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Graph implementations for the JUNG project
package edu.uci.ics.jung.graph;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import edu.uci.ics.jung.graph.util.EdgeType;
import edu.uci.ics.jung.graph.util.Pair;
import edu.uci.ics.jung.graph.util.TreeUtils;
/**
* An implementation of Forest that delegates to a specified DirectedGraph
* instance.
* @author Tom Nelson
*
* @param the vertex type
* @param the edge type
*/
@SuppressWarnings("serial")
public class DelegateForest extends GraphDecorator implements Forest
{
/**
* Creates an instance backed by a new {@code DirectedSparseGraph} instance.
*/
public DelegateForest() {
this(new DirectedSparseGraph());
}
/**
* Creates an instance backed by the input {@code DirectedGraph}.
* @param delegate the graph to which operations will be delegated
*/
public DelegateForest(DirectedGraph delegate) {
super(delegate);
}
/**
* Add an edge to the tree, connecting v1, the parent and v2, the child.
* v1 must already exist in the tree, and v2 must not already exist
* the passed edge must be unique in the tree. Passing an edgeType
* other than EdgeType.DIRECTED may cause an illegal argument exception
* in the delegate graph.
*
* @param e a unique edge to add
* @param v1 the parent node
* @param v2 the child node
* @param edgeType should be EdgeType.DIRECTED
* @return true if this call mutates the underlying graph
* @see edu.uci.ics.jung.graph.Graph#addEdge(java.lang.Object, java.lang.Object, java.lang.Object, edu.uci.ics.jung.graph.util.EdgeType)
*/
@Override
public boolean addEdge(E e, V v1, V v2, EdgeType edgeType) {
if(delegate.getVertices().contains(v1) == false) {
throw new IllegalArgumentException("Tree must already contain "+v1);
}
if(delegate.getVertices().contains(v2)) {
throw new IllegalArgumentException("Tree must not already contain "+v2);
}
return delegate.addEdge(e, v1, v2, edgeType);
}
/**
* Add vertex as a root of the tree
*
* @param vertex the tree root to add
* @return true if this call mutates the underlying graph
* @see edu.uci.ics.jung.graph.Graph#addVertex(java.lang.Object)
*/
@Override
public boolean addVertex(V vertex) {
setRoot(vertex);
return true;
}
/**
* Removes edge from this tree, and the subtree rooted
* at the child vertex incident to edge.
* (The subtree is removed to ensure that the tree in which the edge
* was found is still a tree rather than a forest. To change this
* behavior so that the
* @param edge the edge to remove
* @return true iff the tree was modified
* @see edu.uci.ics.jung.graph.Hypergraph#removeEdge(java.lang.Object)
*/
@Override
public boolean removeEdge(E edge) {
return removeEdge(edge, true);
}
/**
* Removes edge from this tree.
* If remove_subtree is true, removes
* the subtree rooted at the child vertex incident to edge.
* Otherwise, leaves the subtree intact as a new component tree of this
* forest.
* @param edge the edge to remove
* @param remove_subtree if true, remove the subtree
* @return true iff the tree was modified
*/
public boolean removeEdge(E edge, boolean remove_subtree)
{
if (!delegate.containsEdge(edge))
return false;
V child = getDest(edge);
if (remove_subtree)
return removeVertex(child);
else
{
delegate.removeEdge(edge);
return false;
}
}
/**
* Removes vertex from this tree, and the subtree
* rooted at vertex.
* @param vertex the vertex to remove
* @return true iff the tree was modified
* @see edu.uci.ics.jung.graph.Hypergraph#removeVertex(java.lang.Object)
*/
@Override
public boolean removeVertex(V vertex) {
return removeVertex(vertex, true);
}
/**
* Removes vertex from this tree.
* If remove_subtrees is true, removes
* the subtrees rooted at the children of vertex.
* Otherwise, leaves these subtrees intact as new component trees of this
* forest.
