net.sf.saxon.s9api.XsltTransformer Maven / Gradle / Ivy
Show all versions of Saxon-HE Show documentation
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018-2022 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.s9api;
import net.sf.saxon.event.PipelineConfiguration;
import net.sf.saxon.event.Receiver;
import net.sf.saxon.event.SequenceNormalizerWithSpaceSeparator;
import net.sf.saxon.expr.instruct.GlobalContextRequirement;
import net.sf.saxon.expr.instruct.GlobalParameterSet;
import net.sf.saxon.lib.NamespaceConstant;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.serialize.SerializationProperties;
import net.sf.saxon.trans.UncheckedXPathException;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.trans.XmlProcessingException;
import net.sf.saxon.trans.XsltController;
import net.sf.saxon.transpile.CSharpModifiers;
import net.sf.saxon.tree.linked.DocumentImpl;
import javax.xml.transform.Source;
import javax.xml.transform.dom.DOMSource;
import java.net.URI;
/**
* An {@code XsltTransformer} represents a compiled and loaded stylesheet ready for execution.
* The {@code XsltTransformer} holds details of the dynamic evaluation context for the stylesheet.
*
* An {@code XsltTransformer} must not be used concurrently in multiple threads.
* It is safe, however, to reuse the object within a single thread to run the same
* stylesheet several times. Running the stylesheet does not change the context
* that has been established. Some of the public methods are synchronized: this is not because
* multi-threaded execution is supported, rather it is to reduce the damage if multi-threaded
* execution is attempted.
*
* An {@code XsltTransformer} is always constructed by running the {@code Load}
* method of an {@link XsltExecutable}.
*
* An {@code XsltTransformer} is itself a {@link Destination}. This means it is possible to use
* one {@code XsltTransformer} as the destination to receive the results of another transformation,
* this providing a simple way for transformations to be chained into a pipeline. Note however that a
* when the input to a transformation is supplied in this way, it will always be built as a tree in
* memory, rather than the transformation being streamed. As a {@code Destination}, the transformer
* performs Sequence Normalization on its input; that is, it converts the input to a single
* document node. (The main reason for this is that when chaining XSLT transformations, the raw
* output of the first stylesheet is often an element node, but the second stylesheet traditionally
* expects a document node.)
*
* @since 9.0
*/
@CSharpModifiers(code = {"internal"})
public class XsltTransformer extends AbstractXsltTransformer implements Destination {
private QName initialTemplateName;
private GlobalParameterSet parameters;
private Source initialSource;
private Destination destination;
private final DestinationHelper destinationHelper;
private URI destinationBaseUri;
/**
* Protected constructor
*
* @param processor the S9API processor
* @param controller the Saxon controller object
* @param staticParameters the static parameters supplied at stylesheet compile time
*/
protected XsltTransformer(Processor processor, XsltController controller, GlobalParameterSet staticParameters) {
super(processor, controller);
parameters = new GlobalParameterSet(/*staticParameters*/);
destinationHelper = new DestinationHelper(this);
}
/**
* Set the base URI of the resource being written to this destination
*
* @param baseURI the base URI to be used
*/
@Override
public void setDestinationBaseURI(URI baseURI) {
this.destinationBaseUri = baseURI;
}
/**
* Get the base URI of the resource being written to this destination
*
* @return the baseURI, or null if none is known
*/
@Override
public URI getDestinationBaseURI() {
return destinationBaseUri;
}
@Override
public void onClose(Action listener) {
destinationHelper.onClose(listener);
}
@Override
public void closeAndNotify() throws SaxonApiException {
destinationHelper.closeAndNotify();
}
/**
* Set the initial named template for the transformation
*
* @param templateName the name of the initial template, or null to indicate
* that there should be no initial named template. Changed
* in 9.9: the method no longer checks that the named
* template exists.
*/
public void setInitialTemplate(QName templateName) {
initialTemplateName = templateName;
}
/**
* Get the initial named template for the transformation, if one has been set
*
* @return the name of the initial template, or null if none has been set
*/
public QName getInitialTemplate() {
return initialTemplateName;
}
/**
* Set the source document for the transformation.
*
If the source is an instance of {@link net.sf.saxon.om.NodeInfo}, the supplied node is used
* directly as the initial context item of the transformation.
* If the source is an instance of {@link javax.xml.transform.dom.DOMSource}, the DOM node identified
* by the DOMSource is wrapped as a Saxon node, and this is then used as the context item.
* In other cases a new Saxon tree will be built by the transformation engine when the
* transformation starts, unless it is a Saxon-EE streaming transformation, in which case the
* document is processed in streaming fashion as it is being parsed.
* To run a transformation in streaming mode, the source should be supplied as an instance
* of {@link javax.xml.transform.stream.StreamSource} or {@link javax.xml.transform.sax.SAXSource}.
*
* Some kinds of {@code Source} (for example {@code StreamSource} and
* {@code SAXSource}are consumed by use; others (such as {@code DOMSource}) are immutable.
