1 /** 2 * This class is based on the Iterators.FilterIterator class from 3 * araSpect (araspect.sourceforge.net). The original copyright follows ... 4 * 5 * ================================================================= 6 * Copyright (c) 2001,2002 aragost ag, Z�rich, Switzerland. 7 * All rights reserved. 8 * 9 * This software is provided 'as-is', without any express or implied 10 * warranty. In no event will the authors be held liable for any 11 * damages arising from the use of this software. 12 * 13 * Permission is granted to anyone to use this software for any 14 * purpose, including commercial applications, and to alter it and 15 * redistribute it freely, subject to the following restrictions: 16 * 17 * 1. The origin of this software must not be misrepresented; you 18 * must not claim that you wrote the original software. If you 19 * use this software in a product, an acknowledgment in the 20 * product documentation would be appreciated but is not required. 21 * 22 * 2. Altered source versions must be plainly marked as such, and 23 * must not be misrepresented as being the original software. 24 * 25 * 3. This notice may not be removed or altered from any source 26 * distribution. 27 * 28 * ================================================================== 29 * 30 * Changes (c) 2003 University Health Network include the following: 31 * - move to non-nested class 32 * - collapse inherited method remove() 33 * - accept iterator instead of object in constructor 34 * - moved to HAPI package 35 * - Predicate added as an inner class; also changed to an interface 36 * 37 * These changes are distributed under the same terms as the original (above). 38 */ 39 package ca.uhn.hl7v2.util; 40 41 import java.util.*; 42 43 public class FilterIterator<T> implements Iterator<T> { 44 45 private final Predicate<T> predicate; 46 private final Iterator<T> iter; 47 private T nextObject; 48 private boolean nextObjectSet = false; 49 50 public FilterIterator(Iterator<T> iter, Predicate<T> predicate) { 51 this.iter = iter; 52 this.predicate = predicate; 53 } 54 55 public boolean hasNext() { 56 if (nextObjectSet) { 57 return true; 58 } else { 59 return setNextObject(); 60 } 61 } 62 63 public T next() { 64 if (!nextObjectSet) { 65 if (!setNextObject()) { 66 throw new NoSuchElementException(); 67 } 68 } 69 nextObjectSet = false; 70 return nextObject; 71 } 72 73 /** 74 * Set nextObject to the next object. If there are no more 75 * objects then return false. Otherwise, return true. 76 */ 77 private boolean setNextObject() { 78 while (iter.hasNext()) { 79 T object = iter.next(); 80 if (predicate.evaluate(object)) { 81 nextObject = object; 82 nextObjectSet = true; 83 return true; 84 } 85 } 86 return false; 87 } 88 89 /** Throws UnsupportedOperationException */ 90 public void remove() { 91 throw new UnsupportedOperationException(); 92 } 93 94 /** 95 * Interface for evaluating whether an object should be returned by the iterator 96 */ 97 public interface Predicate<T> { 98 boolean evaluate(T obj); 99 } 100 101 }