java/engine/org/apache/derby/impl/sql/compile/XMLConstantNode.java

/*

   Derby - Class org.apache.derby.impl.sql.compile.XMLConstantNode

   Licensed to the Apache Software Foundation (ASF) under one or more
   contributor license agreements.  See the NOTICE file distributed with
   this work for additional information regarding copyright ownership.
   The ASF licenses this file to you 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.derby.impl.sql.compile;

import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.iapi.services.compiler.MethodBuilder;
import org.apache.derby.iapi.services.context.ContextManager;
import org.apache.derby.iapi.types.TypeId;

public final class XMLConstantNode extends ConstantNode
{
    XMLConstantNode(TypeId t, ContextManager cm)
            throws StandardException {
        super(t, true, 0, cm);
    }

    /**
     * Return an Object representing the bind time value of this
     * expression tree.  If the expression tree does not evaluate to
     * a constant at bind time then we return null.
     *
     * @return An Object representing the bind time value of this
     *  expression tree (null if not a bind time constant).
     *
     * @exception StandardException        Thrown on error
     */
    @Override
    Object getConstantValueAsObject() throws StandardException 
    {
        return value.getObject();
    }

    /**
     * This generates the proper constant.  For an XML value,
     * this constant value is simply the XML string (which is
     * just null because null values are the only types of
     * XML constants we can have).
     *
     * @param acb The ExpressionClassBuilder for the class being built
     * @param mb The method the code to place the code
     *
     * @exception StandardException        Thrown on error
     */
    void generateConstant(ExpressionClassBuilder acb, MethodBuilder mb)
        throws StandardException
    {
        // The generated java is the expression:
        // "#getString()"
        mb.push(value.getString());
    }
}