Package org.apache.xml.dtm.ref

Class IncrementalSAXSource_Filter

java.lang.Object
org.apache.xml.dtm.ref.IncrementalSAXSource_Filter
All Implemented Interfaces:
Runnable, IncrementalSAXSource, ContentHandler, DTDHandler, ErrorHandler, LexicalHandler
public class IncrementalSAXSource_Filter
extends Object
implements IncrementalSAXSource, ContentHandler, DTDHandler, LexicalHandler, ErrorHandler, Runnable

IncrementalSAXSource_Filter implements IncrementalSAXSource, using a standard SAX2 event source as its input and parcelling out those events gradually in reponse to deliverMoreNodes() requests. Output from the filter will be passed along to a SAX handler registered as our listener, but those callbacks will pass through a counting stage which periodically yields control back to the controller coroutine.

%REVIEW%: This filter is not currenly intended to be reusable for parsing additional streams/documents. We may want to consider making it resettable at some point in the future. But it's a small object, so that'd be mostly a convenience issue; the cost of allocating each time is trivial compared to the cost of processing any nontrival stream.

For a brief usage example, see the unit-test main() method.

This is a simplification of the old CoroutineSAXParser, focusing specifically on filtering. The resulting controller protocol is _far_ simpler and less error-prone; the only controller operation is deliverMoreNodes(), and the only requirement is that deliverMoreNodes(false) be called if you want to discard the rest of the stream and the previous deliverMoreNodes() didn't return false.

  • Constructor Details

    • IncrementalSAXSource_Filter

      public IncrementalSAXSource_Filter()

    • IncrementalSAXSource_Filter

      public IncrementalSAXSource_Filter​(CoroutineManager co, int controllerCoroutineID)
      Create a IncrementalSAXSource_Filter which is not yet bound to a specific SAX event source.

  • Method Details

    • createIncrementalSAXSource

      public static IncrementalSAXSource createIncrementalSAXSource​(CoroutineManager co, int controllerCoroutineID)

    • init

      public void init​(CoroutineManager co, int controllerCoroutineID, int sourceCoroutineID)

    • setXMLReader

      public void setXMLReader​(XMLReader eventsource)
      Bind our input streams to an XMLReader. Just a convenience routine; obviously you can explicitly register this as a listener with the same effect.

    • setContentHandler

      public void setContentHandler​(ContentHandler handler)
      Description copied from interface: IncrementalSAXSource
      Register a SAX-style content handler for us to output to
      Specified by:
      setContentHandler in interface IncrementalSAXSource

    • setDTDHandler

      public void setDTDHandler​(DTDHandler handler)
      Description copied from interface: IncrementalSAXSource
      Register a SAX-style DTD handler for us to output to
      Specified by:
      setDTDHandler in interface IncrementalSAXSource

    • setLexicalHandler

      public void setLexicalHandler​(LexicalHandler handler)
      Description copied from interface: IncrementalSAXSource
      Register a SAX-style lexical handler for us to output to
      Specified by:
      setLexicalHandler in interface IncrementalSAXSource

    • setErrHandler

      public void setErrHandler​(ErrorHandler handler)

    • setReturnFrequency

      public void setReturnFrequency​(int events)

    • characters

      public void characters​(char[] ch, int start, int length) throws SAXException
      Description copied from interface: ContentHandler
      Receive notification of character data.

      The Parser will call this method to report each chunk of character data. SAX parsers may return all contiguous character data in a single chunk, or they may split it into several chunks; however, all of the characters in any single event must come from the same external entity so that the Locator provides useful information.

      The application must not attempt to read from the array outside of the specified range.

      Individual characters may consist of more than one Java char value. There are two important cases where this happens, because characters can't be represented in just sixteen bits. In one case, characters are represented in a Surrogate Pair, using two special Unicode values. Such characters are in the so-called "Astral Planes", with a code point above U+FFFF. A second case involves composite characters, such as a base character combining with one or more accent characters.

      Your code should not assume that algorithms using char-at-a-time idioms will be working in character units; in some cases they will split characters. This is relevant wherever XML permits arbitrary characters, such as attribute values, processing instruction data, and comments as well as in data reported from this method. It's also generally relevant whenever Java code manipulates internationalized text; the issue isn't unique to XML.

      Note that some parsers will report whitespace in element content using the ignorableWhitespace method rather than this one (validating parsers must do so).

