CandidateComparator.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.felix.resolver.test.util;

import java.util.Comparator;

import org.apache.felix.resolver.Util;
import org.osgi.framework.Version;
import org.osgi.framework.namespace.BundleNamespace;
import org.osgi.framework.namespace.IdentityNamespace;
import org.osgi.framework.namespace.PackageNamespace;
import org.osgi.framework.wiring.BundleCapability;
import org.osgi.resource.Capability;

public class CandidateComparator implements Comparator<Capability>
{
    public int compare(Capability cap1, Capability cap2)
    {
        int c = 0;
        // Always prefer system bundle
        if (cap1 instanceof BundleCapability && !(cap2 instanceof BundleCapability)) {
            c = -1;
        } else if (!(cap1 instanceof BundleCapability) && cap2 instanceof BundleCapability) {
            c = 1;
        }
        // Compare revision capabilities.
        if ((c == 0) && cap1.getNamespace().equals(BundleNamespace.BUNDLE_NAMESPACE))
        {
            c = ((Comparable) cap1.getAttributes().get(BundleNamespace.BUNDLE_NAMESPACE))
                    .compareTo(cap2.getAttributes().get(BundleNamespace.BUNDLE_NAMESPACE));
            if (c == 0)
            {
                Version v1 = (!cap1.getAttributes().containsKey(BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE))
                        ? Version.emptyVersion
                        : (Version) cap1.getAttributes().get(BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE);
                Version v2 = (!cap2.getAttributes().containsKey(BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE))
                        ? Version.emptyVersion
                        : (Version) cap2.getAttributes().get(BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE);
                // Compare these in reverse order, since we want
                // highest version to have priority.
                c = compareVersions(v2, v1);
            }
        }
        // Compare package capabilities.
        else if ((c == 0) && cap1.getNamespace().equals(PackageNamespace.PACKAGE_NAMESPACE))
        {
            c = ((Comparable) cap1.getAttributes().get(PackageNamespace.PACKAGE_NAMESPACE))
                    .compareTo(cap2.getAttributes().get(PackageNamespace.PACKAGE_NAMESPACE));
            if (c == 0)
            {
                Version v1 = (!cap1.getAttributes().containsKey(PackageNamespace.CAPABILITY_VERSION_ATTRIBUTE))
                        ? Version.emptyVersion
                        : (Version) cap1.getAttributes().get(PackageNamespace.CAPABILITY_VERSION_ATTRIBUTE);
                Version v2 = (!cap2.getAttributes().containsKey(PackageNamespace.CAPABILITY_VERSION_ATTRIBUTE))
                        ? Version.emptyVersion
                        : (Version) cap2.getAttributes().get(PackageNamespace.CAPABILITY_VERSION_ATTRIBUTE);
                // Compare these in reverse order, since we want
                // highest version to have priority.
                c = compareVersions(v2, v1);
                // if same version, rather compare on the bundle version
                if (c == 0)
                {
                    v1 = (!cap1.getAttributes().containsKey(BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE))
                            ? Version.emptyVersion
                            : (Version) cap1.getAttributes().get(BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE);
                    v2 = (!cap2.getAttributes().containsKey(BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE))
                            ? Version.emptyVersion
                            : (Version) cap2.getAttributes().get(BundleNamespace.CAPABILITY_BUNDLE_VERSION_ATTRIBUTE);
                    // Compare these in reverse order, since we want
                    // highest version to have priority.
                    c = compareVersions(v2, v1);
                }
            }
        }
        // Compare feature capabilities
        else if ((c == 0) && cap1.getNamespace().equals(IdentityNamespace.IDENTITY_NAMESPACE))
        {
            c = ((Comparable) cap1.getAttributes().get(IdentityNamespace.IDENTITY_NAMESPACE))
                    .compareTo(cap2.getAttributes().get(IdentityNamespace.IDENTITY_NAMESPACE));
            if (c == 0)
            {
                Version v1 = (!cap1.getAttributes().containsKey(IdentityNamespace.CAPABILITY_VERSION_ATTRIBUTE))
                        ? Version.emptyVersion
                        : (Version) cap1.getAttributes().get(IdentityNamespace.CAPABILITY_VERSION_ATTRIBUTE);
                Version v2 = (!cap2.getAttributes().containsKey(IdentityNamespace.CAPABILITY_VERSION_ATTRIBUTE))
                        ? Version.emptyVersion
                        : (Version) cap2.getAttributes().get(IdentityNamespace.CAPABILITY_VERSION_ATTRIBUTE);
                // Compare these in reverse order, since we want
                // highest version to have priority.
                c = compareVersions(v2, v1);
            }
        }
        if (c == 0) {
            // We just want to have a deterministic heuristic
            String n1 = cap1.toString();
            String n2 = cap2.toString();
            c = n1.compareTo(n2);
            if (c == 0) {
                n1 = cap1.getResource().toString();
                n2 = cap2.getResource().toString();
                c = n1.compareTo(n2);
            }
        }
        return c;
    }

    private int compareVersions(Version v1, Version v2) {
        int c = v1.getMajor() - v2.getMajor();
        if (c != 0) {
            return c;
        }
        c = v1.getMinor() - v2.getMinor();
        if (c != 0) {
            return c;
        }
        c = v1.getMicro() - v2.getMicro();
        if (c != 0) {
            return c;
        }
        String q1 = cleanQualifierForComparison(v1.getQualifier());
        String q2 = cleanQualifierForComparison(v2.getQualifier());
        return q1.compareTo(q2);
    }

    private String cleanQualifierForComparison(String qualifier) {
        return qualifier.replaceAll("(redhat-[0-9]{3})([0-9]{3})", "$1-$2");
    }
}