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


1 package net.sf.saxon.functions;
2 import net.sf.saxon.Err;
3 import net.sf.saxon.expr.XPathContext;
4 import net.sf.saxon.expr.StaticContext;
5 import net.sf.saxon.expr.Optimizer;
6 import net.sf.saxon.expr.ExpressionTool;
7 import net.sf.saxon.om.Item;
8 import net.sf.saxon.om.SequenceIterator;
9 import net.sf.saxon.sort.DescendingComparer;
10 import net.sf.saxon.trans.XPathException;
11 import net.sf.saxon.value.*;
12
13 import java.util.Comparator JavaDoc;
14
15 /**
16 * This class implements the min() and max() functions
17 */
18
19 public class Minimax extends CollatingFunction {
20
21     public static final int MIN = 2;
22     public static final int MAX = 3;
23
24     /**
25      * Static analysis: prevent sorting of the argument
26      */
27
28     public void checkArguments(StaticContext env) throws XPathException {
29         super.checkArguments(env);
30         Optimizer opt = env.getConfiguration().getOptimizer();
31         argument[0] = ExpressionTool.unsorted(opt, argument[0], false);
32     }
33
34     /**
35     * Evaluate the function
36     */
37
38     public Item evaluateItem(XPathContext context) throws XPathException {
39         Comparator JavaDoc collator = getAtomicComparer(1, context);
40
41         if (operation == MAX) {
42             collator = new DescendingComparer(collator);
43         }
44
45         SequenceIterator iter = argument[0].iterate(context);
46
47         AtomicValue min = (AtomicValue)iter.next();
48         if (min == null) return null;
49         if (min instanceof UntypedAtomicValue) {
50             try {
51                 min = new DoubleValue(Value.stringToNumber(min.getStringValueCS()));
52             } catch (NumberFormatException JavaDoc e) {
53                 dynamicError("Failure converting " +
54                                                  Err.wrap(min.getStringValueCS()) +
55                                                  " to a number", context);
56             }
57         }
58
59         while (true) {
60             AtomicValue test = (AtomicValue)iter.next();
61             if (test==null) break;
62             AtomicValue test2 = test;
63             if (test instanceof UntypedAtomicValue) {
64                 try {
65                     test2 = new DoubleValue(Value.stringToNumber(test.getStringValueCS()));
66                 } catch (NumberFormatException JavaDoc e) {
67                     dynamicError("Failure converting " +
68                                                      Err.wrap(test.getStringValueCS()) +
69                                                      " to a number", "FORG0001", context);
70                 }
71             }
72             if (test2 instanceof NumericValue && ((NumericValue)test2).isNaN()) {
73                 // if there's a NaN in the sequence, return NaN
74 return test2;
75             }
76             try {
77                 if (collator.compare(test2, min) < 0) {
78                     min = test2;
79                 }
80             } catch (ClassCastException JavaDoc err) {
81                 typeError("Cannot compare " + min.getItemType() +
82                                    " with " + test2.getItemType(), "FORG0007", context);
83                 return null;
84             }
85         }
86         return min;
87     }
88
89 }
90
91
92 //
93 // The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
94 // you may not use this file except in compliance with the License. You may obtain a copy of the
95 // License at http://www.mozilla.org/MPL/
96 //
97 // Software distributed under the License is distributed on an "AS IS" basis,
98 // WITHOUT WARRANTY OF ANY KIND, either express or implied.
99 // See the License for the specific language governing rights and limitations under the License.
100 //
101 // The Original Code is: all this file.
102 //
103 // The Initial Developer of the Original Code is Michael H. Kay.
104 //
105 // Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
106 //
107 // Contributor(s): none.
108 //
109
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