org.apache.karaf.features.internal.service.RequirementSort Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of org.apache.karaf.features.core Show documentation
This bundle is the core implementation of the Karaf features support.
There is a newer version: 4.4.6
Show newest version
/*
 * 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.karaf.features.internal.service;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Set;

import org.apache.felix.utils.resource.CapabilitySet;
import org.apache.felix.utils.resource.SimpleFilter;
import org.osgi.framework.Constants;
import org.osgi.resource.Capability;
import org.osgi.resource.Requirement;
import org.osgi.resource.Resource;

public final class RequirementSort {

    private RequirementSort() {
    }

    /**
     * Sort {@link Resource} based on their {@link Requirement}s and {@link Capability}s.
     *
     * @param resources the resource to sort.
     * @param  the resources type.
     * @return sorted collection of resources.
     */
    public static  Collection sort(Collection resources) {
        Set namespaces = new HashSet<>();
        for (Resource r : resources) {
            for (Capability cap : r.getCapabilities(null)) {
                namespaces.add(cap.getNamespace());
            }
        }
        CapabilitySet capSet = new CapabilitySet(new ArrayList<>(namespaces));
        for (Resource r : resources) {
            for (Capability cap : r.getCapabilities(null)) {
                capSet.addCapability(cap);
            }
        }
        Set sorted = new LinkedHashSet<>();
        Set visited = new LinkedHashSet<>();
        for (T r : resources) {
            visit(r, visited, sorted, capSet);
        }
        return sorted;
    }

    private static  void visit(T resource, Set visited, Set sorted, CapabilitySet capSet) {
        if (!visited.add(resource)) {
            return;
        }
        for (T r : collectDependencies(resource, capSet)) {
            visit(r, visited, sorted, capSet);
        }
        sorted.add(resource);
    }

    @SuppressWarnings("unchecked")
    private static  Set collectDependencies(T resource, CapabilitySet capSet) {
        Set result = new LinkedHashSet<>();
        for (Requirement requirement : resource.getRequirements(null)) {
            String filter = requirement.getDirectives().get(Constants.FILTER_DIRECTIVE);
            SimpleFilter sf = (filter != null)
                    ? SimpleFilter.parse(filter)
                    : SimpleFilter.MATCH_ALL_FILTER;
            for (Capability cap : capSet.match(sf, true)) {
                result.add((T) cap.getResource());
            }
        }
        return result;
    }

}