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IncrementalSAXSource_Xerces.javaAPI DocJava SE 6 API16429Tue Jun 10 00:22:58 BST 2008com.sun.org.apache.xml.internal.dtm.ref

IncrementalSAXSource_Xerces

public class IncrementalSAXSource_Xerces extends Object implements IncrementalSAXSource

IncrementalSAXSource_Xerces takes advantage of the fact that Xerces1 incremental mode is already a coroutine of sorts, and just wraps our IncrementalSAXSource API around it.

Usage example: See main().

Status: Passes simple main() unit-test. NEEDS JAVADOC.

Fields Summary
Method
fParseSomeSetup
Method
fParseSome
Object
fPullParserConfig
Method
fConfigSetInput
Method
fConfigParse
Method
fSetInputSource
Constructor
fConfigInputSourceCtor
Method
fConfigSetByteStream
Method
fConfigSetCharStream
Method
fConfigSetEncoding
Method
fReset
SAXParser
fIncrementalParser
private boolean
fParseInProgress
private static final Object[]
noparms
private static final Object[]
parmsfalse
Constructors Summary
public IncrementalSAXSource_Xerces()
Create a IncrementalSAXSource_Xerces, and create a SAXParser to go with it. Xerces2 incremental parsing is only supported if this constructor is used, due to limitations in the Xerces2 API (as of Beta 3). If you don't like that restriction, tell the Xerces folks that there should be a simpler way to request incremental SAX parsing.


  //
  // Constructors
  //

                                                          
    
		 
	
		try
		{
			// Xerces-2 incremental parsing support (as of Beta 3)
			// ContentHandlers still get set on fIncrementalParser (to get
			// conversion from XNI events to SAX events), but
			// _control_ for incremental parsing must be exercised via the config.
			// 
			// At this time there's no way to read the existing config, only 
			// to assert a new one... and only when creating a brand-new parser.
			//
			// Reflection is used to allow us to continue to compile against
			// Xerces1. If/when we can abandon the older versions of the parser,
			// this will simplify significantly.
			
			// If we can't get the magic constructor, no need to look further.
			Class xniConfigClass=ObjectFactory.findProviderClass(
                            "com.sun.org.apache.xerces.internal.xni.parser.XMLParserConfiguration",
                            ObjectFactory.findClassLoader(), true);
			Class[] args1={xniConfigClass};
			Constructor ctor=SAXParser.class.getConstructor(args1);
			
			// Build the parser configuration object. StandardParserConfiguration
			// happens to implement XMLPullParserConfiguration, which is the API
			// we're going to want to use.
			Class xniStdConfigClass=ObjectFactory.findProviderClass(
                            "com.sun.org.apache.xerces.internal.parsers.StandardParserConfiguration",
                            ObjectFactory.findClassLoader(), true);
			fPullParserConfig=xniStdConfigClass.newInstance();
			Object[] args2={fPullParserConfig};
			fIncrementalParser = (SAXParser)ctor.newInstance(args2);
			
			// Preload all the needed the configuration methods... I want to know they're
			// all here before we commit to trying to use them, just in case the
			// API changes again.
			Class fXniInputSourceClass=ObjectFactory.findProviderClass(
                            "com.sun.org.apache.xerces.internal.xni.parser.XMLInputSource",
                            ObjectFactory.findClassLoader(), true);
			Class[] args3={fXniInputSourceClass};
			fConfigSetInput=xniStdConfigClass.getMethod("setInputSource",args3);

			Class[] args4={String.class,String.class,String.class};
			fConfigInputSourceCtor=fXniInputSourceClass.getConstructor(args4);
			Class[] args5={java.io.InputStream.class};
			fConfigSetByteStream=fXniInputSourceClass.getMethod("setByteStream",args5);
			Class[] args6={java.io.Reader.class};
			fConfigSetCharStream=fXniInputSourceClass.getMethod("setCharacterStream",args6);
			Class[] args7={String.class};
			fConfigSetEncoding=fXniInputSourceClass.getMethod("setEncoding",args7);

			Class[] argsb={Boolean.TYPE};
			fConfigParse=xniStdConfigClass.getMethod("parse",argsb);			
			Class[] noargs=new Class[0];
			fReset=fIncrementalParser.getClass().getMethod("reset",noargs);
		}
		catch(Exception e)
		{
	    // Fallback if this fails (implemented in createIncrementalSAXSource) is
			// to attempt Xerces-1 incremental setup. Can't do tail-call in
			// constructor, so create new, copy Xerces-1 initialization, 
			// then throw it away... Ugh.
			IncrementalSAXSource_Xerces dummy=new IncrementalSAXSource_Xerces(new SAXParser());
			this.fParseSomeSetup=dummy.fParseSomeSetup;
			this.fParseSome=dummy.fParseSome;
			this.fIncrementalParser=dummy.fIncrementalParser;
		}
public IncrementalSAXSource_Xerces(SAXParser parser)
Create a IncrementalSAXSource_Xerces wrapped around an existing SAXParser. Currently this works only for recent releases of Xerces-1. Xerces-2 incremental is currently possible only if we are allowed to create the parser instance, due to limitations in the API exposed by Xerces-2 Beta 3; see the no-args constructor for that code.

exception
if the SAXParser class doesn't support the Xerces incremental parse operations. In that case, caller should fall back upon the IncrementalSAXSource_Filter approach.

