non-releases/trunk_before_flattening/src/java/org/apache/cocoon/xml/xlink/XLinkPipe.java

/*
 * Copyright 1999-2004 The Apache Software Foundation.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.cocoon.xml.xlink;

import org.apache.cocoon.xml.AbstractXMLPipe;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.AttributesImpl;

/**
 * This class implements a SAX consumer wrapper that transforms the
 * general SAX semantic into XLink semantics for easier consumption.
 *
 * Classes should extend this class and overwrite the abstract method
 * to consume the XLink events that come in as SAX events.
 *
 * NOTE: this is based on XLink W3C Candidate Recommendation 3 July 2000
 *
 * @version $Id$
 */
public abstract class XLinkPipe extends AbstractXMLPipe implements XLinkHandler {

    public static final String XLINK_NAMESPACE_URI = "http://www.w3.org/1999/xlink";
    public static final String XLINK_TYPE = "type";
    public static final String XLINK_HREF = "href";
    public static final String XLINK_ROLE = "role";
    public static final String XLINK_ARCROLE = "arcrole";
    public static final String XLINK_TITLE = "title";
    public static final String XLINK_SHOW = "show";
    public static final String XLINK_ACTUATE = "actuate";
    public static final String XLINK_LABEL = "label";
    public static final String XLINK_FROM = "from";
    public static final String XLINK_TO = "to";
    public static final String XLINK_TYPE_SIMPLE = "simple";
    public static final String XLINK_TYPE_EXTENDED = "extended";
    public static final String XLINK_TYPE_LOCATOR = "locator";
    public static final String XLINK_TYPE_ARC = "arc";
    public static final String XLINK_TYPE_RESOURCE = "resource";
    public static final String XLINK_TYPE_TITLE = "title";

    private String extendedLinkElementName = null;
    private String extendedLinkElementURI = null;
    private String linkLocatorElementName = null;
    private String linkLocatorElementURI = null;
    private String linkArcElementName = null;
    private String linkArcElementURI = null;

