80 lines
2.1 KiB
Java
80 lines
2.1 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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/**
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* A <code>FilterIterator</code> filters an <code>Iterator</code> to generate a new one.
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*/
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public class FilterIterator<T> implements java.util.Iterator<T> {
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final Iterator<?> i;
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final Filter f;
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private T next = null;
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private boolean done = false;
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/**
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* @param i the original iterator
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* @param f a filter which defines which elements belong to the generated iterator
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*/
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public FilterIterator(Iterator<?> i, Filter f) {
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if (i == null) {
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throw new IllegalArgumentException("null i");
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}
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if (f == null) {
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throw new IllegalArgumentException("null f");
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}
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this.i = i;
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this.f = f;
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advance();
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}
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/**
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* update the internal state to prepare for the next access to this iterator
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*/
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@SuppressWarnings("unchecked")
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private void advance() {
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while (i.hasNext()) {
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Object o = i.next();
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if (f.accepts(o)) {
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next = (T) o;
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return;
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}
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}
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done = true;
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}
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public T next() throws NoSuchElementException {
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if (done) {
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throw new java.util.NoSuchElementException();
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}
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T o = next;
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advance();
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return o;
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}
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public boolean hasNext() {
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return !done;
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}
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public void remove() throws UnsupportedOperationException {
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throw new java.lang.UnsupportedOperationException();
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}
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@Override
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public String toString() {
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return "filter " + f + " of " + i;
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}
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} |