/**********************************************************************
Copyright (c) 2008 Andy Jefferson and others. All rights reserved.
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.
Contributors:
...
**********************************************************************/
package org.datanucleus.store.rdbms.sql.method;
import java.util.ArrayList;
import java.util.List;
import org.datanucleus.exceptions.NucleusException;
import org.datanucleus.store.rdbms.sql.expression.SQLExpression;
import org.datanucleus.store.rdbms.sql.expression.StringExpression;
/**
* Expression handler to invoke an SQL String function that takes in an expression.
* <ul>
* <li>If the expression is a StringExpression will returns a StringExpression
* <pre>{functionName}({stringExpr})</pre> and args aren't used</li>
* <li>If the expression is null will return a StringExpression
* <pre>{functionName}({args})</pre> and expr isn't used</li>
* </ul>
*/
public abstract class SimpleStringMethod extends AbstractSQLMethod
{
protected abstract String getFunctionName();
/* (non-Javadoc)
* @see org.datanucleus.store.rdbms.sql.method.SQLMethod#getExpression(org.datanucleus.store.rdbms.sql.expression.SQLExpression, java.util.List)
*/
public SQLExpression getExpression(SQLExpression expr, List args)
{
if (expr == null)
{
// We have something like "function({expr})"
return new StringExpression(stmt, getMappingForClass(String.class), getFunctionName(), args);
}
else if (expr instanceof StringExpression)
{
// We have {stringExpr}.method(...)
// TODO Cater for input args
ArrayList functionArgs = new ArrayList();
functionArgs.add(expr);
return new StringExpression(stmt, getMappingForClass(String.class), getFunctionName(), functionArgs);
}
else
{
throw new NucleusException(LOCALISER.msg("060002", getFunctionName(), expr));
}
}
}