/** @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;
}
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;
}
}
/** @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;
}
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;
}