1 /* 2 * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/PredicateSet.java,v 1.18 2005/04/15 20:24:04 elharo Exp $ 3 * $Revision: 1.18 $ 4 * $Date: 2005/04/15 20:24:04 $ 5 * 6 * ==================================================================== 7 * 8 * Copyright (C) 2000-2002 bob mcwhirter & James Strachan. 9 * All rights reserved. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions, and the following disclaimer. 17 * 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions, and the disclaimer that follows 20 * these conditions in the documentation and/or other materials 21 * provided with the distribution. 22 * 23 * 3. The name "Jaxen" must not be used to endorse or promote products 24 * derived from this software without prior written permission. For 25 * written permission, please contact license@jaxen.org. 26 * 27 * 4. Products derived from this software may not be called "Jaxen", nor 28 * may "Jaxen" appear in their name, without prior written permission 29 * from the Jaxen Project Management (pm@jaxen.org). 30 * 31 * In addition, we request (but do not require) that you include in the 32 * end-user documentation provided with the redistribution and/or in the 33 * software itself an acknowledgement equivalent to the following: 34 * "This product includes software developed by the 35 * Jaxen Project (http://www.jaxen.org/)." 36 * Alternatively, the acknowledgment may be graphical using the logos 37 * available at http://www.jaxen.org/ 38 * 39 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 40 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 41 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 42 * DISCLAIMED. IN NO EVENT SHALL THE Jaxen AUTHORS OR THE PROJECT 43 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 45 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 46 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 47 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 48 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 49 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 50 * SUCH DAMAGE. 51 * 52 * ==================================================================== 53 * This software consists of voluntary contributions made by many 54 * individuals on behalf of the Jaxen Project and was originally 55 * created by bob mcwhirter <bob@werken.com> and 56 * James Strachan <jstrachan@apache.org>. For more information on the 57 * Jaxen Project, please see <http://www.jaxen.org/>. 58 * 59 * $Id: PredicateSet.java,v 1.18 2005/04/15 20:24:04 elharo Exp $ 60 */ 61 62 63 64 package org.jaxen.expr; 65 66 import java.io.Serializable; 67 import java.util.ArrayList; 68 import java.util.Collections; 69 import java.util.Iterator; 70 import java.util.List; 71 import org.jaxen.Context; 72 import org.jaxen.ContextSupport; 73 import org.jaxen.JaxenException; 74 import org.jaxen.function.BooleanFunction; 75 76 public class PredicateSet implements Serializable 77 { 78 private List predicates; 79 80 public PredicateSet() 81 { 82 this.predicates = Collections.EMPTY_LIST; 83 } 84 85 public void addPredicate(Predicate predicate) 86 { 87 if ( this.predicates == Collections.EMPTY_LIST ) 88 { 89 this.predicates = new ArrayList(); 90 } 91 92 this.predicates.add( predicate ); 93 } 94 95 public List getPredicates() 96 { 97 return this.predicates; 98 } 99 100 public void simplify() 101 { 102 Iterator predIter = this.predicates.iterator(); 103 Predicate eachPred = null; 104 105 while ( predIter.hasNext() ) 106 { 107 eachPred = (Predicate) predIter.next(); 108 eachPred.simplify(); 109 } 110 } 111 112 public String getText() 113 { 114 StringBuffer buf = new StringBuffer(); 115 116 Iterator predIter = this.predicates.iterator(); 117 Predicate eachPred = null; 118 119 while ( predIter.hasNext() ) 120 { 121 eachPred = (Predicate) predIter.next(); 122 buf.append( eachPred.getText() ); 123 } 124 125 return buf.toString(); 126 } 127 128 // FIXME: Note - this could be *MUCH* more efficient 129 // currently this creates many redundant collections and should halt 130 // evaluation on the first matching item. 131 protected boolean evaluateAsBoolean(List contextNodeSet, 132 ContextSupport support) throws JaxenException 133 { 134 List result = evaluatePredicates( contextNodeSet, support ); 135 136 return ! result.isEmpty(); 137 } 138 139 protected List evaluatePredicates(List contextNodeSet, ContextSupport support) 140 throws JaxenException { 141 // Easy way out (necessary) 142 if (predicates.size() == 0) { 143 return contextNodeSet; 144 } 145 Iterator predIter = predicates.iterator(); 146 147 // initial list to filter 148 List nodes2Filter = contextNodeSet; 149 // apply all predicates 150 while(predIter.hasNext()) { 151 nodes2Filter = 152 applyPredicate((Predicate)predIter.next(), nodes2Filter, support); 153 } 154 155 return nodes2Filter; 156 } 157 158 public List applyPredicate(Predicate predicate, List nodes2Filter, ContextSupport support) 159 throws JaxenException { 160 final int nodes2FilterSize = nodes2Filter.size(); 161 List filteredNodes = new ArrayList(nodes2FilterSize); 162 // Set up a dummy context with a list to hold each node 163 Context predContext = new Context(support); 164 List tempList = new ArrayList(1); 165 predContext.setNodeSet(tempList); 166 // loop through the current nodes to filter and add to the 167 // filtered nodes list if the predicate succeeds 168 for (int i = 0; i < nodes2FilterSize; ++i) { 169 Object contextNode = nodes2Filter.get(i); 170 tempList.clear(); 171 tempList.add(contextNode); 172 predContext.setNodeSet(tempList); 173 // ???? 174 predContext.setPosition(i + 1); 175 predContext.setSize(nodes2FilterSize); 176 Object predResult = predicate.evaluate(predContext); 177 if (predResult instanceof Number) { 178 // Here we assume nodes are in forward or reverse order 179 // as appropriate for axis 180 int proximity = ((Number) predResult).intValue(); 181 if (proximity == (i + 1)) { 182 filteredNodes.add(contextNode); 183 } 184 } 185 else { 186 Boolean includes = 187 BooleanFunction.evaluate(predResult, 188 predContext.getNavigator()); 189 if (includes.booleanValue()) { 190 filteredNodes.add(contextNode); 191 } 192 } 193 } 194 return filteredNodes; 195 } 196 }