		// Reflection is used to allow us to compile against
		// Xerces2. If/when we can abandon the older versions of the parser,
		// this constructor will simply have to fail until/unless the
		// Xerces2 incremental support is made available on previously
		// constructed SAXParser instances.
    fIncrementalParser=parser;
		Class me=parser.getClass();
    Class[] parms={InputSource.class};
    fParseSomeSetup=me.getMethod("parseSomeSetup",parms);
    parms=new Class[0];
    fParseSome=me.getMethod("parseSome",parms);
    // Fallback if this fails (implemented in createIncrementalSAXSource) is
    // to use IncrementalSAXSource_Filter rather than Xerces-specific code.
Methods Summary
public static void_main(java.lang.String[] args)
Simple unit test. Attempt coroutine parsing of document indicated by first argument (as a URI), report progress.

    System.out.println("Starting...");

    CoroutineManager co = new CoroutineManager();
    int appCoroutineID = co.co_joinCoroutineSet(-1);
    if (appCoroutineID == -1)
    {
      System.out.println("ERROR: Couldn't allocate coroutine number.\n");
      return;
    }
    IncrementalSAXSource parser=
      createIncrementalSAXSource();

    // Use a serializer as our sample output
    com.sun.org.apache.xml.internal.serialize.XMLSerializer trace;
    trace=new com.sun.org.apache.xml.internal.serialize.XMLSerializer(System.out,null);
    parser.setContentHandler(trace);
    parser.setLexicalHandler(trace);

    // Tell coroutine to begin parsing, run while parsing is in progress

    for(int arg=0;arg<args.length;++arg)
    {
      try
      {
        InputSource source = new InputSource(args[arg]);
        Object result=null;
        boolean more=true;
        parser.startParse(source);
        for(result = parser.deliverMoreNodes(more);
            result==Boolean.TRUE;
            result = parser.deliverMoreNodes(more))
        {
          System.out.println("\nSome parsing successful, trying more.\n");
            
          // Special test: Terminate parsing early.
          if(arg+1<args.length && "!".equals(args[arg+1]))
          {
            ++arg;
            more=false;
          }
            
        }
        
        if (result instanceof Boolean && ((Boolean)result)==Boolean.FALSE)
        {
          System.out.println("\nParser ended (EOF or on request).\n");
        }
        else if (result == null) {
          System.out.println("\nUNEXPECTED: Parser says shut down prematurely.\n");
        }
        else if (result instanceof Exception) {
          throw new com.sun.org.apache.xml.internal.utils.WrappedRuntimeException((Exception)result);
          //          System.out.println("\nParser threw exception:");
          //          ((Exception)result).printStackTrace();
        }
        
      }

      catch(SAXException e)
      {
        e.printStackTrace();
      }
    }
public static com.sun.org.apache.xml.internal.dtm.ref.IncrementalSAXSourcecreateIncrementalSAXSource()

		try
		{
			return new IncrementalSAXSource_Xerces();
		}
		catch(NoSuchMethodException e)
		{
			// Xerces version mismatch; neither Xerces1 nor Xerces2 succeeded.
			// Fall back on filtering solution.
			IncrementalSAXSource_Filter iss=new IncrementalSAXSource_Filter();
			iss.setXMLReader(new SAXParser());
			return iss;
		}
public static com.sun.org.apache.xml.internal.dtm.ref.IncrementalSAXSourcecreateIncrementalSAXSource(com.sun.org.apache.xerces.internal.parsers.SAXParser parser)

		try
		{
			return new IncrementalSAXSource_Xerces(parser);
		}
		catch(NoSuchMethodException e)
		{
			// Xerces version mismatch; neither Xerces1 nor Xerces2 succeeded.
			// Fall back on filtering solution.
			IncrementalSAXSource_Filter iss=new IncrementalSAXSource_Filter();
			iss.setXMLReader(parser);
			return iss;
		}
public java.lang.ObjectdeliverMoreNodes(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.

