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    1   /*
    2    * $Header: /home/projects/jaxen/scm/jaxen/src/java/main/org/jaxen/expr/PredicateSet.java,v 1.19 2005/06/28 13:44:44 elharo Exp $
    3    * $Revision: 1.19 $
    4    * $Date: 2005/06/28 13:44:44 $
    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 1.19 2005/06/28 13:44:44 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 }