Lightweight tree n-arity structure
/*
* NimbleTree.java
*
* Created on 16 October 2006, 16:45
*
* Tree structure
*/
//package Util.Structures;
import java.util.Stack;
import java.util.ArrayList;
import java.util.Collections;
import java.util.StringTokenizer;
/**
* Lightweight tree n-arity structure
* @author EHemberg
*/
public class NimbleTree<E> {
private TreeNode<E> root,currentNode;
private Stack<TreeNode<E>> freeNodes;// nodes that have been taken off the tree and recycled
private int nodeCount; //Tracks number of nodes in the tree
private int depth; // maximum depth of tree
private int currentLevel; //
private int maxStackSize;
/** Creates a new instance of NimbleTree */
public NimbleTree() {
this.root = newNode();
this.currentNode = this.root;
this.nodeCount = 1;
this.root.setID(this.nodeCount);
this.depth = 0;
this.currentLevel = 0;
//Important to make a new stack
this.freeNodes = new Stack<TreeNode<E>>();
this.maxStackSize = 10;
}
/** Copy constructor
* @param n copied tree
*/
public NimbleTree(NimbleTree<E> n) {
this.root = n.root;
this.currentNode = n.currentNode;
this.nodeCount = n.nodeCount;
this.freeNodes = new Stack<TreeNode<E>>();
this.depth = n.depth;
this.currentLevel = n.currentLevel;
}
protected TreeNode<E> newNode()
{ return new TreeNode<E>();
}
/**
* A static constructor (is this the right term?) where a lisp-style s-expression
* is passed in as a string. This can't be a true constructor because the result
* is a tree over String, not a generic tree.
*/
public static NimbleTree<String> makeTreeOverStringFromSExpression(String input) {
NimbleTree<String> tree = new NimbleTree<String>();
Stack<TreeNode<String>> previousParents = new Stack<TreeNode<String>>();
// Make sure the string is tokenizable
// FIXME allow [] and maybe other delimiters?
input = input.replace("(", " ( ");
input = input.replace(")", " ) ");
StringTokenizer st = new StringTokenizer(input);
boolean firstTimeThrough = true;
while (st.hasMoreTokens()){
String currTok = st.nextToken().trim();
if (currTok.equals("")) {
// Tokenizer gave us an empty token, do nothing.
} else if (currTok.equals("(")) {
// Get the *next* token and make a new subtree on it.
currTok = st.nextToken().trim();
if (firstTimeThrough == true) {
// The tree is of the form "(x)"
// This is the root node: just set its data
firstTimeThrough = false;
tree.getRoot().setData(currTok);
} else {
// This is the root of a new subtree. Save parent,
// then set this node to be the new parent.
tree.addChild(currTok);
tree.getCurrentNode().getEnd().setID(tree.getNodeCount());
previousParents.push(tree.getCurrentNode());
tree.setCurrentNode(tree.getCurrentNode().getEnd());
}
} else if (currTok.equals(")")) {
// Finished adding children to current parent. Go back
// to previous parent (if there was none, it's because
// current parent is root, so we're finished anyway).
if (!previousParents.empty()) {
tree.setCurrentNode(previousParents.pop());
}
} else {
if (firstTimeThrough == true) {
// The tree is of the form "x".
// This is to be the root node: just set its data.
firstTimeThrough = false;
tree.getRoot().setData(currTok);
} else {
// Add a child node to current parent.
tree.addChild(currTok);
tree.getCurrentNode().getEnd().setID(tree.getNodeCount());
}
}
}
return tree;
}
/**
* Set max stack size
* @param i max stack size
*/
public void setMaxStackSize(int i) {
this.maxStackSize = i;
}
/**
* Get max stack size
* @return max stack size
*/
public int getMaxStackSize() {
return this.maxStackSize;
}
/**
* Create nodes and push to the stack
*/
public void populateStack() {
TreeNode<E> tn;
for(int i = 0; i < maxStackSize; i++) {
tn = newNode();
this.freeNodes.push(tn);
}
}
/**
* Get root of tree
* @return tree root
*/
public TreeNode<E> getRoot() {
return this.root;
}
/**
* Set tree root
* @param tn root of tree
*/
public void setRoot(TreeNode<E> tn){
this.root = tn;
}
/**
* Get current node
* @return current node
*/
public TreeNode<E> getCurrentNode(){
return this.currentNode;
}
/**
* Set current node
* @param tn node to be current
*/
public void setCurrentNode(TreeNode<E> tn){
this.currentNode = tn;
}
/**
* Get node count
* @return number of nodes in tree
*/
public int getNodeCount(){
return this.nodeCount;
}
/**
* Set node count
* @param i number to set
*/
public void setNodeCount(int i){
this.nodeCount = i;
}
/**
* Set depth of tree
* @param i depth
*/
public void setDepth(int i) {
this.depth = i;
}
/**
* Get maximum depth of tree
* @return tree max depth
*/
public int getDepth() {
return this.depth;
}
/**
* Get current level
* @return current level
*/
public int getCurrentLevel() {
return this.currentLevel;
}
/**
* Set current level
* @param i level to set
*/
public void setCurrentLevel(int i) {
this.currentLevel = i;
}
/**
* Find all the paths from root to leaves. Used by NGramEDAReproductionOperation.
* @return list of list of TreeNode, each list starting at the root and ending at a leaf.
