org.hibernate.dialect.function.NvlFunction.java Source code

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Here is the source code for org.hibernate.dialect.function.NvlFunction.java

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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
 */
package org.hibernate.dialect.function;

import java.util.List;

import org.hibernate.QueryException;
import org.hibernate.engine.spi.Mapping;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.hibernate.type.Type;

/**
 * Emulation of <tt>coalesce()</tt> on Oracle, using multiple <tt>nvl()</tt> calls
 *
 * @author Gavin King
 */
public class NvlFunction implements SQLFunction {
    @Override
    public boolean hasArguments() {
        return true;
    }

    @Override
    public boolean hasParenthesesIfNoArguments() {
        return true;
    }

    @Override
    public Type getReturnType(Type argumentType, Mapping mapping) throws QueryException {
        return argumentType;
    }

    @Override
    @SuppressWarnings("unchecked")
    public String render(Type argumentType, List args, SessionFactoryImplementor factory) throws QueryException {
        final int lastIndex = args.size() - 1;
        final Object last = args.remove(lastIndex);
        if (lastIndex == 0) {
            return last.toString();
        }
        final Object secondLast = args.get(lastIndex - 1);
        final String nvl = "nvl(" + secondLast + ", " + last + ")";
        args.set(lastIndex - 1, nvl);
        return render(argumentType, args, factory);
    }
}