Package net.sf.saxon.s9api

Class XQueryEvaluator

  • All Implemented Interfaces:
    java.lang.Iterable<XdmItem>, Destination
    public class XQueryEvaluator
extends AbstractDestination
implements java.lang.Iterable<XdmItem>
    An XQueryEvaluator represents a compiled and loaded query ready for execution. The XQueryEvaluator holds details of the dynamic evaluation context for the query.

    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 query several times. Running the query 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.

    An XQueryEvaluator is itself a Destination. This means it is possible to use one XQueryEvaluator as the destination to receive the results of another transformation, this providing a simple way for transformations to be chained into a pipeline. When the query is executed this way, setDestination(Destination) must be called to provide a destination for the result of this query.

    As a Destination, an XQueryEvaluator performs sequence normalization as defined in the Serialization specification, including inserting item separators if required. The input to the query (the global context item) will therefore always be a single document node. This will always be built as a tree in memory, it will never be streamed.

    • Constructor Detail

      • XQueryEvaluator

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

    • Method Detail

      • setSchemaValidationMode

        public void setSchemaValidationMode​(ValidationMode mode)
        Set the schema validation mode for the transformation. This indicates how source documents loaded specifically for this transformation will be handled. This applies to the principal source document if supplied as a SAXSource or StreamSource, and to all documents loaded during the transformation using the doc(), document(), or collection() functions.
        Parameters:
        mode - the validation mode. Passing null causes no change to the existing value. Passing Validation.DEFAULT resets to the initial value, which determines the validation requirements from the Saxon Configuration.

      • getSchemaValidationMode

        public ValidationMode getSchemaValidationMode()
        Get the schema validation mode for the transformation. This indicates how source documents loaded specifically for this transformation will be handled. This applies to the principal source document if supplied as a SAXSource or StreamSource, and to all documents loaded during the transformation using the doc(), document(), or collection() functions.
        Returns:
        the validation mode.

      • setSource

        public void setSource​(javax.xml.transform.Source source)
               throws SaxonApiException
        Set the source document for the query.

        If the source is an instance of NodeInfo, the supplied node is used directly as the context node of the query.

        If the source is an instance of DOMSource, the DOM node identified by the DOMSource is wrapped as a Saxon node, and this is then used as the context item

        In all other cases a new Saxon tree is built, by calling DocumentBuilder.build(javax.xml.transform.Source), and the document node of this tree is then used as the context item for the query.

        Parameters:
        source - the source document to act as the initial context item for the query.
        Throws:
        SaxonApiException

      • setContextItem

        public void setContextItem​(XdmItem item)
                    throws SaxonApiException
        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
        Throws:
        SaxonApiException - if the query declares the context item and does not define it to be external

      • 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
        Throws:
        SaxonApiUncheckedException - if the value is evaluated lazily, and evaluation fails

      • 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​(javax.xml.transform.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 javax.xml.transform.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​(javax.xml.transform.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 javax.xml.transform.ErrorListener getErrorListener()
        Get the error listener.
        Returns:
        the ErrorListener in use

      • setErrorReporter

        public void setErrorReporter​(ErrorReporter reporter)
        Supply a callback which will be notified of all dynamic errors and warnings encountered during this query evaluation.

        Calling this method overwrites the effect of any previous call on setErrorListener(ErrorListener) or setErrorList.

        If no error reporter is supplied by the caller, error information will be written to the standard error stream.

        Parameters:
        reporter - a callback function which will be notified of all Static errors and warnings encountered during a compilation episode.
        Since:
        11.2 and retrofitted to 10.7

      • 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​(Logger 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. Changed in 9.6 to use a Logger

      • getTraceFunctionDestination

        public Logger 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. Changed in 9.6 to use a Logger

      • 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
        java.lang.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.

        This method is designed for use with a query that produces a single node (typically a document node or element node) as its result. If the query produces multiple nodes, the effect depends on the kind of destination. For example, if the result is an XdmDestination, only the last of the nodes will be accessible.

        Parameters:
        destination - The destination where the result document will be sent
        Throws:
        SaxonApiException - if any dynamic error occurs during the query
        java.lang.IllegalStateException - if this is an updating query

      • runStreamed

        public void runStreamed​(javax.xml.transform.Source source,
                        Destination destination)
                 throws SaxonApiException
        Perform the query in streaming mode, sending the results to a specified destination.