*/
public ArrayList<ArrayList<TreeNode<E>>> getRootToLeafPaths() {
ArrayList<TreeNode<E>> leafNodes = new ArrayList<TreeNode<E>>();
// traverse the tree and find the leaf nodes
for (TreeNode<E> node: depthFirstTraversal(getRoot())) {
if (node.size()== 0) {
leafNodes.add(node);
}
}
ArrayList<ArrayList<TreeNode<E>>> paths = new ArrayList<ArrayList<TreeNode<E>>>();
for (TreeNode<E> leaf: leafNodes) {
ArrayList<TreeNode<E>> path = new ArrayList<TreeNode<E>>();
TreeNode<E> current = leaf;
while (current != getRoot()) {
path.add(current);
current = current.getParent();
}
// add the root
path.add(current);
Collections.reverse(path);
paths.add(path);
}
return paths;
}
/**
* Get all the chains of ancestors of length n in this tree. Used
* as sources for NGram model.
*/
public ArrayList<ArrayList<TreeNode<E>>> getAncestorChains(int n) {
ArrayList<ArrayList<TreeNode<E>>> retval = new ArrayList<ArrayList<TreeNode<E>>>();
for (TreeNode<E> node: depthFirstTraversal(getRoot())) {
ArrayList<TreeNode<E>> chain = getAncestorChain(node, n);
if (chain.size() == n) {
Collections.reverse(chain);
retval.add(chain);
}
}
return retval;
}
/**
* Starting at a given node, get a chain of ancestors of length n or less.
*/
public ArrayList<TreeNode<E>> getAncestorChain(TreeNode<E> node, int n) {
ArrayList<TreeNode<E>> retval = new ArrayList<TreeNode<E>>();
TreeNode<E> current = node;
while (retval.size() < n && current != null && current.getData() != null) {
retval.add(current);
current = current.getParent();
}
return retval;
}
/**
* Do a depth-first traversal of the tree starting at a given node.
* @return a list of TreeNodes in depth-first order.
*/
public ArrayList<TreeNode<E>> depthFirstTraversal(TreeNode<E> root) {
ArrayList<TreeNode<E>> retval = new ArrayList<TreeNode<E>>();
retval.add(root);
for (TreeNode<E> child: root) {
retval.addAll(depthFirstTraversal(child));
}
return retval;
}
/**
* Add a child to the current node. Take a node from the free nodes.
* INFINITE LOOP POSSIBILITY??!!
* @param data data contained in the child
*/
public void addChild( E data) {
if(!this.freeNodes.empty()) {
TreeNode<E> n = this.freeNodes.pop();
n.setData(data);
n.setParent(this.currentNode);
n.clear();
this.setDepth(this.depth + 1);
this.currentNode.add(n);
this.nodeCount++;
n.setID(this.nodeCount);
} else {
populateStack();
addChild(data);//Infinite loop possibility
}
}
@Override
public String toString() {
String s = "";
s += root.toString();
return s;
}
/**
* Get some code for drawing this tree using Graphviz.
*/
public String getGraphvizCode() {
String retval = "graph dotFile {\n";
// Write out the nodes.
for (TreeNode<E> n: depthFirstTraversal(root)) {
if (n != null && n.getData() != null) {
retval += "id" + n.getID() + " [label=\"" + n.getData() + "\"];\n";
}
}
// Write out the incoming edge for every node that has a parent.
for (TreeNode<E> n: depthFirstTraversal(root)) {
if (n != null && n.getParent() != null && n.getParent().getData() != null) {
retval += "id" + n.getParent().getID() + " -- id" + n.getID() + ";\n";
}
}
retval += "}";
return retval;
}
}
class TreeNode<E> extends ArrayList<TreeNode<E>>{
private TreeNode<E> parent;
private E data;
private int id;
/** Creates a new instance of TreeNode */
public TreeNode() {
super();
id = 0;
}
/**
* Create node with parent and data
* @param parent node parent
* @param data node data
*/
public TreeNode(TreeNode<E> parent, E data) {
super();
this.parent = parent;
this.data = data;
this.id = 0;
}
/** Copy constructor
* @param copy node to copy
*/
public TreeNode(TreeNode<E> copy) {
super(copy);
for (TreeNode<E> aCopy : copy) {
this.add(new TreeNode<E>(aCopy));
}
this.parent = new TreeNode<E>(copy.parent);
this.data = copy.data;
this.id = copy.id;
}
/**
* Get parent node
* @return parent node
*/
public TreeNode<E> getParent(){
return this.parent;
}
/**
* Set parent node
* @param tn parent node
*/
public void setParent(TreeNode<E> tn) {
this.parent = tn;
}
/**
* Get data in node
* @return data
*/
public E getData() {
return data;
}
/**
* Set data in node
* @param data node data
*/
public void setData(E data) {
this.data = data;
}
/**
* Get node id
* @return int
*/
public int getID() {
return id;
}
/**
* Set node id
* @param int id
*/
public void setID(int id) {
this.id = id;
}
/**
* Get the last node
* @return the last node
*/
public TreeNode<E> getEnd() {
return this.get(this.size() - 1);
}
/**
* Collapse the node to a string
* @return string representation
*/
public String collapse() {
String s = "";
s+=this.getData();
if(this.getParent() != null) {
s += this.getParent().collapse();
}
for (TreeNode<E> e : this) {
s += e.getData().toString();
s += e.getParent().collapse();
}
return s;
}
//Not working
@Override
public String toString() {
String s = "";
s += this.getData() + ":";
for (TreeNode<E> e : this) {
s += e.toString() + " ";
}
return s;
}
}
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