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The XSLT and XQuery Processor
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2023 Saxonica Limited
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
package net.sf.saxon.dom;
import net.sf.saxon.Configuration;
import net.sf.saxon.event.*;
import net.sf.saxon.expr.JPConverter;
import net.sf.saxon.expr.PJConverter;
import net.sf.saxon.expr.StaticProperty;
import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.lib.ActiveSource;
import net.sf.saxon.lib.ExternalObjectModel;
import net.sf.saxon.om.*;
import net.sf.saxon.pattern.AnyNodeTest;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.tree.wrapper.VirtualNode;
import net.sf.saxon.type.ItemType;
import net.sf.saxon.type.Type;
import net.sf.saxon.value.SequenceExtent;
import org.w3c.dom.*;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.dom.DOMSource;
import javax.xml.xpath.XPathConstants;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
/**
* This interface must be implemented by any third-party object model that can
* be wrapped with a wrapper that implements the Saxon Object Model (the NodeInfo interface).
* This implementation of the interface supports wrapping of DOM Documents.
*/
public class DOMObjectModel extends TreeModel implements ExternalObjectModel {
private static final DOMObjectModel THE_INSTANCE = new DOMObjectModel();
private static DocumentBuilderFactory factory = null;
/**
* Get a reusable instance of this class.
* Note, this is not actually a singleton instance; the class also has a public constructor,
* which is needed to support the automatic loading of object models into the Configuration.
*
* @return the singleton instance
*/
public static DOMObjectModel getInstance() {
return THE_INSTANCE;
}
/**
* Create an instance of the DOMObjectModel class.
* When possible, use the getInstance() method in preference, as the instance is then reusable.
*/
public DOMObjectModel() {
}
/**
* Get the name of a characteristic class, which, if it can be loaded, indicates that the supporting libraries
* for this object model implementation are available on the classpath
*
* @return by convention (but not necessarily) the class that implements a document node in the relevant
* external model
*/
@Override
public String getDocumentClassName() {
return "org.w3c.dom.Document";
}
/**
* Get the URI of the external object model as used in the JAXP factory interfaces for obtaining
* an XPath implementation
*/
@Override
public String getIdentifyingURI() {
return XPathConstants.DOM_OBJECT_MODEL;
}
@Override
public String getName() {
return "DOM";
}
/**
* Get a converter from XPath values to values in the external object model
*
* @param targetClass the required class of the result of the conversion. If this class represents
* a node or list of nodes in the external object model, the method should return a converter that takes
* a native node or sequence of nodes as input and returns a node or sequence of nodes in the
* external object model representation. Otherwise, it should return null.
* @return a converter, if the targetClass is recognized as belonging to this object model;
* otherwise null
*/
@Override
public PJConverter getPJConverter(Class targetClass) {
if (Node.class.isAssignableFrom(targetClass) && !NodeOverNodeInfo.class.isAssignableFrom(targetClass)) {
return new PJConverter() {
@Override
public Object convert(Sequence value, Class targetClass, XPathContext context) throws XPathException {
return convertXPathValueToObject(value, targetClass);
}
};
} else if (NodeList.class == targetClass) {
return new PJConverter() {
@Override
public Object convert(Sequence value, Class targetClass, XPathContext context) throws XPathException {
return convertXPathValueToObject(value, targetClass);
}
};
} else {
return null;
}
}
//public NodeSet ns;
@Override
public JPConverter getJPConverter(Class sourceClass, Configuration config) {
if (Node.class.isAssignableFrom(sourceClass) && !NodeOverNodeInfo.class.isAssignableFrom(sourceClass)) {
return new JPConverter() {
@Override
public GroundedValue convert(Object obj, XPathContext context) {
return wrapOrUnwrapNode((Node) obj, context.getConfiguration());
}
@Override
public ItemType getItemType() {
return AnyNodeTest.getInstance();
}
};
} else if (NodeList.class.isAssignableFrom(sourceClass)) {
return new JPConverter() {
@Override
public GroundedValue convert(Object obj, XPathContext context) {
Configuration config = context.getConfiguration();
NodeList list = (NodeList) obj;
final int len = list.getLength();
NodeInfo[] nodes = new NodeInfo[len];
for (int i = 0; i < len; i++) {
nodes[i] = wrapOrUnwrapNode(list.item(i), config);
}
return new SequenceExtent.Of<>(nodes);
}
@Override
public ItemType getItemType() {
return AnyNodeTest.getInstance();
}
@Override
public int getCardinality() {
return StaticProperty.ALLOWS_ZERO_OR_MORE;
}
};
} else if (DOMSource.class.isAssignableFrom(sourceClass)) {
return new JPConverter() {
@Override
public GroundedValue convert(Object obj, XPathContext context) {
return unravel((DOMSource) obj, context.getConfiguration());
}
@Override
public ItemType getItemType() {
return AnyNodeTest.getInstance();
}
};
} else if (DocumentWrapper.class == sourceClass) {
return new JPConverter() {
@Override
public GroundedValue convert(Object obj, XPathContext context) {
return ((DocumentWrapper) obj).getRootNode();
}
@Override
public ItemType getItemType() {
return AnyNodeTest.getInstance();
}
};
} else {
return null;
}
}
/**
* Get a converter that converts a sequence of XPath nodes to this model's representation
* of a node list.
