Java tutorial
/* * Copyright (C) 2013, 2014 Marton Makai * * 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 qdg.view; import java.util.Iterator; import qdg.api.EntityMap; import qdg.api.MixedGraph; import qdg.api.bits.EdgeMutationHandler; import qdg.api.bits.NodeMutationHandler; import qdg.bits.AbstractDiGraph; import com.google.common.base.Function; import com.google.common.collect.Iterators; import com.google.common.collect.UnmodifiableIterator; /** * A bidirected view of a mixed graph. For each arc of the mixed graph we * consider the original and a backward directed view. * Similarly, for each undirected edge of the mixed * graph we introduce a forward and a backward arc. * * @author Marton Makai * */ public class MixedGraphAsBiDiGraph extends AbstractDiGraph { public static class A implements Edge { private Edge original; private boolean backward; public A(Edge original, boolean backward) { this.original = original; this.backward = backward; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + (backward ? 1231 : 1237); result = prime * result + ((original == null) ? 0 : original.hashCode()); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; A other = (A) obj; if (backward != other.backward) return false; if (original == null) { if (other.original != null) return false; } else if (!original.equals(other.original)) return false; return true; } @Override public String toString() { return "Arc [original=" + original + ", backward=" + backward + "]"; } } protected MixedGraph g; public MixedGraphAsBiDiGraph() { } public MixedGraphAsBiDiGraph(MixedGraph g) { this.g = g; } public void setGraph(MixedGraph graph) { this.g = graph; } public MixedGraph getGraph() { return g; } @Override public Node getSource(Edge edge) { A a = (A) edge; if (!a.backward) { return g.getSource(a.original); } else { return g.getTarget(a.original); } } @Override public Node getTarget(Edge edge) { A a = (A) edge; if (!a.backward) { return g.getTarget(a.original); } else { return g.getSource(a.original); } } @Override public Iterator<Node> getNodeIterator() { return g.getNodeIterator(); } private Function<Edge, Edge> forwardEdge = new Function<Edge, Edge>() { @Override public Edge apply(Edge edge) { return new A(edge, false); } }; private Function<Edge, Edge> backwardEdge = new Function<Edge, Edge>() { @Override public Edge apply(Edge edge) { return new A(edge, true); } }; @Override public <V> EntityMap<Node, V> createNodeMap() { return g.createNodeMap(); } @Override public <V> EntityMap<Edge, V> createEdgeMap() { return new ArcMap<V>(); } @Override public Iterator<Edge> getArcIterator() { Iterator<Edge> forwardArcs = Iterators.transform(g.getArcIterator(), forwardEdge); Iterator<Edge> backwardArcs = Iterators.transform(g.getArcIterator(), backwardEdge); Iterator<Edge> forwardUEdges = Iterators.transform(g.getUEdgeIterator(), forwardEdge); Iterator<Edge> backwardUEdges = Iterators.transform(g.getUEdgeIterator(), backwardEdge); return Iterators.concat(forwardArcs, backwardArcs, forwardUEdges, backwardUEdges); } /** * Outgoing arcs from original undirected edges. */ private class OutArcIterator extends UnmodifiableIterator<Edge> { private Node source; private Iterator<Edge> incidentUEdges; public OutArcIterator(Node source) { this.source = source; incidentUEdges = g.getIncidentUEdgeIterator(source); } @Override public boolean hasNext() { return incidentUEdges.hasNext(); } @Override public Edge next() { Edge edge = incidentUEdges.next(); return new A(edge, !g.getSource(edge).equals(source)); } } @Override public Iterator<Edge> getOutArcIterator(Node node) { Iterator<Edge> forwardArcs = Iterators.transform(g.getOutArcIterator(node), forwardEdge); Iterator<Edge> backwardArcs = Iterators.transform(g.getInArcIterator(node), backwardEdge); Iterator<Edge> uEdges = new