moditect#27 Adding several graph algorithms

javac-plugin/pom.xml

@@ -45,6 +45,10 @@
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.google.guava</groupId>
+            <artifactId>guava</artifactId>
+        </dependency>
 
         <dependency>
             <groupId>junit</groupId>

javac-plugin/src/main/java/org/moditect/deptective/internal/graph/Dependency.java

@@ -0,0 +1,53 @@
+/**
+ *  Copyright 2019 The ModiTect authors
+ *
+ *  Licensed 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.moditect.deptective.internal.graph;
+
+import org.moditect.deptective.internal.graph.Dependency;
+
+/**
+ * @author Gerd Wütherich (gw@code-kontor.io)
+ */
+public class Dependency {
+
+    private Node from;
+    private Node to;
+    private int aggregatdWeight;
+
+    public Dependency(Node from, Node to, int aggregatdWeight) {
+        this.from = from;
+        this.to = to;
+        this.aggregatdWeight = aggregatdWeight;
+
+        from.addOutgoingDependency(this);
+    }
+
+    public Node getFrom() {
+        return from;
+    }
+
+    public Node getTo() {
+        return to;
+    }
+
+    public int getAggregatedWeight() {
+        return aggregatdWeight;
+    }
+
+    @Override
+    public String toString() {
+        return "SimpleDependency [from=" + from + ", to=" + to + ", aggregatdWeight=" + aggregatdWeight + "]";
+    }
+}

javac-plugin/src/main/java/org/moditect/deptective/internal/graph/GraphUtils.java