      Specified by:
      characters in interface ContentHandler
      Parameters:
      ch - the characters from the XML document
      start - the start position in the array
      length - the number of characters to read from the array
      Throws:
      SAXException - any SAX exception, possibly wrapping another exception
      See Also:
      ContentHandler.ignorableWhitespace(char[], int, int), Locator

    • endDocument

      public void endDocument() throws SAXException
      Description copied from interface: ContentHandler
      Receive notification of the end of a document.

      There is an apparent contradiction between the documentation for this method and the documentation for ErrorHandler.fatalError(org.xml.sax.SAXParseException). Until this ambiguity is resolved in a future major release, clients should make no assumptions about whether endDocument() will or will not be invoked when the parser has reported a fatalError() or thrown an exception.

      The SAX parser will invoke this method only once, and it will be the last method invoked during the parse. The parser shall not invoke this method until it has either abandoned parsing (because of an unrecoverable error) or reached the end of input.

      Specified by:
      endDocument in interface ContentHandler
      Throws:
      SAXException - any SAX exception, possibly wrapping another exception
      See Also:
      ContentHandler.startDocument()

    • endElement

      public void endElement​(String namespaceURI, String localName, String qName) throws SAXException
      Description copied from interface: ContentHandler
      Receive notification of the end of an element.

      The SAX parser will invoke this method at the end of every element in the XML document; there will be a corresponding startElement event for every endElement event (even when the element is empty).

      For information on the names, see startElement.

      Specified by:
      endElement in interface ContentHandler
      Parameters:
      namespaceURI - the Namespace URI, or the empty string if the element has no Namespace URI or if Namespace processing is not being performed
      localName - the local name (without prefix), or the empty string if Namespace processing is not being performed
      qName - the qualified XML name (with prefix), or the empty string if qualified names are not available
      Throws:
      SAXException - any SAX exception, possibly wrapping another exception

    • endPrefixMapping

      public void endPrefixMapping​(String prefix) throws SAXException
      Description copied from interface: ContentHandler
      End the scope of a prefix-URI mapping.

      See startPrefixMapping for details. These events will always occur immediately after the corresponding endElement event, but the order of endPrefixMapping events is not otherwise guaranteed.

      Specified by:
      endPrefixMapping in interface ContentHandler
      Parameters:
      prefix - the prefix that was being mapped. This is the empty string when a default mapping scope ends.
      Throws:
      SAXException - the client may throw an exception during processing
      See Also:
      ContentHandler.startPrefixMapping(java.lang.String, java.lang.String), ContentHandler.endElement(java.lang.String, java.lang.String, java.lang.String)

    • ignorableWhitespace

      public void ignorableWhitespace​(char[] ch, int start, int length) throws SAXException
      Description copied from interface: ContentHandler
      Receive notification of ignorable whitespace in element content.

      Validating Parsers must use this method to report each chunk of whitespace in element content (see the W3C XML 1.0 recommendation, section 2.10): non-validating parsers may also use this method if they are capable of parsing and using content models.

      SAX parsers may return all contiguous whitespace in a single chunk, or they may split it into several chunks; however, all of the characters in any single event must come from the same external entity, so that the Locator provides useful information.

      The application must not attempt to read from the array outside of the specified range.

      Specified by:
      ignorableWhitespace in interface ContentHandler
      Parameters:
      ch - the characters from the XML document
      start - the start position in the array
      length - the number of characters to read from the array
      Throws:
      SAXException - any SAX exception, possibly wrapping another exception
      See Also:
      ContentHandler.characters(char[], int, int)

    • processingInstruction

      public void processingInstruction​(String target, String data) throws SAXException
      Description copied from interface: ContentHandler
      Receive notification of a processing instruction.

      The Parser will invoke this method once for each processing instruction found: note that processing instructions may occur before or after the main document element.

      A SAX parser must never report an XML declaration (XML 1.0, section 2.8) or a text declaration (XML 1.0, section 4.3.1) using this method.

      Like characters(), processing instruction data may have characters that need more than one char value.

      Specified by:
      processingInstruction in interface ContentHandler
      Parameters:
      target - the processing instruction target
      data - the processing instruction data, or null if none was supplied. The data does not include any whitespace separating it from the target
      Throws:
      SAXException - any SAX exception, possibly wrapping another exception

    • setDocumentLocator

      public void setDocumentLocator​(Locator locator)
      Description copied from interface: ContentHandler
      Receive an object for locating the origin of SAX document events.

