Package com.saxonica.xqj.pull

Class TreeWalker

java.lang.Object

com.saxonica.xqj.pull.TreeWalker

All Implemented Interfaces:

javax.xml.transform.SourceLocator, PullProvider, UnfailingPullProvider, Location, org.xml.sax.Locator

public class TreeWalker
extends java.lang.Object
implements UnfailingPullProvider, Location

This implementation of the Saxon pull interface starts from any NodeInfo, and returns the events corresponding to that node and its descendants (including their attributes and namespaces). This works with any tree model: alternative implementations may be available that take advantage of particular implementations of the tree model.

Method Summary

Modifier and Type	Method	Description
void	close()	Close the event reader.
PullEvent	current()	Get the event most recently returned by next(), or by other calls that change the position, for example getStringValue() and skipToMatchingEnd().
AtomicValue	getAtomicValue()	Get an atomic value.
AttributeMap	getAttributes()	Get the attributes associated with the current element.
int	getColumnNumber()	Return the character position where the current document event ends.
int	getLineNumber()	Return the line number where the current document event ends.
NamePool	getNamePool()	Get the namePool used to lookup all name codes and namespace codes
NamespaceBinding[]	getNamespaceDeclarations()	Get the namespace declarations associated with the current element.
NodeName	getNodeName()	Get the NodeName identifying the name of the current node.
PipelineConfiguration	getPipelineConfiguration()	Get configuration information.
java.lang.String	getPublicId()	Return the public identifier for the current document event.
SchemaType	getSchemaType()	Get the type annotation of the current attribute or element node, or atomic value.
Location	getSourceLocator()	Get the location of the current event.
UnicodeString	getStringValue()	Get the string value of the current attribute, text node, processing-instruction, or atomic value.
java.lang.String	getSystemId()	Return the system identifier for the current document event.
java.util.List<UnparsedEntity>	getUnparsedEntities()	Get a list of unparsed entities.
static UnfailingPullProvider	makeTreeWalker(NodeInfo startNode)	Factory method to get a tree walker starting an a given node
PullEvent	next()	Get the next event
Location	saveLocation()	Get an immutable copy of this Location object.
void	setPipelineConfiguration(PipelineConfiguration pipe)	Set configuration information.
PullEvent	skipToMatchingEnd()	Skip the current subtree.

Methods inherited from class java.lang.Object

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

Method Detail

makeTreeWalker

public static UnfailingPullProvider makeTreeWalker(NodeInfo startNode)

Factory method to get a tree walker starting an a given node

Parameters:

startNode - the start node

Returns:

a PullProvider that delivers events associated with the subtree starting at the given node

setPipelineConfiguration

public void setPipelineConfiguration(PipelineConfiguration pipe)

Set configuration information. This must only be called before any events have been read.

Specified by:

setPipelineConfiguration in interface PullProvider

Parameters:

pipe - the pipeline configuration

getPipelineConfiguration

public PipelineConfiguration getPipelineConfiguration()

Get configuration information.

Specified by:

getPipelineConfiguration in interface PullProvider

Returns:

the pipeline configuration

next

public PullEvent next()
               throws XPathException

Get the next event

Specified by:

next in interface PullProvider

Specified by:

next in interface UnfailingPullProvider

Returns:

an Event object indicating the type of event. The code PullEvent.END_OF_INPUT is returned if there are no more events to return.

Throws:

XPathException - if a dynamic error occurs

current

public PullEvent current()

Get the event most recently returned by next(), or by other calls that change the position, for example getStringValue() and skipToMatchingEnd(). This method does not change the position of the PullProvider.

Specified by:

current in interface PullProvider

Specified by:

current in interface UnfailingPullProvider

Returns:

the current event

getAttributes

public AttributeMap getAttributes()

Get the attributes associated with the current element. This method must be called only after a START_ELEMENT event has been notified. The contents of the returned AttributeMap are immutable.

