Adding graph component

graph/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ 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.
+  -->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <parent>
+    <artifactId>archiva-components</artifactId>
+    <groupId>org.apache.archiva.components</groupId>
+    <version>3.0-SNAPSHOT</version>
+  </parent>
+  <modelVersion>4.0.0</modelVersion>
+
+  <artifactId>archiva-components-graph</artifactId>
+  <name>Archiva Components :: Graph</name>
+  <description>Simple implementation of graph structure and utility class for traversal.</description>
+
+
+  <dependencies>
+    <dependency>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-api</artifactId>
+    </dependency>
+  </dependencies>
+
+
+</project>

graph/src/main/java/org/apache/archiva/components/graph/api/Edge.java

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+package org.apache.archiva.components.graph.api;
+/*
+ * 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.
+ */
+
+/**
+ * The edge links a source vertex to a destination vertex.
+ * A edge instance is always part of a certain graph instance.
+ *
+ * @param <V> The vertex implementation.
+ */
+public interface Edge<V extends Vertex<V>> {
+
+    /**
+     * Returns the identifier of this edge. The id must be unique for given graph.
+     *
+     * @return the identifier of this edge
+     */
+    String getId();
+
+    /**
+     * Returns the label of this edge. The label must not be unique.
+     * If the label was not set, it should return an empty string.
+     * @return the label of this edge, or a empty string
+     */
+    String getLabel();
+
+    /**
+     * Sets the label of this edge to the given string.
+     * @param label the label string, that must not be <code>null</code>
+     * @throws NullPointerException if the label parameter is <code>null</code>
+     */
+    void setLabel(String label) throws NullPointerException;
+
+    /**
+     * Returns the graph where this edge was created.
+     *
+     * @return the graph instance
+     */
+    Graph<V> getGraph();
+
+    /**
+     * Returns the vertex, that is on the source end of this edge.
+     * @return the source vertex
+     */
+    V getSource();
+
+    /**
+     * Returns the vertex, that is on the destination end of this edge.
+     * @return the destination vertex
+     */
+    V getDestination();
+
+    /**
+     * Returns the weight of this edge. For standard graph implementations the default should be 1.0, but
+     * graph implementations may decide to set another default.
+     *
+     * @return the weight of this edge
+     */
+    double getWeight();
+
+
+
+
+}

graph/src/main/java/org/apache/archiva/components/graph/api/Graph.java

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+package org.apache.archiva.components.graph.api;
+/*
+ * 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.
+ */
+
+import org.apache.archiva.components.graph.base.SimpleVertex;
+
+import java.util.Set;
+
+/**
+ *
+ * A graph is the container for vertices. The vertices are connected by edges. Each vertex and
+ * edge instance is coupled to the graph where it was created.
+ *
+ * @param <V>
+ */
+public interface Graph<V extends Vertex<V>> {
+
+    V addVertex(String label);
+
+    void removeVertex(V vertex);
+
+    Edge<V> addEdge(String label, V inVertex, V outVertex);
+
+    void removeEdge(Edge<SimpleVertex> edge);
+
+    V getVertex(String id);
+
+    Edge<V> getEdge(String id);
+
+    Set<V> getVertices();
+
+
+
+}

graph/src/main/java/org/apache/archiva/components/graph/api/TraversalStatus.java

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+package org.apache.archiva.components.graph.api;
+/*
+ * 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.
+ */
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * This class gives information about the status of the graph traversal.
+ * It holds the errors encountered and information about detected cycles.
+ *
+ * @param <V>
+ */
+public class TraversalStatus<V extends Vertex<V>> {
+
+    private int cycles = 0;
+    private List<VisitError<V>> errorList;
+    private List<Vertex<V>> cycleVertices;
+
+    public TraversalStatus() {
+
+    }
+
+    /**
+     * Returns the list of errors
+     * @return a list of errors encountered while executing the consumer function on vertices
+     */
+    public List<VisitError<V>> getErrorList() {
+        return errorList;
+    }
+
+    /**
+     * Returns true, if there were errors while running the consumer function.
+     * @return true, if errors occured on the consumer function, otherwise false
+     */
+    public boolean hasErrors() {
+        return errorList!=null && errorList.size()>0;
+    }
+
+    /**
+     * Add the given error to the list.
+     *
+     * @param vertex the vertex, where the error occured
+     * @param e the exception
+     */
+    public void addError(V vertex, Throwable e) {
+        if (errorList==null) {
+            errorList = new ArrayList<>();
+        }
+        errorList.add(new VisitError(vertex, e));
+    }
+
+    /**
+     * Add another cycle to the counter
+     * @param vertex
+     */
+    public void registerCycle(Vertex<V> vertex) {
+        cycles++;
+        if (cycleVertices==null) {
+            cycleVertices = new ArrayList<>();
+        }
+        cycleVertices.add(vertex);
+    }
+
+    /**
+     * Returns true, if the traversal encountered a cycle.
+     * @return true, if cycle was encountered, otherwise false
+     */
+    public boolean hasCycles() {
+        return cycles>0;
+    }
+
+    /**
+     * Returns the number of detected cycles.
+     *
+     * @return
+     */
+    public int getCycleCount() {
+        return cycles;
+    }
+
+    /**
+     * Returns the vertices, where cycles were detected. The list may contain
+     * duplicated entries, if cycles where detected on different paths.
+     *
+     * @return the list of vertices where cycles were detected
+     */
+    public List<Vertex<V>> getCycleVertices() {
+        return cycleVertices;
+    }
+}

graph/src/main/java/org/apache/archiva/components/graph/api/Vertex.java

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+package org.apache.archiva.components.graph.api;
+/*
+ * 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.
+ */
+
+import java.util.List;
+
+/**
+ * The vertex is a node in a graph structure. The vertex may have connections to and from
+ * other vertices (edges).
+ *
+ * @param <V> The vertex implementation
+ */
+public interface Vertex<V extends Vertex<V>> {
+
+    /**
+     * Returns the identifier of this vertex. The identifier is unique for a given graph.
+     * @return the identifier
+     */
+    String getId();
+
+    /**
+     * Returns the label of this vertex. The label is a name and must not be unique.
+     * If the label was not set it should return a empty string.
+     * @return the label of the vertex or a empty string
+     */
+    String getLabel();
+
+    /**
+     * Sets the label of the vertex
+     * @param label sets the label string, must not be <code>null</code>
+     * @throws NullPointerException if the given label is <code>null</code>
+     */
+    void setLabel(String label) throws NullPointerException;
+
+    /**
+     * Returns the graph where this vertex was created.
+     * @return the graph instance
+     */
+    Graph<V> getGraph();
+
+    /**
+     * Returns all edges that connect to other nodes
+     * @return the edges where this vertex is the source
+     */
+    List<Edge<V>> getOutEdges();
+
+    /**
+     * Returns all edges that connect other nodes to this vertex
+     * @return the edges where this vertex is the destination
+     */
+    List<Edge<V>> getInEdges();
+
+
+}

graph/src/main/java/org/apache/archiva/components/graph/api/VisitError.java

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+package org.apache.archiva.components.graph.api;
+/*
+ * 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.
+ */
+
+public class VisitError<V extends Vertex<V>> {
+
+    private final Throwable exception;
+    private final V vertex;
+
+    public VisitError(V vertex, Throwable exception) {
+        this.exception = exception;
+        this.vertex = vertex;
+    }
+
+    public Throwable getException() {
+        return exception;
+    }
+
+    public V getVertex() {
+        return vertex;
+    }
+}