1/*
2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
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17 * You should have received a copy of the GNU General Public License version
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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24 */
25
26package com.sun.xml.internal.ws.policy;
27
28import com.sun.xml.internal.ws.policy.privateutil.PolicyLogger;
29import java.util.Collection;
30import java.util.LinkedList;
31import java.util.List;
32import java.util.Queue;
33import com.sun.xml.internal.ws.policy.privateutil.LocalizationMessages;
34import com.sun.xml.internal.ws.policy.sourcemodel.wspolicy.NamespaceVersion;
35import java.util.ArrayList;
36
37/**
38 * The instance of this class is intended to provide policy intersection mechanism.
39 *
40 * @author Marek Potociar (marek.potociar@sun.com)
41 */
42public final class PolicyIntersector {
43    static enum CompatibilityMode {
44        STRICT,
45        LAX
46    }
47
48    private static final PolicyIntersector STRICT_INTERSECTOR = new PolicyIntersector(CompatibilityMode.STRICT);
49    private static final PolicyIntersector LAX_INTERSECTOR = new PolicyIntersector(CompatibilityMode.LAX);
50    private static final PolicyLogger LOGGER = PolicyLogger.getLogger(PolicyIntersector.class);
51
52    private CompatibilityMode mode;
53
54    /**
55     * Prevents direct instantiation of this class from outside
56     * @param intersectionMode intersection mode
57     */
58    private PolicyIntersector(CompatibilityMode intersectionMode) {
59        this.mode = intersectionMode;
60    }
61
62    /**
63     * Returns a strict policy intersector that can be used to intersect group of policies.
64     *
65     * @return policy intersector instance.
66     */
67    public static PolicyIntersector createStrictPolicyIntersector() {
68        return PolicyIntersector.STRICT_INTERSECTOR;
69    }
70
71    /**
72     * Returns a strict policy intersector that can be used to intersect group of policies.
73     *
74     * @return policy intersector instance.
75     */
76    public static PolicyIntersector createLaxPolicyIntersector() {
77        return PolicyIntersector.LAX_INTERSECTOR;
78    }
79
80    /**
81     * Performs intersection on the input collection of policies and returns the resulting (intersected) policy. If input policy
82     * collection contains only a single policy instance, no intersection is performed and the instance is directly returned
83     * as a method call result.
84     *
85     * @param policies collection of policies to be intersected. Must not be {@code null} nor empty, otherwise exception is thrown.
86     * @return intersected policy as a result of perfromed policy intersection. A {@code null} value is never returned.
87     *
88     * @throws IllegalArgumentException in case {@code policies} argument is either {@code null} or empty collection.
89     */
90    public Policy intersect(final Policy... policies) {
91        if (policies == null || policies.length == 0) {
92            throw LOGGER.logSevereException(new IllegalArgumentException(LocalizationMessages.WSP_0056_NEITHER_NULL_NOR_EMPTY_POLICY_COLLECTION_EXPECTED()));
93        } else if (policies.length == 1) {
94            return policies[0];
95        }
96
97        // check for "null" and "empty" policy: if such policy is found return "null" policy,
98        // or if all policies are "empty", return "empty" policy
99        boolean found = false;
100        boolean allPoliciesEmpty = true;
101        NamespaceVersion latestVersion = null;
102        for (Policy tested : policies) {
103            if (tested.isEmpty()) {
104                found = true;
105            } else {
106                if (tested.isNull()) {
107                    found = true;
108                }
109                allPoliciesEmpty = false;
110            }
111            if (latestVersion == null) {
112                latestVersion = tested.getNamespaceVersion();
113            } else if (latestVersion.compareTo(tested.getNamespaceVersion()) < 0) {
114                latestVersion = tested.getNamespaceVersion();
115            }
116
117            if (found && !allPoliciesEmpty) {
118                return Policy.createNullPolicy(latestVersion, null, null);
119            }
120        }
121        latestVersion = (latestVersion != null) ? latestVersion : NamespaceVersion.getLatestVersion();
122        if (allPoliciesEmpty) {
123            return Policy.createEmptyPolicy(latestVersion, null, null);
124        }
125
126        // simple tests didn't lead to final answer => let's performe some intersecting ;)
127        final List<AssertionSet> finalAlternatives = new LinkedList<AssertionSet>(policies[0].getContent());
128        final Queue<AssertionSet> testedAlternatives = new LinkedList<AssertionSet>();
129        final List<AssertionSet> alternativesToMerge = new ArrayList<AssertionSet>(2);
130        for (int i = 1; i < policies.length; i++) {
131            final Collection<AssertionSet> currentAlternatives = policies[i].getContent();
132
133            testedAlternatives.clear();
134            testedAlternatives.addAll(finalAlternatives);
135            finalAlternatives.clear();
136
137            AssertionSet testedAlternative;
138            while ((testedAlternative = testedAlternatives.poll()) != null) {
139                for (AssertionSet currentAlternative : currentAlternatives) {
140                    if (testedAlternative.isCompatibleWith(currentAlternative, this.mode)) {
141                        alternativesToMerge.add(testedAlternative);
142                        alternativesToMerge.add(currentAlternative);
143                        finalAlternatives.add(AssertionSet.createMergedAssertionSet(alternativesToMerge));
144                        alternativesToMerge.clear();
145                    }
146                }
147            }
148        }
149
150        return Policy.createPolicy(latestVersion, null, null, finalAlternatives);
151    }
152}
153