/** @see Graph#getAllEdges(Object, Object) */
public Set<E> getAllEdges(V sourceVertex, V targetVertex) {
Set<E> edges = null;
if (containsVertex(sourceVertex) && containsVertex(targetVertex)) {
edges = new ArrayUnenforcedSet<E>();
Iterator<E> iter = getEdgeContainer(sourceVertex).vertexEdges.iterator();
while (iter.hasNext()) {
E e = iter.next();
boolean equalStraight =
sourceVertex.equals(getEdgeSource(e)) && targetVertex.equals(getEdgeTarget(e));
boolean equalInverted =
sourceVertex.equals(getEdgeTarget(e)) && targetVertex.equals(getEdgeSource(e));
if (equalStraight || equalInverted) {
edges.add(e);
}
}
}
return edges;
}
/**
* @param vertexNumber the number which identifies the vertex v in this order.
* @return the identifying numbers of all vertices which are connected to v by an edge incoming to
* v.
*/
public int[] getInEdges(int vertexNumber) {
if (cacheEdges && (incomingEdges[vertexNumber] != null)) {
return incomingEdges[vertexNumber];
}
V v = getVertex(vertexNumber);
Set<E> edgeSet;
if (graph instanceof DirectedGraph<?, ?>) {
edgeSet = ((DirectedGraph<V, E>) graph).incomingEdgesOf(v);
} else {
edgeSet = graph.edgesOf(v);
}
int[] vertexArray = new int[edgeSet.size()];
int i = 0;
for (E edge : edgeSet) {
V source = graph.getEdgeSource(edge), target = graph.getEdgeTarget(edge);
vertexArray[i++] = mapVertexToOrder.get(source.equals(v) ? target : source);
}
if (cacheEdges) {
incomingEdges[vertexNumber] = vertexArray;
}
return vertexArray;
}
public void union(AbstractBaseGraph<V, E> g2) {
if (!(this instanceof DirectedGraph<?, ?> && g2 instanceof DirectedGraph<?, ?>)) {
return;
}
Set<V> vertexSet = g2.vertexSet();
for (V vertex : vertexSet) {
if (!containsVertex(vertex)) addVertex(vertex);
}
for (V vertex : vertexSet) {
Set<E> edgeSet = g2.specifics.outgoingEdgesOf(vertex);
for (E edge : edgeSet) {
V sourceVertex = getEdgeSource(edge);
V targetVertex = getEdgeTarget(edge);
if (!allowingMultipleEdges && containsEdge(sourceVertex, targetVertex)) {
continue;
}
if (!allowingLoops && sourceVertex.equals(targetVertex)) {
continue;
}
if (containsEdge(edge)) {
continue;
} else {
IntrusiveEdge intrusiveEdge = createIntrusiveEdge(edge, sourceVertex, targetVertex);
edgeMap.put(edge, intrusiveEdge);
specifics.addEdgeToTouchingVertices(edge);
}
}
}
}
/** @see AbstractBaseGraph#removeEdgeFromTouchingVertices(Edge) */
public void removeEdgeFromTouchingVertices(E e) {
V source = getEdgeSource(e);
V target = getEdgeTarget(e);
getEdgeContainer(source).removeEdge(e);
if (!source.equals(target)) {
getEdgeContainer(target).removeEdge(e);
}
}
/** @see Graph#addEdge(Object, Object, Object) */
public boolean addEdge(V sourceVertex, V targetVertex, E e) {
if (e == null) {
throw new NullPointerException();
} else if (containsEdge(e)) {
return false;
}
assertVertexExist(sourceVertex);
assertVertexExist(targetVertex);
if (!allowingMultipleEdges && containsEdge(sourceVertex, targetVertex)) {
return false;
}
if (!allowingLoops && sourceVertex.equals(targetVertex)) {
throw new IllegalArgumentException(LOOPS_NOT_ALLOWED);
}
IntrusiveEdge intrusiveEdge = createIntrusiveEdge(e, sourceVertex, targetVertex);
edgeMap.put(e, intrusiveEdge);
specifics.addEdgeToTouchingVertices(e);
return true;
}
/** @see Graph#addEdge(Object, Object) */
public E addEdge(V sourceVertex, V targetVertex) {
assertVertexExist(sourceVertex);
assertVertexExist(targetVertex);
if (!allowingMultipleEdges && containsEdge(sourceVertex, targetVertex)) {
return null;
}
if (!allowingLoops && sourceVertex.equals(targetVertex)) {
throw new IllegalArgumentException(LOOPS_NOT_ALLOWED);
}
E e = edgeFactory.createEdge(sourceVertex, targetVertex);
if (containsEdge(e)) { // this restriction should stay!
return null;
} else {
IntrusiveEdge intrusiveEdge = createIntrusiveEdge(e, sourceVertex, targetVertex);
edgeMap.put(e, intrusiveEdge);
specifics.addEdgeToTouchingVertices(e);
return e;
}
}
/** {@inheritDoc} */
protected void encounterVertexAgain(V vertex, E edge) {
super.encounterVertexAgain(vertex, edge);
int i;
if (root != null) {
// For rooted detection, the path must either
// double back to the root, or to a node of a cycle
// which has already been detected.
