Source code: com/sun/xacml/cond/RoundFunction.java
1
2 /*
3 * @(#)RoundFunction.java
4 *
5 * Copyright 2003-2004 Sun Microsystems, Inc. All Rights Reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 *
10 * 1. Redistribution of source code must retain the above copyright notice,
11 * this list of conditions and the following disclaimer.
12 *
13 * 2. Redistribution in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
18 * be used to endorse or promote products derived from this software without
19 * specific prior written permission.
20 *
21 * This software is provided "AS IS," without a warranty of any kind. ALL
22 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
23 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
24 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
25 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
26 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
27 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
28 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
29 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
30 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
31 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
32 *
33 * You acknowledge that this software is not designed or intended for use in
34 * the design, construction, operation or maintenance of any nuclear facility.
35 */
36
37 package com.sun.xacml.cond;
38
39 import com.sun.xacml.EvaluationCtx;
40
41 import com.sun.xacml.attr.AttributeValue;
42 import com.sun.xacml.attr.DoubleAttribute;
43 import com.sun.xacml.attr.IntegerAttribute;
44
45 import java.util.HashSet;
46 import java.util.List;
47 import java.util.Set;
48
49
50 /**
51 * A class that implements the round function. It takes one double
52 * operand, rounds that value to an integer and returns that integer.
53 * If the operand is indeterminate, an indeterminate result is returned.
54 *
55 * @since 1.0
56 * @author Steve Hanna
57 * @author Seth Proctor
58 */
59 public class RoundFunction extends FunctionBase
60 {
61
62 /**
63 * Standard identifier for the round function.
64 */
65 public static final String NAME_ROUND = FUNCTION_NS + "round";
66
67 /**
68 * Creates a new <code>RoundFunction</code> object.
69 *
70 * @param functionName the standard XACML name of the function to be
71 * handled by this object, including the full namespace
72 *
73 * @throws IllegalArgumentException if the function is unknown
74 */
75 public RoundFunction(String functionName) {
76 super(NAME_ROUND, 0, DoubleAttribute.identifier, false, 1,
77 DoubleAttribute.identifier, false);
78
79 if (! functionName.equals(NAME_ROUND))
80 throw new IllegalArgumentException("unknown round function: "
81 + functionName);
82 }
83
84 /**
85 * Returns a <code>Set</code> containing all the function identifiers
86 * supported by this class.
87 *
88 * @return a <code>Set</code> of <code>String</code>s
89 */
90 public static Set getSupportedIdentifiers() {
91 Set set = new HashSet();
92
93 set.add(NAME_ROUND);
94
95 return set;
96 }
97
98 /**
99 * Evaluate the function, using the specified parameters.
100 *
101 * @param inputs a <code>List</code> of <code>Evaluatable</code>
102 * objects representing the arguments passed to the function
103 * @param context an <code>EvaluationCtx</code> so that the
104 * <code>Evaluatable</code> objects can be evaluated
105 * @return an <code>EvaluationResult</code> representing the
106 * function's result
107 */
108 public EvaluationResult evaluate(List inputs, EvaluationCtx context) {
109
110 // Evaluate the arguments
111 AttributeValue [] argValues = new AttributeValue[inputs.size()];
112 EvaluationResult result = evalArgs(inputs, context, argValues);
113 if (result != null)
114 return result;
115
116 // Now that we have real values, perform the round operation
117 double arg = ((DoubleAttribute) argValues[0]).getValue();
118 double roundValue = Math.round(arg);
119
120 // Make it round half even, not round nearest
121 double lower = Math.floor(arg);
122 double higher = lower + 1;
123
124 if ((arg - lower) == (higher - arg)) {
125 if ((lower % 2) == 0)
126 roundValue = lower;
127 else
128 roundValue = higher;
129 }
130
131 return new EvaluationResult(new DoubleAttribute(roundValue));
132 }
133 }