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Java example source code file (NGCCRuntime.java)
This example Java source code file (NGCCRuntime.java) is included in the alvinalexander.com
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The NGCCRuntime.java Java example source code
/*
* Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package com.sun.xml.internal.xsom.impl.parser.state;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Stack;
import java.util.StringTokenizer;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
/**
* Runtime Engine for RELAXNGCC execution.
*
* This class has the following functionalities:
*
* <ol>
* <li>Managing a stack of NGCCHandler objects and
* switching between them appropriately.
*
* <li>Keep track of all Attributes.
*
* <li>manage mapping between namespace URIs and prefixes.
*
* <li>TODO: provide support for interleaving.
*
* @version $Id: NGCCRuntime.java,v 1.15 2002/09/29 02:55:48 okajima Exp $
* @author Kohsuke Kawaguchi (kk@kohsuke.org)
*/
public class NGCCRuntime implements ContentHandler, NGCCEventSource {
public NGCCRuntime() {
reset();
}
/**
* Sets the root handler, which will be used to parse the
* root element.
* <p>
* This method can be called right after the object is created
* or the reset method is called. You can't replace the root
* handler while parsing is in progress.
* <p>
* Usually a generated class that corresponds to the <start>
* pattern will be used as the root handler, but any NGCCHandler
* can be a root handler.
*
* @exception IllegalStateException
* If this method is called but it doesn't satisfy the
* pre-condition stated above.
*/
public void setRootHandler( NGCCHandler rootHandler ) {
if(currentHandler!=null)
throw new IllegalStateException();
currentHandler = rootHandler;
}
/**
* Cleans up all the data structure so that the object can be reused later.
* Normally, applications do not need to call this method directly,
*
* as the runtime resets itself after the endDocument method.
*/
public void reset() {
attStack.clear();
currentAtts = null;
currentHandler = null;
indent=0;
locator = null;
namespaces.clear();
needIndent = true;
redirect = null;
redirectionDepth = 0;
text = new StringBuffer();
// add a dummy attributes at the bottom as a "centinel."
attStack.push(new AttributesImpl());
}
// current content handler can be acccessed via set/getContentHandler.
private Locator locator;
public void setDocumentLocator( Locator _loc ) { this.locator=_loc; }
/**
* Gets the source location of the current event.
*
* <p>
* One can call this method from RelaxNGCC handlers to access
* the line number information. Note that to
*/
public Locator getLocator() { return locator; }
/** stack of {@link Attributes}. */
private final Stack attStack = new Stack();
/** current attributes set. always equal to attStack.peek() */
private AttributesImpl currentAtts;
/**
* Attributes that belong to the current element.
* <p>
* It's generally not recommended for applications to use
* this method. RelaxNGCC internally removes processed attributes,
* so this doesn't correctly reflect all the attributes an element
* carries.
*/
public Attributes getCurrentAttributes() {
return currentAtts;
}
/** accumulated text. */
private StringBuffer text = new StringBuffer();
/** The current NGCCHandler. Always equals to handlerStack.peek() */
private NGCCEventReceiver currentHandler;
public int replace( NGCCEventReceiver o, NGCCEventReceiver n ) {
if(o!=currentHandler)
throw new IllegalStateException(); // bug of RelaxNGCC
currentHandler = n;
return 0; // we only have one thread.
}
/**
* Processes buffered text.
*
* This method will be called by the start/endElement event to process
* buffered text as a text event.
*
* <p>
* Whitespace handling is a tricky business. Consider the following
* schema fragment:
*
* <xmp>
* <element name="foo">
* <choice>
* <element name="bar">
* <text/>
* </choice>
* </element>
* </xmp>
*
* Assume we hit the following instance:
* <xmp>
* <foo>
* </xmp>
*
* Then this first space needs to be ignored (for otherwise, we will
* end up treating this space as the match to <text/> and won't
* be able to process <bar>.)
*
* Now assume the following instance:
* <xmp>
* <foo/>
* </xmp>
*
* This time, we need to treat this empty string as a text, for
* otherwise we won't be able to accept this instance.
*
* <p>
* This is very difficult to solve in general, but one seemingly
* easy solution is to use the type of next event. If a text is
* followed by a start tag, it follows from the constraint on
* RELAX NG that that text must be either whitespaces or a match
* to <text/>.
*
* <p>
* On the contrary, if a text is followed by a end tag, then it
* cannot be whitespace unless the content model can accept empty,
* in which case sending a text event will be harmlessly ignored
* by the NGCCHandler.
*
* <p>
* Thus this method take one parameter, which controls the
* behavior of this method.
