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 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

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 * 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,

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 *

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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"><empty/></element>

     *     <text/>

     *   </choice>

     * </element>

     * </xmp>

     *

     * Assume we hit the following instance:

     * <xmp>

     * <foo> <bar/></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><ref name="X"/></start>

        // <define name="X">

        //   <element name="root"><empty/></element>

        // </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()</code>.

     * <p>

     * For example, consider the following schema:

     * <pre><xmp>

     *  <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());

    }