      SAX parsers are strongly encouraged (though not absolutely required) to supply a locator: if it does so, it must supply the locator to the application by invoking this method before invoking any of the other methods in the ContentHandler interface.

      The locator allows the application to determine the end position of any document-related event, even if the parser is not reporting an error. Typically, the application will use this information for reporting its own errors (such as character content that does not match an application's business rules). The information returned by the locator is probably not sufficient for use with a search engine.

      Note that the locator will return correct information only during the invocation SAX event callbacks after startDocument returns and before endDocument is called. The application should not attempt to use it at any other time.

      Specified by:
      setDocumentLocator in interface ContentHandler
      Parameters:
      locator - an object that can return the location of any SAX document event
      See Also:
      Locator

    • skippedEntity

      public void skippedEntity​(String name) throws SAXException
      Description copied from interface: ContentHandler
      Receive notification of a skipped entity. This is not called for entity references within markup constructs such as element start tags or markup declarations. (The XML recommendation requires reporting skipped external entities. SAX also reports internal entity expansion/non-expansion, except within markup constructs.)

      The Parser will invoke this method each time the entity is skipped. Non-validating processors may skip entities if they have not seen the declarations (because, for example, the entity was declared in an external DTD subset). All processors may skip external entities, depending on the values of the http://xml.org/sax/features/external-general-entities and the http://xml.org/sax/features/external-parameter-entities properties.

      Specified by:
      skippedEntity in interface ContentHandler
      Parameters:
      name - the name of the skipped entity. If it is a parameter entity, the name will begin with '%', and if it is the external DTD subset, it will be the string "[dtd]"
      Throws:
      SAXException - any SAX exception, possibly wrapping another exception

    • startDocument

      public void startDocument() throws SAXException
      Description copied from interface: ContentHandler
      Receive notification of the beginning of a document.

      The SAX parser will invoke this method only once, before any other event callbacks (except for setDocumentLocator).

      Specified by:
      startDocument in interface ContentHandler
      Throws:
      SAXException - any SAX exception, possibly wrapping another exception
      See Also:
      ContentHandler.endDocument()

    • startElement

      public void startElement​(String namespaceURI, String localName, String qName, Attributes atts) throws SAXException
      Description copied from interface: ContentHandler
      Receive notification of the beginning of an element.

      The Parser will invoke this method at the beginning of every element in the XML document; there will be a corresponding endElement event for every startElement event (even when the element is empty). All of the element's content will be reported, in order, before the corresponding endElement event.

      This event allows up to three name components for each element:

      1. the Namespace URI;
      2. the local name; and
      3. the qualified (prefixed) name.

      Any or all of these may be provided, depending on the values of the http://xml.org/sax/features/namespaces and the http://xml.org/sax/features/namespace-prefixes properties:

      • the Namespace URI and local name are required when the namespaces property is true (the default), and are optional when the namespaces property is false (if one is specified, both must be);
      • the qualified name is required when the namespace-prefixes property is true, and is optional when the namespace-prefixes property is false (the default).

      Note that the attribute list provided will contain only attributes with explicit values (specified or defaulted): #IMPLIED attributes will be omitted. The attribute list will contain attributes used for Namespace declarations (xmlns* attributes) only if the http://xml.org/sax/features/namespace-prefixes property is true (it is false by default, and support for a true value is optional).

      Like characters(), attribute values may have characters that need more than one char value.

      Specified by:
      startElement in interface ContentHandler
      Parameters:
      namespaceURI - the Namespace URI, or the empty string if the element has no Namespace URI or if Namespace processing is not being performed
      localName - the local name (without prefix), or the empty string if Namespace processing is not being performed
      qName - the qualified name (with prefix), or the empty string if qualified names are not available
      atts - the attributes attached to the element. If there are no attributes, it shall be an empty Attributes object. The value of this object after startElement returns is undefined
      Throws:
      SAXException - any SAX exception, possibly wrapping another exception
      See Also:
      ContentHandler.endElement(java.lang.String, java.lang.String, java.lang.String), Attributes, AttributesImpl

    • startPrefixMapping

      public void startPrefixMapping​(String prefix, String uri) throws SAXException
      Description copied from interface: ContentHandler
      Begin the scope of a prefix-URI Namespace mapping.

