org.apache.velocity.anakia.NodeList Maven / Gradle / Ivy
package org.apache.velocity.anakia;
/*
* 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.
*/
import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import org.jdom.Attribute;
import org.jdom.CDATA;
import org.jdom.Comment;
import org.jdom.DocType;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.EntityRef;
import org.jdom.ProcessingInstruction;
import org.jdom.Text;
import org.jdom.output.XMLOutputter;
/**
* Provides a class for wrapping a list of JDOM objects primarily for use in template
* engines and other kinds of text transformation tools.
* It has a {@link #toString()} method that will output the XML serialized form of the
* nodes it contains - again focusing on template engine usage, as well as the
* {@link #selectNodes(String)} method that helps selecting a different set of nodes
* starting from the nodes in this list. The class also implements the {@link java.util.List}
* interface by simply delegating calls to the contained list (the {@link #subList(int, int)}
* method is implemented by delegating to the contained list and wrapping the returned
* sublist into a NodeList).
*
* @author Attila Szegedi
* @version $Id: NodeList.java 463298 2006-10-12 16:10:32Z henning $
*/
public class NodeList implements List, Cloneable
{
private static final AttributeXMLOutputter DEFAULT_OUTPUTTER =
new AttributeXMLOutputter();
/** The contained nodes */
private List nodes;
/**
* Creates an empty node list.
*/
public NodeList()
{
nodes = new ArrayList();
}
/**
* Creates a node list that holds a single {@link Document} node.
* @param document
*/
public NodeList(Document document)
{
this((Object)document);
}
/**
* Creates a node list that holds a single {@link Element} node.
* @param element
*/
public NodeList(Element element)
{
this((Object)element);
}
private NodeList(Object object)
{
if(object == null)
{
throw new IllegalArgumentException(
"Cannot construct NodeList with null.");
}
nodes = new ArrayList(1);
nodes.add(object);
}
/**
* Creates a node list that holds a list of nodes.
* @param nodes the list of nodes this template should hold. The created
* template will copy the passed nodes list, so changes to the passed list
* will not affect the model.
*/
public NodeList(List nodes)
{
this(nodes, true);
}
/**
* Creates a node list that holds a list of nodes.
* @param nodes the list of nodes this template should hold.
* @param copy if true, the created template will copy the passed nodes
* list, so changes to the passed list will not affect the model. If false,
* the model will reference the passed list and will sense changes in it,
* altough no operations on the list will be synchronized.
*/
public NodeList(List nodes, boolean copy)
{
if(nodes == null)
{
throw new IllegalArgumentException(
"Cannot initialize NodeList with null list");
}
this.nodes = copy ? new ArrayList(nodes) : nodes;
}
/**
* Retrieves the underlying list used to store the nodes. Note however, that
* you can fully use the underlying list through the List interface
* of this class itself. You would probably access the underlying list only for
* synchronization purposes.
* @return The internal node List.
*/
public List getList()
{
return nodes;
}
/**
* This method returns the string resulting from concatenation of string
* representations of its nodes. Each node is rendered using its XML
* serialization format. This greatly simplifies creating XML-transformation
* templates, as to output a node contained in variable x as XML fragment,
* you simply write ${x} in the template (or whatever your template engine
* uses as its expression syntax).
* @return The Nodelist as printable object.
*/
public String toString()
{
if(nodes.isEmpty())
{
return "";
}
StringWriter sw = new StringWriter(nodes.size() * 128);
try
{
for(Iterator i = nodes.iterator(); i.hasNext();)
{
Object node = i.next();
if(node instanceof Element)
{
DEFAULT_OUTPUTTER.output((Element)node, sw);
}
else if(node instanceof Attribute)
{
DEFAULT_OUTPUTTER.output((Attribute)node, sw);
}
else if(node instanceof Text)
{
DEFAULT_OUTPUTTER.output((Text)node, sw);
}
else if(node instanceof Document)
{
DEFAULT_OUTPUTTER.output((Document)node, sw);
}
else if(node instanceof ProcessingInstruction)
{
DEFAULT_OUTPUTTER.output((ProcessingInstruction)node, sw);
}
else if(node instanceof Comment)
{
DEFAULT_OUTPUTTER.output((Comment)node, sw);
}
else if(node instanceof CDATA)
{
DEFAULT_OUTPUTTER.output((CDATA)node, sw);
}
else if(node instanceof DocType)
{
DEFAULT_OUTPUTTER.output((DocType)node, sw);
}
else if(node instanceof EntityRef)
{
DEFAULT_OUTPUTTER.output((EntityRef)node, sw);
}
else
{
throw new IllegalArgumentException(
"Cannot process a " +
(node == null
? "null node"
: "node of class " + node.getClass().getName()));
}
}
}
catch(IOException e)
{
// Cannot happen as we work with a StringWriter in memory
throw new Error();
}
return sw.toString();
}
/**
* Returns a NodeList that contains the same nodes as this node list.
* @return A clone of this list.
* @throws CloneNotSupportedException if the contained list's class does
* not have an accessible no-arg constructor.