@@ -0,0 +1,158 @@
+/**
+ *  Copyright 2019 The ModiTect authors
+ *
+ *  Licensed 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.moditect.deptective.internal.graph;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import org.moditect.deptective.internal.graph.impl.DependencyStructureMatrix;
+import org.moditect.deptective.internal.graph.impl.FastFasSorter;
+import org.moditect.deptective.internal.graph.impl.Tarjan;
+
+/**
+ * 
+ * @author Gerd Wütherich (gw@code-kontor.io)
+ */
+public class GraphUtils {
+
+    /**
+     * A directed graph is called strongly connected if there is a path in each direction between each pair of vertices
+     * of the graph. A strongly connected component (SCC) of a directed graph is a maximal strongly connected subgraph.
+     * 
+     * @param nodes the collection of nodes (the directed graph)
+     * @return a list of strongly connected components (SCCs). Note that the result also contains components that
+     *         contain just a single node. If you want to detect 'real' cycle (size > 1) please use {@link GraphUtils#detectCycles(Collection)}.
+     */
+    public static List<List<Node>> detectStronglyConnectedComponents(Collection<Node> nodes) {
+        return new Tarjan<Node>().detectStronglyConnectedComponents(checkNotNull(nodes));
+    }
+
+    /**
+     * Returns all strongly connected subgraphs (size > 1) of the specified graph. 
+     * 
+     * @param nodes 
+     * @return a list of strongly connected components (SCCs) with a size > 1.
+     */
+    public static List<List<Node>> detectCycles(Collection<Node> nodes) {
+        return new Tarjan<Node>().detectStronglyConnectedComponents(nodes).stream().filter(cycle -> cycle.size() > 1)
+                .collect(Collectors.toList());
+    }
+
+    /**
+     * Creates a dependency structure matrix (DSM) for the given graph nodes. 
+     * 
+     * @param nodes the collection of nodes
+     * @return
+     */
+    public static IDependencyStructureMatrix createDependencyStructureMatrix(
+            Collection<Node> nodes) {
+        return new DependencyStructureMatrix(nodes);
+    }
+
+    /**
+     * An adjacency matrix is a square matrix used to represent a finite graph. The elements of the matrix 
+     * indicate whether pairs of vertices are connected (adjacent) or not in the graph.
+     * 
+     * @param nodes the collection of nodes
+     * @return the adjacency matrix for the given list of nodes
+     */
+    public static int[][] computeAdjacencyMatrix(List<Node> nodes) {
+        checkNotNull(nodes);
+        return computeAdjacencyMatrix((Node[]) nodes.toArray(new Node[nodes.size()]));
+    }
+
+    /**
+     * An adjacency matrix is a square matrix used to represent a finite graph. The elements of the matrix 
+     * indicate whether pairs of vertices are connected (adjacent) or not in the graph.
+     * 
+     * @param nodes the array of nodes
+     * @return the adjacency matrix for the given list of nodes
+     */
+    public static int[][] computeAdjacencyMatrix(Node... nodes) {
+        int[][] result = new int[nodes.length][nodes.length];
+        for (int i = 0; i < result.length; i++) {
+            for (int j = 0; j < result.length; j++) {
+                Dependency dependency = nodes[i].getOutgoingDependencyTo(nodes[j]);
+                result[i][j] = dependency != null ? dependency.getAggregatedWeight() : 0;
+            }
+        }
+        return result;
+    }
+
+    /**
+     * An adjacency list is a collection of (unordered) lists used to represent a finite graph. Each list 
+     * describes the set of neighbors of a node. 
+     * 
+     * @param nodes the array of nodes
+     * @return the adjacency list for the given list of nodes
+     */
+    public static int[][] computeAdjacencyList(Collection<Node> nodes) {
+        checkNotNull(nodes);
+        return computeAdjacencyList((Node[]) nodes.toArray(new Node[nodes.size()]));
+    }
+
+    /**
+     * An adjacency list is a collection of (unordered) lists used to represent a finite graph. Each list 
+     * describes the set of neighbors of a node. 
+     * 
+     * @param nodes the array of nodes
+     * @return the adjacency list for the given list of nodes
+     */
+    public static int[][] computeAdjacencyList(Node... nodes) {
+
+        int[][] matrix;
+
+        // prepare
+        int i = 0;
+        Map<Node, Integer> map = new HashMap<Node, Integer>();
+        for (Node iArtifact : nodes) {
+            map.put(iArtifact, i);
+            i++;
+        }
+        matrix = new int[nodes.length][];
+
+        for (Node node : nodes) {
+            Collection<Dependency> dependencies = node.getOutgoingDependenciesTo(Arrays.asList(nodes));
+            if (dependencies == null) {
+                dependencies = Collections.emptyList();
+            }
+            int index = map.get(node);
+            matrix[index] = new int[dependencies.size()];
+            int count = 0;
+            for (Dependency dependency : dependencies) {
+                matrix[index][count] = map.get(dependency.getTo());
+                count++;
+            }
+        }
+        return matrix;
+    }
+
+    /**
+     * Creates a FastFAS based {@link INodeSorter}.
+     * 
+     * @return a FastFAS based {@link INodeSorter}.
+     */
+    public static INodeSorter createFasNodeSorter() {
+        return new FastFasSorter();
+    }
+}

javac-plugin/src/main/java/org/moditect/deptective/internal/graph/IDependencyStructureMatrix.java

@@ -0,0 +1,36 @@
+/**
+ *  Copyright 2019 The ModiTect authors
+ *
+ *  Licensed 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.moditect.deptective.internal.graph;
+
+import java.util.List;
+
+/**
+ * @author Gerd Wütherich (gw@code-kontor.io)
+ */
+public interface IDependencyStructureMatrix {
+
+    List<Node> getOrderedNodes();
+
+    List<Dependency> getUpwardDependencies();
+
+    List<List<Node>> getCycles();
+
+    boolean isCellInCycle(int i, int j);
+
+    boolean isRowInCycle(int i);
+
+    int getWeight(int i, int j);
+}

javac-plugin/src/main/java/org/moditect/deptective/internal/graph/INodeSorter.java

@@ -0,0 +1,33 @@
+/**
+ *  Copyright 2019 The ModiTect authors
+ *
+ *  Licensed 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.moditect.deptective.internal.graph;
+
+import java.util.List;
+
+/**
+ * @author Gerd Wütherich (gw@code-kontor.io)
+ */
+public interface INodeSorter {
+
+    SortResult sort(List<Node> node);
+
+    public interface SortResult {
+
+        List<Node> getOrderedNodes();
+
+        List<Dependency> getUpwardsDependencies();
+    }
+}