        This method must not be used with an updating query.

        This method is designed for use with a query that produces a single node (typically a document node or element node) as its result. If the query produces multiple nodes, the effect depends on the kind of destination. For example, if the result is an XdmDestination, only the last of the nodes will be accessible.

        Parameters:
        source - the input stream whose document node will act as the initial context item. Should be a SAXSource or StreamSource
        destination - The destination where the result document will be sent
        Throws:
        SaxonApiException - if any dynamic error occurs during the query
        java.lang.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
        java.lang.IllegalStateException - if this is an updating query

      • evaluateSingle

        public XdmItem evaluateSingle()
                       throws SaxonApiException
        Evaluate the XQuery expression, returning the result as an XdmItem (that is, a single node or atomic value).
        Returns:
        an XdmItem representing the result of the query, or null if the query returns an empty sequence. If the expression returns a sequence of more than one item, any items after the first are ignored.
        Throws:
        SaxonApiException - if a dynamic error occurs during the query evaluation.
        Since:
        9.2

      • iterator

        public XdmSequenceIterator<XdmItem> iterator()
                                      throws SaxonApiUncheckedException
        Evaluate the query, and return an iterator over its results.

        This method must not be used with an updating query.

        Specified by:
        iterator in interface java.lang.Iterable<XdmItem>
        Returns:
        an Iterator<XdmItem>. The XdmSequenceIterator class is a standard Java Iterator with an additional close() method, which should be called to release resources if the client does not intend to read any more items from the iterator.
        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.
        java.lang.IllegalStateException - if this is an updating query
        Since:
        9.5.1.5. Previously the method returned Iterator<XdmItem>; the signature changed in Saxon 9.5.1.5 for reasons described in bug 2016.

      • stream

        public XdmStream<XdmItem> stream()
                          throws SaxonApiUncheckedException
        Evaluate the query, returning the result as an Stream.
        Returns:
        A stream delivering the results of the query. Each object in this stream will be an instance of XdmItem. Note that the expression may be evaluated lazily, which means that a successful response from this method does not imply that the expression has executed successfully: failures may be reported later while retrieving items from the iterator.
        Throws:
        SaxonApiUncheckedException - if a dynamic error occurs during XPath evaluation that can be detected at this point.

      • getReceiver

        public Receiver getReceiver​(PipelineConfiguration pipe,
                            SerializationProperties params)
                     throws SaxonApiException
        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 query 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 XQueryEvaluator implements Destination, allowing one transformation to receive the results of another in a pipeline.

        Note that when an XQueryEvaluator is used as a Destination, the initial context node set on that XQueryEvaluator (using setSource(javax.xml.transform.Source)) is ignored.

        Specified by:
        getReceiver in interface Destination
        Parameters:
        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.
        params - the output serialization properties
        Returns:
        the Receiver to which events are to be sent.
        Throws:
        SaxonApiException - if the Receiver cannot be created
        java.lang.IllegalStateException - if no Destination has been supplied

      • close

        public void close()
           throws SaxonApiException
        Close this destination, allowing resources to be released. Used when this XQueryEvaluator is acting as the destination of another transformation or query. Saxon calls this method when it has finished writing to the destination.
        Specified by:
        close in interface Destination
        Throws:
        SaxonApiException - if any failure occurs

      • getUpdatedDocuments

        public java.util.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

      • callFunction

        public XdmValue callFunction​(QName function,
                             XdmValue[] arguments)
                      throws SaxonApiException
        Call a global user-defined function in the compiled query.

        If this is called more than once (to evaluate the same function repeatedly with different arguments, or to evaluate different functions) then the sequence of evaluations uses the same values of global variables including external variables (query parameters); the effect of any changes made to query parameters between calls is undefined.

        Parameters:
        function - The name of the function to be called
        arguments - The values of the arguments to be supplied to the function. If necessary these are converted to the required type by applying the function conversion rules.
        Returns:
        the result of the function call as an XdmValue.
        Throws:
        SaxonApiException - if no function has been defined with the given name and arity; or if any of the arguments does not match its required type according to the function signature; or if a dynamic error occurs in evaluating the function.
        Since:
        9.3. Changed in 9.6 to apply the function conversion rules to the supplied arguments.

      • 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