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Java > Open Source Codes > net > sf > saxon > functions > Current


1 package net.sf.saxon.functions;
2 import net.sf.saxon.expr.Expression;
3 import net.sf.saxon.expr.StaticContext;
4 import net.sf.saxon.expr.StaticProperty;
5 import net.sf.saxon.expr.XPathContext;
6 import net.sf.saxon.om.Item;
7 import net.sf.saxon.trans.XPathException;
8
9 /**
10  * Implement the XSLT current() function
11  */
12
13 public class Current extends SystemFunction implements XSLTFunction {
14
15     /**
16     * Get the static properties of this expression (other than its type). The result is
17     * bit-signficant. These properties are used for optimizations. In general, if
18     * property bit is set, it is true, but if it is unset, the value is unknown.
19     */
20
21     public int computeSpecialProperties() {
22         return StaticProperty.CONTEXT_DOCUMENT_NODESET |
23                 StaticProperty.SINGLE_DOCUMENT_NODESET |
24                 StaticProperty.ORDERED_NODESET |
25                 StaticProperty.NON_CREATIVE;
26     }
27
28     /**
29     * preEvaluate: this method suppresses compile-time evaluation by doing nothing
30     * (because the value of the expression depends on the runtime context)
31     */
32
33     public Expression preEvaluate(StaticContext env) {
34         return this;
35     }
36
37     /**
38     * Evaluate in a general context
39     */
40
41     public Item evaluateItem(XPathContext c) throws XPathException {
42         throw new AssertionError JavaDoc("current() function should have been rewritten at compile time");
43         // We rely on the expression being statically rewritten so that current() is promoted to the top level.
44 //return c.getContextItem();
45 //return c.getCurrentStylesheetItem();
46 }
47
48     /**
49     * Determine the dependencies
50     */
51
52     public int getIntrinsicDependencies() {
53        return StaticProperty.DEPENDS_ON_CURRENT_ITEM;
54     }
55
56 }
57
58
59
60
61 //
62 // The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
63 // you may not use this file except in compliance with the License. You may obtain a copy of the
64 // License at http://www.mozilla.org/MPL/
65 //
66 // Software distributed under the License is distributed on an "AS IS" basis,
67 // WITHOUT WARRANTY OF ANY KIND, either express or implied.
68 // See the License for the specific language governing rights and limitations under the License.
69 //
70 // The Original Code is: all this file.
71 //
72 // The Initial Developer of the Original Code is Michael H. Kay.
73 //
74 // Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
75 //
76 // Contributor(s): none.
77 //
78
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