Attributes may be read before or after reading the namespaces of an element, but must not be read after the first child node has been read, or after calling one of the methods skipToEnd(), getStringValue(), or getTypedValue().

Specified by:

getAttributes in interface PullProvider

Specified by:

getAttributes in interface UnfailingPullProvider

Returns:

an AttributeMap representing the attributes of the element that has just been notified.

getNamespaceDeclarations

public NamespaceBinding[] getNamespaceDeclarations()

Get the namespace declarations associated with the current element. This method must be called only after a START_ELEMENT event has been notified. In the case of a top-level START_ELEMENT event (that is, an element that either has no parent node, or whose parent is not included in the sequence being read), the NamespaceDeclarations object returned will contain a namespace declaration for each namespace that is in-scope for this element node. In the case of a non-top-level element, the NamespaceDeclarations will contain a set of namespace declarations and undeclarations, representing the differences between this element and its parent.

It is permissible for this method to return namespace declarations that are redundant.

The NamespaceDeclarations object is guaranteed to remain unchanged until the next START_ELEMENT event, but may then be overwritten. The object should not be modified by the client.

Namespaces may be read before or after reading the attributes of an element, but must not be read after the first child node has been read, or after calling one of the methods skipToEnd(), getStringValue(), or getTypedValue().

Specified by:

getNamespaceDeclarations in interface PullProvider

Specified by:

getNamespaceDeclarations in interface UnfailingPullProvider

Returns:

the namespace declarations associated with the current START_ELEMENT event.

skipToMatchingEnd

public PullEvent skipToMatchingEnd()

Skip the current subtree. This method may be called only immediately after a START_DOCUMENT or START_ELEMENT event. This call returns the matching END_DOCUMENT or END_ELEMENT event; the next call on next() will return the event following the END_DOCUMENT or END_ELEMENT.

Specified by:

skipToMatchingEnd in interface PullProvider

Specified by:

skipToMatchingEnd in interface UnfailingPullProvider

Returns:

the matching END_DOCUMENT or END_ELEMENT event

close

public void close()

Close the event reader. This indicates that no further events are required. It is not necessary to close an event reader after PullEvent.END_OF_INPUT has been reported, but it is recommended to close it if reading terminates prematurely. Once an event reader has been closed, the effect of further calls on next() is undefined.

Specified by:

close in interface PullProvider

Specified by:

close in interface UnfailingPullProvider

getNamePool

public NamePool getNamePool()

Get the namePool used to lookup all name codes and namespace codes

Returns:

the namePool

getNodeName

public NodeName getNodeName()

Get the NodeName identifying the name of the current node. This method can be used after the PullEvent.START_ELEMENT, PullEvent.PROCESSING_INSTRUCTION, PullEvent.ATTRIBUTE, or PullEvent.NAMESPACE events. With some PullProvider implementations, it can also be used after PullEvent.END_ELEMENT, but this is not guaranteed: a client who requires the information at that point (for example, to do serialization) should insert an ElementNameTracker into the pipeline. If called at other times, the result is undefined and may result in an IllegalStateException. If called when the current node is an unnamed namespace node (a node representing the default namespace) the returned value is null.

Specified by:

getNodeName in interface PullProvider

Specified by:

getNodeName in interface UnfailingPullProvider

Returns:

the NodeName. The NodeName can be used to obtain the prefix, local name, and namespace URI.

getStringValue

public UnicodeString getStringValue()

Get the string value of the current attribute, text node, processing-instruction, or atomic value. This method cannot be used to obtain the string value of an element, or of a namespace node. If the most recent event was anything other than PullEvent.START_ELEMENT, PullEvent.TEXT, PullEvent.PROCESSING_INSTRUCTION, or PullEvent.ATOMIC_VALUE, the result is undefined.

Specified by:

getStringValue in interface PullProvider

Specified by:

getStringValue in interface UnfailingPullProvider

Returns:

the string value of the current node, if defined

getSchemaType

public SchemaType getSchemaType()

Get the type annotation of the current attribute or element node, or atomic value. The result of this method is undefined unless the most recent event was START_ELEMENT, START_CONTENT, ATTRIBUTE, or ATOMIC_VALUE.

