com.saxonica.stream
Class SubtreeCopyWatch

java.lang.Object
  com.saxonica.stream.SubtreeCopyWatch

All Implemented Interfaces:

Watch

public class SubtreeCopyWatch
extends Object
implements Watch

This class is used when optimizing a SequentialCopy, that is, when evaluating a construct of the form saxon:stream(doc('a.xml')/a/b/c). When the matched element (c in this example) is encountered, this Watch detects the fact, and activates a Receiver to receive subsequent events and construct a tree being a copy of the subtree rooted at c. On completion, this tree is written to the supplied SequenceWriter. This will often be a Conduit, where hopefully an iterator is waiting for it on another thread.

Constructor Summary

SubtreeCopyWatch(Selection selection, PipelineConfiguration pipe, SequenceWriter pusher)
Create a SubtreeCopyWatch

Method Summary

Receiver	activate(int locationId, int matchKind) Signal that an element has been found that matches the selection that this Watch is looking for.
void	close() The close() method is called immediately before the Watch is destroyed, that is, when the element whose declaration scopes the constraint implemented by this Watch goes out of scope.
void	deactivate(int locationId) Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.
int	getOriginDepth() Get the depth within the XML hierarchy of the element whose element declaration contains the unique/key/keyref constraint that this Watch implements
Selection	getSelection() Get the selection (that is, the restricted XPath expression) that defines the nodes that this Watch is looking for
void	setNamespaceResolver(NamespaceResolver resolver) Set a NamespaceResolver for use by the Watch
void	setOriginDepth(int depth) Set the depth within the XML hierarchy of the element whose element declaration contains the unique/key/keyref constraint that this Watch implements
void	setPipelineConfiguration(PipelineConfiguration pipe) Set the PipelineConfiguration in use

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SubtreeCopyWatch

public SubtreeCopyWatch(Selection selection,
                        PipelineConfiguration pipe,
                        SequenceWriter pusher)

Create a SubtreeCopyWatch

Parameters:

selection - the expression defining the nodes to be copied

pipe - the pipeline configuration information

pusher - the destination of events for the selected nodes

Method Detail

activate

public Receiver activate(int locationId,
                         int matchKind)
                  throws ValidationException

Signal that an element has been found that matches the selection that this Watch is looking for. This method is called by the ConstraintChecker while processing the startElement event that matches the selection. For this purpose, any attributes selected by the last step in the selection are ignored

Specified by:

activate in interface Watch

Parameters:

locationId - the location of the element

matchKind - indicates whether the match was on an element in its own right, or as parent of a matched attribute, or both

Returns:

a Receiver to be notified of all events starting with the startElement event for the matched element, and ending with the endElement event for that element.

Throws:

ValidationException - May be raised if the constraint implemented by this Watch is violated @param locationId

close

public void close()
           throws XPathException

The close() method is called immediately before the Watch is destroyed, that is, when the element whose declaration scopes the constraint implemented by this Watch goes out of scope.

Specified by:

close in interface Watch

Throws:

XPathException

deactivate

public void deactivate(int locationId)
                throws XPathException

Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.

Specified by:

deactivate in interface Watch

Parameters:

locationId - the location of the element

Throws:

ValidationException - May be raised if the constraint implemented by this Watch is violated @param locationId

XPathException

getOriginDepth

public int getOriginDepth()

Get the depth within the XML hierarchy of the element whose element declaration contains the unique/key/keyref constraint that this Watch implements

Specified by:

getOriginDepth in interface Watch

Returns:

The depth at which the watch is scoped. -1 indicates the document node

getSelection

public Selection getSelection()

Get the selection (that is, the restricted XPath expression) that defines the nodes that this Watch is looking for

Specified by:

getSelection in interface Watch

Returns:

the selection

setPipelineConfiguration

public void setPipelineConfiguration(PipelineConfiguration pipe)

Set the PipelineConfiguration in use

Specified by:

setPipelineConfiguration in interface Watch

Parameters:

pipe - the PipelineConfiguration in use

setNamespaceResolver

public void setNamespaceResolver(NamespaceResolver resolver)

Set a NamespaceResolver for use by the Watch

Specified by:

setNamespaceResolver in interface Watch

Parameters:

resolver - the namespace resolver to be used

setOriginDepth

public void setOriginDepth(int depth)

Set the depth within the XML hierarchy of the element whose element declaration contains the unique/key/keyref constraint that this Watch implements

Specified by:

setOriginDepth in interface Watch

Parameters:

depth - The depth at which the watch is scoped