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Groovy: A powerful, dynamic language for the JVM
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.lang.Closure;
import groovy.lang.DelegatingMetaClass;
import groovy.lang.GroovySystem;
import groovy.lang.MetaClass;
import groovy.xml.QName;
import org.codehaus.groovy.runtime.InvokerHelper;
import java.io.PrintWriter;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
/**
* 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
* @author Paul King
*/
public class Node implements Serializable, Cloneable {
static {
// wrap the standard MetaClass with the delegate
setMetaClass(GroovySystem.getMetaClassRegistry().getMetaClass(Node.class), Node.class);
}
private static final long serialVersionUID = 4121134753270542643L;
private Node parent;
private Object name;
private Map attributes;
private Object value;
/**
* Creates a new Node with the same name, no parent, shallow cloned attributes
* and if the value is a NodeList, a (deep) clone of those nodes.
*
* @return the clone
*/
@Override
public Object clone() {
Object newValue = value;
if (value != null && value instanceof NodeList) {
NodeList nodes = (NodeList) value;
newValue = nodes.clone();
}
return new Node(null, name, new HashMap(attributes), newValue);
}
/**
* Creates a new Node named name and if a parent is supplied, adds
* the newly created node as a child of the parent.
*
* @param parent the parent node or null if no parent
* @param name the name of the node
*/
public Node(Node parent, Object name) {
this(parent, name, new NodeList());
}
/**
* Creates a new Node named name with value value and
* if a parent is supplied, adds the newly created node as a child of the parent.
*
* @param parent the parent node or null if no parent
* @param name the name of the node
* @param value the Node value, e.g. some text but in general any Object
*/
public Node(Node parent, Object name, Object value) {
this(parent, name, new HashMap(), value);
}
/**
* Creates a new Node named name with
* attributes specified in the attributes Map. If a parent is supplied,
* the newly created node is added as a child of the parent.
*
* @param parent the parent node or null if no parent
* @param name the name of the node
* @param attributes a Map of name-value pairs
*/
public Node(Node parent, Object name, Map attributes) {
this(parent, name, attributes, new NodeList());
}
/**
* Creates a new Node named name with value value and
* with attributes specified in the attributes Map. If a parent is supplied,
* the newly created node is added as a child of the parent.
*
* @param parent the parent node or null if no parent
* @param name the name of the node
* @param attributes a Map of name-value pairs
* @param value the Node value, e.g. some text but in general any Object
*/
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) {
getParentList(parent).add(this);
}
}
private static List getParentList(Node parent) {
Object parentValue = parent.value();
List parentList;
if (parentValue instanceof List) {
parentList = (List) parentValue;
} else {
parentList = new NodeList();
parentList.add(parentValue);
parent.setValue(parentList);
}
return parentList;
}
/**
* Appends a child to the current node.
*
* @param child the child to append
* @return true
*/
public boolean append(Node child) {
child.setParent(this);
return getParentList(this).add(child);
}
/**
* Removes a child of the current node.
*
* @param child the child to remove
* @return true if the param was a child of the current node
*/
public boolean remove(Node child) {
child.setParent(null);
return getParentList(this).remove(child);
}
/**
* Creates a new node as a child of the current node.
*
* @param name the name of the new node
* @param attributes the attributes of the new node
* @return the newly created Node
*/
public Node appendNode(Object name, Map attributes) {
return new Node(this, name, attributes);
}
/**
* Creates a new node as a child of the current node.
*
* @param name the name of the new node
* @return the newly created Node
*/
public Node appendNode(Object name) {
return new Node(this, name);
}
/**
* Creates a new node as a child of the current node.
*
* @param name the name of the new node
* @param value the value of the new node
* @return the newly created Node
*/
public Node appendNode(Object name, Object value) {
return new Node(this, name, value);
}
/**
* Creates a new node as a child of the current node.
