charconstantnode.java

derby database source code.good for you.

/*

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

   Copyright 1997, 2004 The Apache Software Foundation or its licensors, as applicable.

   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.derby.impl.sql.compile;

import org.apache.derby.iapi.types.StringDataValue;
import org.apache.derby.iapi.types.TypeId;


import org.apache.derby.iapi.error.StandardException;

import org.apache.derby.iapi.services.compiler.MethodBuilder;

import org.apache.derby.impl.sql.compile.ExpressionClassBuilder;
import org.apache.derby.iapi.reference.SQLState;

import org.apache.derby.iapi.util.ReuseFactory;

import java.sql.Types;

public final class CharConstantNode extends ConstantNode
{
	/**
	 * Initializer for a CharConstantNode.
	 *
	 * @param arg1	A String containing the value of the constant
	 * @param arg2	The factory to get the TypeId
	 *			and DataTypeServices factories from.
	 *
	 * - OR *
	 *
	 * @param arg1	The TypeId for the type of the node
	 *
	 * @exception StandardException
	 */
	public void init(
					Object arg1)
		throws StandardException
	{
		if (arg1 instanceof TypeId)
		{
			super.init(
						arg1,
						Boolean.TRUE,
						ReuseFactory.getInteger(0));
		}
		else
		{
			String val = (String) arg1;

			super.init(
				TypeId.CHAR_ID,
				(val == null) ? Boolean.TRUE : Boolean.FALSE,
				(val != null) ?
					ReuseFactory.getInteger(val.length()) :
					ReuseFactory.getInteger(0));

			setValue(getDataValueFactory().getCharDataValue(val));
		}
	}

	/**
	 * Initializer for a CharConstantNode of a specific length.
	 *
	 * @param newValue	A String containing the value of the constant
	 * @param newLength The length of the new value of the constant
	 * @param typeCompilationFactory	The factory to get the TypeId
	 *			and DataTypeServices factories from.
	 *
	 * @exception StandardException
	 */
	public void init(
					Object newValue, 
					Object newLength)
		throws StandardException
	{
		String val = (String) newValue;
		int newLen = ((Integer) newLength).intValue();

		super.init(
			 TypeId.CHAR_ID,
			 (val == null) ? Boolean.TRUE : Boolean.FALSE,
			 newLength);

		if (val.length() > newLen)
		{
			throw StandardException.newException(SQLState.LANG_STRING_TRUNCATION, "CHAR", val, String.valueOf(newLen));
		}

		// Blank pad the string if necessesary
		while (val.length() < newLen)
		{
			val = val + ' ';
		}

		setValue(getDataValueFactory().getCharDataValue(val));
	}

	/**
	 * Return the value from this CharConstantNode
	 *
	 * @return	The value of this CharConstantNode.
	 *
	 * @exception StandardException		Thrown on error
	 */

	public String	getString() throws StandardException
	{
		return value.getString();
	}

	/**
	 * Return the length
	 *
	 * @return	The length of the value this node represents
	 *
	 * @exception StandardException		Thrown on error
	 */

	//public int	getLength() throws StandardException
	//{
	//	return value.getLength();
	//}

	/**
	 * 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.
	 * This is useful for bind time resolution of VTIs.
	 * RESOLVE: What do we do for primitives?
	 *
	 * @return	An Object representing the bind time value of this expression tree.
	 *			(null if not a bind time constant.)
	 *
	 * @exception StandardException		Thrown on error
	 */
	Object getConstantValueAsObject() throws StandardException 
	{
		return value.getString();
	}

	/**
	 * This generates the proper constant.  It is implemented
	 * by every specific constant node (e.g. IntConstantNode).
	 *
	 * @param acb	The ExpressionClassBuilder for the class being built
	 * @param mb	The method the code to place the code
	 *
	 * @return		The compiled Expression, 
	 *
	 * @exception StandardException		Thrown on error
	 */
	void generateConstant(ExpressionClassBuilder acb, MethodBuilder mb) throws StandardException
	{
		// The generated java is the expression:
		// "#getString()"
		mb.push(getString());
	}
}