* In the general case, therefore, the {@code Source} object that is supplied by this method
* does not survive a call on {@link #transform()}.
*
* @param source the principal source document for the transformation
*/
public synchronized void setSource(Source source) {
if (source instanceof NodeInfo) {
setInitialContextNode(new XdmNode((NodeInfo) source));
} else if (source instanceof DOMSource) {
if (((DOMSource)source).getNode() == null) {
DocumentImpl doc = new DocumentImpl();
doc.setConfiguration(controller.getConfiguration());
setInitialContextNode(new XdmNode(doc));
} else {
NodeInfo n = processor.getUnderlyingConfiguration().unravel(source);
setInitialContextNode(new XdmNode(n));
}
} else {
initialSource = source;
}
}
/**
* Set the initial context node for the transformation.
* In XSLT 3.0 terms, this sets the initial match selection (the sequence to which the
* initial implicit call of xsl:applyTemplates is applied). It also determines how the
* global context item for evaluating global variables is set: following the XSLT 1.0 and 2.0 rules
* (XSLT 2.0 section 9.5): "For a global variable or the default value of a stylesheet parameter,
* the expression or sequence constructor specifying the variable value is evaluated with a singleton
* focus based on the root node of the tree containing the initial context node."
* This value is ignored in the case where the {@link XsltTransformer} is used as the
* {@link Destination} of another process. In that case the initial context node will always
* be the document node of the document that is being streamed to this destination.
* Calling this method has the side-effect of setting the initial source to null.
*
* @param node the initial context node, or null if there is to be no initial context node
* @throws SaxonApiUncheckedException if the node is unsuitable, for example if it was
* built using the wrong Configuration
*/
public synchronized void setInitialContextNode(XdmNode node) throws SaxonApiUncheckedException {
try {
if (node == null) {
initialSource = null;
controller.setGlobalContextItem(null);
} else {
initialSource = node.getUnderlyingNode().asActiveSource();
controller.setGlobalContextItem(node.getUnderlyingNode().getRoot());
}
} catch (XPathException e) {
throw new SaxonApiUncheckedException(e);
}
}
/**
* Get the initial context node for the transformation, if one has been set
*
* @return the initial context node, or null if none has been set. This will not necessarily
* be the same {@link XdmNode} instance as was supplied, but it will be an XdmNode object that represents
* the same underlying node.
*/
public XdmNode getInitialContextNode() {
if (initialSource instanceof NodeInfo) {
return (XdmNode) XdmValue.wrap((NodeInfo) initialSource);
} else {
return null;
}
}
/**
* Set the value of a stylesheet parameter.
*
* If the stylesheet does not have a parameter with this name, then the supplied value will
* simply be ignored (no error occurs)
*
* If the stylesheet has a parameter with this name, and the supplied value does not match the
* required type, then no error will be reported at this stage, but a dynamic error will occur
* when the parameter value is first used. Supplied values are converted to the required type
* using the function conversion rules.
*
* If the stylesheet has a parameter with this name, and the parameter is declared
* with static="yes", or if a parameter with the same name was supplied to the
* {@link XsltCompiler}, then no error will be reported at this stage, but an error
* will be reported when the transformation is initiated. Static parameters must be initialized
* using {@link XsltCompiler#setParameter(QName, XdmValue)}.
*
* @param name the name of the stylesheet parameter, as a QName
* @param value the value of the stylesheet parameter, or null to clear a previously set value
* @throws SaxonApiUncheckedException if the value is lazily evaluated, and evaluation fails
*/
public synchronized void setParameter(QName name, XdmValue value) {
try {
parameters.put(name.getStructuredQName(),
value == null ? null : ((Sequence) value.getUnderlyingValue()).materialize());
} catch (UncheckedXPathException e) {
throw new SaxonApiUncheckedException(e);
}
}
/**
* Clear the values of all parameters that have been set
*/
public synchronized void clearParameters() {
parameters = new GlobalParameterSet();
}
/**
* Get the value that has been set for a stylesheet parameter
*
* @param name the parameter whose name is required
* @return the value that has been set for the parameter, or null if no value has been set
*/
public synchronized XdmValue getParameter(QName name) {
Sequence oval = parameters.get(name.getStructuredQName());
return oval == null ? null : XdmValue.wrap(oval);
}
/**
* Set the destination to be used for the result of the transformation.
*
* This method can be used to chain transformations into a pipeline, by using one
* {@link XsltTransformer} as the destination of another
*
* The {@code Destination} object will generally be modified by a transformation
* (that is, by a call on {@link #transform()}), and in general a {@code Destination}
* cannot be used more than once. Therefore, if this {@code XsltTransformer} is used
* for multiple transformations then a new {@code Destination} should be set for each one.