OutArcIterator(node); return Iterators.concat(forwardArcs, backwardArcs, uEdges); } /** * Incoming arcs from original undirected edges. */ private class InArcIterator extends UnmodifiableIterator<Edge> { private Node target; private Iterator<Edge> incidentUEdges; public InArcIterator(Node target) { this.target = target; incidentUEdges = g.getIncidentUEdgeIterator(target); } @Override public boolean hasNext() { return incidentUEdges.hasNext(); } @Override public Edge next() { Edge edge = incidentUEdges.next(); return new A(edge, !g.getTarget(edge).equals(target)); } } @Override public Iterator<Edge> getInArcIterator(Node node) { Iterator<Edge> forwardArcs = Iterators.transform(g.getInArcIterator(node), forwardEdge); Iterator<Edge> backwardArcs = Iterators.transform(g.getOutArcIterator(node), backwardEdge); Iterator<Edge> uEdges = new InArcIterator(node); return Iterators.concat(forwardArcs, backwardArcs, uEdges); } @Override public Iterator<Edge> getIncidentArcIterator(Node node) { Iterator<Edge> forwardArcs = Iterators.transform(g.getIncidentArcIterator(node), forwardEdge); Iterator<Edge> backwardArcs = Iterators.transform(g.getIncidentArcIterator(node), backwardEdge); Iterator<Edge> forwardUEdges = Iterators.transform(g.getIncidentEdgeIterator(node), forwardEdge); Iterator<Edge> backwardUEdges = Iterators.transform(g.getIncidentUEdgeIterator(node), backwardEdge); return Iterators.concat(forwardArcs, backwardArcs, forwardUEdges, backwardUEdges); } protected class ArcMap<V> implements EntityMap<Edge, V> { private EntityMap<Edge, V> forwardArcs, backwardArcs; private EntityMap<Edge, V> forwardUEdges, backwardUEdges; public ArcMap() { this(g.<V>createArcMap(), g.<V>createArcMap(), g.<V>createUEdgeMap(), g.<V>createUEdgeMap()); } public ArcMap(EntityMap<Edge, V> forwardArcs, EntityMap<Edge, V> backwardArcs, EntityMap<Edge, V> forwardUEdges, EntityMap<Edge, V> backwardUEdges) { this.forwardArcs = forwardArcs; this.backwardArcs = backwardArcs; this.forwardUEdges = forwardUEdges; this.backwardUEdges = backwardUEdges; } @Override public V put(Edge k, V v) { A a = (A) k; if (g.isDirected(a.original)) { if (!a.backward) { return forwardArcs.put((Edge) a.original, v); } else { return backwardArcs.put((Edge) a.original, v); } } else { if (!a.backward) { return forwardUEdges.put((Edge) a.original, v); } else { return backwardUEdges.put((Edge) a.original, v); } } } @Override public V get(Object k) { A a = (A) k; if (g.isDirected(a.original)) { if (!a.backward) { return forwardArcs.get((Edge) a.original); } else { return backwardArcs.get((Edge) a.original); } } else { if (!a.backward) { return forwardUEdges.get((Edge) a.original); } else { return backwardUEdges.get((Edge) a.original); } } } } /** * Wraps maps of the underlying graph to a map of the view. * * @param forwardArcs * @param backwardArcs * @param forwardUEdges * @param backwardUEdges * @return */ public <V> EntityMap<Edge, V> createArcMap(EntityMap<Edge, V> forwardArcs, EntityMap<Edge, V> backwardArcs, EntityMap<Edge, V> forwardUEdges, EntityMap<Edge, V> backwardUEdges) { return new ArcMap<V>(forwardArcs, backwardArcs, forwardUEdges, backwardUEdges); } @Override public <V> EntityMap<Edge, V> createArcMap() { return new ArcMap<V>(); } @Override public Node addNode() { throw new UnsupportedOperationException(); } @Override public void remove(Node n) { throw new UnsupportedOperationException(); } @Override public Edge addArc(Node source, Node target) { throw new UnsupportedOperationException(); } @Override public void remove(Edge arc) { throw new UnsupportedOperationException(); } @Override public void addNodeMutationHandler(NodeMutationHandler handler) { throw new UnsupportedOperationException(); } @Override public void addEdgeMutationHandler(EdgeMutationHandler handler) { throw new UnsupportedOperationException(); } }