com.saxonica.pull
Class TreeWalker

java.lang.Object
  extended by com.saxonica.pull.TreeWalker
All Implemented Interfaces:
SourceLocator, PullProvider

public class TreeWalker
extends Object
implements PullProvider, SourceLocator

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.


Field Summary
 
Fields inherited from interface net.sf.saxon.pull.PullProvider
ATOMIC_VALUE, ATTRIBUTE, COMMENT, END_DOCUMENT, END_ELEMENT, END_OF_INPUT, NAMESPACE, PROCESSING_INSTRUCTION, START_DOCUMENT, START_ELEMENT, START_OF_INPUT, TEXT
 
Method Summary
 void close()
          Close the event reader.
 int 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.
 AttributeCollection getAttributes()
          Get the attributes associated with the current element.
 int getColumnNumber()
          Return the character position where the current document event ends.
 int getFingerprint()
          Get the fingerprint of the name of the element.
 int getLineNumber()
          Return the line number where the current document event ends.
 int getNameCode()
          Get the nameCode identifying the name of the current node.
 NamePool getNamePool()
          Get the namePool used to lookup all name codes and namespace codes
 NamespaceDeclarations getNamespaceDeclarations()
          Get the namespace declarations associated with the current element.
 PipelineConfiguration getPipelineConfiguration()
          Get configuration information.
 String getPublicId()
          Return the public identifier for the current document event.
 SourceLocator getSourceLocator()
          Get the location of the current event.
 CharSequence getStringValue()
          Get the string value of the current attribute, text node, processing-instruction, or atomic value.
 String getSystemId()
          Return the system identifier for the current document event.
 int getTypeAnnotation()
          Get the type annotation of the current attribute or element node, or atomic value.
 List getUnparsedEntities()
          Get a list of unparsed entities.
static PullProvider makeTreeWalker(NodeInfo startNode)
          Factory method to get a tree walker starting an a given node
 int next()
          Get the next event
 void setPipelineConfiguration(PipelineConfiguration pipe)
          Set configuration information.
 int 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 PullProvider 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 int next()
         throws XPathException
Get the next event

Specified by:
next in interface PullProvider
Returns:
an integer code indicating the type of event. The code PullProvider.END_OF_INPUT is returned if there are no more events to return.
Throws:
XPathException

current

public int 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
Returns:
the current event

getAttributes

public AttributeCollection getAttributes()
                                  throws XPathException
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 AttributeCollection are guaranteed to remain unchanged until the next START_ELEMENT event, but may be modified thereafter. The object should not be modified by the client.

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
Returns:
an AttributeCollection representing the attributes of the element that has just been notified.
Throws:
XPathException

getNamespaceDeclarations

public NamespaceDeclarations getNamespaceDeclarations()
                                               throws XPathException
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
Returns:
the namespace declarations associated with the current START_ELEMENT event.
Throws:
XPathException

skipToMatchingEnd

public int skipToMatchingEnd()
                      throws XPathException
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
Returns:
the matching END_DOCUMENT or END_ELEMENT event
Throws:
XPathException

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 PullProvider.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

getNamePool

public NamePool getNamePool()
Get the namePool used to lookup all name codes and namespace codes

Returns:
the namePool

getNameCode

public int getNameCode()
Get the nameCode identifying the name of the current node. This method can be used after the PullProvider.START_ELEMENT, PullProvider.PROCESSING_INSTRUCTION, PullProvider.ATTRIBUTE, or PullProvider.NAMESPACE events. With some PullProvider implementations, including this one, it can also be used after PullProvider.END_ELEMENT. 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 -1.

Specified by:
getNameCode in interface PullProvider
Returns:
the nameCode. The nameCode can be used to obtain the prefix, local name, and namespace URI from the name pool.

getFingerprint

public int getFingerprint()
Get the fingerprint of the name of the element. This is similar to the nameCode, except that it does not contain any information about the prefix: so two elements with the same fingerprint have the same name, excluding prefix. This method can be used after the PullProvider.START_ELEMENT, PullProvider.END_ELEMENT, PullProvider.PROCESSING_INSTRUCTION, PullProvider.ATTRIBUTE, or PullProvider.NAMESPACE events. 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 -1.

Specified by:
getFingerprint in interface PullProvider
Returns:
the fingerprint. The fingerprint can be used to obtain the local name and namespace URI from the name pool.

getStringValue

public CharSequence getStringValue()
                            throws XPathException
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 PullProvider.START_ELEMENT, PullProvider.TEXT, PullProvider.PROCESSING_INSTRUCTION, or PullProvider.ATOMIC_VALUE, the result is undefined.

Specified by:
getStringValue in interface PullProvider
Returns:
the String Value of the node in question, defined according to the rules in the XPath data model.
Throws:
XPathException

getTypeAnnotation

public int getTypeAnnotation()
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:
getTypeAnnotation in interface PullProvider
Returns:
the type code. This code is the fingerprint of a type name, which may be resolved to a SchemaType by access to the Configuration.

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
Returns:
the atomic value

getSourceLocator

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

getPublicId

public 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 SourceLocator
Returns:
A string containing the public identifier, or null if none is available.
See Also:
getSystemId()

getSystemId

public 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 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 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 SourceLocator
Returns:
The column number, or -1 if none is available.
See Also:
getLineNumber()

getUnparsedEntities

public List getUnparsedEntities()
Get a list of unparsed entities.

Specified by:
getUnparsedEntities in interface PullProvider
Returns:
a list of unparsed entities, or null if the information is not available, or an empty list if there are no unparsed entities.


Copyright (c) Saxonica Limited. All rights reserved.