*/
public Object clone()
throws CloneNotSupportedException
{
NodeList clonedList = (NodeList)super.clone();
clonedList.cloneNodes();
return clonedList;
}
private void cloneNodes()
throws CloneNotSupportedException
{
Class listClass = nodes.getClass();
try
{
List clonedNodes = (List)listClass.newInstance();
clonedNodes.addAll(nodes);
nodes = clonedNodes;
}
catch(IllegalAccessException e)
{
throw new CloneNotSupportedException("Cannot clone NodeList since"
+ " there is no accessible no-arg constructor on class "
+ listClass.getName());
}
catch(InstantiationException e)
{
// Cannot happen as listClass represents a concrete, non-primitive,
// non-array, non-void class - there's an instance of it in "nodes"
// which proves these assumptions.
throw new Error();
}
}
/**
* Returns the hash code of the contained list.
* @return The hashcode of the list.
*/
public int hashCode()
{
return nodes.hashCode();
}
/**
* Tests for equality with another object.
* @param o the object to test for equality
* @return true if the other object is also a NodeList and their contained
* {@link List} objects evaluate as equals.
*/
public boolean equals(Object o)
{
return o instanceof NodeList
? ((NodeList)o).nodes.equals(nodes)
: false;
}
/**
* Applies an XPath expression to the node list and returns the resulting
* node list. In order for this method to work, your application must have
* access to werken.xpath library
* classes. The implementation does cache the parsed format of XPath
* expressions in a weak hash map, keyed by the string representation of
* the XPath expression. As the string object passed as the argument is
* usually kept in the parsed template, this ensures that each XPath
* expression is parsed only once during the lifetime of the template that
* first invoked it.
* @param xpathString the XPath expression you wish to apply
* @return a NodeList representing the nodes that are the result of
* application of the XPath to the current node list. It can be empty.
*/
public NodeList selectNodes(String xpathString)
{
return new NodeList(XPathCache.getXPath(xpathString).applyTo(nodes), false);
}
// List methods implemented hereafter
/**
* @see java.util.List#add(java.lang.Object)
*/
public boolean add(Object o)
{
return nodes.add(o);
}
/**
* @see java.util.List#add(int, java.lang.Object)
*/
public void add(int index, Object o)
{
nodes.add(index, o);
}
/**
* @see java.util.List#addAll(java.util.Collection)
*/
public boolean addAll(Collection c)
{
return nodes.addAll(c);
}
/**
* @see java.util.List#addAll(int, java.util.Collection)
*/
public boolean addAll(int index, Collection c)
{
return nodes.addAll(index, c);
}
/**
* @see java.util.List#clear()
*/
public void clear()
{
nodes.clear();
}
/**
* @see java.util.List#contains(java.lang.Object)
*/
public boolean contains(Object o)
{
return nodes.contains(o);
}
/**
* @see java.util.List#containsAll(java.util.Collection)
*/
public boolean containsAll(Collection c)
{
return nodes.containsAll(c);
}
/**
* @see java.util.List#get(int)
*/
public Object get(int index)
{
return nodes.get(index);
}
/**
* @see java.util.List#indexOf(java.lang.Object)
*/
public int indexOf(Object o)
{
return nodes.indexOf(o);
}
/**
* @see java.util.List#isEmpty()
*/
public boolean isEmpty()
{
return nodes.isEmpty();
}
/**
* @see java.util.List#iterator()
*/
public Iterator iterator()
{
return nodes.iterator();
}
/**
* @see java.util.List#lastIndexOf(java.lang.Object)
*/
public int lastIndexOf(Object o)
{
return nodes.lastIndexOf(o);
}
/**
* @see java.util.List#listIterator()
*/
public ListIterator listIterator()
{
return nodes.listIterator();
}
/**
* @see java.util.List#listIterator(int)
*/
public ListIterator listIterator(int index)
{
return nodes.listIterator(index);
}
/**
* @see java.util.List#remove(int)
*/
public Object remove(int index)
{
return nodes.remove(index);
}
/**
* @see java.util.List#remove(java.lang.Object)
*/
public boolean remove(Object o)
{
return nodes.remove(o);
}
/**
* @see java.util.List#removeAll(java.util.Collection)
*/
public boolean removeAll(Collection c)
{
return nodes.removeAll(c);
}
/**
* @see java.util.List#retainAll(java.util.Collection)
*/
public boolean retainAll(Collection c)
{
return nodes.retainAll(c);
}
/**
* @see java.util.List#set(int, java.lang.Object)
*/
public Object set(int index, Object o)
{
return nodes.set(index, o);
}
/**
* @see java.util.List#size()
*/
public int size()
{
return nodes.size();
}
/**
* @see java.util.List#subList(int, int)
*/
public List subList(int fromIndex, int toIndex)
{
return new NodeList(nodes.subList(fromIndex, toIndex));
}
/**
* @see java.util.List#toArray()
*/
public Object[] toArray()
{
return nodes.toArray();
}
/**
* @see java.util.List#toArray(java.lang.Object[])
*/
public Object[] toArray(Object[] a)
{
return nodes.toArray(a);
}
/**
* A special subclass of XMLOutputter that will be used to output
* Attribute nodes. As a subclass of XMLOutputter it can use its protected
* method escapeAttributeEntities() to serialize the attribute
* appropriately.
*/
private static final class AttributeXMLOutputter extends XMLOutputter
{
/**
* @param attribute
* @param out
* @throws IOException
*/
public void output(Attribute attribute, Writer out)
throws IOException
{
out.write(" ");
out.write(attribute.getQualifiedName());
out.write("=");
out.write("\"");
out.write(escapeAttributeEntities(attribute.getValue()));
out.write("\"");
}
}
}
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