* specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.internal.impl;

import java.util.*;

import org.apache.maven.project.CycleDetectedException;

class Graph {
    private enum DfsState {
        VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);

import java.util.List;
import java.util.Map;
import java.util.Set;

class Graph {

    final Map<String, Set<String>> graph = new LinkedHashMap<>();

    synchronized void addEdge(String from, String to) throws CycleDetectedException {
        if (graph.computeIfAbsent(from, l -> new HashSet<>()).add(to)) {
            List<String> cycle = visitCycle(graph, Collections.singleton(to), new HashMap<>(), new LinkedList<>());

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.project;

import java.util.*;

class Graph {
    private enum DfsState {
        VISITING,
        VISITED
    }

    final Map<String, Vertex> vertices = new LinkedHashMap<>();

    public Vertex getVertex(String id) {
        return vertices.get(id);

         *       v3-v4
         *
         */
        v1 = graph.addVertex(new ArtifactMetadata("g", "a1", "1.0"));
        graph.setEntry(v1);
        v2 = graph.addVertex(new ArtifactMetadata("g", "a2", "1.0"));
        v3 = graph.addVertex(new ArtifactMetadata("g", "a3", "1.0"));
        v4 = graph.addVertex(new ArtifactMetadata("g", "a4", "1.0"));

        // v1-->v2
        graph.addEdge(v1, v2, new MetadataGraphEdge("1.1", true, null, null, 2, 1));

import org.apache.maven.api.model.Parent;
import org.apache.maven.api.model.Plugin;
import org.apache.maven.artifact.ArtifactUtils;
import org.apache.maven.project.Graph.Vertex;

/**
 * ProjectSorter
 */
public class ProjectSorter {
    private Graph graph;

    private List<MavenProject> sortedProjects;

    private Map<String, MavenProject> projectMap;

    /**
     * Sort a list of projects.
     * <ul>

        Graph graph = new Graph();
        graph.addVertex("a");
        assertEquals(1, graph.getVertices().size());
        assertEquals("a", graph.getVertex("a").getLabel());
        graph.addVertex("a");
        assertEquals(1, graph.getVertices().size());
        assertEquals("a", graph.getVertex("a").getLabel());

        graph.addVertex("b");

         *   v1<
         *      v3-v4
         *
         */
        graph = new MetadataGraph(4, 3);
        v1 = graph.addVertex(new ArtifactMetadata("g", "a1", "1.0"));
        graph.setEntry(v1);
        v2 = graph.addVertex(new ArtifactMetadata("g", "a2", "1.0"));
        v3 = graph.addVertex(new ArtifactMetadata("g", "a3", "1.0"));
        v4 = graph.addVertex(new ArtifactMetadata("g", "a4", "1.0"));

        // v1-->v2

     * in <code>ArtifactScopeEnum</code>
     *
     * @param graph the "dirty" graph to be simplified via conflict resolution
     * @param scope scope for which the graph should be resolved
     *
     * @return resulting "clean" graph for the specified scope
     *
     * @since 3.0
     */
    MetadataGraph resolveConflicts(MetadataGraph graph, ArtifactScopeEnum scope)
            throws GraphConflictResolutionException;

    /**
     *  null in dirty graph, actual
     *  scope for conflict-resolved graph
     */
    ArtifactScopeEnum scope;

    // ------------------------------------------------------------------------
    /**
     * init graph
     */
    public MetadataGraph(int nVertices) {
        init(nVertices, 2 * nVertices);
    }

    public MetadataGraph(int nVertices, int nEdges) {

    private final Map<MavenProject, Integer> order;

    private final Map<String, MavenProject> projects;

    /**
     * Creates a new project dependency graph based on the specified projects.
     *
     * @param projects The projects to create the dependency graph with
     * @throws DuplicateProjectException
     * @throws CycleDetectedException
     */
    public DefaultProjectDependencyGraph(Collection<MavenProject> projects)