      The information from this event is not necessary for normal Namespace processing: the SAX XML reader will automatically replace prefixes for element and attribute names when the http://xml.org/sax/features/namespaces feature is true (the default).

      There are cases, however, when applications need to use prefixes in character data or in attribute values, where they cannot safely be expanded automatically; the start/endPrefixMapping event supplies the information to the application to expand prefixes in those contexts itself, if necessary.

      Note that start/endPrefixMapping events are not guaranteed to be properly nested relative to each other: all startPrefixMapping events will occur immediately before the corresponding startElement event, and all endPrefixMapping events will occur immediately after the corresponding endElement event, but their order is not otherwise guaranteed.

      There should never be start/endPrefixMapping events for the "xml" prefix, since it is predeclared and immutable.

      Specified by:
      startPrefixMapping in interface ContentHandler
      Parameters:
      prefix - the Namespace prefix being declared. An empty string is used for the default element namespace, which has no prefix.
      uri - the Namespace URI the prefix is mapped to
      Throws:
      SAXException - the client may throw an exception during processing
      See Also:
      ContentHandler.endPrefixMapping(java.lang.String), ContentHandler.startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)

    • comment

      public void comment​(char[] ch, int start, int length) throws SAXException
      Description copied from interface: LexicalHandler
      Report an XML comment anywhere in the document.

      This callback will be used for comments inside or outside the document element, including comments in the external DTD subset (if read). Comments in the DTD must be properly nested inside start/endDTD and start/endEntity events (if used).

      Specified by:
      comment in interface LexicalHandler
      Parameters:
      ch - An array holding the characters in the comment.
      start - The starting position in the array.
      length - The number of characters to use from the array.
      Throws:
      SAXException - The application may raise an exception.

    • endCDATA

      public void endCDATA() throws SAXException
      Description copied from interface: LexicalHandler
      Report the end of a CDATA section.
      Specified by:
      endCDATA in interface LexicalHandler
      Throws:
      SAXException - The application may raise an exception.
      See Also:
      LexicalHandler.startCDATA()

    • endDTD

      public void endDTD() throws SAXException
      Description copied from interface: LexicalHandler
      Report the end of DTD declarations.

      This method is intended to report the end of the DOCTYPE declaration; if the document has no DOCTYPE declaration, this method will not be invoked.

      Specified by:
      endDTD in interface LexicalHandler
      Throws:
      SAXException - The application may raise an exception.
      See Also:
      LexicalHandler.startDTD(java.lang.String, java.lang.String, java.lang.String)

    • endEntity

      public void endEntity​(String name) throws SAXException
      Description copied from interface: LexicalHandler
      Report the end of an entity.
      Specified by:
      endEntity in interface LexicalHandler
      Parameters:
      name - The name of the entity that is ending.
      Throws:
      SAXException - The application may raise an exception.
      See Also:
      LexicalHandler.startEntity(java.lang.String)

    • startCDATA

      public void startCDATA() throws SAXException
      Description copied from interface: LexicalHandler
      Report the start of a CDATA section.

      The contents of the CDATA section will be reported through the regular characters event; this event is intended only to report the boundary.

      Specified by:
      startCDATA in interface LexicalHandler
      Throws:
      SAXException - The application may raise an exception.
      See Also:
      LexicalHandler.endCDATA()

    • startDTD

      public void startDTD​(String name, String publicId, String systemId) throws SAXException
      Description copied from interface: LexicalHandler
      Report the start of DTD declarations, if any.

      This method is intended to report the beginning of the DOCTYPE declaration; if the document has no DOCTYPE declaration, this method will not be invoked.

      All declarations reported through DTDHandler or DeclHandler events must appear between the startDTD and endDTD events. Declarations are assumed to belong to the internal DTD subset unless they appear between startEntity and endEntity events. Comments and processing instructions from the DTD should also be reported between the startDTD and endDTD events, in their original order of (logical) occurrence; they are not required to appear in their correct locations relative to DTDHandler or DeclHandler events, however.

      Note that the start/endDTD events will appear within the start/endDocument events from ContentHandler and before the first startElement event.