    public void startElement( String uri, String name, String raw, Attributes attr ) throws SAXException
    {
        String type = attr.getValue( XLINK_NAMESPACE_URI, XLINK_TYPE );
        if ( type != null )
        {
            if ( type.equals( XLINK_TYPE_SIMPLE ) )
            {
                if ( this.extendedLinkElementName != null )
                {
                    throw new SAXException( "An XLink simple link cannot be included into an 'extended' element" );
                }
                else if ( this.linkLocatorElementName != null )
                {
                    throw new SAXException( "An XLink simple link cannot be included into a 'locator' element" );
                }
                else if ( this.linkArcElementName != null )
                {
                    throw new SAXException( "An XLink simple link cannot be included into an 'arc' element" );
                }
                String href = attr.getValue( XLINK_NAMESPACE_URI, XLINK_HREF );
                String role = attr.getValue( XLINK_NAMESPACE_URI, XLINK_ROLE );
                String arcrole = attr.getValue( XLINK_NAMESPACE_URI, XLINK_ARCROLE );
                String title = attr.getValue( XLINK_NAMESPACE_URI, XLINK_TITLE );
                String show = attr.getValue( XLINK_NAMESPACE_URI, XLINK_SHOW );
                String actuate = attr.getValue( XLINK_NAMESPACE_URI, XLINK_ACTUATE );
                simpleLink( href, role, arcrole, title, show, actuate, uri, name, raw, attr );
            }
            else if ( type.equals( XLINK_TYPE_EXTENDED ) )
            {
                if ( this.extendedLinkElementName != null )
                {
                    throw new SAXException( "An XLink extended link cannot include another 'extended' element" );
                }
                else if ( this.linkLocatorElementName != null )
                {
                    throw new SAXException( "An XLink extended link cannot be included into a 'locator' element" );
                }
                else if ( this.linkArcElementName != null )
                {
                    throw new SAXException( "An XLink extended link cannot be included into an 'arc' element" );
                }
                String role = attr.getValue( XLINK_NAMESPACE_URI, XLINK_ROLE );
                String title = attr.getValue( XLINK_NAMESPACE_URI, XLINK_TITLE );
                this.extendedLinkElementName = name;
                this.extendedLinkElementURI = uri;
                startExtendedLink( role, title, uri, name, raw, attr );
            }
            else if ( type.equals( XLINK_TYPE_LOCATOR ) )
            {
                if ( this.extendedLinkElementName == null )
                {
                    throw new SAXException( "An XLink locator must be included into an 'extended' element" );
                }
                else if ( this.linkLocatorElementName != null )
                {
                    throw new SAXException( "An XLink locator  cannot be included into another 'locator' element" );
                }
                else if ( this.linkArcElementName != null )
                {
                    throw new SAXException( "An XLink locator cannot be included into an 'arc' element" );
                }
                String href = attr.getValue( XLINK_NAMESPACE_URI, XLINK_HREF );
                String role = attr.getValue( XLINK_NAMESPACE_URI, XLINK_ROLE );
                String title = attr.getValue( XLINK_NAMESPACE_URI, XLINK_TITLE );
                String label = attr.getValue( XLINK_NAMESPACE_URI, XLINK_LABEL );
                this.linkLocatorElementName = name;
                this.linkLocatorElementURI = uri;
                startLocator( href, role, title, label, uri, name, raw, attr );
            }
            else if ( type.equals( XLINK_TYPE_ARC ) )
            {
                if ( this.extendedLinkElementName == null )
                {
                    throw new SAXException( "An XLink arc must be included into an 'extended' element" );
                }
                else if ( this.linkLocatorElementName != null )
                {
                    throw new SAXException( "An XLink arc cannot be included into a 'locator' element" );
                }
                else if ( this.linkArcElementName != null )
                {
                    throw new SAXException( "An XLink arc cannot be included into another 'arc' element" );
                }
                String arcrole = attr.getValue( XLINK_NAMESPACE_URI, XLINK_ARCROLE );
                String title = attr.getValue( XLINK_NAMESPACE_URI, XLINK_TITLE );
                String show = attr.getValue( XLINK_NAMESPACE_URI, XLINK_SHOW );
                String actuate = attr.getValue( XLINK_NAMESPACE_URI, XLINK_ACTUATE );
                String from = attr.getValue( XLINK_NAMESPACE_URI, XLINK_FROM );
                String to = attr.getValue( XLINK_NAMESPACE_URI, XLINK_TO );
                this.linkArcElementName = name;
                this.linkArcElementURI = uri;
                startArc( arcrole, title, show, actuate, from, to, uri, name, raw, attr );
            }
            else if ( type.equals( XLINK_TYPE_RESOURCE ) )
            {
                if ( this.extendedLinkElementName == null )
                {
                    throw new SAXException( "An XLink resource must be included into an 'extended' element" );
                }
                String role = attr.getValue( XLINK_NAMESPACE_URI, XLINK_ROLE );
                String title = attr.getValue( XLINK_NAMESPACE_URI, XLINK_TITLE );
                String label = attr.getValue( XLINK_NAMESPACE_URI, XLINK_LABEL );
                linkResource( role, title, label, uri, name, raw, attr );
            }
            else if ( type.equals( XLINK_TYPE_TITLE ) )
            {
                if ( ( this.extendedLinkElementName == null )
                        && ( this.linkLocatorElementName == null )
                        && ( this.linkArcElementName == null ) )
                {
                    throw new SAXException( "An XLink title must be included into an 'extended', 'locator' or 'arc' element" );
                }
                linkTitle( uri, name, raw, attr );
            }
            else
            {
                super.startElement( uri, name, raw, attr );
            }
        }
        else
        {
            super.startElement( uri, name, raw, attr );
        }
    }

    public void endElement( String uri, String name, String raw ) throws SAXException
    {
        if ( ( name.equals( this.extendedLinkElementName ) ) && ( uri.equals( this.extendedLinkElementURI ) ) )
        {
            this.extendedLinkElementName = null;
            this.extendedLinkElementURI = null;
            this.endExtendedLink( uri, name, raw );
        }
        else if ( ( name.equals( this.linkLocatorElementName ) ) && ( uri.equals( this.linkLocatorElementURI ) ) )
        {
            this.linkLocatorElementName = null;
            this.linkLocatorElementURI = null;
            this.endLocator( uri, name, raw );
        }
        else if ( ( name.equals( this.linkArcElementName ) ) && ( uri.equals( this.linkArcElementURI ) ) )
        {
            this.linkArcElementName = null;
            this.linkArcElementURI = null;
            this.endArc( uri, name, raw );
        }
        else
        {
            super.endElement( uri, name, raw );
        }
    }