Specified by:

getSchemaType in interface PullProvider

Specified by:

getSchemaType in interface UnfailingPullProvider

Returns:

the type code.

getAtomicValue

public AtomicValue getAtomicValue()

Get an atomic value. This call may be used only when the last event reported was ATOMIC_VALUE. This indicates that the PullProvider is reading a sequence that contains a free-standing atomic value; it is never used when reading the content of a node.

Specified by:

getAtomicValue in interface PullProvider

Specified by:

getAtomicValue in interface UnfailingPullProvider

Returns:

the atomic value

getSourceLocator

public Location getSourceLocator()

Get the location of the current event. For an event stream representing a real document, the location information should identify the location in the lexical XML source. For a constructed document, it should identify the location in the query or stylesheet that caused the node to be created. A value of null can be returned if no location information is available.

Specified by:

getSourceLocator in interface PullProvider

Specified by:

getSourceLocator in interface UnfailingPullProvider

Returns:

the SourceLocator giving the location of the current event, or null if no location information is available

getPublicId

public java.lang.String getPublicId()

Return the public identifier for the current document event.

The return value is the public identifier of the document entity or of the external parsed entity in which the markup that triggered the event appears.

Specified by:

getPublicId in interface Location

Specified by:

getPublicId in interface org.xml.sax.Locator

Specified by:

getPublicId in interface javax.xml.transform.SourceLocator

Returns:

A string containing the public identifier, or null if none is available.

See Also:

getSystemId()

getSystemId

public java.lang.String getSystemId()

Return the system identifier for the current document event.

The return value is the system identifier of the document entity or of the external parsed entity in which the markup that triggered the event appears.

If the system identifier is a URL, the parser must resolve it fully before passing it to the application.

Specified by:

getSystemId in interface Location

Specified by:

getSystemId in interface org.xml.sax.Locator

Specified by:

getSystemId in interface javax.xml.transform.SourceLocator

Returns:

A string containing the system identifier, or null if none is available.

See Also:

getPublicId()

getLineNumber

public int getLineNumber()

Return the line number where the current document event ends.

Warning: The return value from the method is intended only as an approximation for the sake of error reporting; it is not intended to provide sufficient information to edit the character content of the original XML document.

The return value is an approximation of the line number in the document entity or external parsed entity where the markup that triggered the event appears.

Specified by:

getLineNumber in interface Location

Specified by:

getLineNumber in interface org.xml.sax.Locator

Specified by:

getLineNumber in interface javax.xml.transform.SourceLocator

Returns:

The line number, or -1 if none is available.

See Also:

getColumnNumber()

getColumnNumber

public int getColumnNumber()

Return the character position where the current document event ends.

Warning: The return value from the method is intended only as an approximation for the sake of error reporting; it is not intended to provide sufficient information to edit the character content of the original XML document.

The return value is an approximation of the column number in the document entity or external parsed entity where the markup that triggered the event appears.

Specified by:

getColumnNumber in interface Location

Specified by:

getColumnNumber in interface org.xml.sax.Locator

Specified by:

getColumnNumber in interface javax.xml.transform.SourceLocator

Returns:

The column number, or -1 if none is available.

See Also:

getLineNumber()

saveLocation

public Location saveLocation()

Get an immutable copy of this Location object. By default Location objects may be mutable, so they should not be saved for later use. The result of this operation holds the same location information, but in an immutable form.

Specified by:

saveLocation in interface Location

Returns:

an immutable copy (which may be the original object, if it is already immutable)

getUnparsedEntities

public java.util.List<UnparsedEntity> getUnparsedEntities()

Get a list of unparsed entities.

Specified by:

getUnparsedEntities in interface PullProvider

Specified by:

getUnparsedEntities in interface UnfailingPullProvider

Returns:

a list of unparsed entities, or null if the information is not available, or an empty list if there are no unparsed entities.