*
* @param node an example of the kind of node used in this model
* @return if the model does not recognize this node as one of its own, return null. Otherwise
* return a PJConverter that takes a list of XPath nodes (represented as NodeInfo objects) and
* returns a collection of nodes in this object model
*/
@Override
public PJConverter getNodeListCreator(Object node) {
if (node == null ||
node instanceof Node ||
node instanceof DOMSource ||
node instanceof DocumentWrapper ||
(node instanceof VirtualNode && ((VirtualNode) node).getRealNode() instanceof Node)) {
return new PJConverter() {
/*@Nullable*/
@Override
public Object convert(Sequence value, Class targetClass, XPathContext context) throws XPathException {
return convertXPathValueToObject(value, NodeList.class);
}
};
} else {
return null;
}
}
/**
* Test whether this object model recognizes a particular kind of JAXP Result object,
* and if it does, return a Receiver that builds an instance of this data model from
* a sequence of events. If the Result is not recognised, or is not a {@code DOMResult}, return null.
* @return either a Receiver that can be used to build a DOM instance, or null
*/
@Override
public Receiver getDocumentBuilder(Result result) throws XPathException {
if (result instanceof DOMResult) {
DOMWriter emitter = new DOMWriter();
Node root = ((DOMResult) result).getNode();
if (root instanceof NodeOverNodeInfo && !(((NodeOverNodeInfo) root).getUnderlyingNodeInfo() instanceof MutableNodeInfo)) {
throw new XPathException("Supplied DOMResult is a non-mutable Saxon implementation");
}
// JDK 1.5 adds a nextSibling() property to identify the insertion point among the siblings
Node nextSibling = ((DOMResult) result).getNextSibling();
if (root == null) {
try {
if (factory == null) {
factory = DocumentBuilderFactory.newInstance();
}
DocumentBuilder docBuilder = factory.newDocumentBuilder();
Document out = docBuilder.newDocument();
((DOMResult) result).setNode(out);
emitter.setNode(out);
} catch (ParserConfigurationException e) {
throw new XPathException(e);
}
} else {
emitter.setNode(root);
emitter.setNextSibling(nextSibling);
}
return emitter;
}
return null;
}
@Override
public Builder makeBuilder(PipelineConfiguration pipe) {
DOMWriter dw = new DOMWriter();
dw.setPipelineConfiguration(pipe);
return dw;
}
/**
* Give this ExternalObjectModel the opportunity of recognising a Source object and returning
* an ActiveSource, which will be used to send an instance of this external model to a supplied
* Receiver. The default implementation returns null.
