
1.7 KiB
Java
/*******************************************************************************
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* Copyright (c) 2002 - 2006 IBM Corporation.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*******************************************************************************/
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package com.ibm.wala.util.collections;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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import com.ibm.wala.util.debug.Assertions;
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/**
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*
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* A singleton iterator for an object which is guaranteed to be not-null. Exploiting this invariant
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* allows this class to be slightly more efficient than Collections.iterator()
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*
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* @author sfink
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*/
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public class NonNullSingletonIterator<T> implements Iterator<T> {
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private T it;
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/**
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* @param o the single object in this collection, must be non-null
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*/
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public NonNullSingletonIterator(T o) {
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if (Assertions.verifyAssertions) {
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Assertions._assert(o != null);
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}
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this.it = o;
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}
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/* (non-Javadoc)
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* @see java.util.Iterator#hasNext()
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*/
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public boolean hasNext() {
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return it != null;
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}
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/* (non-Javadoc)
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* @see java.util.Iterator#next()
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*/
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public T next() {
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if (it == null) {
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throw new NoSuchElementException();
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} else {
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T result = it;
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it = null;
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return result;
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}
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}
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/* (non-Javadoc)
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* @see java.util.Iterator#remove()
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*/
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public void remove() {
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Assertions.UNREACHABLE();
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}
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}
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