MultiSourceElementReplacementVisitor.java

/*
 * JBoss, Home of Professional Open Source.
 * See the COPYRIGHT.txt file distributed with this work for information
 * regarding copyright ownership.  Some portions may be licensed
 * to Red Hat, Inc. under one or more contributor license agreements.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 
 * This library 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
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301 USA.
 */

package org.teiid.dqp.internal.process.multisource;

import org.teiid.api.exception.query.QueryMetadataException;
import org.teiid.core.TeiidComponentException;
import org.teiid.core.types.DataTypeManager;
import org.teiid.query.metadata.QueryMetadataInterface;
import org.teiid.query.sql.lang.Command;
import org.teiid.query.sql.navigator.PreOrPostOrderNavigator;
import org.teiid.query.sql.symbol.Constant;
import org.teiid.query.sql.symbol.ElementSymbol;
import org.teiid.query.sql.symbol.Expression;
import org.teiid.query.sql.visitor.ExpressionMappingVisitor;


public class MultiSourceElementReplacementVisitor extends ExpressionMappingVisitor {
    
    private String bindingName;
    private QueryMetadataInterface metadata;
    
    public MultiSourceElementReplacementVisitor(String bindingName, QueryMetadataInterface metadata) {
        super(null);
        this.bindingName = bindingName;
        this.metadata = metadata;
    }
    
    public Expression replaceExpression(Expression expr) {
        if(expr instanceof ElementSymbol) {
            ElementSymbol elem = (ElementSymbol) expr;
            Object metadataID = elem.getMetadataID();            
            try {
				if(metadata.isMultiSourceElement(metadataID)) {
				    Constant bindingConst = new Constant(this.bindingName, DataTypeManager.DefaultDataClasses.STRING);
				    return bindingConst;
				}
			} catch (QueryMetadataException e) {
			} catch (TeiidComponentException e) {
			}
        }
        
        return expr;
    }
    
    public static void visit(String bindingName, QueryMetadataInterface metadata, Command processingCommand) {
        MultiSourceElementReplacementVisitor visitor = new MultiSourceElementReplacementVisitor(bindingName, metadata);
        PreOrPostOrderNavigator nav = new PreOrPostOrderNavigator(visitor, PreOrPostOrderNavigator.PRE_ORDER, true);
        nav.setSkipEvaluatable(true);
        processingCommand.acceptVisitor(nav);
    }
    
}