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 Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
void	characters(char[] ch, int start, int length)
void	comment(char[] ch, int start, int length)
protected void	count_and_yield(boolean moreExpected) In the SAX delegation code, I've inlined the count-down in the hope of encouraging compilers to deliver better performance.
static IncrementalSAXSource	createIncrementalSAXSource(CoroutineManager co, int controllerCoroutineID)
Object	deliverMoreNodes(boolean parsemore) deliverMoreNodes() is a simple API which tells the coroutine parser that we need more nodes.
void	endCDATA()
void	endDocument()
void	endDTD()
void	endElement(String namespaceURI, String localName, String qName)
void	endEntity(String name)
void	endPrefixMapping(String prefix)
void	error(SAXParseException exception)
void	fatalError(SAXParseException exception)
int	getControllerCoroutineID()
CoroutineManager	getCoroutineManager()
int	getSourceCoroutineID()
void	ignorableWhitespace(char[] ch, int start, int length)
void	init(CoroutineManager co, int controllerCoroutineID, int sourceCoroutineID)
void	notationDecl(String a, String b, String c)
void	processingInstruction(String target, String data)
void	run()
void	setContentHandler(ContentHandler handler) Register a SAX-style content handler for us to output to
void	setDocumentLocator(Locator locator)
void	setDTDHandler(DTDHandler handler) Register a SAX-style DTD handler for us to output to
void	setErrHandler(ErrorHandler handler)
void	setLexicalHandler(LexicalHandler handler) Register a SAX-style lexical handler for us to output to
void	setReturnFrequency(int events)
void	setXMLReader(XMLReader eventsource) Bind our input streams to an XMLReader.
void	skippedEntity(String name)
void	startCDATA()
void	startDocument()
void	startDTD(String name, String publicId, String systemId)
void	startElement(String namespaceURI, String localName, String qName, Attributes atts)
void	startEntity(String name)
void	startParse(InputSource source) Launch a thread that will run an XMLReader's parse() operation within a thread, feeding events to this IncrementalSAXSource_Filter.
void	startPrefixMapping(String prefix, String uri)
void	unparsedEntityDecl(String a, String b, String c, String d)
void	warning(SAXParseException exception)

Methods inherited from class java.lang.Object

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

Constructor Detail

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 Detail

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

Specified by:

characters in interface ContentHandler

Throws:

SAXException

endDocument

public void endDocument()
                 throws SAXException

Specified by:

endDocument in interface ContentHandler

Throws:

SAXException

endElement

public void endElement(String namespaceURI,
                       String localName,
                       String qName)
                throws SAXException

Specified by:

endElement in interface ContentHandler

Throws:

SAXException

endPrefixMapping

public void endPrefixMapping(String prefix)
                      throws SAXException

Specified by:

endPrefixMapping in interface ContentHandler

Throws:

SAXException

ignorableWhitespace

public void ignorableWhitespace(char[] ch,
                                int start,
                                int length)
                         throws SAXException

Specified by:

ignorableWhitespace in interface ContentHandler

Throws:

SAXException

processingInstruction

public void processingInstruction(String target,
                                  String data)
                           throws SAXException

Specified by:

processingInstruction in interface ContentHandler

Throws:

SAXException

setDocumentLocator

public void setDocumentLocator(Locator locator)

Specified by:

setDocumentLocator in interface ContentHandler

skippedEntity

public void skippedEntity(String name)
                   throws SAXException

Specified by:

skippedEntity in interface ContentHandler

Throws:

SAXException

startDocument

public void startDocument()
                   throws SAXException

Specified by:

startDocument in interface ContentHandler

Throws:

SAXException

startElement

public void startElement(String namespaceURI,
                         String localName,
                         String qName,
                         Attributes atts)
                  throws SAXException

Specified by:

startElement in interface ContentHandler

Throws:

SAXException

startPrefixMapping

public void startPrefixMapping(String prefix,
                               String uri)
                        throws SAXException

Specified by:

startPrefixMapping in interface ContentHandler

Throws:

SAXException

comment

public void comment(char[] ch,
                    int start,
                    int length)
             throws SAXException

Specified by:

comment in interface LexicalHandler

Throws:

SAXException

endCDATA

public void endCDATA()
              throws SAXException

Specified by:

endCDATA in interface LexicalHandler

Throws:

SAXException

endDTD

public void endDTD()
            throws SAXException

Specified by:

endDTD in interface LexicalHandler

Throws:

SAXException

endEntity

public void endEntity(String name)
               throws SAXException

Specified by:

endEntity in interface LexicalHandler

Throws:

SAXException

startCDATA

public void startCDATA()
                throws SAXException

Specified by:

startCDATA in interface LexicalHandler

Throws:

SAXException

startDTD

public void startDTD(String name,
                     String publicId,
                     String systemId)
              throws SAXException

Specified by:

startDTD in interface LexicalHandler

Throws:

SAXException

startEntity

public void startEntity(String name)
                 throws SAXException

Specified by:

startEntity in interface LexicalHandler

Throws:

SAXException

notationDecl

public void notationDecl(String a,
                         String b,
                         String c)
                  throws SAXException

Specified by:

notationDecl in interface DTDHandler

Throws:

SAXException

unparsedEntityDecl

public void unparsedEntityDecl(String a,
                               String b,
                               String c,
                               String d)
                        throws SAXException

Specified by:

unparsedEntityDecl in interface DTDHandler

Throws:

SAXException

error

public void error(SAXParseException exception)
           throws SAXException

Specified by:

error in interface ErrorHandler

Throws:

SAXException

fatalError

public void fatalError(SAXParseException exception)
                throws SAXException

Specified by:

fatalError in interface ErrorHandler

Throws:

SAXException

warning

public void warning(SAXParseException exception)
             throws SAXException

Specified by:

warning in interface ErrorHandler

Throws:

SAXException

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()

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.