Source code: com/sun/xacml/cond/LogicalFunction.java
1
2 /*
3 * @(#)LogicalFunction.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.BooleanAttribute;
43
44 import java.util.HashSet;
45 import java.util.Iterator;
46 import java.util.List;
47 import java.util.Set;
48
49
50 /**
51 * A class that implements the logical functions "or" and "and".
52 * These functions take any number of boolean arguments and evaluate
53 * them one at a time, starting with the first argument. As soon as
54 * the result of the function can be determined, evaluation stops and
55 * that result is returned. During this process, if any argument
56 * evaluates to indeterminate, an indeterminate result is returned.
57 *
58 * @since 1.0
59 * @author Steve Hanna
60 * @author Seth Proctor
61 */
62 public class LogicalFunction extends FunctionBase
63 {
64
65 /**
66 * Standard identifier for the or function.
67 */
68 public static final String NAME_OR = FUNCTION_NS + "or";
69
70 /**
71 * Standard identifier for the and function.
72 */
73 public static final String NAME_AND = FUNCTION_NS + "and";
74
75 // internal identifiers for each of the supported functions
76 private static final int ID_OR = 0;
77 private static final int ID_AND = 1;
78
79 /**
80 * Creates a new <code>LogicalFunction</code> object.
81 *
82 * @param functionName the standard XACML name of the function to be
83 * handled by this object, including the full namespace
84 *
85 * @throws IllegalArgumentException if the functionName is unknown
86 */
87 public LogicalFunction(String functionName) {
88 super(functionName, getId(functionName), BooleanAttribute.identifier,
89 false, -1, BooleanAttribute.identifier, false);
90 }
91
92 /**
93 * Private helper that looks up the private id based on the function name.
94 */
95 private static int getId(String functionName) {
96 if (functionName.equals(NAME_OR))
97 return ID_OR;
98 else if (functionName.equals(NAME_AND))
99 return ID_AND;
100 else
101 throw new IllegalArgumentException("unknown logical function: " +
102 functionName);
103 }
104
105 /**
106 * Returns a <code>Set</code> containing all the function identifiers
107 * supported by this class.
108 *
109 * @return a <code>Set</code> of <code>String</code>s
110 */
111 public static Set getSupportedIdentifiers() {
112 Set set = new HashSet();
113
114 set.add(NAME_OR);
115 set.add(NAME_AND);
116
117 return set;
118 }
119
120 /**
121 * Evaluate the function, using the specified parameters.
122 *
123 * @param inputs a <code>List</code> of <code>Evaluatable</code>
124 * objects representing the arguments passed to the function
125 * @param context an <code>EvaluationCtx</code> so that the
126 * <code>Evaluatable</code> objects can be evaluated
127 * @return an <code>EvaluationResult</code> representing the
128 * function's result
129 */
130 public EvaluationResult evaluate(List inputs, EvaluationCtx context) {
131
132 // Evaluate the arguments one by one. As soon as we can
133 // return a result, do so. Return Indeterminate if any argument
134 // evaluated is indeterminate.
135 Iterator it = inputs.iterator();
136 while (it.hasNext()) {
137 Evaluatable eval = (Evaluatable)(it.next());
138
139 // Evaluate the argument
140 EvaluationResult result = eval.evaluate(context);
141 if (result.indeterminate())
142 return result;
143
144 AttributeValue value = result.getAttributeValue();
145 boolean argBooleanValue = ((BooleanAttribute)value).getValue();
146
147 switch (getFunctionId()) {
148 case ID_OR:
149 if (argBooleanValue)
150 return EvaluationResult.getTrueInstance();
151 break;
152 case ID_AND:
153 if (!argBooleanValue)
154 return EvaluationResult.getFalseInstance();
155 break;
156 }
157 }
158
159 if (getFunctionId() == ID_OR)
160 return EvaluationResult.getFalseInstance();
161 else
162 return EvaluationResult.getTrueInstance();
163 }
164 }