if (vertex.equals(root)) {
i = 0;
} else if ((cycleSet != null) && cycleSet.contains(vertex)) {
i = 0;
} else {
return;
}
} else {
i = path.indexOf(vertex);
}
if (i > -1) {
if (cycleSet == null) {
// we're doing yes/no cycle detection
throw new CycleDetectedException();
} else {
for (; i < path.size(); ++i) {
cycleSet.add(path.get(i));
}
}
}
}
private void assertGetPath(V endVertex) {
if (endVertex.equals(this.startVertex)) {
throw new IllegalArgumentException("The end vertex is the same as the start vertex!");
}
if (!this.graph.containsVertex(endVertex)) {
throw new IllegalArgumentException("Graph must contain the end vertex!");
}
}
/** @see Graph#getEdge(Object, Object) */
public E getEdge(V sourceVertex, V targetVertex) {
if (containsVertex(sourceVertex) && containsVertex(targetVertex)) {
Iterator<E> iter = getEdgeContainer(sourceVertex).vertexEdges.iterator();
while (iter.hasNext()) {
E e = iter.next();
boolean equalStraight =
sourceVertex.equals(getEdgeSource(e)) && targetVertex.equals(getEdgeTarget(e));
boolean equalInverted =
sourceVertex.equals(getEdgeTarget(e)) && targetVertex.equals(getEdgeSource(e));
if (equalStraight || equalInverted) {
return e;
}
}
}
return null;
}
/**
* Updates outgoing vertices of the vertex. For each outgoing vertex, the new paths are obtained
* by concatenating the specified edge to the calculated paths of the specified vertex. If the
* weight of a new path is greater than the weight of any path stored so far at the outgoing
* vertex then the path is not added, otherwise it is added to the list of paths in increasing
* order of weight. Complexity =
*
* <ul>
* <li>O(<code>d(v)*k*(m+n)</code>) where <code>d(v)</code> is the outgoing degree of the
* specified vertex, <code>k</code> is the maximum number of shortest paths to compute,
* <code>m</code> is the number of edges of the graph and <code>n</code> is the number of
* vertices of the graph
* </ul>
*
* @param vertex
* @param improvedVertices
*/
private void updateOutgoingVertices(V vertex, Set<V> improvedVertices) {
// try to add new paths for the target vertices of the outgoing edges
// of the vertex in argument.
for (Iterator<E> iter = edgesOfIterator(vertex); iter.hasNext(); ) {
E edge = iter.next();
V vertexReachedByEdge = Graphs.getOppositeVertex(this.graph, edge, vertex);
// check if the path does not loop over the start vertex.
if (!vertexReachedByEdge.equals(this.startVertex)) {
if (this.seenDataContainer.containsKey(vertexReachedByEdge)) {
boolean relaxed = tryToAddNewPaths(vertexReachedByEdge, edge);
if (relaxed) {
improvedVertices.add(vertexReachedByEdge);
}
} else {
boolean relaxed = tryToAddFirstPaths(vertexReachedByEdge, edge);
if (relaxed) {
improvedVertices.add(vertexReachedByEdge);
}
}
}
}
}
/**
* Returns the list of vertices whose path has been improved during the current pass. Complexity =
*
* <ul>
* <li>O(<code>m*k*(m+n)</code>) where <code>k</code> is the maximum number of shortest paths to
* compute, <code>m</code> is the number of edges of the graph and <code>n</code> is the
* number of vertices of the graph
* </ul>
*
* @see java.util.Iterator#next()
*/
@Override
public Set<V> next() {
if (!this.startVertexEncountered) {
encounterStartVertex();
}
// at the i-th pass the shortest paths with i edges are calculated.
if (hasNext()) {
Set<V> improvedVertices = new HashSet<>();
for (V vertex : this.prevImprovedVertices) {
if (!vertex.equals(this.endVertex)) {
updateOutgoingVertices(vertex, improvedVertices);
}
}
savePassData(improvedVertices);
this.passNumber++;
return improvedVertices;
}
throw new NoSuchElementException();
}
private V findPath(V root) {
Set<V> used = new HashSet<>();
Queue<V> q = new ArrayDeque<>();
// Expand graph back from its contracted state
path.clear();
contracted.clear();
graph.vertexSet().forEach(vertex -> contracted.put(vertex, vertex));
used.add(root);
q.add(root);
while (!q.isEmpty()) {
V v = q.remove();
for (E e : graph.edgesOf(v)) {
V to = graph.getEdgeSource(e);
if (to.equals(v)) {
to = graph.getEdgeTarget(e);
}
if ((contracted.get(v).equals(contracted.get(to))) || to.equals(match.get(v))) {
continue;
}
// Check whether we've hit a 'blossom'
if ((to.equals(root)) || ((match.containsKey(to)) && (path.containsKey(match.get(to))))) {
V stem = lowestCommonAncestor(v, to);
Set<V> blossom = new HashSet<>();
markPath(v, to, stem, blossom);
markPath(to, v, stem, blossom);
graph
.vertexSet()
.stream()
.filter(i -> contracted.containsKey(i) && blossom.contains(contracted.get(i)))
.forEach(
i -> {
contracted.put(i, stem);
if (!used.contains(i)) {
used.add(i);
q.add(i);
}
});
// Check whether we've had hit a loop (of even length (!) presumably)
} else if (!path.containsKey(to)) {
path.put(to, v);
if (!match.containsKey(to)) {
return to;
}
to = match.get(to);
used.add(to);
q.add(to);
}
}
}
return null;
}
