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Java > Open Source Codes > net > sf > saxon > style > SaxonWhile


1 package net.sf.saxon.style;
2 import net.sf.saxon.expr.Expression;
3 import net.sf.saxon.expr.ExpressionTool;
4 import net.sf.saxon.instruct.Executable;
5 import net.sf.saxon.instruct.While;
6 import net.sf.saxon.om.AttributeCollection;
7 import net.sf.saxon.om.Axis;
8 import net.sf.saxon.value.EmptySequence;
9 import net.sf.saxon.trans.XPathException;
10
11 import javax.xml.transform.TransformerConfigurationException JavaDoc;
12
13
14 /**
15 * Handler for saxon:while elements in stylesheet.
16 * The saxon:while element has a mandatory attribute test, a boolean expression.
17 * The content is output repeatedly so long as the test condition is true.
18 */
19
20 public class SaxonWhile extends StyleElement {
21
22     private Expression test;
23
24     /**
25     * Determine whether this node is an instruction.
26     * @return true - it is an instruction
27     */
28
29     public boolean isInstruction() {
30         return true;
31     }
32
33     /**
34     * Determine whether this type of element is allowed to contain a template-body
35     * @return true: yes, it may contain a template-body
36     */
37
38     public boolean mayContainSequenceConstructor() {
39         return true;
40     }
41
42     public void prepareAttributes() throws XPathException {
43
44         String JavaDoc testAtt=null;
45
46         AttributeCollection atts = getAttributeList();
47
48         for (int a=0; a<atts.getLength(); a++) {
49             int nc = atts.getNameCode(a);
50             String JavaDoc f = getNamePool().getClarkName(nc);
51             if (f==StandardNames.TEST) {
52                 testAtt = atts.getValue(a);
53             } else {
54                 checkUnknownAttribute(nc);
55             }
56         }
57
58         if (testAtt==null) {
59             reportAbsence("test");
60             return;
61         }
62         test = makeExpression(testAtt);
63     }
64
65     public void validate() throws XPathException {
66         checkWithinTemplate();
67         test = typeCheck("test", test);
68     }
69
70     public Expression compile(Executable exec) throws XPathException {
71         Expression action = compileSequenceConstructor(exec, iterateAxis(Axis.CHILD), true);
72         if (action == null) {
73             action = EmptySequence.getInstance();
74         }
75         //try {
76 While w = new While(test, action);
77             ExpressionTool.makeParentReferences(w);
78             return w;
79 // } catch (XPathException e) {
80 // compileError(e);
81 // return null;
82 // }
83 }
84
85 }
86
87 //
88 // The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
89 // you may not use this file except in compliance with the License. You may obtain a copy of the
90 // License at http://www.mozilla.org/MPL/
91 //
92 // Software distributed under the License is distributed on an "AS IS" basis,
93 // WITHOUT WARRANTY OF ANY KIND, either express or implied.
94 // See the License for the specific language governing rights and limitations under the License.
95 //
96 // The Original Code is: all this file.
97 //
98 // The Initial Developer of the Original Code is Michael H. Kay.
99 //
100 // Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
101 //
102 // Contributor(s): none.
103 //
104
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