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    1   /*
    2    * $Header$
    3    * $Revision$
    4    * $Date$
    5    *
    6    * ====================================================================
    7    *
    8    * Copyright (C) 2005 Elliotte Rusty Harold.
    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   * $Id$
    60   */
    61  package org.jaxen.expr;
    62
    63  import java.util.Comparator;
    64  import java.util.Iterator;
    65
    66  import org.jaxen.Navigator;
    67  import org.jaxen.UnsupportedAxisException;
    68
    69
    70  class NodeComparator implements Comparator {
    71
    72      private Navigator navigator;
    73
    74
    75      NodeComparator(Navigator navigator) {
    76          this.navigator = navigator;
    77      }
    78
    79      public int compare(Object o1, Object o2) {
    80
    81          if (navigator == null) return 0;
    82
    83          if (isNonChild(o1) && isNonChild(o2)) {
    84
    85              try {
    86                  Object p1 = navigator.getParentNode(o1);
    87                  Object p2 = navigator.getParentNode(o2);
    88
    89                  if (p1 == p2) {
    90                      if (navigator.isNamespace(o1) && navigator.isAttribute(o2)) {
    91                          return -1;
    92                      }
    93                      else if (navigator.isNamespace(o2) && navigator.isAttribute(o1)) {
    94                          return 1;
    95                      }
    96                  }
    97
    98                  return compare(p1, p2);
    99              }
    100             catch (UnsupportedAxisException ex) {
    101                 return 0;
    102             }
    103
    104         }
    105
    106         try {
    107             int depth1 = getDepth(o1);
    108             int depth2 = getDepth(o2);
    109
    110             Object a1 = o1;
    111             Object a2 = o2;
    112
    113             while (depth1 > depth2) {
    114                 a1 = navigator.getParentNode(a1);
    115                 depth1--;
    116             }
    117             if (a1 == o2) return 1;
    118
    119             while (depth2 > depth1) {
    120                 a2 = navigator.getParentNode(a2);
    121                 depth2--;
    122             }
    123             if (a2 == o1) return -1;
    124
    125             // a1 and a2 are now at same depth; and are not the same
    126             while (true) {
    127                 Object p1 = navigator.getParentNode(a1);
    128                 Object p2 = navigator.getParentNode(a2);
    129                 if (p1 == p2) {
    130                     return compareSiblings(a1, a2);
    131                 }
    132                 a1 = p1;
    133                 a2 = p2;
    134             }
    135
    136         }
    137         catch (UnsupportedAxisException ex) {
    138             return 0; // ???? should I throw an exception instead?
    139         }
    140     }
    141
    142
    143     private boolean isNonChild(Object o) {
    144         return navigator.isAttribute(o) || navigator.isNamespace(o);
    145     }
    146
    147     private int compareSiblings(Object sib1, Object sib2)
    148       throws UnsupportedAxisException {
    149
    150         Iterator following = navigator.getFollowingSiblingAxisIterator(sib1);
    151         while (following.hasNext()) {
    152             Object next = following.next();
    153             if (next.equals(sib2)) return -1;
    154         }
    155         return 1;
    156
    157     }
    158
    159     private int getDepth(Object o) throws UnsupportedAxisException {
    160
    161         int depth = 0;
    162         Object parent = o;
    163
    164         while ((parent = navigator.getParentNode(parent)) != null) {
    165             depth++;
    166         }
    167         return depth;
    168
    169     }
    170
    171 }