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Plugin for DataNucleus providing persistence to RDBMS datastores.

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/**********************************************************************
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.mapping.java.JavaTypeMapping;
import org.datanucleus.store.rdbms.sql.SQLStatement;
import org.datanucleus.store.rdbms.sql.expression.IntegerLiteral;
import org.datanucleus.store.rdbms.sql.expression.NumericExpression;
import org.datanucleus.store.rdbms.sql.expression.ParameterLiteral;
import org.datanucleus.store.rdbms.sql.expression.SQLExpression;
import org.datanucleus.store.rdbms.sql.expression.SQLExpressionFactory;
import org.datanucleus.store.rdbms.sql.expression.StringExpression;
import org.datanucleus.store.rdbms.sql.expression.StringLiteral;
import org.datanucleus.util.Localiser;

/**
 * Expression handler to evaluate {stringExpression}.length().
 * Returns a NumericExpression CHAR_LENGTH({stringExpr}).
 */
public class StringLengthMethod implements SQLMethod
{
    /* (non-Javadoc)
     * @see org.datanucleus.store.rdbms.sql.method.SQLMethod#getExpression(org.datanucleus.store.rdbms.sql.expression.SQLExpression, java.util.List)
     */
    public SQLExpression getExpression(SQLStatement stmt, SQLExpression expr, List args)
    {
        if (!expr.isParameter() && expr instanceof StringLiteral)
        {
            SQLExpressionFactory exprFactory = stmt.getSQLExpressionFactory();
            JavaTypeMapping m = exprFactory.getMappingForType(int.class, false);
            String val = (String)((StringLiteral)expr).getValue();
            return new IntegerLiteral(stmt, m, Integer.valueOf(val.length()), null);
        }
        else if (expr instanceof StringExpression || expr instanceof ParameterLiteral)
        {
            ArrayList funcArgs = new ArrayList();
            funcArgs.add(expr);
            return new NumericExpression(stmt, stmt.getSQLExpressionFactory().getMappingForType(int.class), "CHAR_LENGTH", funcArgs);
        }
        else
        {
            throw new NucleusException(Localiser.msg("060001", "length", expr));
        }
    }
}