    // Default XLinkHandler implementation (defaults to copy over)

    public void simpleLink( String href, String role, String arcrole, String title, String show, String actuate, String uri, String name, String raw, Attributes attr ) throws SAXException
    {
        AttributesImpl newattr = new AttributesImpl( attr );
        int hrefIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_HREF );
        int roleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_ROLE );
        int arcroleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_ARCROLE );
        int titleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_TITLE );
        int showIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_SHOW );
        int actuateIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_ACTUATE );
        if ( hrefIndex > -1 )
            newattr.setValue( hrefIndex, href );
        if ( roleIndex > -1 )
            newattr.setValue( roleIndex, role );
        if ( arcroleIndex > -1 )
            newattr.setValue( arcroleIndex, arcrole );
        if ( titleIndex > -1 )
            newattr.setValue( titleIndex, title );
        if ( showIndex > -1 )
            newattr.setValue( showIndex, show );
        if ( actuateIndex > -1 )
            newattr.setValue( actuateIndex, actuate );
        super.startElement( uri, name, raw, newattr );
    }

    public void startExtendedLink( String role, String title, String uri, String name, String raw, Attributes attr ) throws SAXException
    {
        AttributesImpl newattr = new AttributesImpl( attr );
        int roleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_ROLE );
        int titleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_TITLE );
        if ( roleIndex > -1 )
            newattr.setValue( roleIndex, role );
        if ( titleIndex > -1 )
            newattr.setValue( titleIndex, title );
        super.startElement( uri, name, raw, newattr );
    }

    public void startLocator( String href, String role, String title, String label, String uri, String name, String raw, Attributes attr ) throws SAXException
    {
        AttributesImpl newattr = new AttributesImpl( attr );
        int hrefIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_HREF );
        int roleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_ROLE );
        int titleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_TITLE );
        int labelIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_LABEL );
        if ( hrefIndex > -1 )
            newattr.setValue( hrefIndex, href );
        if ( roleIndex > -1 )
            newattr.setValue( roleIndex, role );
        if ( titleIndex > -1 )
            newattr.setValue( titleIndex, title );
        if ( labelIndex > -1 )
            newattr.setValue( labelIndex, label );
        super.startElement( uri, name, raw, newattr );
    }

    public void startArc( String arcrole, String title, String show, String actuate, String from, String to, String uri, String name, String raw, Attributes attr ) throws SAXException
    {
        AttributesImpl newattr = new AttributesImpl( attr );
        int arcroleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_ARCROLE );
        int titleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_TITLE );
        int showIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_SHOW );
        int actuateIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_ACTUATE );
        int fromIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_FROM );
        int toIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_TO );
        if ( arcroleIndex > -1 )
            newattr.setValue( arcroleIndex, arcrole );
        if ( titleIndex > -1 )
            newattr.setValue( titleIndex, title );
        if ( showIndex > -1 )
            newattr.setValue( showIndex, show );
        if ( actuateIndex > -1 )
            newattr.setValue( actuateIndex, actuate );
        if ( fromIndex > -1 )
            newattr.setValue( actuateIndex, from );
        if ( toIndex > -1 )
            newattr.setValue( actuateIndex, to );
        super.startElement( uri, name, raw, newattr );
    }

    public void linkResource( String role, String title, String label, String uri, String name, String raw, Attributes attr ) throws SAXException
    {
        AttributesImpl newattr = new AttributesImpl( attr );
        int roleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_ROLE );
        int titleIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_TITLE );
        int labelIndex = attr.getIndex( XLINK_NAMESPACE_URI, XLINK_LABEL );
        if ( roleIndex > -1 )
            newattr.setValue( roleIndex, role );
        if ( titleIndex > -1 )
            newattr.setValue( titleIndex, title );
        if ( labelIndex > -1 )
            newattr.setValue( labelIndex, label );
        super.startElement( uri, name, raw, newattr );
    }

    public void linkTitle( String uri, String name, String raw, Attributes attr ) throws SAXException
    {
        super.startElement( uri, name, raw, attr );
    }

    public void endExtendedLink( String uri, String name, String raw ) throws SAXException
    {
        super.endElement( uri, name, raw );
    }

    public void endLocator( String uri, String name, String raw ) throws SAXException
    {
        super.endElement( uri, name, raw );
    }

    public void endArc( String uri, String name, String raw ) throws SAXException
    {
        super.endElement( uri, name, raw );
    }
}