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1 /* 2 * $Header: /home/cvs/jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/expression/ExpressionSupport.java,v 1.6 2002/07/13 01:03:27 plynch Exp $ 3 * $Revision: 1.6 $ 4 * $Date: 2002/07/13 01:03:27 $ 5 * 6 * ==================================================================== 7 * 8 * The Apache Software License, Version 1.1 9 * 10 * Copyright (c) 1999-2002 The Apache Software Foundation. All rights 11 * reserved. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 17 * 1. Redistributions of source code must retain the above copyright 18 * notice, this list of conditions and the following disclaimer. 19 * 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in 22 * the documentation and/or other materials provided with the 23 * distribution. 24 * 25 * 3. The end-user documentation included with the redistribution, if 26 * any, must include the following acknowlegement: 27 * "This product includes software developed by the 28 * Apache Software Foundation (http://www.apache.org/)." 29 * Alternately, this acknowlegement may appear in the software itself, 30 * if and wherever such third-party acknowlegements normally appear. 31 * 32 * 4. The names "The Jakarta Project", "Commons", and "Apache Software 33 * Foundation" must not be used to endorse or promote products derived 34 * from this software without prior written permission. For written 35 * permission, please contact apache@apache.org. 36 * 37 * 5. Products derived from this software may not be called "Apache" 38 * nor may "Apache" appear in their names without prior written 39 * permission of the Apache Group. 40 * 41 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 42 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 43 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 44 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR 45 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 46 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 47 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 48 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 49 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 50 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 51 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 52 * SUCH DAMAGE. 53 * ==================================================================== 54 * 55 * This software consists of voluntary contributions made by many 56 * individuals on behalf of the Apache Software Foundation. For more 57 * information on the Apache Software Foundation, please see 58 * <http://www.apache.org/>;. 59 * 60 * $Id: ExpressionSupport.java,v 1.6 2002/07/13 01:03:27 plynch Exp $ 61 */ 62 package org.apache.commons.jelly.expression; 63 64 import java.util.Collections; 65 import java.util.Collection; 66 import java.util.Enumeration; 67 import java.util.Iterator; 68 import java.util.List; 69 import java.util.Map; 70 71 import org.apache.commons.collections.ArrayIterator; 72 import org.apache.commons.collections.EnumerationIterator; 73 import org.apache.commons.collections.SingletonIterator; 74 75 import org.apache.commons.jelly.JellyContext; 76 77 /*** <p><code>ExpressionSupport</code> 78 * an abstract base class for Expression implementations 79 * which provides default implementations of some of the 80 * typesafe evaluation methods.</p> 81 * 82 * @author <a href="mailto:jstrachan@apache.org">James Strachan</a> 83 * @version $Revision: 1.6 $ 84 */ 85 public abstract class ExpressionSupport implements Expression { 86 87 protected static final Iterator EMPTY_ITERATOR = Collections.EMPTY_LIST.iterator(); 88 89 // inherit javadoc from interface 90 public String evaluateAsString(JellyContext context) { 91 Object value = evaluate(context); 92 if ( value != null ) { 93 return value.toString(); 94 } 95 return null; 96 } 97 98 // inherit javadoc from interface 99 public boolean evaluateAsBoolean(JellyContext context) { 100 Object value = evaluate(context); 101 if ( value instanceof Boolean ) { 102 Boolean b = (Boolean) value; 103 return b.booleanValue(); 104 } 105 else if ( value instanceof String ) { 106 // return Boolean.getBoolean( (String) value ); 107 String str = (String) value; 108 109 if ( str.equals( "on" ) 110 || 111 str.equals( "yes" ) 112 || 113 str.equals( "1" ) 114 || 115 str.equals( "true" ) ) 116 { 117 return true; 118 } 119 else 120 { 121 return false; 122 } 123 124 } 125 return false; 126 } 127 128 // inherit javadoc from interface 129 public Iterator evaluateAsIterator(JellyContext context) { 130 Object value = evaluate(context); 131 if ( value == null ) { 132 return EMPTY_ITERATOR; 133 } 134 else 135 if ( value instanceof Iterator ) { 136 return (Iterator) value; 137 } 138 else if ( value instanceof List ) { 139 List list = (List) value; 140 return list.iterator(); 141 } 142 else if ( value instanceof Map ) { 143 Map map = (Map) value; 144 return map.entrySet().iterator(); 145 } 146 else if ( value.getClass().isArray() ) { 147 return new ArrayIterator( value ); 148 } 149 else if ( value instanceof Enumeration ) { 150 return new EnumerationIterator((Enumeration ) value); 151 } 152 else if ( value instanceof Collection ) { 153 Collection collection = (Collection) value; 154 return collection.iterator(); 155 } 156 else { 157 // XXX: should we return single iterator? 158 return new SingletonIterator( value ); 159 } 160 } 161 }

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