parameterhandler.java

rule engine drools-2.0-beta-18

package org.drools.io;

/*
 * $Id: ParameterHandler.java,v 1.4 2004/11/28 02:22:18 simon Exp $
 *
 * Copyright 2001-2003 (C) The Werken Company. All Rights Reserved.
 *
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 *
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * 3. The name "drools" must not be used to endorse or promote products derived
 * from this Software without prior written permission of The Werken Company.
 * For written permission, please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "drools" nor may
 * "drools" appear in their names without prior written permission of The Werken
 * Company. "drools" is a trademark of The Werken Company.
 *
 * 5. Due credit should be given to The Werken Company. (http://werken.com/)
 *
 * THIS SOFTWARE IS PROVIDED BY THE WERKEN COMPANY AND CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE WERKEN COMPANY OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 */
import org.drools.rule.Declaration;
import org.drools.rule.Rule;
import org.drools.rule.InvalidRuleException;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

import java.util.HashSet;

/**
 * @author mproctor
 */
class ParameterHandler extends BaseAbstractHandler implements Handler
{
    ParameterHandler( RuleSetReader ruleSetReader )
    {
        this.ruleSetReader = ruleSetReader;

        if ( this.validParents == null && validPeers == null )
        {
            this.validParents = new HashSet( );
            this.validParents.add( Rule.class );

            this.validPeers = new HashSet( );
            this.validPeers.add( null );
            this.validPeers.add( Declaration.class );

            this.allowNesting = false;
        }
    }

    public Object start( String uri, String localName, Attributes attrs ) throws SAXException
    {
        Rule rule = (Rule) ruleSetReader.getParent( Rule.class );

        String identifier = attrs.getValue( "identifier" );

        if ( identifier == null || identifier.trim( ).equals( "" ) )
        {
            throw new SAXParseException(
                    "<parameter> requires an 'identifier' attribute",
                    ruleSetReader.getLocator( ) );
        }

        identifier = identifier.trim( );

        try
        {
            return rule.addParameterDeclaration( identifier, null );
        }
        catch ( InvalidRuleException e )
        {
            throw new SAXParseException( "'" + identifier + "' is already defined", ruleSetReader.getLocator() );
        }
    }

    public Object end( String uri, String localName ) throws SAXException
    {
        Declaration declaration = (Declaration) ruleSetReader.getCurrent( );
        Rule rule = (Rule) ruleSetReader.getParent( Rule.class );

        if ( rule == null || declaration == null )
        {
            throw new SAXParseException( "unable to construct <parameter>",
                    ruleSetReader.getLocator( ) );
        }

        if ( declaration.getObjectType( ) == null )
        {
            throw new SAXParseException( "<parameter> requires an object-type",
                    ruleSetReader.getLocator( ) );
        }

        return null;
    }

    public boolean popParent()
    {
        return true;
    }

    public Class generateNodeFor()
    {
        return Declaration.class;
    }
}