      Specified by:
      startDTD in interface LexicalHandler
      Parameters:
      name - The document type name.
      publicId - The declared public identifier for the external DTD subset, or null if none was declared.
      systemId - The declared system identifier for the external DTD subset, or null if none was declared. (Note that this is not resolved against the document base URI.)
      Throws:
      SAXException - The application may raise an exception.
      See Also:
      LexicalHandler.endDTD(), LexicalHandler.startEntity(java.lang.String)

    • startEntity

      public void startEntity​(String name) throws SAXException
      Description copied from interface: LexicalHandler
      Report the beginning of some internal and external XML entities.

      The reporting of parameter entities (including the external DTD subset) is optional, and SAX2 drivers that report LexicalHandler events may not implement it; you can use the http://xml.org/sax/features/lexical-handler/parameter-entities feature to query or control the reporting of parameter entities.

      General entities are reported with their regular names, parameter entities have '%' prepended to their names, and the external DTD subset has the pseudo-entity name "[dtd]".

      When a SAX2 driver is providing these events, all other events must be properly nested within start/end entity events. There is no additional requirement that events from DeclHandler or DTDHandler be properly ordered.

      Note that skipped entities will be reported through the skippedEntity event, which is part of the ContentHandler interface.

      Because of the streaming event model that SAX uses, some entity boundaries cannot be reported under any circumstances:

      • general entities within attribute values
      • parameter entities within declarations

      These will be silently expanded, with no indication of where the original entity boundaries were.

      Note also that the boundaries of character references (which are not really entities anyway) are not reported.

      All start/endEntity events must be properly nested.

      Specified by:
      startEntity in interface LexicalHandler
      Parameters:
      name - The name of the entity. If it is a parameter entity, the name will begin with '%', and if it is the external DTD subset, it will be "[dtd]".
      Throws:
      SAXException - The application may raise an exception.
      See Also:
      LexicalHandler.endEntity(java.lang.String), DeclHandler.internalEntityDecl(java.lang.String, java.lang.String), DeclHandler.externalEntityDecl(java.lang.String, java.lang.String, java.lang.String)

    • notationDecl

      public void notationDecl​(String a, String b, String c) throws SAXException
      Description copied from interface: DTDHandler
      Receive notification of a notation declaration event.

      It is up to the application to record the notation for later reference, if necessary; notations may appear as attribute values and in unparsed entity declarations, and are sometime used with processing instruction target names.

      At least one of publicId and systemId must be non-null. If a system identifier is present, and it is a URL, the SAX parser must resolve it fully before passing it to the application through this event.

      There is no guarantee that the notation declaration will be reported before any unparsed entities that use it.

      Specified by:
      notationDecl in interface DTDHandler
      Parameters:
      a - The notation name.
      b - The notation's public identifier, or null if none was given.
      c - The notation's system identifier, or null if none was given.
      Throws:
      SAXException - Any SAX exception, possibly wrapping another exception.
      See Also:
      DTDHandler.unparsedEntityDecl(java.lang.String, java.lang.String, java.lang.String, java.lang.String), Attributes

    • unparsedEntityDecl

      public void unparsedEntityDecl​(String a, String b, String c, String d) throws SAXException
      Description copied from interface: DTDHandler
      Receive notification of an unparsed entity declaration event.

      Note that the notation name corresponds to a notation reported by the notationDecl event. It is up to the application to record the entity for later reference, if necessary; unparsed entities may appear as attribute values.

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

      Specified by:
      unparsedEntityDecl in interface DTDHandler
      Parameters:
      a - The unparsed entity's name.
      b - The entity's public identifier, or null if none was given.
      c - The entity's system identifier.
      d - The name of the associated notation.
      Throws:
      SAXException - Any SAX exception, possibly wrapping another exception.
      See Also:
      DTDHandler.notationDecl(java.lang.String, java.lang.String, java.lang.String), Attributes

    • error

      public void error​(SAXParseException exception) throws SAXException
      Description copied from interface: ErrorHandler
      Receive notification of a recoverable error.

      This corresponds to the definition of "error" in section 1.2 of the W3C XML 1.0 Recommendation. For example, a validating parser would use this callback to report the violation of a validity constraint. The default behaviour is to take no action.

      The SAX parser must continue to provide normal parsing events after invoking this method: it should still be possible for the application to process the document through to the end. If the application cannot do so, then the parser should report a fatal error even if the XML recommendation does not require it to do so.

      Filters may use this method to report other, non-XML errors as well.

