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 * 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

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package com.sun.tools.internal.xjc.reader.xmlschema.bindinfo;

import com.sun.xml.internal.bind.v2.WellKnownNamespace;

import java.util.ArrayList;

import org.xml.sax.Attributes;

import org.xml.sax.ContentHandler;

import org.xml.sax.Locator;

import org.xml.sax.SAXException;

import org.xml.sax.XMLFilter;

import org.xml.sax.helpers.XMLFilterImpl;

/**

 * {@link XMLFilter} that can fork an event to another {@link ContentHandler}

 * in the middle.

 *

 * <p>

 * The side handler receives SAX events before the next handler in the filter chain does.

 *

 * @author Kohsuke Kawaguchi

 */

public class ForkingFilter extends XMLFilterImpl {

    /**

     * Non-null if we are also forking events to this handler.

     */

    private ContentHandler side;

    /**

     * The depth of the current element that the {@link #side} handler

     * is seeing.

     */

    private int depth;

    /**

     * In-scope namespace mapping.

     * namespaces[2n  ] := prefix

     * namespaces[2n+1] := namespace URI

     */

    private final ArrayList<String> namespaces = new ArrayList<String>();

    private Locator loc;

    public ForkingFilter() {

    }

    public ForkingFilter(ContentHandler next) {

        setContentHandler(next);

    }

    public ContentHandler getSideHandler() {

        return side;

    }

    @Override

    public void setDocumentLocator(Locator locator) {

        super.setDocumentLocator(locator);

        this.loc = locator;

    }

    public Locator getDocumentLocator() {

        return loc;

    }

    @Override

    public void startDocument() throws SAXException {

        reset();

        super.startDocument();

    }

    private void reset() {

        namespaces.clear();

        side = null;

        depth = 0;

    }

    @Override

    public void endDocument() throws SAXException {

        loc = null;

        reset();

        super.endDocument();

    }

    @Override

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

        if (WellKnownNamespace.XML_NAMESPACE_URI.equals(uri)) return; //xml prefix shall not be declared based on jdk api javadoc

        if(side!=null)

            side.startPrefixMapping(prefix,uri);

        namespaces.add(prefix);

        namespaces.add(uri);

        super.startPrefixMapping(prefix,uri);

    }

    @Override

    public void endPrefixMapping(String prefix) throws SAXException {

        if ("xml".equals(prefix)) return; //xml prefix shall not be declared based on jdk api javadoc

        if(side!=null)

            side.endPrefixMapping(prefix);

        super.endPrefixMapping(prefix);

        namespaces.remove(namespaces.size()-1);

        namespaces.remove(namespaces.size()-1);

    }

    @Override

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

        if(side!=null) {

            side.startElement(uri,localName,qName,atts);

            depth++;

        }

        super.startElement(uri, localName, qName, atts);

    }

    /**

     * Starts the event forking.

     */

    public void startForking(String uri, String localName, String qName, Attributes atts, ContentHandler side) throws SAXException {

        if(this.side!=null)     throw new IllegalStateException();  // can't fork to two handlers

        this.side = side;

        depth = 1;

        side.setDocumentLocator(loc);

        side.startDocument();

        for( int i=0; i<namespaces.size(); i+=2 )

            side.startPrefixMapping(namespaces.get(i),namespaces.get(i+1));

        side.startElement(uri,localName,qName,atts);

    }

    @Override

    public void endElement(String uri, String localName, String qName) throws SAXException {

        if(side!=null) {

            side.endElement(uri,localName,qName);

            depth--;

            if(depth==0) {

                for( int i=namespaces.size()-2; i>=0; i-=2 )

                    side.endPrefixMapping(namespaces.get(i));

                side.endDocument();

                side = null;

            }

        }

        super.endElement(uri, localName, qName);

    }

    @Override

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

        if(side!=null)

            side.characters(ch, start, length);

        super.characters(ch, start, length);

    }

    @Override

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

        if(side!=null)

            side.ignorableWhitespace(ch, start, length);

        super.ignorableWhitespace(ch, start, length);

    }

}