*
* @param supplied a supplied Source
* @return an ActiveSource object if the source is recognised, or null if not
*/
@Override
public ActiveSource getActiveSource(Source supplied) {
if (supplied instanceof DOMSource) {
return new ActiveDOMSource((DOMSource) supplied);
}
return null;
}
public static void sendDOMSource(DOMSource source, Receiver receiver) throws XPathException {
Node startNode = source.getNode();
if (startNode == null) {
// Send an empty document
receiver.open();
receiver.startDocument(ReceiverOption.NONE);
receiver.endDocument();
receiver.close();
} else {
// Do a quick check (not guaranteed to catch all cases) that this isn't a non-namespace-aware DOM,
// to catch the common case of failing to set namespace-awareness on the DOM factory
if (startNode.getNodeType() == Type.DOCUMENT) {
Element top = ((Document) startNode).getDocumentElement();
if (top != null && top.getNamespaceURI() == null) {
if (top.getNodeName().contains(":")) {
issueWarning(receiver, "Supplied DOM uses namespaces, but is not created as namespace-aware");
} else if (top.hasAttribute("xmlns")) {
issueWarning(receiver, "Supplied DOM declares a default namespace, but is not created as namespace-aware");
}
}
}
DOMSender driver = new DOMSender(startNode, receiver);
driver.setSystemId(source.getSystemId());
receiver.open();
driver.send();
receiver.close();
}
}
private static void issueWarning(Receiver receiver, String text) {
try {
Configuration config = receiver.getPipelineConfiguration().getConfiguration();
config.getLogger().warning("WARNING: " + text);
} catch (Exception err) {
System.err.println("WARNING: " + text);
}
}
/**
* Wrap a DOM node using this object model to return the corresponding Saxon node.
*
* @param node the DOM node to be wrapped
* @param config the Saxon Configuration
* @return the wrapped DOM node
* @since 9.2
*/
public NodeInfo wrap(Node node, Configuration config) {
// Supplied source is an ordinary DOM Node: wrap it
Document dom;
if (node.getNodeType() == Node.DOCUMENT_NODE) {
dom = (Document) node;
} else {
dom = node.getOwnerDocument();
}
DocumentWrapper docWrapper = new DocumentWrapper(dom, node.getBaseURI(), config);
return docWrapper.wrap(node);
}
/**
* Copy a DOM node to create a node in a different tree model
*
* @param node the DOM node to be copied
* @param model the target tree model
* @param config the Saxon Configuration
* @return the copied node
* @throws net.sf.saxon.trans.XPathException
* if the operation fails
* @since 9.2
*/
public NodeInfo copy(Node node, TreeModel model, Configuration config) throws XPathException {
PipelineConfiguration pipe = config.makePipelineConfiguration();
Builder builder = model.makeBuilder(pipe);
builder.open();
Sender.send(new DOMSource(node), builder, null);
NodeInfo result = builder.getCurrentRoot();
builder.close();
return result;
}
/**
* Wrap or unwrap a node using this object model to return the corresponding Saxon node. If the supplied
* source does not belong to this object model, return null
*/
@Override
public NodeInfo unravel(Source source, Configuration config) {
if (source instanceof DOMSource) {
Node dsnode = ((DOMSource) source).getNode();
if (!(dsnode instanceof NodeOverNodeInfo)) {
// Supplied source is an ordinary DOM Node: wrap it
Document dom;
if (dsnode.getNodeType() == Node.DOCUMENT_NODE) {
dom = (Document) dsnode;
} else {
dom = dsnode.getOwnerDocument();
}
DocumentWrapper docWrapper = new DocumentWrapper(dom, source.getSystemId(), config);
return docWrapper.wrap(dsnode);
}
}
return null;
}
/**
* Wrap a DOM Node as a NodeInfo, unless it already wraps a NodeInfo, inwhich case unwrap it
*
* @param node the node to be wrapped
* @param config the Saxon Configuration. This must be the same Configuration, or one that is compatible with,
* the Configuration used to compile and execute the query or stylesheet.
* @return the new wrapper node
*/
private NodeInfo wrapOrUnwrapNode(Node node, Configuration config) {
if (node instanceof NodeOverNodeInfo) {
return ((NodeOverNodeInfo) node).getUnderlyingNodeInfo();
} else {
TreeInfo doc = wrapDocument(node, "", config);
return wrapNode(doc, node);
}
}
/**
* Convert an XPath value to an object in this object model. If the supplied value can be converted
* to an object in this model, of the specified class, then the conversion should be done and the
* resulting object returned. If the value cannot be converted, the method should return null. Note
* that the supplied class might be a List, in which case the method should inspect the contents of the
* Value to see whether they belong to this object model.
