baseexpressionactivation.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.impl.sql.execute.BaseExpressionActivation

   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.execute;

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

import org.apache.derby.iapi.services.sanity.SanityManager;

import org.apache.derby.iapi.types.DataValueDescriptor;
import org.apache.derby.catalog.types.UserDefinedTypeIdImpl;

import org.apache.derby.iapi.services.context.ContextManager;
import org.apache.derby.iapi.services.context.Context;

import org.apache.derby.iapi.jdbc.ConnectionContext;

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

import org.apache.derby.iapi.sql.execute.ExecutionContext;
import org.apache.derby.iapi.sql.execute.ExecutionFactory;

import org.apache.derby.iapi.sql.conn.LanguageConnectionContext;
import org.apache.derby.iapi.store.access.TransactionController;
import org.apache.derby.iapi.reference.Attribute;

import org.apache.derby.iapi.sql.ResultSet;

import java.sql.Connection;
import java.sql.SQLException;

/**
 * BaseExpressionActivation
 *
 * Support needed by Expression evaluators (Filters) and by
 * ResultSet materializers (Activations)
 */
public abstract class BaseExpressionActivation
{

	
	//
	// constructors
	//
	BaseExpressionActivation()
	{
		super();
	}


	/**
	 * Get the minimum value of 4 input values.  If less than 4 values, input
	 * NULL.  If more than 4 input values, call this multiple times to
	 * accumulate results.  Also have judge's type as parameter to have a base
	 * upon which the comparison is based.  An example use is for code 
	 * generation in bug 3858.
	 * 
	 * @param v1		1st value
	 * @param v2		2nd value
	 * @param v3		3rd value
	 * @param v4		4th value
	 * @param judgeTypeFormatId		type format id of the judge
	 * @param judgeUserJDBCTypeId	JDBC type id if judge is user type;
	 *								-1 if not user type
	 *
	 * @return	The minimum value of the 4.
	 */
	public static DataValueDescriptor minValue(DataValueDescriptor v1,
											  DataValueDescriptor v2,
											  DataValueDescriptor v3,
											  DataValueDescriptor v4,
											  int judgeTypeFormatId,
											  int judgeUserJDBCTypeId)
										throws StandardException
	{
		DataValueDescriptor judge;
		if (judgeUserJDBCTypeId == -1)
			judge = (DataValueDescriptor) new TypeId(judgeTypeFormatId, null).getNull();
		else
			judge = (DataValueDescriptor) new TypeId(judgeTypeFormatId, new UserDefinedTypeIdImpl()).getNull();
			
		DataValueDescriptor minVal = v1;
		if (v2 != null && judge.lessThan(v2, minVal).equals(true))
			minVal = v2;
		if (v3 != null && judge.lessThan(v3, minVal).equals(true))
			minVal = v3;
		if (v4 != null && judge.lessThan(v4, minVal).equals(true))
			minVal = v4;
		return minVal;
	}


	/**
	 * Get the maximum value of 4 input values.  If less than 4 values, input
	 * NULL.  If more than 4 input values, call this multiple times to
	 * accumulate results.  Also have judge's type as parameter to have a base
	 * upon which the comparison is based.  An example use is for code 
	 * generation in bug 3858.
	 * 
	 * @param v1		1st value
	 * @param v2		2nd value
	 * @param v3		3rd value
	 * @param v4		4th value
	 * @param judgeTypeFormatId		type format id of the judge
	 * @param judgeUserJDBCTypeId	JDBC type id if judge is user type;
	 *								-1 if not user type
	 *
	 * @return	The maximum value of the 4.
	 */
	public static DataValueDescriptor maxValue(DataValueDescriptor v1,
											  DataValueDescriptor v2,
											  DataValueDescriptor v3,
											  DataValueDescriptor v4,
											  int judgeTypeFormatId,
											  int judgeUserJDBCTypeId)
										throws StandardException
	{
		DataValueDescriptor judge;
		if (judgeUserJDBCTypeId == -1)
			judge =  new TypeId(judgeTypeFormatId, null).getNull();
		else
			judge =  new TypeId(judgeTypeFormatId, new UserDefinedTypeIdImpl()).getNull();

		DataValueDescriptor maxVal = v1;
		if (v2 != null && judge.greaterThan(v2, maxVal).equals(true))
			maxVal = v2;
		if (v3 != null && judge.greaterThan(v3, maxVal).equals(true))
			maxVal = v3;
		if (v4 != null && judge.greaterThan(v4, maxVal).equals(true))
			maxVal = v4;
		return maxVal;
	}

}