* @param vertex the vertex to remove
* @param remove_subtrees if true, remove the subtrees
* rooted at vertex's children
* @return true iff the tree was modified
*/
public boolean removeVertex(V vertex, boolean remove_subtrees)
{
if (!delegate.containsVertex(vertex))
return false;
if (remove_subtrees)
for(V v : new ArrayList(delegate.getSuccessors(vertex)))
removeVertex(v, true);
return delegate.removeVertex(vertex);
}
/**
* returns an ordered list of the nodes beginning at the root
* and ending at the passed child node, including all intermediate
* nodes.
* @param child the last node in the path from the root
* @return an ordered list of the nodes from root to child
*/
public List getPath(V child) {
if (!delegate.containsVertex(child))
return null;
List list = new ArrayList();
list.add(child);
V parent = getParent(child);
while(parent != null) {
list.add(list.size(), parent);
parent = getParent(parent);
}
return list;
}
public V getParent(V child) {
if (!delegate.containsVertex(child))
return null;
Collection parents = delegate.getPredecessors(child);
if(parents.size() > 0) {
return parents.iterator().next();
}
return null;
}
/**
* @return the root of the tree, or null if the tree has > 1 roots
*/
public V getRoot() {
V root = null;
for (V v : delegate.getVertices()) {
if (delegate.getPredecessorCount(v) == 0) {
if (root == null) {
root = v;
} else {
// we've found > 1 root, return null
return null;
}
}
}
return root;
}
/**
* adds root as a root of the tree
* @param root the initial tree root
*/
public void setRoot(V root) {
delegate.addVertex(root);
}
/**
* removes a node from the tree, causing all descendants of
* the removed node also to be removed
* @param orphan the node to remove
* @return whether this call mutates the underlying graph
*/
public boolean removeChild(V orphan) {
return removeVertex(orphan);
}
/**
* computes and returns the depth of the tree from the
* root to the passed vertex
*
* @param v the node who's depth is computed
* @return the depth to the passed node.
*/
public int getDepth(V v) {
return getPath(v).size();
}
/**
* computes and returns the height of the tree
*
* @return the height
*/
public int getHeight() {
int height = 0;
for(V v : getVertices()) {
height = Math.max(height, getDepth(v));
}
return height;
}
/**
* @param v the vertex to test
* @return true if v is neither a leaf
* nor a root
*/
public boolean isInternal(V v) {
return isLeaf(v) == false && isRoot(v) == false;
}
/**
* @param v the vertex to test
* @return {@code true} if {@code v} has no child nodes.
*/
public boolean isLeaf(V v) {
return getChildren(v).size() == 0;
}
/**
* @param v the vertex whose children are to be returned
* @return the children of {@code v}.
*/
public Collection getChildren(V v) {
return delegate.getSuccessors(v);
}
/**
* @param v the vertex to test
* @return {@code true} if {@code v} has no parent node.
*/
public boolean isRoot(V v) {
return getParent(v) == null;
}
@Override
public int getIncidentCount(E edge)
{
return 2;
}
@SuppressWarnings("unchecked")
@Override
public boolean addEdge(E edge, Collection vertices) {
Pair pair = null;
if(vertices instanceof Pair) {
pair = (Pair)vertices;
} else {
pair = new Pair(vertices);
}
return addEdge(edge, pair.getFirst(), pair.getSecond());
}
/**
* @return the root of each tree of this forest as a {@code Collection}.
*/
public Collection getRoots() {
Collection roots = new HashSet();
for(V v : delegate.getVertices()) {
if(delegate.getPredecessorCount(v) == 0) {
roots.add(v);
}
}
return roots;
}
public Collection> getTrees() {
Collection> trees = new HashSet>();
for(V v : getRoots()) {
Tree tree = new DelegateTree();
tree.addVertex(v);
TreeUtils.growSubTree(this, tree, v);
trees.add(tree);
}
return trees;
}
/**
* Adds {@code tree} to this graph as an element of this forest.
*
* @param tree the tree to add to this forest as a component
*/
public void addTree(Tree tree) {
TreeUtils.addSubTree(this, tree, null, null);
}
public int getChildCount(V vertex)
{
return delegate.getSuccessorCount(vertex);
}
public Collection getChildEdges(V vertex)
{
return delegate.getOutEdges(vertex);
}
public E getParentEdge(V vertex)
{
if (isRoot(vertex))
return null;
return delegate.getInEdges(vertex).iterator().next();
}
}