001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.commons.collections.functors; 018 019 import java.io.Serializable; 020 021 import org.apache.commons.collections.Closure; 022 import org.apache.commons.collections.Predicate; 023 024 /** 025 * Closure implementation that executes a closure repeatedly until a condition is met, 026 * like a do-while or while loop. 027 * 028 * @since Commons Collections 3.0 029 * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ 030 * 031 * @author Stephen Colebourne 032 */ 033 public class WhileClosure implements Closure, Serializable { 034 035 /** Serial version UID */ 036 private static final long serialVersionUID = -3110538116913760108L; 037 038 /** The test condition */ 039 private final Predicate iPredicate; 040 /** The closure to call */ 041 private final Closure iClosure; 042 /** The flag, true is a do loop, false is a while */ 043 private final boolean iDoLoop; 044 045 /** 046 * Factory method that performs validation. 047 * 048 * @param predicate the predicate used to evaluate when the loop terminates, not null 049 * @param closure the closure the execute, not null 050 * @param doLoop true to act as a do-while loop, always executing the closure once 051 * @return the <code>while</code> closure 052 * @throws IllegalArgumentException if the predicate or closure is null 053 */ 054 public static Closure getInstance(Predicate predicate, Closure closure, boolean doLoop) { 055 if (predicate == null) { 056 throw new IllegalArgumentException("Predicate must not be null"); 057 } 058 if (closure == null) { 059 throw new IllegalArgumentException("Closure must not be null"); 060 } 061 return new WhileClosure(predicate, closure, doLoop); 062 } 063 064 /** 065 * Constructor that performs no validation. 066 * Use <code>getInstance</code> if you want that. 067 * 068 * @param predicate the predicate used to evaluate when the loop terminates, not null 069 * @param closure the closure the execute, not null 070 * @param doLoop true to act as a do-while loop, always executing the closure once 071 */ 072 public WhileClosure(Predicate predicate, Closure closure, boolean doLoop) { 073 super(); 074 iPredicate = predicate; 075 iClosure = closure; 076 iDoLoop = doLoop; 077 } 078 079 /** 080 * Executes the closure until the predicate is false. 081 * 082 * @param input the input object 083 */ 084 public void execute(Object input) { 085 if (iDoLoop) { 086 iClosure.execute(input); 087 } 088 while (iPredicate.evaluate(input)) { 089 iClosure.execute(input); 090 } 091 } 092 093 /** 094 * Gets the predicate in use. 095 * 096 * @return the predicate 097 * @since Commons Collections 3.1 098 */ 099 public Predicate getPredicate() { 100 return iPredicate; 101 } 102 103 /** 104 * Gets the closure. 105 * 106 * @return the closure 107 * @since Commons Collections 3.1 108 */ 109 public Closure getClosure() { 110 return iClosure; 111 } 112 113 /** 114 * Is the loop a do-while loop. 115 * 116 * @return true is do-while, false if while 117 * @since Commons Collections 3.1 118 */ 119 public boolean isDoLoop() { 120 return iDoLoop; 121 } 122 123 }