*
* <p>
* TODO: according to the constraint of RELAX NG, if characters
* follow an end tag, then they must be either whitespaces or
* must match to <text/>.
*
* @param possiblyWhitespace
* True if the buffered character can be ignorabale. False if
* it needs to be consumed.
*/
private void processPendingText(boolean ignorable) throws SAXException {
if(ignorable && text.toString().trim().length()==0)
; // ignore. See the above javadoc comment for the description
else
currentHandler.text(text.toString()); // otherwise consume this token
// truncate StringBuffer, but avoid excessive allocation.
if(text.length()>1024) text = new StringBuffer();
else text.setLength(0);
}
public void processList( String str ) throws SAXException {
StringTokenizer t = new StringTokenizer(str, " \t\r\n");
while(t.hasMoreTokens())
currentHandler.text(t.nextToken());
}
public void startElement(String uri, String localname, String qname, Attributes atts)
throws SAXException {
if(redirect!=null) {
redirect.startElement(uri,localname,qname,atts);
redirectionDepth++;
} else {
processPendingText(true);
// System.out.println("startElement:"+localname+"->"+_attrStack.size());
currentHandler.enterElement(uri, localname, qname, atts);
}
}
/**
* Called by the generated handler code when an enter element
* event is consumed.
*
* <p>
* Pushes a new attribute set.
*
* <p>
* Note that attributes are NOT pushed at the startElement method,
* because the processing of the enterElement event can trigger
* other attribute events and etc.
* <p>
* This method will be called from one of handlers when it truely
* consumes the enterElement event.
*/
public void onEnterElementConsumed(
String uri, String localName, String qname,Attributes atts) throws SAXException {
attStack.push(currentAtts=new AttributesImpl(atts));
nsEffectiveStack.push( new Integer(nsEffectivePtr) );
nsEffectivePtr = namespaces.size();
}
public void onLeaveElementConsumed(String uri, String localName, String qname) throws SAXException {
attStack.pop();
if(attStack.isEmpty())
currentAtts = null;
else
currentAtts = (AttributesImpl)attStack.peek();
nsEffectivePtr = ((Integer)nsEffectiveStack.pop()).intValue();
}
public void endElement(String uri, String localname, String qname)
throws SAXException {
if(redirect!=null) {
redirect.endElement(uri,localname,qname);
redirectionDepth--;
if(redirectionDepth!=0)
return;
// finished redirection.
for( int i=0; i<namespaces.size(); i+=2 )
redirect.endPrefixMapping((String)namespaces.get(i));
redirect.endDocument();
redirect = null;
// then process this element normally
}
processPendingText(false);
currentHandler.leaveElement(uri, localname, qname);
// System.out.println("endElement:"+localname);
}
public void characters(char[] ch, int start, int length) throws SAXException {
if(redirect!=null)
redirect.characters(ch,start,length);
else
text.append(ch,start,length);
}
public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException {
if(redirect!=null)
redirect.ignorableWhitespace(ch,start,length);
else
text.append(ch,start,length);
}
public int getAttributeIndex(String uri, String localname) {
return currentAtts.getIndex(uri, localname);
}
public void consumeAttribute(int index) throws SAXException {
final String uri = currentAtts.getURI(index);
final String local = currentAtts.getLocalName(index);
final String qname = currentAtts.getQName(index);
final String value = currentAtts.getValue(index);
currentAtts.removeAttribute(index);
currentHandler.enterAttribute(uri,local,qname);
currentHandler.text(value);
currentHandler.leaveAttribute(uri,local,qname);
}
public void startPrefixMapping( String prefix, String uri ) throws SAXException {
if(redirect!=null)
redirect.startPrefixMapping(prefix,uri);
else {
namespaces.add(prefix);
namespaces.add(uri);
}
}
public void endPrefixMapping( String prefix ) throws SAXException {
if(redirect!=null)
redirect.endPrefixMapping(prefix);
else {
namespaces.remove(namespaces.size()-1);
namespaces.remove(namespaces.size()-1);
}
}
public void skippedEntity( String name ) throws SAXException {
if(redirect!=null)
redirect.skippedEntity(name);
}
public void processingInstruction( String target, String data ) throws SAXException {
if(redirect!=null)
redirect.processingInstruction(target,data);
}
/** Impossible token. This value can never be a valid XML name. */
static final String IMPOSSIBLE = "\u0000";
public void endDocument() throws SAXException {
// consume the special "end document" token so that all the handlers
// currently at the stack will revert to their respective parents.
