Source code: diffxml/Patch/Reverse.java
1 /*
2 Program to reverse "sense" of a patch
3
4 Copyright (C) 2002 Adrian Mouat
5
6 This program is free software; you can redistribute it and/or
7 modify it under the terms of the GNU General Public License
8 as published by the Free Software Foundation; either version 2
9 of the License, or (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19
20 Author: Adrian Mouat
21 email: amouat@postmaster.co.uk
22 */
23
24 package diffxml.Patch;
25
26 import org.w3c.dom.Document;
27 import org.w3c.dom.Element;
28 import org.w3c.dom.Node;
29 import org.w3c.dom.Attr;
30 import org.w3c.dom.traversal.*;
31
32 public class Reverse
33 {
34
35 public static Document go(Document patch)
36 {
37 Node root=patch.getDocumentElement();
38 NodeIterator ni = ((DocumentTraversal) patch).createNodeIterator
39 (root, NodeFilter.SHOW_ELEMENT, null, false);
40
41 Node op=ni.nextNode();
42 //Check reveresable delta doc
43
44 if (! (op.getNodeName().equals("delta") && ((Element)op).getAttribute("reverse_patch").equals("true")) )
45 {
46 System.err.println("Not a reversable delta");
47 System.exit(2);
48 }
49
50 //Loop through nodes, reversing ops
51
52 op=ni.nextNode();
53
54 while (op!=null)
55 {
56 String op_name=op.getNodeName();
57
58 if (op_name.equals("insert"))
59 {
60 //We want an insert to become a delete of the inserted node
61 Element del=patch.createElement("delete");
62
63 //XPath of node is parent path plus domcn
64 String path=((Element)op).getAttribute("parent");
65 path=path+"/node()["+((Element)op).getAttribute("childno")+"]";
66 del.setAttribute("node",path);
67
68 //charpos remains the same
69 String charpos=((Element)op).getAttribute("charpos");
70 if (charpos!="")
71 del.setAttribute("charpos",charpos);
72
73 //set length
74 if ( ((Element)op).getAttribute("type").equals(""+Node.TEXT_NODE))
75 del.setAttribute("length",""+op.getNodeValue().length());
76 //Update node
77 op.getParentNode().replaceChild(del,op);
78 }
79 else if (op_name.equals("delete"))
80 {
81 //We want delete to become insert
82 Element ins=patch.createElement("insert");
83
84 //Parent node is truncated path
85 String path=((Element)op).getAttribute("node");
86 ins.setAttribute("parent", path.substring(0,path.lastIndexOf("/")));
87 //Assume childno is last bit of path
88 //MAY NOT ALWAYS WORK!!!
89 ins.setAttribute("childno",
90 path.substring(path.lastIndexOf("node()[")+7,
91 path.lastIndexOf("]")));
92
93 //Leave charpos the same
94 String charpos=((Element)op).getAttribute("charpos");
95 if (charpos!="")
96 ins.setAttribute("charpos",charpos);
97
98 //Leave nodetype the same
99 ins.setAttribute("nodetype",((Element)op).getAttribute("nodetype"));
100
101 //Value remains the same
102 ins.appendChild(op.getLastChild());
103 op.getParentNode().replaceChild(ins,op);
104 }
105 else if (op_name.equals("move"))
106 {
107 //Want move to swap parent and node, old_char and new_char
108
109 //Store old values
110 String path=((Element)op).getAttribute("node");
111 String par_path=((Element)op).getAttribute("parent");
112
113 //Parent node is truncated path
114 ((Element)op).setAttribute("parent", (path.substring(0,path.lastIndexOf("/")-1)));
115 //Assume childno is last bit of path
116 //MAY NOT ALWAYS WORK!!!
117 ((Element)op).setAttribute("childno",
118 path.substring(path.lastIndexOf("node()["+1),
119 path.lastIndexOf("]")-1));
120
121 //Swap charpos
122 String ocharpos=((Element)op).getAttribute("old_charpos");
123 String ncharpos=((Element)op).getAttribute("new_charpos");
124
125 if (ocharpos!="")
126 ((Element)op).setAttribute("new_charpos",ocharpos);
127
128 if (ncharpos!="")
129 ((Element)op).setAttribute("old_charpos",ncharpos);
130 }
131 op=ni.nextNode();
132 }
133 return patch;
134 }
135 }
136
137