net.sf.saxon.s9api.XQueryEvaluator Maven / Gradle / Ivy
package net.sf.saxon.s9api;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.SequenceIterator;
import net.sf.saxon.om.ValueRepresentation;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.query.DynamicQueryContext;
import net.sf.saxon.query.XQueryExpression;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.SequenceExtent;
import net.sf.saxon.value.AtomicValue;
import net.sf.saxon.value.EmptySequence;
import net.sf.saxon.trace.TraceListener;
import javax.xml.transform.TransformerException;
import javax.xml.transform.URIResolver;
import javax.xml.transform.ErrorListener;
import javax.xml.transform.Source;
import java.util.Iterator;
/**
* An XQueryEvaluator represents a compiled and loaded stylesheet ready for execution.
* The XQueryEvaluator holds details of the dynamic evaluation context for the stylesheet.
*
* An XQueryEvaluator 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.
*
* An XQueryEvaluator is always constructed by running the Load
* method of an {@link net.sf.saxon.s9api.XQueryExecutable}.
*
* An XQueryEvaluator is itself a Iterable. This makes it possible to
* evaluate the results in a for-each expression.
*/
public class XQueryEvaluator implements Iterable {
private Processor processor;
private XQueryExpression expression;
private DynamicQueryContext context;
private Destination destination;
/**
* Protected constructor
* @param expression the XQuery expression
*/
protected XQueryEvaluator(Processor processor, XQueryExpression expression) {
this.processor = processor;
this.expression = expression;
this.context = new DynamicQueryContext(expression.getExecutable().getConfiguration());
}
/**
* Set the source document for the query. This method is equivalent to building
* a document from the supplied source object, and then supplying the document node of
* the resulting document as the initial context node.
* @param source the principal source document for the transformation
*/
public void setSource(Source source) throws SaxonApiException {
setContextItem(processor.newDocumentBuilder().build(source));
}
/**
* Set the initial context item for the query
* @param item the initial context item, or null if there is to be no initial context item
*/
public void setContextItem(XdmItem item) {
context.setContextItem(item == null ? null : (Item)item.getUnderlyingValue());
}
/**
* Get the initial context item for the query, if one has been set
* @return the initial context item, or null if none has been set. This will not necessarily
* be the same object as was supplied, but it will be an XdmItem object that represents
* the same underlying node or atomic value.
*/
public XdmItem getContextItem() {
return (XdmItem)XdmValue.wrap(context.getContextItem());
}
/**
* Set the value of external variable defined in the query
* @param name the name of the external variable, as a QName
* @param value the value of the external variable, or null to clear a previously set value
*/
public void setExternalVariable(QName name, XdmValue value) {
context.setParameter(name.getClarkName(),
(value == null ? null : value.getUnderlyingValue()));
}
/**
* Get the value that has been set for an external variable
* @param name the name of the external variable whose value is required
* @return the value that has been set for the external variable, or null if no value has been set
*/
public XdmValue getExternalVariable(QName name) {
Object oval = context.getParameter(name.getClarkName());
if (oval == null) {
return null;
}
if (oval instanceof ValueRepresentation) {
return XdmValue.wrap((ValueRepresentation)oval);
}
throw new IllegalStateException(oval.getClass().getName());
}
/**
* Set an object that will be used to resolve URIs used in
* fn:document() and related functions.
*
* @param resolver An object that implements the URIResolver interface, or
* null.
*/
public void setURIResolver(URIResolver resolver) {
context.setURIResolver(resolver);
}
/**
* Get the URI resolver.
*
* @return the user-supplied URI resolver if there is one, or the
* system-defined one otherwise
*/
public URIResolver getURIResolver() {
return context.getURIResolver();
}
/**
* Set the error listener. The error listener receives reports of all run-time
* errors and can decide how to report them.
*
* @param listener the ErrorListener to be used
*/
public void setErrorListener(ErrorListener listener) {
context.setErrorListener(listener);
}
/**
* Get the error listener.
*
* @return the ErrorListener in use
*/
public ErrorListener getErrorListener() {
return context.getErrorListener();
}
/**
* Set a TraceListener which will receive messages relating to the evaluation of all expressions.
* This option has no effect unless the query was compiled to enable tracing.
* @param listener the TraceListener to use
*/
public void setTraceListener(TraceListener listener) {
context.setTraceListener(listener);
}
/**
* Get the registered TraceListener, if any
* @return listener the TraceListener in use, or null if none has been set
*/
public TraceListener getTraceListener() {
return context.getTraceListener();
}
/**
* Set the destination of the query
* @param destination the destination to which the results of the query will be sent
*/
public void setDestination(Destination destination) {
this.destination = destination;
}
/**
* Perform the query, sending the results to a previously specified destination
* @throws net.sf.saxon.s9api.SaxonApiException if any dynamic error occurs during the query
* @throws IllegalStateException if no Destination has been supplied for the query results
*/
public void run() throws SaxonApiException {
try {
expression.run(context, destination.getReceiver(expression.getExecutable().getConfiguration()), null);
} catch (TransformerException e) {
throw new SaxonApiException(e);
}
}
/**
* Perform the query, sending the results to a specified destination
* @param destination The destination where the result document will be sent
* @throws net.sf.saxon.s9api.SaxonApiException if any dynamic error occurs during the query
*/
public void run(Destination destination) throws SaxonApiException {
try {
expression.run(context, destination.getReceiver(expression.getExecutable().getConfiguration()), null);
} catch (TransformerException e) {
throw new SaxonApiException(e);
}
}
/**
* Perform the query, returning the results as an XdmValue
* @return an XdmValue representing the results of the query
* @throws SaxonApiException if the query fails with a dynamic error
*/
public XdmValue evaluate() throws SaxonApiException {
try {
SequenceIterator iter = expression.iterator(context);
ValueRepresentation result = SequenceExtent.makeSequenceExtent(iter);
if (result instanceof NodeInfo) {
return new XdmNode((NodeInfo)result);
} else if (result instanceof AtomicValue) {
return new XdmAtomicValue((AtomicValue)result);
} else if (result instanceof EmptySequence) {
return XdmEmptySequence.getInstance();
} else {
return new XdmValue(result);
}
} catch (XPathException e) {
throw new SaxonApiException(e);
}
}
/**
* Get an iterator over the results of the query
* @throws SaxonApiUncheckedException if a dynamic error is detected while constructing the iterator.
* It is also possible for an SaxonApiUncheckedException to be thrown by the hasNext() method of the
* returned iterator if a dynamic error occurs while evaluating the result sequence.
*/
public Iterator iterator() throws SaxonApiUncheckedException {
try {
return new XdmSequenceIterator(expression.iterator(context));
} catch (XPathException e) {
throw new SaxonApiUncheckedException(e);
}
}
/**
* Get the underlying dynamic context object. This provides an escape hatch to the underlying
* implementation classes, which contain methods that may change from one release to another.
* @return the underlying object representing the dynamic context for query execution
*/
public DynamicQueryContext getUnderlyingQueryContext() {
return context;
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (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.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Contributor(s):
//
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