*
* @param name the name of the new node
* @param attributes the attributes of the new node
* @param value the value of the new node
* @return the newly created Node
*/
public Node appendNode(Object name, Map attributes, Object value) {
return new Node(this, name, attributes, value);
}
/**
* Replaces the current node with nodes defined using builder-style notation via a Closure.
*
* @param c A Closure defining the new nodes using builder-style notation.
* @return the original now replaced node
*/
public Node replaceNode(Closure c) {
if (parent() == null) {
throw new UnsupportedOperationException("Replacing the root node is not supported");
}
appendNodes(c);
getParentList(parent()).remove(this);
this.setParent(null);
return this;
}
/**
* Replaces the current node with the supplied node.
*
* @param n the new Node
* @return the original now replaced node
*/
public Node replaceNode(Node n) {
if (parent() == null) {
throw new UnsupportedOperationException("Replacing the root node is not supported");
}
List tail = getTail();
parent().appendNode(n.name(), n.attributes(), n.value());
parent().children().addAll(tail);
getParentList(parent()).remove(this);
this.setParent(null);
return this;
}
private List getTail() {
List list = parent().children();
int afterIndex = list.indexOf(this);
List tail = new ArrayList(list.subList(afterIndex + 1, list.size()));
list.subList(afterIndex + 1, list.size()).clear();
return tail;
}
/**
* Adds sibling nodes (defined using builder-style notation via a Closure) after the current node.
*
* @param c A Closure defining the new sibling nodes to add using builder-style notation.
*/
public void plus(Closure c) {
if (parent() == null) {
throw new UnsupportedOperationException("Adding sibling nodes to the root node is not supported");
}
appendNodes(c);
}
private void appendNodes(Closure c) {
List tail = getTail();
for (Node child : buildChildrenFromClosure(c)) {
parent().appendNode(child.name(), child.attributes(), child.value());
}
parent().children().addAll(tail);
}
private static List buildChildrenFromClosure(Closure c) {
NodeBuilder b = new NodeBuilder();
Node newNode = (Node) b.invokeMethod("dummyNode", c);
return newNode.children();
}
/**
* Extension point for subclasses to override the metaclass. The default
* one supports the property and @ attribute notations.
*
* @param metaClass the original metaclass
* @param nodeClass the class whose metaclass we wish to override (this class or a subclass)
*/
protected static void setMetaClass(final MetaClass metaClass, Class nodeClass) {
// TODO Is protected static a bit of a smell?
// TODO perhaps set nodeClass to be Class
final MetaClass newMetaClass = new DelegatingMetaClass(metaClass) {
@Override
public Object getAttribute(final Object object, final String attribute) {
Node n = (Node) object;
return n.get("@" + attribute);
}
@Override
public void setAttribute(final Object object, final String attribute, final Object newValue) {
Node n = (Node) object;
n.attributes().put(attribute, newValue);
}
@Override
public Object getProperty(Object object, String property) {
if (object instanceof Node) {
Node n = (Node) object;
return n.get(property);
}
return super.getProperty(object, property);
}
@Override
public void setProperty(Object object, String property, Object newValue) {
if (property.startsWith("@")) {
setAttribute(object, property.substring(1), newValue);
return;
}
delegate.setProperty(object, property, newValue);
}
};
GroovySystem.getMetaClassRegistry().setMetaClass(nodeClass, newMetaClass);
}
/**
* Returns the textual representation of the current node and all its child nodes.
*
* @return the text value of the node including child text
*/
public String text() {
if (value instanceof String) {
return (String) value;
}
if (value instanceof NodeList) {
return ((NodeList) value).text();
}
if (value instanceof Collection) {
Collection coll = (Collection) value;
String previousText = null;
StringBuilder sb = null;
for (Object child : coll) {
String childText = null;
if (child instanceof String) {
childText = (String) child;
} else if (child instanceof Node) {
childText = ((Node) child).text();
}
if (childText != null) {
if (previousText == null) {
previousText = childText;
} else {
if (sb == null) {
sb = new StringBuilder();
sb.append(previousText);
}
sb.append(childText);
}
}
}
if (sb != null) {
return sb.toString();
} else {
if (previousText != null) {
return previousText;
}
return "";
}
}
return "" + value;
}
/**
* Returns an Iterator of the children of the node.
