KickJava   Java API By Example, From Geeks To Geeks.

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


1 package net.sf.saxon.functions;
2 import net.sf.saxon.Controller;
3 import net.sf.saxon.expr.*;
4 import net.sf.saxon.om.DocumentInfo;
5 import net.sf.saxon.om.EmptyIterator;
6 import net.sf.saxon.om.Item;
7 import net.sf.saxon.om.SequenceIterator;
8 import net.sf.saxon.sort.DocumentOrderIterator;
9 import net.sf.saxon.sort.LocalOrderComparer;
10 import net.sf.saxon.style.StandardNames;
11 import net.sf.saxon.trans.KeyManager;
12 import net.sf.saxon.trans.XPathException;
13 import net.sf.saxon.value.AtomicValue;
14 import net.sf.saxon.value.Cardinality;
15 import net.sf.saxon.value.StringValue;
16
17
18 public class Idref extends SystemFunction {
19
20     /**
21     * Simplify: add a second implicit argument, the context document
22     */
23
24      public Expression simplify(StaticContext env) throws XPathException {
25         Idref f = (Idref)super.simplify(env);
26         f.addContextDocumentArgument(1, "idref");
27         return f;
28     }
29
30     public void checkArguments(StaticContext env) throws XPathException {
31         super.checkArguments(env);
32         Optimizer opt = env.getConfiguration().getOptimizer();
33         argument[0] = ExpressionTool.unsorted(opt, argument[0], false);
34     }
35
36     /**
37     * Get the static properties of this expression (other than its type). The result is
38     * bit-signficant. These properties are used for optimizations. In general, if
39     * property bit is set, it is true, but if it is unset, the value is unknown.
40     */
41
42     public int computeSpecialProperties() {
43         int prop = StaticProperty.ORDERED_NODESET |
44                 StaticProperty.SINGLE_DOCUMENT_NODESET |
45                 StaticProperty.NON_CREATIVE;
46         if ((getNumberOfArguments() == 1) ||
47                 (argument[1].getSpecialProperties() & StaticProperty.CONTEXT_DOCUMENT_NODESET) != 0) {
48             prop |= StaticProperty.CONTEXT_DOCUMENT_NODESET;
49         }
50         return prop;
51     }
52
53     /**
54     * preEvaluate: this method suppresses compile-time evaluation by doing nothing
55     */
56
57     public Expression preEvaluate(StaticContext env) {
58         return this;
59     }
60
61     /**
62     * Enumerate the results of the expression
63     */
64
65     public SequenceIterator iterate(XPathContext context) throws XPathException {
66
67         Controller controller = context.getController();
68
69         Item arg2 = argument[1].evaluateItem(context);
70         if (!(arg2 instanceof DocumentInfo)) {
71             dynamicError("In the idref() function," +
72                             " the context node must be in a tree whose root is a document node", context);
73             return null;
74         }
75         DocumentInfo doc = (DocumentInfo)arg2;
76
77         int fprint = StandardNames.XS_IDREFS;
78
79         // If the argument is a singleton, we evaluate the function
80 // directly; otherwise we recurse to evaluate it once for each Item
81 // in the sequence.
82
83         Expression expression = argument[0];
84         if (Cardinality.allowsMany(expression.getCardinality())) {
85             IdrefMappingFunction map = new IdrefMappingFunction();
86             map.document = doc;
87             map.keyContext = context;
88
89             SequenceIterator keys = argument[0].iterate(context);
90             SequenceIterator allValues = new MappingIterator(keys, map, null);
91             return new DocumentOrderIterator(allValues, LocalOrderComparer.getInstance());
92         } else {
93             AtomicValue keyValue = (AtomicValue)argument[0].evaluateItem(context);
94             if (keyValue == null) {
95                 return EmptyIterator.getInstance();
96             }
97             KeyManager keyManager = controller.getKeyManager();
98             return keyManager.selectByKey(fprint, doc, keyValue, context);
99
100         }
101     }
102
103     private static class IdrefMappingFunction implements MappingFunction {
104         public DocumentInfo document;
105         public XPathContext keyContext;
106
107         /**
108         * Implement the MappingFunction interface
109         */
110
111         public Object JavaDoc map(Item item, XPathContext context) throws XPathException {
112             KeyManager keyManager = keyContext.getController().getKeyManager();
113             AtomicValue keyValue;
114             if (item instanceof AtomicValue) {
115                 keyValue = (AtomicValue)item;
116             } else {
117                 keyValue = new StringValue(item.getStringValue());
118             }
119             return keyManager.selectByKey(
120                     StandardNames.XS_IDREFS, document, keyValue, keyContext);
121
122         }
123     }
124
125 }
126
127 //
128 // The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
129 // you may not use this file except in compliance with the License. You may obtain a copy of the
130 // License at http://www.mozilla.org/MPL/
131 //
132 // Software distributed under the License is distributed on an "AS IS" basis,
133 // WITHOUT WARRANTY OF ANY KIND, either express or implied.
134 // See the License for the specific language governing rights and limitations under the License.
135 //
136 // The Original Code is: all this file.
137 //
138 // The Initial Developer of the Original Code is Michael H. Kay.
139 //
140 // Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
141 //
142 // Contributor(s): none.
143 //
144
Popular Tags