param
parsemore If true, tells the incremental parser to generate another chunk of output. If false, tells the parser that we're satisfied and it can terminate parsing of this document.
return
Boolean.TRUE if the CoroutineParser believes more data may be available for further parsing. Boolean.FALSE if parsing ran to completion. Exception if the parser objected for some reason.

    if(!parsemore)
    {
      fParseInProgress=false;
      return Boolean.FALSE;
    }

    Object arg;
    try {
      boolean keepgoing = parseSome();
      arg = keepgoing ? Boolean.TRUE : Boolean.FALSE;
    } catch (SAXException ex) {
      arg = ex;
    } catch (IOException ex) {
      arg = ex;
    } catch (Exception ex) {
      arg = new SAXException(ex);
    }
    return arg;
private booleanparseSome()

      
		   
					 
	
		// Take next parsing step, return false iff parsing complete:
		if(fConfigSetInput!=null)
		{
			Object ret=(Boolean)(fConfigParse.invoke(fPullParserConfig,parmsfalse));
			return ((Boolean)ret).booleanValue();
		}
		else
		{
			Object ret=fParseSome.invoke(fIncrementalParser,noparms);
			return ((Boolean)ret).booleanValue();
		}
private booleanparseSomeSetup(org.xml.sax.InputSource source)

		if(fConfigSetInput!=null)
		{
			// Obtain input from SAX inputSource object, construct XNI version of
			// that object. Logic adapted from Xerces2.
			Object[] parms1={source.getPublicId(),source.getSystemId(),null};
			Object xmlsource=fConfigInputSourceCtor.newInstance(parms1);
			Object[] parmsa={source.getByteStream()};
			fConfigSetByteStream.invoke(xmlsource,parmsa);
			parmsa[0]=source.getCharacterStream();
			fConfigSetCharStream.invoke(xmlsource,parmsa);
			parmsa[0]=source.getEncoding();
			fConfigSetEncoding.invoke(xmlsource,parmsa);

			// Bugzilla5272 patch suggested by Sandy Gao.
			// Has to be reflection to run with Xerces2
			// after compilation against Xerces1. or vice
			// versa, due to return type mismatches.
			Object[] noparms=new Object[0];
			fReset.invoke(fIncrementalParser,noparms);
			
			parmsa[0]=xmlsource;
			fConfigSetInput.invoke(fPullParserConfig,parmsa);
			
			// %REVIEW% Do first pull. Should we instead just return true?
			return parseSome();
		}
		else
		{
			Object[] parm={source};
			Object ret=fParseSomeSetup.invoke(fIncrementalParser,parm);
			return ((Boolean)ret).booleanValue();
		}
public voidsetContentHandler(org.xml.sax.ContentHandler handler)

    // Typecast required in Xerces2; SAXParser doesn't inheret XMLReader
    // %OPT% Cast at asignment?
    ((XMLReader)fIncrementalParser).setContentHandler(handler);
public voidsetDTDHandler(org.xml.sax.DTDHandler handler)

    // Typecast required in Xerces2; SAXParser doesn't inheret XMLReader
    // %OPT% Cast at asignment?
    ((XMLReader)fIncrementalParser).setDTDHandler(handler);
public voidsetLexicalHandler(org.xml.sax.ext.LexicalHandler handler)

    // Not supported by all SAX2 parsers but should work in Xerces:
    try 
    {
      // Typecast required in Xerces2; SAXParser doesn't inheret XMLReader
      // %OPT% Cast at asignment?
      ((XMLReader)fIncrementalParser).setProperty("http://xml.org/sax/properties/lexical-handler",
                                     handler);
    }
    catch(org.xml.sax.SAXNotRecognizedException e)
    {
      // Nothing we can do about it
    }
    catch(org.xml.sax.SAXNotSupportedException e)
    {
      // Nothing we can do about it
    }
public voidstartParse(org.xml.sax.InputSource source)
startParse() is a simple API which tells the IncrementalSAXSource to begin reading a document.

throws
SAXException is parse thread is already in progress or parsing can not be started.

    if (fIncrementalParser==null)
      throw new SAXException(XMLMessages.createXMLMessage(XMLErrorResources.ER_STARTPARSE_NEEDS_SAXPARSER, null)); //"startParse needs a non-null SAXParser.");
    if (fParseInProgress)
      throw new SAXException(XMLMessages.createXMLMessage(XMLErrorResources.ER_STARTPARSE_WHILE_PARSING, null)); //"startParse may not be called while parsing.");

    boolean ok=false;

    try
    {
      ok = parseSomeSetup(source);
    }
    catch(Exception ex)
    {
      throw new SAXException(ex);
    }
    
    if(!ok)
      throw new SAXException(XMLMessages.createXMLMessage(XMLErrorResources.ER_COULD_NOT_INIT_PARSER, null)); //"could not initialize parser with");