*
* @return the iterator of the nodes children
*/
public Iterator iterator() {
return children().iterator();
}
/**
* Returns a List of the nodes children.
*
* @return the nodes children
*/
public List children() {
if (value == null) {
return new NodeList();
}
if (value instanceof List) {
return (List) value;
}
// we're probably just a String
List result = new NodeList();
result.add(value);
return result;
}
/**
* Returns a Map of the attributes of the node or an empty Map
* if the node does not have any attributes.
*
* @return the attributes of the node
*/
public Map attributes() {
return attributes;
}
/**
* Provides lookup of attributes by key.
*
* @param key the key of interest
* @return the attribute matching the key or null if no match exists
*/
public Object attribute(Object key) {
return (attributes != null) ? attributes.get(key) : null;
}
/**
* Returns an Object representing the name of the node.
*
* @return the name or null if name is empty
*/
public Object name() {
return name;
}
/**
* Returns an Object representing the value of the node.
*
* @return the value or null if value is empty
*/
public Object value() {
return value;
}
/**
* Adds or replaces the value of the node.
*
* @param value the new value of the node
*/
public void setValue(Object value) {
this.value = value;
}
/**
* Returns the parent of the node.
*
* @return the parent or null for the root node
*/
public Node parent() {
return parent;
}
/**
* Adds or replaces the parent of the node.
*
* @param parent the new parent of the node
*/
protected void setParent(Node parent) {
this.parent = 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();
}
return getByName(key);
}
/**
* 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 (Object child : children()) {
if (child instanceof Node) {
Node childNode = (Node) child;
Object childNodeName = childNode.name();
if (name.matches(childNodeName)) {
answer.add(childNode);
}
}
}
return answer;
}
/**
* Provides lookup of elements by name.
*
* @param name the name of interest
* @return the nodes matching name
*/
private NodeList getByName(String name) {
NodeList answer = new NodeList();
for (Object child : children()) {
if (child instanceof Node) {
Node childNode = (Node) child;
Object childNodeName = childNode.name();
if (childNodeName instanceof QName) {
QName qn = (QName) childNodeName;
if (qn.matches(name)) {
answer.add(childNode);
}
} else if (name.equals(childNodeName)) {
answer.add(childNode);
}
}
}
return answer;
}
/**
* Provides 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);
if (children.size() > 1 || (children.size() == 1 && !(children.get(0) instanceof String))) answer.addAll(children);
} else if (child instanceof String) {
answer.add(child);
}
}
return answer;
}
/**
* Provides 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 (Object child : working) {
answer.add(child);
if (child instanceof Node) {
Node childNode = (Node) child;
List children = childNode.getDirectChildren();
if (children.size() > 1 || (children.size() == 1 && !(children.get(0) instanceof String))) nextLevelChildren.addAll(children);
}
}
}
return answer;
}
/**
* Returns the list of any direct String nodes of this node.
*
* @return the list of String values from this node
* @since 2.3.0
*/
public List localText() {
List answer = new ArrayList();
for (Iterator iter = InvokerHelper.asIterator(value); iter.hasNext(); ) {
Object child = iter.next();
if (!(child instanceof Node)) {
answer.add(child.toString());
}
}
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);
} else if (child instanceof String) {
answer.add(child);
}
}
return answer;
}
public String toString() {
return name + "[attributes=" + attributes + "; value=" + value + "]";
}
/**
* Writes the node to the specified PrintWriter.
*
* @param out the writer receiving the output
*/
public void print(PrintWriter out) {
new NodePrinter(out).print(this);
}
}