*
* @param destination the destination to be used for the result of this transformation
*/
public void setDestination(Destination destination) {
this.destination = destination;
}
/**
* Get the destination that was specified in a previous call of {@link #setDestination}
*
* @return the destination, or null if none has been supplied
*/
public Destination getDestination() {
return destination;
}
/**
* Perform the transformation. If this method is used, a destination must have been supplied
* previously.
*
*
Calling this method will in general consume any {@code Source} and {@code Destination}
* that have been supplied, so a new {@code Source} and {@code Destination} are needed for each
* transformation. Other properties of this {@code XsltTransformer} (for example, the values
* of parameters, the initial template, and initial mode) are left unchanged after the
* transformation completes.
*
* If no source has been supplied (using {@link #setSource(Source)}), then the method
* looks to see whether an initial named template has been supplied (using {@link #setInitialTemplate(QName)},
* and if so, the transformation starts with that named template. In the absence of an initial named template,
* it looks to see if the stylesheet includes a template named {@code xsl:initial-template}, and if so,
* uses that as the entry point. If there is no source and no initial template, the method fails.
*
* @throws SaxonApiException if any dynamic error occurs during the transformation
* @throws IllegalStateException if no destination has been supplied
*/
public synchronized void transform() throws SaxonApiException {
Source initialSelection = initialSource;
boolean reset = false;
if (destination == null) {
throw new IllegalStateException("No destination has been supplied");
}
try {
Receiver out = getDestinationReceiver(controller, destination);
GlobalContextRequirement gcr = controller.getExecutable().getGlobalContextRequirement();
if ((gcr == null || !gcr.isAbsentFocus()) && initialSelection != null) {
if (initialSelection instanceof NodeInfo) {
reset = maybeSetGlobalContextItem((NodeInfo) initialSelection);
} else if (initialSelection instanceof DOMSource) {
NodeInfo node = controller.prepareInputTree(initialSelection);
reset = maybeSetGlobalContextItem(node);
initialSelection = node.asActiveSource();
} else {
NodeInfo node = controller.makeSourceTree(initialSelection, getSchemaValidationMode().getNumber());
reset = maybeSetGlobalContextItem(node);
initialSelection = node.asActiveSource();
}
}
if (baseOutputUriWasSet) {
out.setSystemId(getBaseOutputURI());
}
controller.initializeController(parameters);
if (initialTemplateName != null) {
controller.callTemplate(initialTemplateName.getStructuredQName(), out);
} else if (initialSelection != null) {
applyTemplatesToSource(initialSelection, out);
} else {
QName entryPoint = new QName("xsl", NamespaceConstant.XSLT, "initial-template");
controller.callTemplate(entryPoint.getStructuredQName(), out);
}
destination.closeAndNotify();
} catch (XPathException e) {
if (!e.hasBeenReported()) {
getErrorReporter().report(new XmlProcessingException(e));
e.setHasBeenReported(true);
}
throw new SaxonApiException(e);
} finally {
if (reset) {
controller.clearGlobalContextItem();
}
}
}
private boolean maybeSetGlobalContextItem(Item item) throws XPathException {
if (controller.getGlobalContextItem() == null) {
controller.setGlobalContextItem(item, true);
return true;
} else {
return false;
}
}
/**
* Return a Receiver which can be used to supply the principal source document for the transformation.
* This method is intended primarily for internal use, though it can also
* be called by a user application that wishes to feed events into the transformation engine.
*
* Saxon calls this method to obtain a Receiver, to which it then sends
* a sequence of events representing the content of an XML document. This method is provided so that
* {@code XsltTransformer} implements {@code Destination}, allowing one transformation
* to receive the results of another in a pipeline.
*
* Before calling this method, the {@link #setDestination} method must be called to supply a destination
* for the transformation.
*
* Note that when an {@code XsltTransformer} is used as a {@code Destination}, the initial
* context node set on that {@code XsltTransformer} using {@link #setInitialContextNode(XdmNode)} is ignored,
* as is the source set using {@link #setSource(javax.xml.transform.Source)}.
*
* @param pipe The Saxon configuration. This is supplied so that the destination can
* use information from the configuration (for example, a reference to the name pool)
* to construct or configure the returned Receiver.
* @param params serialization parameters (not relevant here since we aren't serializing; except
* possibly for the item-separator property)
* @return the Receiver to which events are to be sent.
* @throws SaxonApiException if the Receiver cannot be created
* @throws IllegalStateException if no Destination has been supplied
*/
@Override
public Receiver getReceiver(PipelineConfiguration pipe, SerializationProperties params) throws SaxonApiException {
if (destination == null) {
throw new IllegalStateException("No destination has been supplied");
}
Receiver rt = getReceivingTransformer(controller, parameters, destination);
rt = new SequenceNormalizerWithSpaceSeparator(rt);
rt.setPipelineConfiguration(pipe);
return rt;
}
/**
* Close this destination, allowing resources to be released. Used when this XsltTransformer is acting
* as the destination of another transformation. Saxon calls this method when it has finished writing
* to the destination.
*/
@Override
public void close() {
}
}