*
* @param value the XPath value to be converted
* @param target the class of object required
* @return the result of the conversion
* @throws XPathException if the target class is explicitly associated with this object model, but the
* supplied value cannot be converted to the appropriate class
*/
public static Object convertXPathValueToObject(Sequence value, Class target) throws XPathException {
// We accept the object if (a) the target class is Node, Node[], or NodeList,
// or (b) the supplied object is a node, or sequence of nodes, that wrap DOM nodes,
// provided that the target class is Object or a collection class
boolean requireDOM =
Node.class.isAssignableFrom(target) || (target == NodeList.class) ||
(target.isArray() && Node.class.isAssignableFrom(target.getComponentType()));
// Note: we allow the declared type of the method argument to be a subclass of Node. If the actual
// node supplied is the wrong kind of node, this will result in a Java exception.
boolean allowDOM =
target == Object.class || target.isAssignableFrom(ArrayList.class) ||
target.isAssignableFrom(HashSet.class) ||
(target.isArray() && target.getComponentType() == Object.class);
if (!(requireDOM || allowDOM)) {
return null;
}
List nodes = new ArrayList<>(20);
SequenceIterator iter = value.iterate();
for (Item item; (item = iter.next()) != null; ) {
if (item instanceof VirtualNode) {
Object o = ((VirtualNode) item).getRealNode();
if (o instanceof Node) {
nodes.add((Node) o);
continue;
}
}
if (requireDOM) {
if (item instanceof NodeInfo) {
nodes.add(NodeOverNodeInfo.wrap((NodeInfo) item));
} else {
throw new XPathException(
"Cannot convert XPath value to Java object: required class is " + target.getName() +
"; supplied value has type " + Type.displayTypeName(item));
}
} else {
return null; // DOM Nodes are not actually required; let someone else try the conversion
}
}
if (nodes.isEmpty() && !requireDOM) {
return null; // empty sequence supplied - try a different mapping
}
if (Node.class.isAssignableFrom(target)) {
if (nodes.size() != 1) {
throw new XPathException("Cannot convert XPath value to Java object: requires a single DOM Node" +
" but supplied value contains " + nodes.size() + " nodes");
}
return nodes.get(0);
// could fail if the node is of the wrong kind
} else if (target == NodeList.class) {
return new DOMNodeList(nodes);
} else if (target.isArray() && target.getComponentType() == Node.class) {
return nodes.toArray(new Node[0]);
} else if (target.isAssignableFrom(ArrayList.class)) {
return nodes;
} else if (target.isAssignableFrom(HashSet.class)) {
return new HashSet<>(nodes);
} else {
// after all this work, give up
return null;
}
}
/**
* Wrap a document node in the external object model in a document wrapper that implements
* the Saxon DocumentInfo interface. (However, if the supplied object is a wrapper for a Saxon
* NodeInfo object, then we unwrap it.
*
* @param node a node (any node) in the third party document
* @param baseURI the base URI of the node (supply "" if unknown)
* @param config the Saxon configuration (which among other things provides access to the NamePool)
* @return the wrapper, which must implement DocumentInfo
*/
private TreeInfo wrapDocument(Object node, String baseURI, Configuration config) {
if (node instanceof DocumentOverNodeInfo) {
return (TreeInfo) ((DocumentOverNodeInfo) node).getUnderlyingNodeInfo();
}
if (node instanceof NodeOverNodeInfo) {
return ((NodeOverNodeInfo) node).getUnderlyingNodeInfo().getTreeInfo();
}
if (node instanceof org.w3c.dom.Node) {
if (((Node) node).getNodeType() == Node.DOCUMENT_NODE) {
Document doc = (org.w3c.dom.Document) node;
return new DocumentWrapper(doc, baseURI, config);
} else if (((Node) node).getNodeType() == Node.DOCUMENT_FRAGMENT_NODE) {
DocumentFragment doc = (org.w3c.dom.DocumentFragment) node;
return new DocumentWrapper(doc, baseURI, config);
} else {
Document doc = ((org.w3c.dom.Node) node).getOwnerDocument();
return new DocumentWrapper(doc, baseURI, config);
}
}
throw new IllegalArgumentException("Unknown node class " + node.getClass());
}
/**
* Wrap a node within the external object model in a node wrapper that implements the Saxon
* VirtualNode interface (which is an extension of NodeInfo)
*
* @param document the document wrapper, as a DocumentInfo object
* @param node the node to be wrapped. This must be a node within the document wrapped by the
* DocumentInfo provided in the first argument
* @return the wrapper for the node, as an instance of VirtualNode
*/
private NodeInfo wrapNode(TreeInfo document, Object node) {
return ((DocumentWrapper) document).wrap((Node) node);
}
}