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/*
* Copyright 2003-2007 the original author or authors.
*
* 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 groovy.util;
import groovy.xml.QName;
import org.codehaus.groovy.runtime.InvokerHelper;
import java.io.PrintWriter;
import java.util.*;
/**
* Represents an arbitrary tree node which can be used for structured metadata or any arbitrary XML-like tree.
* A node can have a name, a value and an optional Map of attributes.
* Typically the name is a String and a value is either a String or a List of other Nodes,
* though the types are extensible to provide a flexible structure, e.g. you could use a
* QName as the name which includes a namespace URI and a local name. Or a JMX ObjectName etc.
* So this class can represent metadata like {foo a=1 b="abc"} or nested metadata like {foo a=1 b="123" { bar x=12 text="hello" }}
*
* @author James Strachan
* @version $Revision: 8098 $
*/
public class Node implements java.io.Serializable {
private static final long serialVersionUID = 4121134753270542643L;
private Node parent;
private Object name;
private Map attributes;
private Object value;
public Node(Node parent, Object name) {
this(parent, name, new ArrayList());
}
public Node(Node parent, Object name, Object value) {
this(parent, name, new HashMap(), value);
}
public Node(Node parent, Object name, Map attributes) {
this(parent, name, attributes, new ArrayList());
}
public Node(Node parent, Object name, Map attributes, Object value) {
this.parent = parent;
this.name = name;
this.attributes = attributes;
this.value = value;
if (parent != null) {
Object parentValue = parent.value();
List parentList;
if (parentValue instanceof List) {
parentList = (List) parentValue;
} else {
parentList = new NodeList();
parentList.add(parentValue);
parent.setValue(parentList);
}
parentList.add(this);
}
}
public String text() {
if (value instanceof String) {
return (String) value;
}
else if (value instanceof Collection) {
Collection coll = (Collection) value;
String previousText = null;
StringBuffer buffer = null;
for (Iterator iter = coll.iterator(); iter.hasNext();) {
Object child = iter.next();
if (child instanceof String) {
String childText = (String) child;
if (previousText == null) {
previousText = childText;
}
else {
if (buffer == null) {
buffer = new StringBuffer();
buffer.append(previousText);
}
buffer.append(childText);
}
}
}
if (buffer != null) {
return buffer.toString();
}
else {
if (previousText != null) {
return previousText;
}
}
}
return "";
}
public Iterator iterator() {
return children().iterator();
}
public List children() {
if (value == null) {
return new ArrayList();
}
else if (value instanceof List) {
return (List) value;
}
else {
// we're probably just a String
return java.util.Collections.singletonList(value);
}
}
public Map attributes() {
return attributes;
}
public Object attribute(Object key) {
return (attributes != null) ? attributes.get(key) : null;
}
public Object name() {
return name;
}
public Object value() {
return value;
}
public void setValue(Object value) {
this.value = value;
}
public Node parent() {
return parent;
}
/**
* Provides lookup of elements by non-namespaced name
* @param key the name (or shortcut key) of the node(s) of interest
* @return the nodes which match key
*/
public Object get(String key) {
if (key != null && key.charAt(0) == '@') {
String attributeName = key.substring(1);
return attributes().get(attributeName);
}
if ("..".equals(key)) {
return parent();
}
if ("*".equals(key)) {
return children();
}
if ("**".equals(key)) {
return depthFirst();
}
// iterate through list looking for node with name 'key'
List answer = new NodeList();
for (Iterator iter = children().iterator(); iter.hasNext();) {
Object child = iter.next();
if (child instanceof Node) {
Node childNode = (Node) child;
Object childNodeName = childNode.name();
if (childNodeName != null && childNodeName.equals(key)) {
answer.add(childNode);
}
}
}
return answer;
}
/**
* Provides lookup of elements by QName.
*
* @param name the QName of interest
* @return the nodes matching name
*/
public NodeList getAt(QName name) {
NodeList answer = new NodeList();
for (Iterator iter = children().iterator(); iter.hasNext();) {
Object child = iter.next();
if (child instanceof Node) {
Node childNode = (Node) child;
Object childNodeName = childNode.name();
if (childNodeName != null && childNodeName.equals(name)) {
answer.add(childNode);
}
}
}
return answer;
}
/**
* Provide a collection of all the nodes in the tree
* using a depth first traversal.
*
* @return the list of (depth-first) ordered nodes
*/
public List depthFirst() {
List answer = new NodeList();
answer.add(this);
answer.addAll(depthFirstRest());
return answer;
}
private List depthFirstRest() {
List answer = new NodeList();
for (Iterator iter = InvokerHelper.asIterator(value); iter.hasNext(); ) {
Object child = iter.next();
if (child instanceof Node) {
Node childNode = (Node) child;
List children = childNode.depthFirstRest();
answer.add(childNode);
answer.addAll(children);
}
}
return answer;
}
/**
* Provide a collection of all the nodes in the tree
* using a breadth-first traversal.
*
* @return the list of (breadth-first) ordered nodes
*/
public List breadthFirst() {
List answer = new NodeList();
answer.add(this);
answer.addAll(breadthFirstRest());
return answer;
}
private List breadthFirstRest() {
List answer = new NodeList();
List nextLevelChildren = getDirectChildren();
while (!nextLevelChildren.isEmpty()) {
List working = new NodeList(nextLevelChildren);
nextLevelChildren = new NodeList();
for (Iterator iter = working.iterator(); iter.hasNext(); ) {
Node childNode = (Node) iter.next();
answer.add(childNode);
List children = childNode.getDirectChildren();
nextLevelChildren.addAll(children);
}
}
return answer;
}
private List getDirectChildren() {
List answer = new NodeList();
for (Iterator iter = InvokerHelper.asIterator(value); iter.hasNext(); ) {
Object child = iter.next();
if (child instanceof Node) {
Node childNode = (Node) child;
answer.add(childNode);
}
}
return answer;
}
public String toString() {
return name + "[attributes=" + attributes + "; value=" + value + "]";
}
public void print(PrintWriter out) {
new NodePrinter(out).print(this);
}
}
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