Class XQueryEvaluator

java.lang.Object
net.sf.saxon.s9api.XQueryEvaluator
All Implemented Interfaces:
Iterable<XdmItem>

public class XQueryEvaluator extends Object implements Iterable<XdmItem>
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 XQueryExecutable.

An XQueryEvaluator is itself a Iterable. This makes it possible to evaluate the results in a for-each expression.

  • Constructor Details

    • XQueryEvaluator

      protected XQueryEvaluator(Processor processor, XQueryExpression expression)
      Protected constructor
      Parameters:
      processor - the Saxon processor
      expression - the XQuery expression
  • Method Details

    • setSource

      public void setSource(Source source) throws SaxonApiException
      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.
      Parameters:
      source - the principal source document for the transformation
      Throws:
      SaxonApiException
    • setContextItem

      public void setContextItem(XdmItem item)
      Set the initial context item for the query
      Parameters:
      item - the initial context item, or null if there is to be no initial context item
    • getContextItem

      public XdmItem getContextItem()
      Get the initial context item for the query, if one has been set
      Returns:
      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.
    • setExternalVariable

      public void setExternalVariable(QName name, XdmValue value)
      Set the value of external variable defined in the query
      Parameters:
      name - the name of the external variable, as a QName
      value - the value of the external variable, or null to clear a previously set value
    • getExternalVariable

      public XdmValue getExternalVariable(QName name)
      Get the value that has been set for an external variable
      Parameters:
      name - the name of the external variable whose value is required
      Returns:
      the value that has been set for the external variable, or null if no value has been set
    • setURIResolver

      public void setURIResolver(URIResolver resolver)
      Set an object that will be used to resolve URIs used in fn:doc() and related functions.
      Parameters:
      resolver - An object that implements the URIResolver interface, or null.
    • getURIResolver

      public URIResolver getURIResolver()
      Get the URI resolver.
      Returns:
      the user-supplied URI resolver if there is one, or the system-defined one otherwise
    • setErrorListener

      public void setErrorListener(ErrorListener listener)
      Set the error listener. The error listener receives reports of all run-time errors and can decide how to report them.
      Parameters:
      listener - the ErrorListener to be used
    • getErrorListener

      public ErrorListener getErrorListener()
      Get the error listener.
      Returns:
      the ErrorListener in use
    • setTraceListener

      public void setTraceListener(TraceListener listener)
      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.
      Parameters:
      listener - the TraceListener to use
    • getTraceListener

      public TraceListener getTraceListener()
      Get the registered TraceListener, if any
      Returns:
      listener the TraceListener in use, or null if none has been set
    • setTraceFunctionDestination

      public void setTraceFunctionDestination(PrintStream stream)
      Set the destination for output from the fn:trace() function. By default, the destination is System.err. If a TraceListener is in use, this is ignored, and the trace() output is sent to the TraceListener.
      Parameters:
      stream - the PrintStream to which trace output will be sent. If set to null, trace output is suppressed entirely. It is the caller's responsibility to close the stream after use.
      Since:
      9.1
    • getTraceFunctionDestination

      public PrintStream getTraceFunctionDestination()
      Get the destination for output from the fn:trace() function.
      Returns:
      the PrintStream to which trace output will be sent. If no explicitly destination has been set, returns System.err. If the destination has been set to null to suppress trace output, returns null.
      Since:
      9.1
    • setDestination

      public void setDestination(Destination destination)
      Set the destination to be used for the query results
      Parameters:
      destination - the destination to which the results of the query will be sent
    • run

      public void run() throws SaxonApiException
      Perform the query.

      • In the case of a non-updating query, the results are sent to the registered Destination.
      • In the case of an updating query, all updated documents will be available after query execution as the result of the getUpdatedDocuments() method.
      Throws:
      SaxonApiException - if any dynamic error occurs during the query
      IllegalStateException - if this is a non-updating query and no Destination has been supplied for the query results
    • run

      public void run(Destination destination) throws SaxonApiException
      Perform the query, sending the results to a specified destination. This method must not be used with an updating query
      Parameters:
      destination - The destination where the result document will be sent
      Throws:
      SaxonApiException - if any dynamic error occurs during the query
      IllegalStateException - if this is an updating query
    • evaluate

      public XdmValue evaluate() throws SaxonApiException
      Perform the query, returning the results as an XdmValue. This method must not be used with an updating query
      Returns:
      an XdmValue representing the results of the query
      Throws:
      SaxonApiException - if the query fails with a dynamic error
      IllegalStateException - if this is an updating query
    • iterator

      public Iterator<XdmItem> iterator() throws SaxonApiUncheckedException
      Get an iterator over the results of the query. This method must not be used with an updating query
      Specified by:
      iterator in interface Iterable<XdmItem>
      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.
      IllegalStateException - if this is an updating query
    • getUpdatedDocuments

      public Iterator<XdmNode> getUpdatedDocuments()
      After executing an updating query using the run() method, iterate over the root nodes of the documents updated by the query.

      The results remain available until a new query is executed. This method returns the results of the most recently executed query. It does not consume the results.

      Returns:
      an iterator over the root nodes of documents (or other trees) that were updated by the query
      Since:
      9.1
    • getUnderlyingQueryContext

      public DynamicQueryContext getUnderlyingQueryContext()
      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.
      Returns:
      the underlying object representing the dynamic context for query execution