      Specified by:
      error in interface ErrorHandler
      Parameters:
      exception - The error information encapsulated in a SAX parse exception.
      Throws:
      SAXException - Any SAX exception, possibly wrapping another exception.
      See Also:
      SAXParseException

    • fatalError

      public void fatalError​(SAXParseException exception) throws SAXException
      Description copied from interface: ErrorHandler
      Receive notification of a non-recoverable error.

      There is an apparent contradiction between the documentation for this method and the documentation for ContentHandler.endDocument(). Until this ambiguity is resolved in a future major release, clients should make no assumptions about whether endDocument() will or will not be invoked when the parser has reported a fatalError() or thrown an exception.

      This corresponds to the definition of "fatal error" in section 1.2 of the W3C XML 1.0 Recommendation. For example, a parser would use this callback to report the violation of a well-formedness constraint.

      The application must assume that the document is unusable after the parser has invoked this method, and should continue (if at all) only for the sake of collecting additional error messages: in fact, SAX parsers are free to stop reporting any other events once this method has been invoked.

      Specified by:
      fatalError in interface ErrorHandler
      Parameters:
      exception - The error information encapsulated in a SAX parse exception.
      Throws:
      SAXException - Any SAX exception, possibly wrapping another exception.
      See Also:
      SAXParseException

    • warning

      public void warning​(SAXParseException exception) throws SAXException
      Description copied from interface: ErrorHandler
      Receive notification of a warning.

      SAX parsers will use this method to report conditions that are not errors or fatal errors as defined by the XML recommendation. The default behaviour is to take no action.

      The SAX parser must continue to provide normal parsing events after invoking this method: it should still be possible for the application to process the document through to the end.

      Filters may use this method to report other, non-XML warnings as well.

      Specified by:
      warning in interface ErrorHandler
      Parameters:
      exception - The warning information encapsulated in a SAX parse exception.
      Throws:
      SAXException - Any SAX exception, possibly wrapping another exception.
      See Also:
      SAXParseException

    • getSourceCoroutineID

      public int getSourceCoroutineID()

    • getControllerCoroutineID

      public int getControllerCoroutineID()

    • getCoroutineManager

      public CoroutineManager getCoroutineManager()
      Returns:
      the CoroutineManager this CoroutineFilter object is bound to. If you're using the do...() methods, applications should only need to talk to the CoroutineManager once, to obtain the application's Coroutine ID.

    • count_and_yield

      protected void count_and_yield​(boolean moreExpected) throws SAXException

      In the SAX delegation code, I've inlined the count-down in the hope of encouraging compilers to deliver better performance. However, if we subclass (eg to directly connect the output to a DTM builder), that would require calling super in order to run that logic... which seems inelegant. Hence this routine for the convenience of subclasses: every [frequency] invocations, issue a co_yield.

      Parameters:
      moreExepected - Should always be true unless this is being called at the end of endDocument() handling.
      Throws:
      SAXException

    • startParse

      public void startParse​(InputSource source) throws SAXException
      Launch a thread that will run an XMLReader's parse() operation within a thread, feeding events to this IncrementalSAXSource_Filter. Mostly a convenience routine, but has the advantage that -- since we invoked parse() -- we can halt parsing quickly via a StopException rather than waiting for the SAX stream to end by itself.
      Specified by:
      startParse in interface IncrementalSAXSource
      Throws:
      SAXException - is parse thread is already in progress or parsing can not be started.

    • run

      public void run()
      Description copied from interface: Runnable
      Starts executing the active part of the class' code. This method is called when a thread is started that has been created with a class which implements Runnable.
      Specified by:
      run in interface Runnable

    • deliverMoreNodes

      public Object deliverMoreNodes​(boolean parsemore)
      deliverMoreNodes() is a simple API which tells the coroutine parser that we need more nodes. This is intended to be called from one of our partner routines, and serves to encapsulate the details of how incremental parsing has been achieved.
      Specified by:
      deliverMoreNodes in interface IncrementalSAXSource
      Parameters:
      parsemore - If true, tells the incremental filter to generate another chunk of output. If false, tells the filter that we're satisfied and it can terminate parsing of this document.
      Returns:
      Boolean.TRUE if there may be more events available by invoking deliverMoreNodes() again. Boolean.FALSE if parsing has run to completion (or been terminated by deliverMoreNodes(false). Or an exception object if something malfunctioned. %REVIEW% We _could_ actually throw the exception, but that would require runinng deliverMoreNodes() in a try/catch... and for many applications, exception will be simply be treated as "not TRUE" in any case.