//
// this is necessary to handle a grammar like
// <start>[
// <define name="X">
// <element name="root">
// </define>
//
// With this grammar, when the endElement event is consumed, two handlers
// are on the stack (because a child object won't revert to its parent
// unless it sees a next event.)
// pass around an "impossible" token.
currentHandler.leaveElement(IMPOSSIBLE,IMPOSSIBLE,IMPOSSIBLE);
reset();
}
public void startDocument() {}
//
//
// event dispatching methods
//
//
public void sendEnterAttribute( int threadId,
String uri, String local, String qname) throws SAXException {
currentHandler.enterAttribute(uri,local,qname);
}
public void sendEnterElement( int threadId,
String uri, String local, String qname, Attributes atts) throws SAXException {
currentHandler.enterElement(uri,local,qname,atts);
}
public void sendLeaveAttribute( int threadId,
String uri, String local, String qname) throws SAXException {
currentHandler.leaveAttribute(uri,local,qname);
}
public void sendLeaveElement( int threadId,
String uri, String local, String qname) throws SAXException {
currentHandler.leaveElement(uri,local,qname);
}
public void sendText(int threadId, String value) throws SAXException {
currentHandler.text(value);
}
//
//
// redirection of SAX2 events.
//
//
/** When redirecting a sub-tree, this value will be non-null. */
private ContentHandler redirect = null;
/**
* Counts the depth of the elements when we are re-directing
* a sub-tree to another ContentHandler.
*/
private int redirectionDepth = 0;
/**
* This method can be called only from the enterElement handler.
* The sub-tree rooted at the new element will be redirected
* to the specified ContentHandler.
*
* <p>
* Currently active NGCCHandler will only receive the leaveElement
* event of the newly started element.
*
* @param uri,local,qname
* Parameters passed to the enter element event. Used to
* simulate the startElement event for the new ContentHandler.
*/
public void redirectSubtree( ContentHandler child,
String uri, String local, String qname ) throws SAXException {
redirect = child;
redirect.setDocumentLocator(locator);
redirect.startDocument();
// TODO: when a prefix is re-bound to something else,
// the following code is potentially dangerous. It should be
// modified to report active bindings only.
for( int i=0; i<namespaces.size(); i+=2 )
redirect.startPrefixMapping(
(String)namespaces.get(i),
(String)namespaces.get(i+1)
);
redirect.startElement(uri,local,qname,currentAtts);
redirectionDepth=1;
}
//
//
// validation context implementation
//
//
/** in-scope namespace mapping.
* namespaces[2n ] := prefix
* namespaces[2n+1] := namespace URI */
private final ArrayList namespaces = new ArrayList();
/**
* Index on the namespaces array, which points to
* the top of the effective bindings. Because of the
* timing difference between the startPrefixMapping method
* and the execution of the corresponding actions,
* this value can be different from <code>namespaces.size().
* <p>
* For example, consider the following schema:
* <pre><![CDATA[
* <oneOrMore>
* <element name="foo"><empty/></element>
* </oneOrMore>
* code fragment X
* <element name="bob"/>
* </xmp></pre>
* Code fragment X is executed after we see a startElement event,
* but at this time the namespaces variable already include new
* namespace bindings declared on "bob".
*/
private int nsEffectivePtr=0;
/**
* Stack to preserve old nsEffectivePtr values.
*/
private final Stack nsEffectiveStack = new Stack();
public String resolveNamespacePrefix( String prefix ) {
for( int i = nsEffectivePtr-2; i>=0; i-=2 )
if( namespaces.get(i).equals(prefix) )
return (String)namespaces.get(i+1);
// no binding was found.
if(prefix.equals("")) return ""; // return the default no-namespace
if(prefix.equals("xml")) // pre-defined xml prefix
return "http://www.w3.org/XML/1998/namespace";
else return null; // prefix undefined
}
// error reporting
protected void unexpectedX(String token) throws SAXException {
throw new SAXParseException(MessageFormat.format(
"Unexpected {0} appears at line {1} column {2}",
new Object[]{
token,
new Integer(getLocator().getLineNumber()),
new Integer(getLocator().getColumnNumber()) }),
getLocator());
}
//
//
// trace functions
//
//
private int indent=0;
private boolean needIndent=true;
private void printIndent() {
for( int i=0; i<indent; i++ )
System.out.print(" ");
}
public void trace( String s ) {
if(needIndent) {
needIndent=false;
printIndent();
}
System.out.print(s);
}
public void traceln( String s ) {
trace(s);
trace("\n");
needIndent=true;
}
}
</pre>
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